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Raj S, Shree N, Ganesh KM. Effect of glass compression plate on EBT-XD film dosimetry for pretreatment quality assurance of stereotactic body radiotherapy. Rep Pract Oncol Radiother 2024; 29:357-361. [PMID: 39144269 PMCID: PMC11321779 DOI: 10.5603/rpor.101095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 05/31/2024] [Indexed: 08/16/2024] Open
Abstract
Background EBT-XD film specially designed for high dose verifications such as stereotactic treatments. The dose response of the film can be affected by several factors, the curly nature of the film being one of them. In this study this curly nature of the film was investigated for stereotactic body radiotherapy (SBRT) plan verifications. Materials and methods For this study, 18 SBRT (11 prostate, 3 spines, and 4 lungs) cases were enrolled. For all the cases, VMAT plans were created in the Monaco treatment planning system and plan was delivered in Elekta Versa HD linear accelerator and delivered fluence was captured by EBT-XD films. All films were scanned with and without a compression plate. All the films were analyzed using the single-channel film method using the red channel. Results A significant difference in the gamma passing rates (GPR) for the films scanned with and without the compression plate was observed. The maximum percentage differences in GPR between using and not using a compression plate were 12.7% for 1% 1 mm, 8.1% for 2% 2 mm, 7.5% for 3% 2 mm, and 5% for 3% 3mm criteria. Similarly, the mean %difference in GPR was 5.8% for 1% 1 mm, 2.4% for 2% 2 mm, 1.6% for 3% 2 mm and 0.96% for 3% 3 mm criteria. Conclusion The results suggest that placing a compression plate over the film during scanning provided a great advantage in achieving a more accurate gamma passing rate irrespective of gamma criteria.
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Affiliation(s)
- Sathiya Raj
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India
| | - Nithya Shree
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India
| | - K M Ganesh
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India
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Palmiero A, Liu K, Colnot J, Chopra N, Neill D, Connell L, Velasquez B, Koong AC, Lin SH, Balter P, Tailor R, Robert C, Germond JF, Jorge PG, Geyer R, Beddar S, Moeckli R, Schüler E. On the acceptance, commissioning, and quality assurance of electron FLASH units. ARXIV 2024:arXiv:2405.15146v1. [PMID: 38827455 PMCID: PMC11142322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Background & Purpose FLASH or ultra-high dose rate (UHDR) radiation therapy (RT) has gained attention in recent years for its ability to spare normal tissues relative to conventional dose rate (CDR) RT in various preclinical trials. However, clinical implementation of this promising treatment option has been limited because of the lack of availability of accelerators capable of delivering UHDR RT. Commercial options are finally reaching the market that produce electron beams with average dose rates of up to 1000 Gy/s. We established a framework for the acceptance, commissioning, and periodic quality assurance (QA) of electron FLASH units and present an example of commissioning. Methods A protocol for acceptance, commissioning, and QA of UHDR linear accelerators was established by combining and adapting standards and professional recommendations for standard linear accelerators based on the experience with UHDR at four clinical centers that use different UHDR devices. Non-standard dosimetric beam parameters considered included pulse width, pulse repetition frequency, dose per pulse, and instantaneous dose rate, together with recommendations on how to acquire these measurements. Results The 6- and 9-MeV beams of an UHDR electron device were commissioned by using this developed protocol. Measurements were acquired with a combination of ion chambers, beam current transformers (BCTs), and dose-rate-independent passive dosimeters. The unit was calibrated according to the concept of redundant dosimetry using a reference setup. Conclusions This study provides detailed recommendations for the acceptance testing, commissioning, and routine QA of low-energy electron UHDR linear accelerators. The proposed framework is not limited to any specific unit, making it applicable to all existing eFLASH units in the market. Through practical insights and theoretical discourse, this document establishes a benchmark for the commissioning of UHDR devices for clinical use.
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Affiliation(s)
- Allison Palmiero
- Department of Radiation Oncology, James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, Ohio, USA
| | - Kevin Liu
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
| | - Julie Colnot
- INSERM U1030, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Nitish Chopra
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Denae Neill
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Luke Connell
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
| | - Brett Velasquez
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Albert C. Koong
- Division of Radiation Oncology, Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Steven H. Lin
- Division of Radiation Oncology, Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Peter Balter
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Ramesh Tailor
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Charlotte Robert
- INSERM U1030, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Jean-François Germond
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Rue du Grand-Pré-1, Lausanne CH-1007, Switzerland
| | - Patrik Gonçalves Jorge
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Rue du Grand-Pré-1, Lausanne CH-1007, Switzerland
| | - Reiner Geyer
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Rue du Grand-Pré-1, Lausanne CH-1007, Switzerland
| | - Sam Beddar
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
| | - Raphael Moeckli
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Rue du Grand-Pré-1, Lausanne CH-1007, Switzerland
| | - Emil Schüler
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
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Smyth L, Alves A, Collins K, Beveridge S. Gafchromic EBT3 film provides equivalent dosimetric performance to EBT-XD film for stereotactic radiosurgery dosimetry. Phys Eng Sci Med 2024:10.1007/s13246-024-01430-z. [PMID: 38739345 DOI: 10.1007/s13246-024-01430-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 04/18/2024] [Indexed: 05/14/2024]
Abstract
The accurate assessment of film results is highly dependent on the methodology and techniques used to process film. This study aims to compare the performance of EBT3 and EBT-XD film for SRS dosimetry using two different film processing methods. Experiments were performed in a solid water slab and an anthropomorphic head phantom. For each experiment, the net optical density of the film was calculated using two different methods; taking the background (initial) optical density from 1) an unirradiated film from the same film lot as the irradiated film (stock to stock (S-S) method), and 2) a scan of the same piece of film taken prior to irradiation (film to film (F-F) method). EBT3 and EBT-XD performed similarly across the suite of experiments when using the green channel only or with triple channel RGB dosimetry. The dosimetric performance of EBT-XD was improved across all colour channels by using an F-F method, particularly for the blue channel. In contrast, EBT3 performed similarly well regardless of the net optical density method used. Across 21 SRS treatment plans, the average per-pixel agreement between EBT3 and EBT-XD films, normalised to the 20 Gy prescription dose, was within 2% and 4% for the non-target (2-10 Gy) and target (> 10 Gy) regions, respectively, when using the F-F method. At doses relevant to SRS, EBT3 provides comparable dosimetric performance to EBT-XD. In addition, an S-S dosimetry method is suitable for EBT3 while an F-F method should be adopted if using EBT-XD.
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Affiliation(s)
- Lloyd Smyth
- Australian Radiation Protection And Nuclear Safety Agency, Australian Clinical Dosimetry Service, Yallambie, VIC, Australia
| | - Andrew Alves
- Australian Radiation Protection And Nuclear Safety Agency, Australian Clinical Dosimetry Service, Yallambie, VIC, Australia
| | - Katherine Collins
- Australian Radiation Protection And Nuclear Safety Agency, Australian Clinical Dosimetry Service, Yallambie, VIC, Australia
| | - Sabeena Beveridge
- Australian Radiation Protection And Nuclear Safety Agency, Australian Clinical Dosimetry Service, Yallambie, VIC, Australia.
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Hill MA, Staut N, Thompson JM, Verhaegen F. Dosimetric validation of SmART-RAD Monte Carlo modelling for x-ray cabinet radiobiology irradiators. Phys Med Biol 2024; 69:095014. [PMID: 38518380 PMCID: PMC11031639 DOI: 10.1088/1361-6560/ad3720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 02/23/2024] [Accepted: 03/22/2024] [Indexed: 03/24/2024]
Abstract
Objective. Accuracy and reproducibility in the measurement of radiation dose and associated reporting are critically important for the validity of basic and preclinical radiobiological studies performed with kilovolt x-ray radiation cabinets. This is essential to enable results of radiobiological studies to be repeated, as well as enable valid comparisons between laboratories. In addition, the commonly used single point dose value hides the 3D dose heterogeneity across the irradiated sample. This is particularly true for preclinical rodent models, and is generally difficult to measure directly. Radiation transport simulations integrated in an easy to use application could help researchers improve quality of dosimetry and reporting.Approach. This paper describes the use and dosimetric validation of a newly-developed Monte Carlo (MC) tool, SmART-RAD, to simulate the x-ray field in a range of standard commercial x-ray cabinet irradiators used for preclinical irradiations. Comparisons are made between simulated and experimentally determined dose distributions for a range of configurations to assess the potential use of this tool in determining dose distributions through samples, based on more readily available air-kerma calibration point measurements.Main results. Simulations gave very good dosimetric agreement with measured depth dose distributions in phantoms containing both water and bone equivalent materials. Good spatial and dosimetric agreement between simulated and measured dose distributions was obtained when using beam-shaping shielding.Significance. The MC simulations provided by SmART-RAD provide a useful tool to go from a limited number of dosimetry measurements to detailed 3D dose distributions through a non-homogeneous irradiated sample. This is particularly important when trying to determine the dose distribution in more complex geometries. The use of such a tool can improve reproducibility and dosimetry reporting in preclinical radiobiological research.
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Affiliation(s)
- Mark A Hill
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, ORCRB Roosevelt Drive, Oxford OX3 7DQ, United Kingdom
| | - Nick Staut
- SmART Scientific Solutions BV, Maastricht, The Netherlands
| | - James M Thompson
- MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, ORCRB Roosevelt Drive, Oxford OX3 7DQ, United Kingdom
| | - Frank Verhaegen
- SmART Scientific Solutions BV, Maastricht, The Netherlands
- Department of Radiation Oncology (Maastro), Research Institute for Oncology & Reproduction, Maastricht University Medical Centre+, Maastricht, The Netherlands
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Uijtewaal P, Borman P, Cote B, LeChasseur Y, Therriault-Proulx F, Flores R, Smith S, Koenig G, Raaymakers B, Fast M. Performance characterization of a novel hybrid dosimetry insert for simultaneous spatial, temporal, and motion-included dosimetry for MR-linac. Med Phys 2024; 51:2983-2997. [PMID: 38088939 DOI: 10.1002/mp.16870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 11/13/2023] [Accepted: 11/17/2023] [Indexed: 04/05/2024] Open
Abstract
BACKGROUND Several (online) adaptive radiotherapy procedures are available to maximize healthy tissue sparing in the presence of inter/intrafractional motion during stereotactic body radiotherapy (SBRT) on an MR-linac. The increased treatment complexity and the motion-delivery interplay during these treatments require MR-compatible motion phantoms with time-resolved dosimeters to validate end-to-end workflows. This is not possible with currently available phantoms. PURPOSE Here, we demonstrate a new commercial hybrid film-scintillator cassette, combining high spatial resolution radiochromic film with four time-resolved plastic scintillator dosimeters (PSDs) in an MRI-compatible motion phantom. METHODS First, the PSD's performance for consistency, dose linearity, and pulse repetition frequency (PRF) dependence was evaluated using an RW3 solid water slab phantom. We then demonstrated the MRI4D scintillator cassette's suitability for time-resolved and motion-included quality assurance for adapt-to-shape (ATS), trailing, gating, and multileaf collimator (MLC) tracking adaptations on a 1.5 T MR-linac. To do this, the cassette was inserted into the Quasar MRI4D phantom, which we used statically or programmed with artificial and patient-derived motion. Simultaneously with dose measurements, the beam-gating latency was estimated from the time difference between the target entering/leaving the gating window and the beam-on/off times derived from the time-resolved dose measurements. RESULTS Experiments revealed excellent detector consistency (standard deviation ≤ $\le$ 0.6%), dose linearity (R2 = 1), and only very low PRF dependence ( ≤ $\le$ 0.4%). The dosimetry cassette demonstrated a near-perfect agreement during an ATS workflow between the time-resolved PSD and treatment planning system (TPS) dose (0%-2%). The high spatial resolution film measurements confirmed this with a 1%/1-mm local gamma pass-rate of 90%. When trailing patient-derived prostate motion for a prostate SBRT delivery, the time-resolved cassette measurements demonstrated how trailing mitigated the motion-induced dose reductions from 1%-17% to 1%-2% compared to TPS dose. The cassette's simultaneously measured spatial dose distribution highlighted the dosimetric gain of trailing by improving the 3%/3-mm local gamma pass-rates from 80% to 97% compared to the static dose. Similarly, the cassette demonstrated the benefit of real-time adaptations when compensating patient-derived respiratory motion by showing how the TPS dose was restored from 2%-56% to 0%-12% (gating) and 1%-26% to 1%-7% (MLC tracking) differences. Larger differences are explainable by TPS-PSD coregistration uncertainty combined with a steep dose gradient outside the PTV. The cassette also demonstrated how the spatial dose distributions were drastically improved by the real-time adaptations with 1%/1-mm local gamma pass-rates that were increased from 8 to 79% (gating) and from 35 to 89% (MLC tracking). The cassette-determined beam-gating latency agreed within ≤ $\le$ 12 ms with the ground truth latency measurement. Film and PSD dose agreed well for most cases (differences relative to TPS dose < $<$ 4%), while film-PSD coregistration uncertainty caused relative differences of 5%-8%. CONCLUSIONS This study demonstrates the excellent suitability of a new commercial hybrid film-scintillator cassette for simultaneous spatial, temporal, and motion-included dosimetry.
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Affiliation(s)
- Prescilla Uijtewaal
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Pim Borman
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | | | | | | | | | | | | | - Martin Fast
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
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Liu K, Velasquez B, Schüler E. Technical note: High-dose and ultra-high dose rate (UHDR) evaluation of Al 2 O 3 :C optically stimulated luminescent dosimeter nanoDots and powdered LiF:Mg,Ti thermoluminescent dosimeters for radiation therapy applications. Med Phys 2024; 51:2311-2319. [PMID: 37991111 PMCID: PMC10939935 DOI: 10.1002/mp.16832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 09/11/2023] [Accepted: 10/25/2023] [Indexed: 11/23/2023] Open
Abstract
BACKGROUND Dosimetry in ultra-high dose rate (UHDR) electron beamlines poses a significant challenge owing to the limited usability of standard dosimeters in high dose and high dose-per-pulse (DPP) applications. PURPOSE In this study, Al2 O3 :C nanoDot optically stimulated luminescent dosimeters (OSLDs), single-use powder-based LiF:Mg,Ti thermoluminescent dosimeters (TLDs), and Gafchromic EBT3 film were evaluated at extended dose ranges (up to 40 Gy) in conventional dose rate (CONV) and UHDR beamlines to determine their usability for calibration and dose verification in the setting of FLASH radiation therapy. METHODS OSLDs and TLDs were evaluated against established dose-rate-independent Gafchromic EBT3 film with regard to the potential influence of mean dose rate, instantaneous dose rate, and DPP on signal response. The dosimeters were irradiated at CONV or UHDR conditions on a 9-MeV electron beam. Under UHDR conditions, different settings of pulse repetition frequency (PRF), pulse width (PW), and pulse amplitude were used to characterize the individual dosimeters' response in order to isolate their potential dependencies on dose, dose rate, and DPP. RESULTS The OSLDs, TLDs, and Gafchromic EBT3 film were found to be suitable at a dose range of up to 40 Gy without any indication of saturation in signal. The response of OSLDs and TLDs in UHDR conditions were found to be independent of mean dose rate (up to 1440 Gy/s), instantaneous dose rate (up to 2 MGy/s), and DPP (up to 7 Gy), with uncertainties on par with nominal values established in CONV beamlines (± 4%). In cross-comparing the response of OSLDs, TLDs and Gafchromic film at dose rates of 0.18-245 Gy/s, the coefficient of variation or relative standard deviation in the measured dose between the three dosimeters (inter-dosimeter comparison) was found to be within 2%. CONCLUSIONS We demonstrated the dynamic range of OSLDs, TLDs, and Gafchromic film to be suitable up to 40 Gy, and we developed a protocol that can be used to accurately translate the measured signal in each respective dosimeter to dose. OSLDs and powdered TLDs were shown to be viable for dosimetric measurement in UHDR beamlines, providing dose measurements with accuracies on par with Gafchromic EBT3 film and their concurrent use demonstrating a means for redundant dosimetry in UHDR conditions.
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Affiliation(s)
- Kevin Liu
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- The University of Texas MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences, Houston, Texas, USA
| | - Brett Velasquez
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Emil Schüler
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- The University of Texas MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences, Houston, Texas, USA
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Mittauer KE, Tolakanahalli R, Kotecha R, Chuong MD, Mehta MP, Gutierrez AN, Bassiri N. Commissioning Intracranial Stereotactic Radiosurgery for a Magnetic Resonance-Guided Radiation Therapy (MRgRT) System: MR-RT Localization and Dosimetric End-to-End Validation. Int J Radiat Oncol Biol Phys 2024; 118:512-524. [PMID: 37793574 DOI: 10.1016/j.ijrobp.2023.08.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 08/04/2023] [Accepted: 08/13/2023] [Indexed: 10/06/2023]
Abstract
PURPOSE This is the first reporting of the MRIdian A3iTM intracranial package (BrainTxTM) and benchmarks the end-to-end localization and dosimetric accuracy for commissioning an magnetic resonace (MR)-guided stereotactic radiosurgery program. We characterized the localization accuracy between MR and radiation (RT) isocenter through an end-to-end hidden target test, relative dose profile intercomparison, and absolute dose validation. METHODS AND MATERIALS BrainTx consists of a dedicated head coil, integrated mask immobilization system, and high-resolution MR sequences. Coil and baseplate attenuation was quantified. An in-house phantom (Cranial phantOm foR magNetic rEsonance Localization of a stereotactIc radiosUrgery doSimeter, CORNELIUS) was developed from a mannequin head filled with silicone gel, film, and MR BB with pinprick. A hidden target test evaluated MR-RT localization of the 1×1×1 mm3 TrueFISP MR and relative dose accuracy in film for a 1 cm diameter (International Electrotechnical Commission (IEC)-X/IEC-Y) and 1.5 cm diameter (IEC-Y/IEC-Z) spherical target. Two clinical cases (irregular-shaped target and target abutting brainstem) were mapped to the CORNELIUS phantom for feasibility assessment. A 2-dimensional (2D)-gamma compared calculated and measured dose for spherical and clinical targets with 1 mm/1% and 2 mm/2% criteria, respectively. A small-field chamber (A26MR) measured end-to-end absolute dose for a 1 cm diameter target. RESULTS Coil and baseplate attenuation were 0.7% and 2.7%, respectively. The displacement of MR to RT localization as defined through the pinprick was 0.49 mm (IEC-X), 0.27 mm (IEC-Y), and 0.51 mm (IEC-Z) (root mean square 0.76 mm). The reproducibility across IEC-Y demonstrated high fidelity (<0.02 mm). Gamma pass rates were 97.1% and 95.4% for 1 cm and 1.5 cm targets, respectively. Dose profiles for an irregular-shaped target and abutting organ-at-risk-target demonstrated pass rates of 99.0% and 92.9%, respectively. The absolute end-to-end dose difference was <1%. CONCLUSIONS All localization and dosimetric evaluation demonstrated submillimeter accuracy, per the TG-142, TG-101, MPPG 9.a. criteria for SRS/SRT systems, indicating acceptable delivery capabilities with a 1 mm setup margin.
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Affiliation(s)
- Kathryn E Mittauer
- Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, Florida; Herbert Wertheim College of Medicine, Florida International University, Miami, Florida.
| | - Ranjini Tolakanahalli
- Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, Florida; Herbert Wertheim College of Medicine, Florida International University, Miami, Florida
| | - Rupesh Kotecha
- Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, Florida; Herbert Wertheim College of Medicine, Florida International University, Miami, Florida
| | - Michael D Chuong
- Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, Florida; Herbert Wertheim College of Medicine, Florida International University, Miami, Florida
| | - Minesh P Mehta
- Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, Florida; Herbert Wertheim College of Medicine, Florida International University, Miami, Florida
| | - Alonso N Gutierrez
- Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, Florida; Herbert Wertheim College of Medicine, Florida International University, Miami, Florida
| | - Nema Bassiri
- Department of Radiation Oncology, Miami Cancer Institute, Baptist Health South Florida, Miami, Florida; Herbert Wertheim College of Medicine, Florida International University, Miami, Florida
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8
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Byrne KE, Poirier Y, Xu J, Gerry A, Foley MJ, Jackson IL, Sawant A, Jiang K. Technical note: A small animal irradiation platform for investigating the dependence of the FLASH effect on electron beam parameters. Med Phys 2024; 51:1421-1432. [PMID: 38207016 DOI: 10.1002/mp.16909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 10/30/2023] [Accepted: 12/12/2023] [Indexed: 01/13/2024] Open
Abstract
BACKGROUND The recent rediscovery of the FLASH effect, a normal tissue sparing phenomenon observed in ultra-high dose rate (UHDR) irradiations, has instigated a surge of research endeavors aiming to close the gap between experimental observation and clinical treatment. However, the dependences of the FLASH effect and its underpinning mechanisms on beam parameters are not well known, and large-scale in vivo studies using murine models of human cancer are needed for these investigations. PURPOSE To commission a high-throughput, variable dose rate platform providing uniform electron fields (≥15 cm diameter) at conventional (CONV) and UHDRs for in vivo investigations of the FLASH effect and its dependences on pulsed electron beam parameters. METHODS A murine whole-thoracic lung irradiation (WTLI) platform was constructed using a 1.3 cm thick Cerrobend collimator forming a 15 × 1.6 cm2 slit. Control of dose and dose rate were realized by adjusting the number of monitor units and couch vertical position, respectively. Achievable doses and dose rates were investigated using Gafchromic EBT-XD film at 1 cm depth in solid water and lung-density phantoms. Percent depth dose (PDD) and dose profiles at CONV and various UHDRs were also measured at depths from 0 to 2 cm. A radiation survey was performed to assess radioactivation of the Cerrobend collimator by the UHDR electron beam in comparison to a precision-machined copper alternative. RESULTS This platform allows for the simultaneous thoracic irradiation of at least three mice. A linear relationship between dose and number of monitor units at a given UHDR was established to guide the selection of dose, and an inverse-square relationship between dose rate and source distance was established to guide the selection of dose rate between 20 and 120 Gy·s-1 . At depths of 0.5 to 1.5 cm, the depth range relevant to murine lung irradiation, measured PDDs varied within ±1.5%. Similar lateral dose profiles were observed at CONV and UHDRs with the dose penumbrae widening from 0.3 mm at 0 cm depth to 5.1 mm at 2.0 cm. The presence of lung-density plastic slabs had minimal effect on dose distributions as compared to measurements made with only solid water slabs. Instantaneous dose rate measurements of the activated copper collimator were up to two orders of magnitude higher than that of the Cerrobend collimator. CONCLUSIONS A high-throughput, variable dose rate platform has been developed and commissioned for murine WTLI electron FLASH radiotherapy. The wide field of our UHDR-enabled linac allows for the simultaneous WTLI of at least three mice, and for the average dose rate to be modified by changing the source distance, without affecting dose distribution. The platform exhibits uniform, and comparable dose distributions at CONV and UHDRs up to 120 Gy·s-1 , owing to matched and flattened 16 MeV CONV and UHDR electron beams. Considering radioactivation and exposure to staff, Cerrobend collimators are recommended above copper alternatives for electron FLASH research. This platform enables high-throughput animal irradiation, which is preferred for experiments using a large number of animals, which are required to effectively determine UHDR treatment efficacies.
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Affiliation(s)
- Kevin E Byrne
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
- Department of Physics, School of Natural Sciences, University of Galway, Galway, Ireland
| | - Yannick Poirier
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Junliang Xu
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Andrew Gerry
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Mark J Foley
- Department of Physics, School of Natural Sciences, University of Galway, Galway, Ireland
| | - Isabel Lauren Jackson
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Kai Jiang
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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9
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Esplen N, Egoriti L, Planche T, Rädel S, Koay HW, Humphries B, Ren X, Ford N, Hoehr C, Gottberg A, Bazalova-Carter M. Dosimetric characterization of a novel UHDR megavoltage X-ray source for FLASH radiobiological experiments. Sci Rep 2024; 14:822. [PMID: 38191885 PMCID: PMC10774358 DOI: 10.1038/s41598-023-50412-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Accepted: 12/19/2023] [Indexed: 01/10/2024] Open
Abstract
A first irradiation platform capable of delivering 10 MV X-ray beams at ultra-high dose rates (UHDR) has been developed and characterized for FLASH radiobiological research at TRIUMF. Delivery of both UHDR (FLASH mode) and low dose-rate conventional (CONV mode) irradiations was demonstrated using a common source and experimental setup. Dose rates were calculated using film dosimetry and a non-intercepting beam monitoring device; mean values for a 100 μA pulse (peak) current were nominally 82.6 and 4.40 × 10-2 Gy/s for UHDR and CONV modes, respectively. The field size for which > 40 Gy/s could be achieved exceeded 1 cm down to a depth of 4.1 cm, suitable for total lung irradiations in mouse models. The calculated delivery metrics were used to inform subsequent pre-clinical treatments. Four groups of 6 healthy male C57Bl/6J mice were treated using thoracic irradiations to target doses of either 15 or 30 Gy using both FLASH and CONV modes. Administration of UHDR X-ray irradiation to healthy mouse models was demonstrated for the first time at the clinically-relevant beam energy of 10 MV.
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Affiliation(s)
- Nolan Esplen
- Physics and Astronomy, University of Victoria, Victoria, V8P 5C2, Canada
| | - Luca Egoriti
- TRIUMF, Vancouver, V6T 2A3, Canada
- Chemistry, University of British Columbia, Vancouver, V6T 1Z1, Canada
| | | | | | | | | | - Xi Ren
- Physics and Astronomy, University of British Columbia, Vancouver, V6T 1Z1, Canada
| | - Nancy Ford
- Physics and Astronomy, University of British Columbia, Vancouver, V6T 1Z1, Canada
- Oral Biological and Medical Sciences, University of British Columbia, Vancouver, V6T 1Z1, Canada
| | - Cornelia Hoehr
- Physics and Astronomy, University of Victoria, Victoria, V8P 5C2, Canada
- TRIUMF, Vancouver, V6T 2A3, Canada
| | - Alexander Gottberg
- Physics and Astronomy, University of Victoria, Victoria, V8P 5C2, Canada
- TRIUMF, Vancouver, V6T 2A3, Canada
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Tang C, Yuan J, Guo H, Dai Z, Liu B, Xi H, He J, Niu S. Quantify the Effect of Air Gap Errors on Skin Dose for Breast Cancer Radiotherapy. Technol Cancer Res Treat 2024; 23:15330338241258566. [PMID: 38803305 PMCID: PMC11135118 DOI: 10.1177/15330338241258566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024] Open
Abstract
Purpose: Determining the impact of air gap errors on the skin dose in postoperative breast cancer radiotherapy under dynamic intensity-modulated radiation therapy (IMRT) techniques. Methods: This was a retrospective study that involved 55 patients who underwent postoperative radiotherapy following modified radical mastectomy. All plans employed tangential IMRT, with a prescription dose of 50 Gy, and bolus added solely to the chest wall. Simulated air gap depth errors of 2 mm, 3 mm, and 5 mm were introduced at depression or inframammary fold areas on the skin, resulting in the creation of air gaps named Air2, Air3, and Air5. Utilizing a multivariable GEE, the average dose (Dmean) of the local skin was determined to evaluate its relationship with air gap volume and the lateral beam's average angle (AALB). Additionally, an analysis was conducted on the impact of gaps on local skin. Results: When simulating an air gap depth error of 2 mm, the average Dmean in plan2 increased by 0.46 Gy compared to the initial plan (planO) (p < .001). For the 3-mm air gap, the average Dmean of plan3 was 0.51 Gy higher than that of planO (p < .001). When simulating the air gap as 5 mm, the average Dmean of plan5 significantly increased by 0.59 Gy compared to planO (p < .001). The TCP results showed a similar trend to those of Dmean. As the depth of air gap error increases, NTCP values also gradually rise. The linear regression of the multivariable GEE equation indicates that the volume of air gaps and the AALB are strong predictors of Dmean. Conclusion: With small irregular air gap errors simulated in 55 patients, the values of skin's Dmean, TCP, and NTCP increased. A multivariable linear GEE regression model may effectively explain the impact of air gap volume and AALB on the local skin.
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Affiliation(s)
- Chunbo Tang
- Department of Radiation Oncology, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
- Jiangxi Clinical Research Center for Cancer, Ganzhou, China
| | - Jun Yuan
- Department of Radiation Oncology, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
- Jiangxi Clinical Research Center for Cancer, Ganzhou, China
| | - Hailiang Guo
- Department of Radiation Oncology, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
- Jiangxi Clinical Research Center for Cancer, Ganzhou, China
| | - Zhongyang Dai
- Department of Radiation Oncology, First Affiliated Hospital of Gannan Medical University, Ganzhou, China
- Jiangxi Clinical Research Center for Cancer, Ganzhou, China
| | - Biaoshui Liu
- Department of Radiation Oncology, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Haiyan Xi
- Department of Radiation Oncology, Nanchang People's Hospital, Nanchang, China
| | - Ji He
- School of Biomedical Engineering, Fourth Affiliated Hospital of Guangzhou, Guangzhou Medical University, Guangzhou, China
| | - Shanzhou Niu
- School of Mathematics and Computer Science / Ganzhou Key Laboratory of Computational Imaging, Gannan Normal University, Ganzhou, China
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Lin YF, Hsieh CH, Tien HJ, Lee YH, Chen YC, Lai LH, Hsu SM, Shueng PW. Evaluation of cutout factors with small and narrow fields using various dosimetry detectors in electron beam keloid radiotherapy. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2024; 32:1177-1184. [PMID: 38905079 DOI: 10.3233/xst-240059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/23/2024]
Abstract
BACKGROUND The inherent problems in the existence of electron equilibrium and steep dose fall-off pose difficulties for small- and narrow-field dosimetry. OBJECTIVE To investigate the cutout factors for keloid electron radiotherapy using various dosimetry detectors for small and narrow fields. METHOD The measurements were performed in a solid water phantom with nine different cutout shapes. Five dosimetry detectors were used in the study: pinpoint 3D ionization chamber, Farmer chamber, semiflex chamber, Classic Markus parallel plate chamber, and EBT3 film. RESULTS The results demonstrated good agreement between the semiflex and pinpoint chambers. Furthermore, there was no difference between the Farmer and pinpoint chambers for large cutouts. For the EBT3 film, half of the cases had differences greater than 1%, and the maximum discrepancy compared with the reference chamber was greater than 2% for the narrow field. CONCLUSION The parallel plate, semiflex chamber and EBT3 film are suitable dosimeters that are comparable with pinpoint 3D chambers in small and narrow electron fields. Notably, a semiflex chamber could be an alternative option to a pinpoint 3D chamber for cutout widths≥3 cm. It is very important to perform patient-specific cutout factor calibration with an appropriate dosimeter for keloid radiotherapy.
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Affiliation(s)
- Yu-Fang Lin
- Department of Radiology, Division of Radiation Oncology, Far Eastern Memorial Hospital, New Taipei City, Taiwan
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Chen-Hsi Hsieh
- Department of Radiology, Division of Radiation Oncology, Far Eastern Memorial Hospital, New Taipei City, Taiwan
- School of Medicine, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Institute of Traditional Medicine, School of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
- School of Nursing, Yuan Ze University, Taoyuan, Taiwan
| | - Hui-Ju Tien
- Department of Radiology, Division of Radiation Oncology, Far Eastern Memorial Hospital, New Taipei City, Taiwan
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yi-Huan Lee
- Department of Radiology, Division of Radiation Oncology, Far Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Yi-Chun Chen
- Department of Radiology, Division of Radiation Oncology, Far Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Lu-Han Lai
- Department of Medical Imaging and Radiological Technology, Yuanpei University of Medical Technology, Hsinchu, Taiwan
| | - Shih-Ming Hsu
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Pei-Wei Shueng
- Department of Radiology, Division of Radiation Oncology, Far Eastern Memorial Hospital, New Taipei City, Taiwan
- School of Medicine, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
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12
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Liu K, Jorge PG, Tailor R, Moeckli R, Schüler E. Comprehensive evaluation and new recommendations in the use of Gafchromic EBT3 film. Med Phys 2023; 50:7252-7262. [PMID: 37403570 PMCID: PMC10766858 DOI: 10.1002/mp.16593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 06/06/2023] [Accepted: 06/11/2023] [Indexed: 07/06/2023] Open
Abstract
BACKGROUND Gafchromic film's unique properties of tissue-equivalence, dose-rate independence, and high spatial resolution make it an attractive choice for many dosimetric applications. However, complicated calibration processes and film handling limits its routine use. PURPOSE We evaluated the performance of Gafchromic EBT3 film after irradiation under a variety of measurement conditions to identify aspects of film handling and analysis for simplified but robust film dosimetry. METHODS The short- (from 5 min to 100 h) and long-term (months) film response was evaluated for clinically relevant doses of up to 50 Gy for accuracy in dose determination and relative dose distributions. The dependence of film response on film-read delay, film batch, scanner type, and beam energy was determined. RESULTS Scanning the film within a 4-h window and using a standard 24-h calibration curve introduced a maximum error of 2% over a dose range of 1-40 Gy, with lower doses showing higher uncertainty in dose determination. Relative dose measurements demonstrated <1 mm difference in electron beam parameters such as depth of 50% of the maximum dose value (R50 ), independent of when the film was scanned after irradiation or the type of calibration curve used (batch-specific or time-specific calibration curve) if the same default scanner was used. Analysis of films exposed over a 5-year period showed that using the red channel led to the lowest variation in the measured net optical density values for different film batches, with doses >10 Gy having the lowest coefficient of variation (<1.7%). Using scanners of similar design produced netOD values within 3% after exposure to doses of 1-40 Gy. CONCLUSIONS This is the first comprehensive evaluation of the temporal and batch dependence of Gafchromic EBT3 film evaluated on consolidated data over 8 years. The relative dosimetric measurements were insensitive to the type of calibration applied (batch- or time-specific) and in-depth time-dependent dosimetric signal behaviors can be established for film scanned outside of the recommended 16-24 h post-irradiation window. We generated guidelines based on our findings to simplify film handling and analysis and provide tabulated dose- and time-dependent correction factors to achieve this without reducing the accuracy of dose determination.
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Affiliation(s)
- Kevin Liu
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
| | - Patrik Gonçalves Jorge
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Ramesh Tailor
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
| | - Raphaël Moeckli
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Emil Schüler
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
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13
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Ashraf MR, Krimmer J, Zalavri L, Gu X, Wang L, Chuang CF. Angular correction methodology and characterization of a high-resolution CMOS array for patient specific quality assurance on a robotic arm linac. J Appl Clin Med Phys 2023; 24:e14110. [PMID: 37528747 PMCID: PMC10647992 DOI: 10.1002/acm2.14110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 07/02/2023] [Accepted: 07/14/2023] [Indexed: 08/03/2023] Open
Abstract
PURPOSE To develop an angular correction methodology and characterize a high-resolution complementary metal-oxide-semiconductor (CMOS) array for patient specific quality assurance on a robotic arm linear accelerator. METHODS Beam path files from the treatment planning software (TPS) were used to calculate the angle of radiation beam with respect to the detector plane. Beams from multiple discrete angles were delivered to the CMOS detector array and an angular dependency look up table (LUT) was created. The LUT was then used to correct for the angular dependency of the detector. An iso-centric 5 mm fixed cone, non iso-centric multi-target fixed cone, 10 mm Iris and a multi-leaf collimator (MLC) based collimated plan were delivered to the phantom and compared to the TPS with and without angular correction applied. Additionally, the CMOS array was compared to gafchromic film and a diode array. RESULTS Large errors of up to 30% were observed for oblique angles. When angular correction was applied, the gamma passing rate increased from 99.2% to 100% (average gamma value decreased from 0.29 to 0.14) for the 5-mm iso-centric cone plan. Similarly, the passing rate increased from 84.0% to 100% for the Iris plan and from 49.98% to 98.4% for the MLC plan when angular correction was applied. For the multi-target plan, applying angular correction improved the gamma passing rate from 94% to 99.6%. The 5 mm iso-centric fixed cone plan was also delivered to film, and the gamma passing rate was 91.3% when using gafchromic film as the reference dataset, whereas the diode array provided insufficient sampling for this plan. CONCLUSION A methodology of calculating the beam angle based on the beam path files was developed and validated. The array was demonstrated to be superior to other quality assurance tools because of its sub-millimeter spatial resolution and immediate read out of the results.
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Affiliation(s)
| | | | - Laszlo Zalavri
- Department of Radiation OncologyStanford UniversityPalo AltoCaliforniaUSA
| | - Xuejun Gu
- Department of Radiation OncologyStanford UniversityPalo AltoCaliforniaUSA
| | - Lei Wang
- Department of Radiation OncologyStanford UniversityPalo AltoCaliforniaUSA
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14
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Ogawa S, Yasui K, Hayashi N, Saito Y, Hayashi S. Impact of Dose Perturbations Around Brachytherapy Seeds in External-Beam Radiotherapy Planning: A Fundamental and Clinical Validation Using Treatment Planning System-Based Monte Carlo Simulations. Cureus 2023; 15:e48041. [PMID: 38046495 PMCID: PMC10689119 DOI: 10.7759/cureus.48041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2023] [Indexed: 12/05/2023] Open
Abstract
Background This study evaluates dose perturbations caused by nonradioactive seeds in clinical cases by employing treatment planning system-based Monte Carlo (TPS-MC) simulation. Methodology We investigated dose perturbation using a water-equivalent phantom and 20 clinical cases of prostate cancer (10 cases with seeds and 10 cases without seeds) treated at Fujita Health University Hospital, Japan. First, dose calculations for a simple geometry were performed using the RayStation MC algorithm for a water-equivalent phantom with and without a seed. TPS-independent Monte Carlo (full-MC) simulations and film measurements were conducted to verify the accuracy of TPS-MC simulation. Subsequently, dose calculations using TPS-MC were performed on CT images of clinical cases of prostate cancer with and without seeds, and the dose distributions were compared. Results In clinical cases, dose calculations using MC simulations revealed hotspots around the seeds. However, the size of the hotspot was not correlated with the number of seeds. The maximum difference in dose perturbation between TPS-MC simulations and film measurements was 3.9%, whereas that between TPS-MC simulations and full-MC simulations was 3.7%. The dose error of TPS-MC was negligible for multiple beams or rotational irradiation. Conclusions Hotspots were observed in dose calculations using TPS-MC performed on CT images of clinical cases with seeds. The dose calculation accuracy around the seeds using TPS-MC simulations was comparable to that of film measurements and full-MC simulations, with differences within 3.9%. Although the clinical impact of hotspots occurring around the seeds is minimal, utilizing MC simulations on TPSs can be beneficial to verify their presence.
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Affiliation(s)
- Shuta Ogawa
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, JPN
- Department of Radiation Physics and Technology, Southern Tohoku Proton Therapy Center, Koriyama, JPN
| | - Keisuke Yasui
- School of Medical Sciences, Fujita Health University, Toyoake, JPN
| | - Naoki Hayashi
- School of Medical Sciences, Fujita Health University, Toyoake, JPN
| | - Yasunori Saito
- Division of Radiology, Fujita Health University Hospital, Toyoake, JPN
- School of Medical Sciences, Fujita Health University, Toyoake, JPN
| | - Shinya Hayashi
- Department of Radiation Oncology, Fujita Health University School of Medicine, Toyoake, JPN
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15
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Vanreusel V, Gasparini A, Galante F, Mariani G, Pacitti M, Colijn A, Reniers B, Yalvac B, Vandenbroucke D, Peeters M, Leblans P, Felici G, Verellen D, de Freitas Nascimento L. Optically stimulated luminescence system as an alternative for radiochromic film for 2D reference dosimetry in UHDR electron beams. Phys Med 2023; 114:103147. [PMID: 37804712 DOI: 10.1016/j.ejmp.2023.103147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 08/18/2023] [Accepted: 09/21/2023] [Indexed: 10/09/2023] Open
Abstract
Radiotherapy is part of the treatment of over 50% of cancer patients. Its efficacy is limited by the radiotoxicity to the healthy tissue. FLASH-RT is based on the biological effect that ultra-high dose rates (UHDR) and very short treatment times strongly reduce normal tissue toxicity, while preserving the anti-tumoral effect. Despite many positive preclinical results, the translation of FLASH-RT to the clinic is hampered by the lack of accurate dosimetry for UHDR beams. To date radiochromic film is commonly used for dose assessment but has the drawback of lengthy and cumbersome read out procedures. In this work, we investigate the equivalence of a 2D OSL system to radiochromic film dosimetry in terms of dose rate independency. The comparison of both systems was done using the ElectronFlash linac. We investigated the dose rate dependence by variation of the (1) modality, (2) pulse repetition frequency, (3) pulse length and (4) source to surface distance. Additionally, we compared the 2D characteristics by field size measurements. The OSL calibration showed transferable between conventional and UHDR modality. Both systems are equally independent of average dose rate, pulse length and instantaneous dose rate. The OSL system showed equivalent in field size determination within 3 sigma. We show the promising nature of the 2D OSL system to serve as alternative for radiochromic film in UHDR electron beams. However, more in depth characterization is needed to assess its full potential.
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Affiliation(s)
- Verdi Vanreusel
- Research in Dosimetric Applications, SCK CEN, Boeretang 200, 2400 Mol, Belgium; CORE, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium; Iridium Netwerk, Oosterveldlaan 22, 2610 Wilrijk, Belgium.
| | - Alessia Gasparini
- CORE, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium; Iridium Netwerk, Oosterveldlaan 22, 2610 Wilrijk, Belgium
| | - Federica Galante
- Sordina IORT Technologies S.p.A., Via dell'Industria, 1/A, 04011 Aprilia, Latina, Italy
| | - Giulia Mariani
- Sordina IORT Technologies S.p.A., Via dell'Industria, 1/A, 04011 Aprilia, Latina, Italy
| | - Matteo Pacitti
- Sordina IORT Technologies S.p.A., Via dell'Industria, 1/A, 04011 Aprilia, Latina, Italy
| | - Arnaud Colijn
- CORE, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - Brigitte Reniers
- NuTeC, CMK, Hasselt University, Wetenschapspark 27, 3590 Diepenbeek, Belgium
| | - Burak Yalvac
- NuTeC, CMK, Hasselt University, Wetenschapspark 27, 3590 Diepenbeek, Belgium
| | | | | | - Paul Leblans
- Agfa N.V., Septestraat 27, 2640 Mortsel, Belgium
| | - Giuseppe Felici
- Sordina IORT Technologies S.p.A., Via dell'Industria, 1/A, 04011 Aprilia, Latina, Italy
| | - Dirk Verellen
- CORE, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium; Iridium Netwerk, Oosterveldlaan 22, 2610 Wilrijk, Belgium
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16
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Jung S, Kim B, Lee SY, Chang WI, Son J, Park JM, Choi CH, Lee JH, Wu HG, Kim JI, Kim JH. Novel tongue-positioning device to reduce tongue motions during radiation therapy for head and neck cancer: Geometric and dosimetric evaluation. PLoS One 2023; 18:e0291712. [PMID: 37733674 PMCID: PMC10513285 DOI: 10.1371/journal.pone.0291712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 09/04/2023] [Indexed: 09/23/2023] Open
Abstract
This study aimed to assess the performance of a tongue-positioning device in interfractional tongue position reproducibility by cone-beam computed tomography (CBCT). Fifty-two patients treated with radiation therapy (RT) while using a tongue positioning device were included in the study. All patients were treated with 28 or 30 fractions using the volumetric modulated arc therapy technique. CBCT images were acquired at the 1st, 7th, 11th, 15th, 19th, 23th, and 27th fractions. Tongues on planning computed tomography (pCT) and CBCT images were contoured in the treatment planning system. Geometric differences in the tongue between pCT and CBCT were assessed by the Dice similarity coefficient (DSC) and averaged Hausdorff distance (AHD). Two-dimensional in vivo measurements using radiochromic films were performed in 13 patients once a week during sessions. The planned dose distributions were compared with the measured dose distributions using gamma analysis with criteria of 3%/3 mm. In all patients, the mean DSC at the 1st fraction (pCT versus 1st CBCT) was 0.80 while the mean DSC at the 27th fraction (pCT versus 27th CBCT) was 0.77 with statistical significance (p-value = 0.015). There was no statistically significant difference in DSC between the 1st fraction and any other fraction, except for the 27th fraction. There was statistically significant difference in AHD between the 1st fraction and the 19th, 23th, and 27th fractions (p-value < 0.05). In vivo measurements showed an average gamma passing rate of 90.54%. There was no significant difference between measurements at the 1st week and those at other weeks. The tongue geometry during RT was compared between pCT and CBCT. In conclusion, the novel tongue-positioning device was found to minimize interfractional variations in position and shape of the tongue.
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Affiliation(s)
- Seongmoon Jung
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Nuclear Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Bitbyeol Kim
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Sung Young Lee
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Won Ick Chang
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Jaeman Son
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
| | - Jong Min Park
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Chang Heon Choi
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Joo Ho Lee
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Hong-Gyun Wu
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jung-in Kim
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jin Ho Kim
- Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea
- Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea
- Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
- Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Republic of Korea
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17
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Rousseau A, Stien C, Gouriou J, Bordy JM, Boissonnat G, Chabert I, Dufreneix S, Blideanu V. End-to-end quality assurance for stereotactic radiotherapy with Fricke-Xylenol orange-Gelatin gel dosimeter and dual-wavelength cone-beam optical CT readout. Phys Med 2023; 113:102656. [PMID: 37625218 DOI: 10.1016/j.ejmp.2023.102656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 06/04/2023] [Accepted: 08/05/2023] [Indexed: 08/27/2023] Open
Abstract
PURPOSE The end-to-end (E2E) quality assurance (QA) test is a unique tool for validating the treatment chain undergone by patients in external radiotherapy. It should be conducted in three dimensions (3D) to get accurate results. This study aims to implement these tests with Fricke-Xylenol orange-Gelatin (FXG) gel dosimeter and a newly developed dual-wavelength reading method on the Vista16™ optical Computed Tomography (CT) scanner (ModusQA) for three treatment techniques in stereotactic radiotherapy, on Novalis (Varian) and CyberKnife (Accuray) linear accelerators. METHODS The tests were performed in head phantoms. Gel measurements were compared with planned dose distributions and measured by film and ion chamber measurements by plotting isodose curves and dose profiles, and by conducting a 3D local gamma-index analysis (2%/2mm criteria). RESULTS Gamma passing rates were higher than 95 %. Point dose differences between treatment planning and gel and ion chamber measurements at the isocenter were < 2.3 % for both treatments delivered on the Novalis accelerator, while this difference was higher than 4 % for the treatment delivered on the CyberKnife, highlighting a small overdosing of the tumor volume. A good agreement was observed between gel and film dose profiles. CONCLUSIONS This study presents the successful implementation of 3D E2E QA tests for stereotactic radiotherapy with FXG gel dosimetry and a dual-wavelength reading method on an optical CT scanner. This dosimetric method provides 3D absolute dose distributions in the 0.25 - 10 Gy dose range with a high spatial resolution and a dose uncertainty of around 2 % (k=1).
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Affiliation(s)
- Alice Rousseau
- Université Paris-Saclay, CEA, List, Laboratoire National Henri Becquerel (LNE-LNHB), Palaiseau, France.
| | - Christel Stien
- Université Paris-Saclay, CEA, List, Laboratoire National Henri Becquerel (LNE-LNHB), Palaiseau, France
| | - Jean Gouriou
- Université Paris-Saclay, CEA, List, Laboratoire National Henri Becquerel (LNE-LNHB), Palaiseau, France
| | - Jean-Marc Bordy
- Université Paris-Saclay, CEA, List, Laboratoire National Henri Becquerel (LNE-LNHB), Palaiseau, France
| | - Guillaume Boissonnat
- Université Paris-Saclay, CEA, List, Laboratoire National Henri Becquerel (LNE-LNHB), Palaiseau, France
| | | | - Stéphane Dufreneix
- Université Paris-Saclay, CEA, List, Laboratoire National Henri Becquerel (LNE-LNHB), Palaiseau, France; Institut de Cancérologie de l'Ouest, Angers, France
| | - Valentin Blideanu
- Université Paris-Saclay, CEA, List, Laboratoire National Henri Becquerel (LNE-LNHB), Palaiseau, France
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18
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Pecić S, Vićić M, Belča I, Stojadinović S, Nidžović B, Kurij L, Dević S. Physical wedge as a tool for radiochromic film calibration. Z Med Phys 2023:S0939-3889(23)00077-6. [PMID: 37393128 DOI: 10.1016/j.zemedi.2023.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 05/17/2023] [Accepted: 05/31/2023] [Indexed: 07/03/2023]
Abstract
Reliable calibration is one of the major challenges in using radiochromic films (RCF) for radiation dosimetry. In this study the feasibility of using dose gradients produced by a physical wedge (PW) for RCF calibration was investigated. The aim was to establish an efficient and reproducible method for calibrating RCF using a PW. Film strips were used to capture the wedge dose profile for five different exposures and the acquired scans were processed to generate corresponding net optical density wedge profiles. The proposed method was compared to the benchmark calibration, following the guidelines for precise calibration using uniform dose fields. The results of the benchmark comparison presented in this paper showed that using a single film strip for measuring wedge dose profile is sufficient for estimating a reliable calibration curve within the recorded dose range. Furthermore, the PW calibration can be extrapolated or extended by using multiple gradients for the optimal coverage of the desired calibration dose range. The method outlined in this paper can be readily replicated using the equipment and expertise commonly found in a radiotherapy center. Once the dose profile and central axis attenuation coefficient of the PW are determined, they can serve as a reference for a variety of calibrations using different types and batches of film. This investigation demonstrated that the calibration curves obtained with the presented PW calibration method are within the bounds of the measurement uncertainty evaluated for the conventional uniform dose field calibration method.
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Affiliation(s)
- Stevan Pecić
- Faculty of Physics, University of Belgrade, Studentski trg 12-16, Belgrade 11000, Serbia.
| | - Miloš Vićić
- Faculty of Physics, University of Belgrade, Studentski trg 12-16, Belgrade 11000, Serbia
| | - Ivan Belča
- Faculty of Physics, University of Belgrade, Studentski trg 12-16, Belgrade 11000, Serbia
| | - Strahinja Stojadinović
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas 75390, TX, United States
| | - Borko Nidžović
- Institute of Oncology and Radiology of Serbia, Pasterova 14, Belgrade 11000, Serbia
| | - Ljubomir Kurij
- University Clinical Center of Serbia, Center for Neurooncology, Gamma Knife, Koste Todorovića 4, Belgrade 11000, Serbia
| | - Slobodan Dević
- Medical Physics Unit, McGill University, Montreal H4A 3J1, QC, Canada; Department of Radiation Oncology, SMBD Jewish General Hospital, Montreal H3T 1E2, QC, Canada
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19
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Endarko E, Aisyah S, Hariyanto AP, Haekal M, Kavilani N, Syafi'i A. Dosimetry Evaluation of Treatment Planning Systems in Patient-Specific 3D Printed Anthropomorphic Phantom for Breast Cancer after Mastectomy using a Single-Beam 3D-CRT Technique for Megavoltage Electron Radiation Therapy. J Biomed Phys Eng 2023; 13:217-226. [PMID: 37312896 PMCID: PMC10258204 DOI: 10.31661/jbpe.v0i0.2111-1428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 03/20/2022] [Indexed: 06/15/2023]
Abstract
Background The patient-specific 3D printed anthropomorphic phantom is used for breast cancer after mastectomy developed by the laboratory of medical physics and biophysics, Department of Physics, Institut Teknologi Sepuluh Nopember, Indonesia. This phantom is applied to simulate and measure the radiation interactions occurring in the human body either using the treatment planning system (TPS) or direct measurement with external beam therapy (EBT) 3 film. Objective This study aimed to provide dose measurements in the patient-specific 3D printed anthropomorphic phantom using a TPS and direct measurements using single-beam three-dimensional conformal radiation therapy (3DCRT) technique with electron energy of 6 MeV. Material and Methods In this experimental study, the patient-specific 3D printed anthropomorphic phantom was used for post-mastectomy radiation therapy. TPS on the phantom was conducted using a 3D-CRT technique with RayPlan 9A software. The single-beam radiation was delivered to the phantom with an angle perpendicular to the breast plane at 337.3° at 6 MeV with a total prescribed dose of 5000 cGy/25 fractions with 200 cGy per fraction. Results The doses at planning target volume (PTV) and right lung confirmed a non-significant difference both for TPS and direct measurement with P-values of 0.074 and 0.143, respectively. The dose at the spinal cord showed statistically significant differences with a P-value of 0.002. The result presented a similar skin dose value using either TPS or direct measurement. Conclusion The patient-specific 3D printed anthropomorphic phantom for breast cancer after mastectomy on the right side has good potential as an alternative to the evaluation of dosimetry for radiation therapy.
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Affiliation(s)
- Endarko Endarko
- Department of Physics, Institut Teknologi Sepuluh Nopember, Kampus ITS - Sukolilo Surabaya 60111, East Java, Indonesia
| | - Siti Aisyah
- Medical Physicist of Radiotherapy Installation, Naval Hospital Dr. Ramelan, Surabaya 60244, East Java, Indonesia
| | - Aditya Prayugo Hariyanto
- Department of Physics, Institut Teknologi Sepuluh Nopember, Kampus ITS - Sukolilo Surabaya 60111, East Java, Indonesia
| | - Mohammad Haekal
- Department of Physics, Institut Teknologi Sepuluh Nopember, Kampus ITS - Sukolilo Surabaya 60111, East Java, Indonesia
| | - Nandia Kavilani
- Medical Physicist of Radiotherapy Installation, Naval Hospital Dr. Ramelan, Surabaya 60244, East Java, Indonesia
| | - Ahmad Syafi'i
- Medical Physicist of Radiotherapy Installation, Naval Hospital Dr. Ramelan, Surabaya 60244, East Java, Indonesia
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20
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Mittal A, Shaw R, Binjola A, Natanasabapathi G, Sharma DN. Paper based radiochromic film for the detection and measurement of therapeutic radiation doses in radiotherapy: A preliminary study. Radiat Phys Chem Oxf Engl 1993 2023. [DOI: 10.1016/j.radphyschem.2022.110696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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21
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Dufreneix S, Kirié C, Autret D. Evaluation of stereotactic VMAT lung treatment plans for small moving targets. Phys Med 2023; 107:102547. [PMID: 36804692 DOI: 10.1016/j.ejmp.2023.102547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 01/09/2023] [Accepted: 02/13/2023] [Indexed: 02/19/2023] Open
Abstract
PURPOSE The aim of this study is to perform patient quality controls and end-to-end tests for stereotactic VMAT lung treatment plans and to investigate the influence of various parameters on the results. METHOD 18 plans were defined by an experimental design methodology to cover a large variety of stereotactic VMAT lung treatments including different doses per fraction, target diameters, target movements and respiratory parameters. Plans were first controlled using portal dosimetry and a homogeneous static cylindrical phantom. End-to-end tests were then performed in a dynamic respiratory thorax phantom. Measurements were conducted with ionization chamber and films. Calculations were performed with the AcurosXB and AAA algorithms in 6 FFF. RESULTS Portal dosimetry gave excellent gamma pass rates (greater than 97.1 %) and dose deviations between measurement and calculations in a homogeneous static phantom were smaller than 2 %. The methodology followed for comparing calculated and measured doses in a moving target was validated in static fields (largest deviation smaller than 2 %). End-to-end tests showed mean deviations of 1.9 %, 3.3 % and 6.6 % for the 3, 2 and 1 cm diameter's target respectively. Deviations increased for larger movements for the 1 cm lesion. CONCLUSION End-to-end tests revealed that stereotactic VMAT lung treatment plans for moving targets can be delivered within 5 % for 3 and 2 cm diameter targets and amplitudes up to 1.5 cm. The AcurosXB and AAA algorithms however tend to underestimate the dose to the target. Even with satisfactory patient quality controls like portal dosimetry, extra care should be taken for GTV lesions smaller than 2 cm.
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Affiliation(s)
- S Dufreneix
- Institut de Cancérologie de l'Ouest, Angers, France; CEA, List, Laboratoire National Henri Becquerel (LNE-LNHB), Palaiseau, France.
| | - C Kirié
- Institut de Cancérologie de l'Ouest, Angers, France
| | - D Autret
- Institut de Cancérologie de l'Ouest, Angers, France
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22
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Gedam VR, Pradhan A. EVALUATION OF PATIENT-SPECIFIC IMRT QUALITY ASSURANCE AND POINT DOSE MEASUREMENT FOR COMPLEX HEAD AND NECK AND BRAIN CANCER USING GAFCHROMIC EBT3 FILM. RADIATION PROTECTION DOSIMETRY 2023; 199:164-170. [PMID: 36515393 DOI: 10.1093/rpd/ncac250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 09/13/2022] [Accepted: 11/04/2022] [Indexed: 06/17/2023]
Abstract
Patient-specific intensity-modulated radiation therapy (IMRT) quality assurance (QA) is essential for complex radiotherapy treatment as it involves complex intensity modulation and high-dose gradient regions. IMRT QA was performed by point dose verification and two-dimensional (2D) dose distribution measurement using gamma method. Calibrated External Beam Therapy 3 (EBT3) film was used for point dose and pre-treatment verification of 10 IMRT plans, five complex Head and Neck (HN) and five brain cases. The gamma passing rate (GPR) was evaluated for 3%/3 mm gamma criteria and compared with 2D array. Isocentre dose was measured for all 10 IMRT plans on EBT3 film. Percentage deviation of point dose measurement from TPS calculated was found 0.4% for brain cases and 2.9% for HN cases. The GPR for 3%/3 mm criteria was obtained higher than 95% for brain and HN cases. Results suggest that film dosimetry is also a reliable verification system for patient-specific IMRT QA as the 2D array.
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Affiliation(s)
- Varsha R Gedam
- Department of Medical Physics, Delhi State Cancer Institute, Dilshad Garden 110095, Delhi, India
- Department of Physics, GLA University, Mathura 281406, Uttar Pradesh, India
| | - Anirudh Pradhan
- Centre for Cosmology, Astrophysics, and Space Science, GLA University, Mathura 281406, Uttar Pradesh, India
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23
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Small field output factor measurement and verification for CyberKnife robotic radiotherapy and radiosurgery system using 3D polymer gel, ionization chamber, diode, diamond and scintillator detectors, Gafchromic film and Monte Carlo simulation. Appl Radiat Isot 2023; 192:110576. [PMID: 36473319 DOI: 10.1016/j.apradiso.2022.110576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 11/19/2022] [Accepted: 11/21/2022] [Indexed: 11/24/2022]
Abstract
The dosimetry of small fields has become tremendously important with the advent of intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery, where small field segments or very small fields are used to treat tumors. With high dose gradients in the stereotactic radiosurgery or radiotherapy treatment, small field dosimetry becomes challenging due to the lack of lateral electronic equilibrium in the field, x-ray source occlusion, and detector volume averaging. Small volume and tissue-equivalent detectors are recommended to overcome the challenges. With the lack of a perfect radiation detector, studies on available detectors are ongoing with reasonable disagreement and uncertainties. The joint IAEA and AAPM international code of practice (CoP) for small field dosimetry, TRS 483 (Alfonso et al., 2017) provides guidelines and recommendations for the dosimetry of small static fields in external beam radiotherapy. The CoP provides a methodology for field output factor (FOF) measurements and use of field output correction factors for a series of small field detectors and strongly recommends additional measurements, data collection and verification for CyberKnife (CK) robotic stereotactic radiotherapy/radiosurgery system using the listed detectors and more new detectors so that the FOFs can be implemented clinically. The present investigation is focused on using 3D gel along with some other commercially available detectors for the measurement and verification of field output factors (FOFs) for the small fields available in the CK system. The FOF verification was performed through a comparison with published data and Monte Carlo simulation. The results of this study have proved the suitability of an in-house developed 3D polymer gel dosimeter, several commercially available detectors, and Gafchromic films as a part of small field dosimetric measurements for the CK system.
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24
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Lim SB, Tang G. Evaluation of OrthoChromic OC-1 films for photon radiotherapy application. JOURNAL OF RADIATION RESEARCH 2023; 64:105-112. [PMID: 36453442 PMCID: PMC9855338 DOI: 10.1093/jrr/rrac080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 10/07/2022] [Indexed: 06/17/2023]
Abstract
A new film dosimetry system consists of the new OrthoChromic™ OC-1 film, and a novel calibration procedure was evaluated. Two films, C1 and C2, were exposed simultaneously using the 6FFF beam with a step-wedge pattern of five steps ranging from 590 to 3000 cGy. C1 was used for calibration, and C2 was used for calibration curve validation. The second scan of C2 was done by rotating the film by 90-deg. To evaluate the effectiveness of the non-uniform scanner response correction with the new system, a film was exposed to a 20 × 20 cm2 field. The beam profile measured with the film was compared to the IBA cc04 measurements in water. Films were irradiated to characterize the energy response, dynamic range and temporal growth effect. Open (MLC-defined) and clinical fields were radiated to evaluate the overall performance of the new system. The new calibration procedure was validated with an average dose difference of 1.6% and a gamma (2%,2 mm) passing rate of 100%. With C2 scanned 90-deg rotated, the average dose difference was 1.3%. The average difference between cc04 and film was 0.4%. The St between films and diode/cc04 were within -0.3% difference for 1 × 1 to 14 × 14 cm2 and -2.8% for 0.5 × 0.5 cm2. For clinical fields, the average gamma (3%,2 mm) was 98.8%. These results were consistent with EBT3 film and MapCheck measurements with a dose > 400 cGy. The results have shown that the OC-1 film system can achieve accurate results for QA measurements, but more considerable uncertainty was observed within the low dose range.
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Affiliation(s)
- Seng Boh Lim
- Corresponding author. Department of Medical Physics, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, New York 10065, USA. E-mail:
| | - Grace Tang
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, New York 10065, USA
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25
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Liu K, Palmiero A, Chopra N, Velasquez B, Li Z, Beddar S, Schüler E. Dual beam-current transformer design for monitoring and reporting of electron ultra-high dose rate (FLASH) beam parameters. J Appl Clin Med Phys 2023; 24:e13891. [PMID: 36601691 PMCID: PMC9924113 DOI: 10.1002/acm2.13891] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 12/12/2022] [Accepted: 12/15/2022] [Indexed: 01/06/2023] Open
Abstract
PURPOSE To investigate the usefulness and effectiveness of a dual beam-current transformer (BCTs) design to monitor and record the beam dosimetry output and energy of pulsed electron FLASH (eFLASH) beams in real-time, and to inform on the usefulness of this design for future eFLASH beam control. METHODS Two BCTs are integrated into the head of a FLASH Mobetron system, one located after the primary scattering foil and the other downstream of the secondary scattering foil. The response of the BCTs was evaluated individually to monitor beam output as a function of dose, scattering conditions, and ability to capture physical beam parameters such as pulse width (PW), pulse repetition frequency (PRF), and dose per pulse (DPP), and in combination to determine beam energy using the ratio of the lower-to-upper BCT signal. RESULTS A linear relationship was observed between the absorbed dose measured on Gafchromic film and the BCT signals for both the upper and lower BCT (R2 > 0.99). A linear relationship was also observed in the BCT signals as a function of the number of pulses delivered regardless of the PW, DPP, or PRF (R2 > 0.99). The lower-to-upper BCT ratio was found to correlate strongly with the energy of the eFLASH beam due to differential beam attenuation caused by the secondary scattering foil. The BCTs were also able to provide accurate information about the PW, PRF, energy, and DPP for each individual pulse delivered in real-time. CONCLUSION The dual BCT system integrated within the FLASH Mobetron was shown to be a reliable monitoring system able to quantify accelerator performance and capture all essential physical beam parameters on a pulse-by-pulse basis, and the ratio between the two BCTs was strongly correlated with beam energy. The fast signal readout and processing enables the BCTs to provide real-time information on beam output and energy and is proposed as a system suitable for accurate beam monitoring and control of eFLASH beams.
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Affiliation(s)
- Kevin Liu
- Department of Radiation PhysicsDivision of Radiation OncologyThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA,Graduate School of Biomedical SciencesThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
| | - Allison Palmiero
- Department of Radiation PhysicsDivision of Radiation OncologyThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
| | - Nitish Chopra
- Department of Radiation PhysicsDivision of Radiation OncologyThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
| | - Brett Velasquez
- Department of Radiation PhysicsDivision of Radiation OncologyThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
| | - Ziyi Li
- Department of BiostatisticsDivision of Basic SciencesThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
| | - Sam Beddar
- Department of Radiation PhysicsDivision of Radiation OncologyThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA,Graduate School of Biomedical SciencesThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
| | - Emil Schüler
- Department of Radiation PhysicsDivision of Radiation OncologyThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA,Graduate School of Biomedical SciencesThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
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26
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Sorensen SP, Jani SS, Pinnaduwage DS, Yan X, Srivastava SP. Technical note: Absolute dose measurements of a vault-free radiosurgery system. Med Phys 2022; 49:7733-7741. [PMID: 35964159 DOI: 10.1002/mp.15912] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 07/12/2022] [Accepted: 07/30/2022] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Methods for accurate absolute dose (AD) calibration are essential for the proper functioning of radiotherapy treatment machines. Many systems do not conform to TG-51 calibration standards, and modifications are required. TG-21 calibration is also a viable methodology for these situations with the appropriate setup, equipment, and factors. It has been shown that both these methods result in minimal errors. A similar approach has been taken in calibrating the dose for a recent vault-free radiosurgery system. PURPOSE To evaluate modified TG-21 and TG-51 protocols for AD calibrations of the ZAP-X radiosurgery system using ion chambers, film, and thermoluminescent dosimeters (TLDs). METHODS The current treatment planning system for ZAP-X requires AD calibration at dmax (7 mm) and 450 mm source-to-axis distance. Both N D , w 60 C o [ G y / C ] $N_{D,w}^{{60}Co}[ {Gy/C} ]$ and Nx [R/C] calibration coefficients were provided by an accredited dosimetry calibration laboratory for a physikalisch technische werkstatten (PTW) 31010 chamber (0.125 cc). The vendor provides an f-bracket that can be mounted on the collimator. Various phantoms can then be attached to the f-bracket. A custom acrylic phantom was designed based on recommendations from TG-21 and technical report series-398 that places the chamber at 500 mm from the source with a depth of 44-mm acrylic and 456-mm SSD. Nx along with other TG-21 parameters was used to calculate the AD. Measurements using a PTW MP3-XS water tank and the same chamber were used to calculate AD using N D , w 60 C o $N_{D,w}^{{60}Co}$ and TG-51 factors. Dose verification was performed using Gafchromic film and 3rd party TLDs. RESULTS Measurements from TG-51, TG-21 (utilizing the custom acrylic phantom), film, and TLDs agreed to within ± 2%. CONCLUSIONS A modified TG-51 AD calculation in water is preferred but may not be practical due to the difficulty in tank setup. The TG-21 modified protocol using a custom acrylic phantom is an accurate alternative option for dose calibration. Both of these methods are within acceptable agreement and provide confidence in the system's AD calibration.
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Affiliation(s)
- Stephen P Sorensen
- Department of Radiation Oncology, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Shyam S Jani
- Department of Radiation Oncology, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Dilini S Pinnaduwage
- Department of Radiation Oncology, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Xiangsheng Yan
- Department of Radiation Oncology, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
| | - Shiv P Srivastava
- Department of Radiation Oncology, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA
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Hanušová T, Linhart V, Vrba T. PLASTIC SCINTILLATOR BASED 2D DETECTOR FOR PHOTON RADIOTHERAPY: PRELIMINARY RESULTS. RADIATION PROTECTION DOSIMETRY 2022; 198:566-572. [PMID: 36005955 DOI: 10.1093/rpd/ncac100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/07/2022] [Accepted: 02/22/2022] [Indexed: 06/15/2023]
Abstract
A proof-of-concept study of a new detector based on a thin plastic scintillator monitored by a Charge-Coupled Device (CCD) camera designed for monitoring and characterisation of Linac photon beams is presented. The response of the detector is compared with radiochromic film using 6 and 18 MV radiotherapeutic beams. We have observed: (i) all instruments survived the secondary radiation fields during Linac operation, (ii) it was possible to process the measured data using statistical techniques and (iii) the processed data from the CCD camera qualitatively correspond to film dosimetry results. A statistical technique based on the selection of minimal values provides the clearest results. Quantitatively, CCD and film results can only be compared as 6 to 18 MV response rates. We have observed that the rates from the CCD data are systematically higher than the rates from film dosimetry. Differences are not too high, namely 1.9-2.4 times the combined standard deviation.
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Affiliation(s)
- Tereza Hanušová
- Department of Dosimetry and Application of Ionizing Radiation, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Prague 1, Czech Republic
- Department of Medical Physics, Thomayer University Hospital, Vídeňská 800, 140 59 Prague 4, Czech Republic
| | - Vladimír Linhart
- Department of Dosimetry and Application of Ionizing Radiation, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Prague 1, Czech Republic
| | - Tomáš Vrba
- Department of Dosimetry and Application of Ionizing Radiation, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, 115 19 Prague 1, Czech Republic
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28
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Addo DA, Kaufmann EE, Tagoe SN, Kyere AK. Characterization of GafChromic EBT2 film dose measurements using a tissue-equivalent water phantom for a Theratron® Equinox Cobalt-60 teletherapy machine. PLoS One 2022; 17:e0271000. [PMID: 35984784 PMCID: PMC9390906 DOI: 10.1371/journal.pone.0271000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 06/21/2022] [Indexed: 11/19/2022] Open
Abstract
Purpose
In vivo dosimetry is a quality assurance tool that provides post-treatment measurement of the absorbed dose as delivered to the patient. This dosimetry compares the prescribed and measured dose delivered to the target volume. In this study, a tissue-equivalent water phantom provided the simulation of the human environment. The skin and entrance doses were measured using GafChromic EBT2 film for a Theratron® Equinox Cobalt-60 teletherapy machine.
Methods
We examined the behaviors of unencapsulated films and custom-made film encapsulation. Films were cut to 1 cm × 1 cm, calibrated, and used to assess skin dose depositions and entrance dose. We examined the response of the film for variations in field size, source to skin distance (SSD), gantry angle and wedge angle.
Results
The estimated uncertainty in EBT2 film for absorbed dose measurement in phantom was ±1.72%. Comparison of the measurements of the two film configurations for the various irradiation parameters were field size (p = 0.0193, α = 0.05, n = 11), gantry angle (p = 0.0018, α = 0.05, n = 24), SSD (p = 0.1802, α = 0.05, n = 11) and wedge angle (p = 0.6834, α = 0.05, n = 4). For a prescribed dose of 200 cGy and at reference conditions (open field 10 cm x 10 cm, SSD = 100 cm, and gantry angle = 0º), the measured skin dose using the encapsulation material was 70% while that measured with the unencapsulated film was 24%. At reference irradiation conditions, the measured skin dose using the unencapsulated film was higher for open field configurations (24%) than wedged field configurations (19%). Estimation of the entrance dose using the unencapsulated film was within 3% of the prescribed dose.
Conclusions
GafChromic EBT2 film measurements were significantly affected at larger field sizes and gantry angles. Furthermore, we determined a high accuracy in entrance dose estimations using the film.
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Affiliation(s)
- Daniel Akwei Addo
- Department of Computer Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
- * E-mail:
| | - Elsie Effah Kaufmann
- Department of Biomedical Engineering, School of Engineering Sciences, University of Ghana, Legon, Accra, Ghana
| | - Samuel Nii Tagoe
- National Radiotherapy Oncology and Nuclear Medicine Centre, Korle-Bu, Accra, Ghana
- School of Biomedical and Allied health Sciences, University of Ghana, Accra, Ghana
| | - Augustine Kwame Kyere
- Medical Physics Department, Graduate School of Nuclear and Allied Sciences, University of Ghana, Atomic, Accra, Ghana
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29
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Gondré M, Conrad M, Vallet V, Bourhis J, Bochud F, Moeckli R. Commissioning and validation of RayStation treatment planning system for CyberKnife M6. J Appl Clin Med Phys 2022; 23:e13732. [PMID: 35856911 PMCID: PMC9359029 DOI: 10.1002/acm2.13732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 07/04/2022] [Accepted: 07/05/2022] [Indexed: 11/23/2022] Open
Abstract
Background RaySearch (AB, Stockholm) has released a module for CyberKnife (CK) planning within its RayStation (RS) treatment planning system (TPS). Purpose To create and validate beam models of fixed, Iris, and multileaf collimators (MLC) of the CK M6 for Monte Carlo (MC) and collapsed cone (CC) algorithms in the RS TPS. Methods Measurements needed for the creation of the beam models were performed in a water tank with a stereotactic PTW 60018 diode. Both CC and MC models were optimized in RS by minimizing the differences between the measured and computed profiles and percentage depth doses. The models were then validated by comparing dose from the plans created in RS with both single and multiple beams in different phantom conditions with the corresponding measured dose. Irregular field shapes and off‐axis beams were also tested for the MLC. Validation measurements were performed using an A1SL ionization chamber, EBT3 Gafchromic films, and a PTW 1000 SRS detector. Finally, patient‐specific QAs with gamma criteria of 3%/1 mm were performed for each model. Results The models were created in a straightforward manner with efficient tools available in RS. The differences between computed and measured doses were within ±1% for most of the configurations tested and reached a maximum of 3.2% for measurements at a depth of 19.5‐cm. With respect to all collimators and algorithms, the maximum averaged dose difference was 0.8% when considering absolute dose measurements on the central axis. The patient‐specific QAs led to a mean result of 98% of points fulfilling gamma criteria. Conclusions We created both CC and MC models for fixed, Iris, and MLC collimators in RS. The dose differences for all collimators and algorithms were within ±1%, except for depths larger than 9 cm. This allowed us to validate both models for clinical use.
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Affiliation(s)
- Maude Gondré
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Mireille Conrad
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Véronique Vallet
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Jean Bourhis
- Radio-Oncology Department, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - François Bochud
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Raphaël Moeckli
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
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Resch AF, Padilla Cabal F, Regodic M, Lechner W, Heilemann G, Kuess P, Georg D, Palmans H. Accelerating and improving radiochromic film calibration by utilizing the dose ratio in photon and proton beams. Med Phys 2022; 49:6150-6160. [PMID: 35754376 PMCID: PMC9543697 DOI: 10.1002/mp.15828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 06/08/2022] [Accepted: 06/09/2022] [Indexed: 11/12/2022] Open
Abstract
Purpose Radiochromic films are versatile 2D dosimeters with high‐resolution and near tissue equivalence. To assure high precision and accuracy, a time‐consuming calibration process is required. To improve the time efficiency, a novel calibration method utilizing the ratio of the same dose profile measured at different monitor units (MUs) is introduced and tested in a proton and photon beam. Methods The calibration procedure employs the dose ratio of film measurements of the same relative profile for different absolute dose values. Hence, the ratio of the dose is constant at any point of the profile, but the ratio of the net optical densities is not constant. The key idea of the method is to optimize the calibration function until the ratio of the calculated doses is constant. The proposed method was tested in the dose range between 0.25–12 and 1–6 Gy in a proton and photon beam, respectively. A radial symmetric profile and a rectangular profile were created, both having a central plateau region of about 3 cm diameter and a dose falloff of about 1.5 cm at larger distances. The dose falloff region was used as input for the optimization method and the central plateau region served as dose reference points. Only the plateau region of the highest dose entered the optimization as an additional objective. The measured data were randomly split into differently sized training and test sets. The optimization was repeated 1000 times with random start value initialization using the same start values for the standard and the gradient method. Finally, a proton plan with four dose levels was created, which were separated spatially, to test the possibility of a full calibration within a single measurement. Results Parameter estimation was possible with as low as one dose ratio used for optimization in both the photon and the proton case, yet exhibiting a high sensitivity on the dose level. The root mean squared deviation (RMSD) of the dose was less than 1% when the dose ratio was in the order of 20, whereas the median RMSD of all optimizations was 1.7%. Using four dose levels for optimization resulted in a median RMSD of 1% when randomly selecting the dose levels. Having at least one dose ratio of about 20 included in the optimization considerably improved the RMSD of the calibration function. Using six or eight dose levels reduced the sensitivity on the dose level selection and the median RMSD was 0.8%. A full calibration was possible in a single measurement having four dose levels in one plan but spatially separated. Conclusions The number of measurements required to obtain an EBT3 film calibration function could be reduced using the proposed dose ratio method while maintaining the same accuracy as with the standard method.
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Affiliation(s)
- Andreas F. Resch
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Fatima Padilla Cabal
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Milovan Regodic
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Wolfgang Lechner
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Gerd Heilemann
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Peter Kuess
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Dietmar Georg
- Division Medical Radiation PhysicsDepartment of Radiation OncologyMedical University of Vienna/AKH WienViennaAustria
| | - Hugo Palmans
- MedAustron Ion Therapy CentreWiener NeustadtAustria
- Medical Radiation ScienceNational Physical LaboratoryTeddingtonUnited Kingdom
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Evaluation of SRS MapCHECK with StereoPHAN phantom as a new pre-treatment system verification for SBRT plans. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2022. [DOI: 10.2478/pjmpe-2022-0010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Introduction: The aim of this study was to evaluate the new 2-Dimensional diode array SRS MapCHECK (SunNuclear, Melbourne, USA) with dedicated phantom StereoPHAN (SunNuclear, Melbourne, USA) for the pre-treatment verification of the stereotactic body radiotherapy (SBRT).
Material and methods: For the system, the short and mid-long stability, dose linearity with MU, angular dependence, and field size dependence (ratio of relative output factor) were measured. The results of verification for 15 pre-treatment cancer patients (5 brains, 5 lungs, and 5 livers) performed with SRS MapCHECK and EBT3 Gafchromic films were compared. All the SBRT plans were optimized with the Eclipse (v. 15.6, Varian, Palo Alto, USA) treatment planning system (TPS) using the Acuros XB (Varian, Palo Alto, USA) dose calculation algorithm and were delivered to the Varian EDGE® (Varian, Palo Alto, USA) accelerator equipped with a high-definition multileaf collimator. The 6MV flattening-filter-free beam (FFF) was used.
Results: Short and mid-long stability of SRS MapCHECK was very good (0.1%-0.2%), dose linearity with MU and dependence of the response of the detector on field size results were also acceptable (for dose linearity R2 = 1 and 6% difference between microDiamond and SRS MapCHECK response for the smallest field of 1 × 1 cm2). The angular dependence was very good except for the angles close to 90° and 270°. For pre-treatment plan verification, the gamma method was used with the criteria of 3% dose difference and 3 mm distance to agreement (3%/3 mm), and 2%/2 mm, 1%/1 mm, 3%/1 mm, and 2%/1 mm. The highest passing rate for all criteria was observed on the SRS MapCHECK system.
Conclusions: It is concluded that SRS MapCHECK with StereoPHAN has sufficient potential for pre-treatment verification of the SBRT plans, so that verification of stereotactic plans can be significantly accelerated.
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Poirier Y, Xu J, Mossahebi S, Therriault‐Proulx F, Sawant A. Technical note: Characterization and practical applications of a novel plastic scintillator for on‐line dosimetry for ultra‐high dose rate (FLASH). Med Phys 2022; 49:4682-4692. [DOI: 10.1002/mp.15671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 03/23/2022] [Accepted: 03/30/2022] [Indexed: 11/06/2022] Open
Affiliation(s)
- Yannick Poirier
- University of Maryland School of Medicine Baltimore MD 21201
- McGill University Montreal QC H3A 2T5 Canada
| | - Junliang Xu
- University of Maryland School of Medicine Baltimore MD 21201
| | - Sina Mossahebi
- University of Maryland School of Medicine Baltimore MD 21201
| | | | - Amit Sawant
- University of Maryland School of Medicine Baltimore MD 21201
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Jeong S, Cheon W, Shin D, Lim YK, Jeong J, Kim H, Yoon M, Lee SB. Development of a dosimetry system for therapeutic X-rays using a flexible amorphous silicon thin-film solar cell with a scintillator screen. Med Phys 2022; 49:4768-4779. [PMID: 35396722 DOI: 10.1002/mp.15664] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 04/01/2022] [Accepted: 04/03/2022] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To evaluate the dosimetric characteristics and applications of a dosimetry system composed of a flexible amorphous silicon thin-film solar cell and scintillator screen (STFSC-SS) for therapeutic X-rays. METHODS The real-time dosimetry system was composed of a flexible a-Si thin film solar cell (0.2-mm thick), a scintillator screen to increase its efficiency, and an electrometer to measure the generated charge. The dosimetric characteristics of the developed system were evaluated, including its energy dependence, dose linearity, and angular dependence. Calibration factors for the signal measured by the system and absorbed dose-to-water were obtained by setting reference conditions. The application and correction accuracy of the developed system were evaluated by comparing the absorbed dose-to-water measured using a patient treatment beam with that measured using the ion chamber. RESULTS The responses of STFSC-SS to energy, field size, depth, and source-to-surface distance (SSD) were more dependent on measurement conditions than were the responses of the ion chamber, although the former dependence was due to the scintillator screen, not the solar cell. The signal of STFSC-SS were also dependent on dose rate, while the responses of solar cell alone and scintillator screen were not dependent on dose rate. The scintillator screen reduced the output of solar cell 6 and 15 MV by 0.60% and 0.55%, respectively. The absorbed doses-to-water measured using STFSC-SS for patient treatment beam differed by 0.4% compared to those measured using the ionization chamber. The uncertainties of the developed system for 6 and 15 MV photon beams were 1.8% and 1.7%, respectively, confirming the accuracy and applicability of this system. CONCLUSIONS ; The thin film solar cell-based detector developed in this study can accurately measure absorbed dose-to-water. The increased signal resulting from the use of the scintillator screen is advantageous for measuring low doses and stable signal output. In addition, this system is flexible, making it applicable to curved surfaces such as a patient's body, and is cost-effective. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Seonghoon Jeong
- Proton Therapy Center, National Cancer Center, Goyang, Korea
| | - Wonjoong Cheon
- Proton Therapy Center, National Cancer Center, Goyang, Korea
| | - Dongho Shin
- Proton Therapy Center, National Cancer Center, Goyang, Korea
| | - Young Kyung Lim
- Proton Therapy Center, National Cancer Center, Goyang, Korea
| | - Jonghwi Jeong
- Proton Therapy Center, National Cancer Center, Goyang, Korea
| | - Haksoo Kim
- Proton Therapy Center, National Cancer Center, Goyang, Korea
| | - Myonggeun Yoon
- Department of Bio-convergence Engineering, Korea University, Seoul, Korea
| | - Se Byeong Lee
- Proton Therapy Center, National Cancer Center, Goyang, Korea
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Patterson E, Oborn BM, Cutajar D, Jelen U, Liney G, Rosenfeld AB, Metcalfe PE. Characterizing magnetically focused contamination electrons by off-axis irradiation on an inline MRI-Linac. J Appl Clin Med Phys 2022; 23:e13591. [PMID: 35333000 PMCID: PMC9195023 DOI: 10.1002/acm2.13591] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 12/10/2021] [Accepted: 03/02/2022] [Indexed: 11/18/2022] Open
Abstract
Purpose The aim of this study is to investigate off‐axis irradiation on the Australian MRI‐Linac using experiments and Monte Carlo simulations. Simulations are used to verify experimental measurements and to determine the minimum offset distance required to separate electron contamination from the photon field. Methods Dosimetric measurements were performed using a microDiamond detector, Gafchromic® EBT3 film, and MOSkinTM. Three field sizes were investigated including 1.9 × 1.9, 5.8 × 5.8, and 9.7 × 9.6 cm2. Each field was offset a maximum distance, approximately 10 cm, from the central magnetic axis (isocenter). Percentage depth doses (PDDs) were collected at a source‐to‐surface distance (SSD) of 1.8 m for fields collimated centrally and off‐axis. PDD measurements were also acquired at isocenter for each off‐axis field to measure electron contamination. Monte Carlo simulations were used to verify experimental measurements, determine the minimum field offset distance, and demonstrate the use of a spoiler to absorb electron contamination. Results Off‐axis irradiation separates the majority of electron contamination from an x‐ray beam and was found to significantly reduce in‐field surface dose. For the 1.9 × 1.9, 5.8 × 5.8, and 9.7 × 9.6 cm2 field, surface dose was reduced from 120.9% to 24.9%, 229.7% to 39.2%, and 355.3% to 47.3%, respectively. Monte Carlo simulations generally were within experimental error to MOSkinTM and microDiamond, and used to determine the minimum offset distance, 2.1 cm, from the field edge to isocenter. A water spoiler 2 cm thick was shown to reduce electron contamination dose to near zero. Conclusions Experimental and simulation data were acquired for a range of field sizes to investigate off‐axis irradiation on an inline MRI‐Linac. The skin sparing effect was observed with off‐axis irradiation, a feature that cannot be achieved to the same extent with other methods, such as bolusing, for beams at isocenter.
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Affiliation(s)
| | - Bradley M Oborn
- Centre for Medical Radiation Physics, Wollongong, NSW, Australia.,Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, NSW, Australia
| | - Dean Cutajar
- Centre for Medical Radiation Physics, Wollongong, NSW, Australia
| | - Urszula Jelen
- Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia
| | - Gary Liney
- Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia
| | - Anatoly B Rosenfeld
- Centre for Medical Radiation Physics, Wollongong, NSW, Australia.,Illawarra Health Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia
| | - Peter E Metcalfe
- Centre for Medical Radiation Physics, Wollongong, NSW, Australia.,Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia
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35
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Brown TAD, Ayers RG, Popple RA. Commissioning a multileaf collimator virtual cone for the stereotactic radiosurgery of trigeminal neuralgia. J Appl Clin Med Phys 2022; 23:e13562. [PMID: 35157356 PMCID: PMC9121036 DOI: 10.1002/acm2.13562] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 12/15/2021] [Accepted: 02/02/2022] [Indexed: 11/13/2022] Open
Abstract
A multileaf collimator (MLC), virtual‐cone treatment technique has been commissioned for trigeminal neuralgia (TGN) at Tri‐Cities Cancer Center (TCCC). This novel technique was initially developed at the University of Alabama in Birmingham (UAB); it is designed to produce a spherical dose profile similar to a fixed, 5‐mm conical collimator distribution. Treatment is delivered with a 10‐MV flattening‐filter‐free (FFF) beam using a high‐definition MLC on a Varian Edge linear accelerator. Absolute dose output and profile measurements were performed in a 20 × 20 × 14 cm3 solid‐water phantom using an Exradin W2 scintillation detector and Gafchromic EBT3 film. Dose output constancy for the virtual cone was evaluated over 6 months using an Exradin A11 parallel plate chamber. The photo‐neutron dose generated by these treatments was assessed at distances of 50 and 100 cm from isocenter using a Ludlum Model 30–7 Series Neutron Meter. TGN treatments at TCCC have been previously delivered at 6‐MV FFF using a 5‐mm stereotactic cone. To assess the dosimetric impact of using a virtual cone, eight patients previously treated for TGN with a 5‐mm cone were re‐planned using a virtual cone. Seven patients have now been treated for TGN using a virtual cone at TCCC. Patient‐specific quality assurance was performed for each patient using Gafchromic EBT‐XD film inside a Standard Imaging Stereotactic Dose Verification Phantom. The commissioning results demonstrate that the virtual‐cone dosimetry, first described at UAB, is reproducible on a second Edge linear accelerator at an independent clinical site. The virtual cone is a credible alternative to a physical, stereotactic cone for the treatment of TGN at TCCC.
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Affiliation(s)
| | - Rex G Ayers
- Northwest Medical Physics Center, Lynnwood, Washington, USA
| | - Richard A Popple
- Department of Radiation Oncology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
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36
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Measurement uncertainty analysis of radiophotoluminescent glass dosimeter reader system based on GD-352M for estimation of protection quantity. NUCLEAR ENGINEERING AND TECHNOLOGY 2022. [DOI: 10.1016/j.net.2021.08.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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37
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Dunn L, Godwin G, Hellyer J, Xu X. A method for time‐independent film dosimetry: Can we obtain accurate patient‐specific QA results at any time postirradiation? J Appl Clin Med Phys 2022; 23:e13534. [PMID: 35049118 PMCID: PMC8906213 DOI: 10.1002/acm2.13534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 12/15/2021] [Accepted: 12/30/2021] [Indexed: 11/09/2022] Open
Affiliation(s)
- Leon Dunn
- St Vincent's GenesisCare Centre for radiation oncology St Vincent's Hospital Basement Level Building C, 41 Victoria Parade, Fitzroy VIC 3065 Melbourne Victoria 3065 Australia
| | - Guy Godwin
- Redland Icon Cancer Care Bayside Business Park, 16/24 Weippin St, Cleveland QLD Brisbane Queensland 4163 Australia
| | - James Hellyer
- Macquarie University GenesisCare Centre for radiation oncology Hospital Building Suite 1, Level B2, 3 Technology Pl, Macquarie University NSW Sydney New South Wales 2109 Australia
| | - Xiaolei Xu
- St Vincent's GenesisCare Centre for radiation oncology St Vincent's Hospital Basement Level Building C, 41 Victoria Parade, Fitzroy VIC 3065 Melbourne Victoria 3065 Australia
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Cook H, Lambert J, Thomas R, Palmans H, Hussein M, Clark CH, Royle G, Pettingell J, Lourenço A. Development of a heterogeneous phantom to measure range in clinical proton therapy beams. Phys Med 2022; 93:59-68. [PMID: 34968893 DOI: 10.1016/j.ejmp.2021.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 11/16/2021] [Accepted: 11/20/2021] [Indexed: 11/24/2022] Open
Abstract
PURPOSE In particle therapy, determination of range by measurement or calculation can be a significant source of uncertainty. This work investigates the development of a bespoke Range Length Phantom (RaLPh) to allow independent determination of proton range in tissue. This phantom is intended to be used as an audit device. METHOD RaLPh was designed to be compact and allows different configurations of tissue substitute slabs, to facilitate measurement of range using radiochromic film. Fourteen RaLPh configurations were tested, using two types of proton fluence optimised water substitutes, two types of bone substitute, and one lung substitute slabs. These were designed to mimic different complex tissue interfaces. Experiments were performed using a 115 MeV mono-energetic scanning proton beam to investigate the proton range for each configuration. Validation of the measured film ranges was performed via Monte Carlo simulations and ionisation chamber measurements. The phantom was then assessed as an audit device, by comparing film measurements with Treatment Planning System (TPS) predicted ranges. RESULTS Varying the phantom slab configurations allowed for measurable range differences, and the best combinations of heterogeneous material gave agreement between film and Monte Carlo on average within 0.2% and on average within 0.3% of ionisation chamber measurements. Results against the TPS suggest a material density override is currently required to enable the phantom to be an audit device. CONCLUSION This study found that a heterogeneous phantom with radiochromic film can provide range verification as part of a dedicated audit for clinical proton therapy beams.
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Affiliation(s)
- H Cook
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom; Medical Radiation Science, National Physical Laboratory, Teddington, TW11 0LW, United Kingdom.
| | - J Lambert
- Medical Physics Department, The Rutherford Cancer Centre South Wales, Newport NP10 8FZ, United Kingdom
| | - R Thomas
- Medical Radiation Science, National Physical Laboratory, Teddington, TW11 0LW, United Kingdom
| | - H Palmans
- Medical Radiation Science, National Physical Laboratory, Teddington, TW11 0LW, United Kingdom; Medical Physics Group, MedAustron Ion Therapy Center, A-2700 Wiener Neustadt, Austria
| | - M Hussein
- Medical Radiation Science, National Physical Laboratory, Teddington, TW11 0LW, United Kingdom
| | - C H Clark
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom; Medical Radiation Science, National Physical Laboratory, Teddington, TW11 0LW, United Kingdom; Radiotherapy Physics, University College London Hospital, NW1 2BU, United Kingdom; Radiotherapy Trials Quality Assurance Group (RTTQA), Mount Vernon Cancer Centre, HA6 2RN, United Kingdom
| | - G Royle
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom
| | - J Pettingell
- Medical Physics Department, The Rutherford Cancer Centre South Wales, Newport NP10 8FZ, United Kingdom
| | - A Lourenço
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, United Kingdom; Medical Radiation Science, National Physical Laboratory, Teddington, TW11 0LW, United Kingdom
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Yang B, Tang KK, Huang CY, Geng H, Lam WW, Wong YS, Tse MY, Lau KK, Cheung KY, Yu SK. Out-of-field dose and its constituent components for a 1.5 T MR-Linac. Phys Med Biol 2021; 66. [PMID: 34700308 DOI: 10.1088/1361-6560/ac3346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Accepted: 10/26/2021] [Indexed: 11/11/2022]
Abstract
This study aims to quantify the relative contributions of phantom scatter, collimator scatter and head leakage to the out-of-field doses (OFDs) of both static fields and clinical intensity-modulated radiation therapy (IMRT) treatments in a 1.5 T MR-Linac. The OFDs of static fields were measured at increasing distances from the field edge in an MR-conditional water phantom. Inline scans at depths of dmax (14 mm), 50 and 100 mm were performed for static fields of 5 × 5, 10 × 10 and 15 × 15 cm2under three different conditions: full scatter, with phantom scatter prevented, and head leakage only. Crossline scans at isocenter and offset positions were performed in full scatter condition. EBT3 radiochromic films were placed at 100 mm depth of solid water phantom to measure the OFD of clinical IMRT plans. All water tank data were normalized to Dmax of a 10 × 10 cm2field and the film results were presented as a fraction of the target mean dose.The OFD in the inline direction varied from 3.5% (15 × 15 cm2, 100 mm depth, 50 mm distance) to 0.014% (5 × 5 cm2, dmax, 400 mm distance). For all static fields, the collimator scatter was higher than the phantom scatter and head leakage at a distance of 100-400 mm. Head leakage remained the smallest among the three components, except at long distances (>375 mm) with small field size. Compared to the inline scans, the crossline scans at the isocenter showed higher doses at distances longer than 80 mm. All crossline profiles at longitudinal offset positions showed a cone shape with laterally shifted maxima. The OFD of IMRT deliveries varied with different target size. For prostate stereotactic body radiation therapy (SBRT) treatment, the OFD decreased from 2% to 0.03% at a distance of 50-500 mm. The OFDs have been measured for a 1.5 T MR-Linac. The presented dosimetric data are valuable for radiation safety assessments on patients treated with the MR-Linac, such as evaluating carcinogenic risk and radiation exposure to cardiac implantable electronic devices.
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Affiliation(s)
- Bin Yang
- Medical Physics Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong, People's Republic of China
| | - Ka Keung Tang
- Medical Physics Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong, People's Republic of China
| | - Chen-Yu Huang
- Medical Physics Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong, People's Republic of China
| | - Hui Geng
- Medical Physics Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong, People's Republic of China
| | - Wai Wang Lam
- Medical Physics Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong, People's Republic of China
| | - Yeung Sum Wong
- Medical Physics Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong, People's Republic of China
| | - Mei Yan Tse
- Medical Physics Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong, People's Republic of China
| | - Ka Ki Lau
- Medical Physics Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong, People's Republic of China
| | - Kin Yin Cheung
- Medical Physics Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong, People's Republic of China
| | - Siu Ki Yu
- Medical Physics Department, Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong, People's Republic of China
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40
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Petti PL, Rivard MJ, Alvarez PE, Bednarz G, Daniel Bourland J, DeWerd LA, Drzymala RE, Johansson J, Kunugi K, Ma L, Meltsner SG, Neyman G, Seuntjens JP, Shiu AS, Goetsch SJ. Recommendations on the practice of calibration, dosimetry, and quality assurance for gamma stereotactic radiosurgery: Report of AAPM Task Group 178. Med Phys 2021; 48:e733-e770. [DOI: 10.1002/mp.14831] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 02/21/2021] [Accepted: 02/24/2021] [Indexed: 12/25/2022] Open
Affiliation(s)
- Paula L. Petti
- Gamma Knife Center Washington Hospital Fremont CA 94538 USA
| | - Mark J. Rivard
- Department of Radiation Oncology Alpert Medical School of Brown University Providence RI 02903 USA
| | - Paola E. Alvarez
- Radiological Physics Center University of Texas MD Anderson Cancer Center Houston TX 77054 USA
| | - Greg Bednarz
- Department of Radiation Oncology University of Pittsburgh Medical Center Pittsburgh PA 15232 USA
| | - J. Daniel Bourland
- Department of Radiation Oncology Wake Forest University Winston‐Salem NC 27157 USA
| | - Larry A. DeWerd
- Accredited Dosimetry and Calibration Laboratory University of Wisconsin Madison WI 53705 USA
| | - Robert E. Drzymala
- Department of Radiation Oncology Washington University Saint Louis MO 63119 USA
| | | | - Keith Kunugi
- Accredited Dosimetry and Calibration Laboratory University of Wisconsin Madison WI 53705 USA
| | - Lijun Ma
- Department of Radiation Oncology University California–San Francisco San Francisco CA 94143 USA
| | - Sheridan G. Meltsner
- Department of Radiation Oncology Duke University Medical Center Durham NC 27713 USA
| | - Gennady Neyman
- Department of Radiation Oncology The Cleveland Clinic Cleveland OH 44195 USA
| | - Jan P. Seuntjens
- Department of Medical Physics McGill University Montreal QC H4A3J1 Canada
| | - Almon S. Shiu
- Department of Radiation Oncology University of Southern California Los Angeles CA 90033 USA
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41
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Calibration of Gafchromic XR-RV3 film under interventional radiology conditions. POLISH JOURNAL OF MEDICAL PHYSICS AND ENGINEERING 2021. [DOI: 10.2478/pjmpe-2021-0020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Abstract
Introduction: The purpose of the study was the calibration of Gafchromic films in clinical interventional radiology conditions and the assessment of the influence of dose range, the shape of the fitting curve, and its practical application. The aim of the work was to show how practically perform calibration in a wide range of doses.
Material and methods: Gafchromic XR–RV3 films were included in the study. The calibration was performed for A and B film series separately. Doses from the range of 0 – 8 Gy were used. Film dosimeters were read out in reflective mode with a commercial flatbed scanner.
Results: Among various degrees of a polynomial function, the best fit, which fulfilled the chosen criterion of 95% agreement between measured and reconstructed doses and simple equation criterion, was observed for third-degree polynomial. The fitting curve where the dose is the function of optical density (logMPV) was demonstrated to be more precise than the fitting curve based on MPV only. To minimize the difference between dose absorbed by the film and dose reconstructed from the fitting curve below 5% it is necessary to divide the calibration range of 0 – 8 Gy into two subranges for use in interventional radiology. This difference was set at a maximum level of 3.8% and 1.9% for the lowand high-dose range, respectively. Each series of films may have a slightly different calibration curve, especially for the low dose range. A deviation of up to 36% between two batches of Gafchromic film was observed.
Conclusions: For the third-degree polynomial fitting function (one of the recommended in the literature) calibration should be done into low and high dose ranges and for each batch separately. A systematic error higher than 20% could be introduced when the fitting curve from one film batch is applied to the other film batch.
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42
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Bradley DA, Ee LS, Mat Nawi SN, Abdul Sani SF, Khandaker M, Alzimami K, Jambi L. Graphite sheets in study of radiation dosimetry and associated investigations of damage. Appl Radiat Isot 2021; 174:109769. [PMID: 34048993 DOI: 10.1016/j.apradiso.2021.109769] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 05/01/2021] [Accepted: 05/03/2021] [Indexed: 10/21/2022]
Abstract
Present work builds upon prior investigations concerning the novel use of graphite-rich polymer pencil-lead for passive radiation dosimetry. Working with photon-mediated interactions at levels of dose familiar in radiotherapy, exploratory investigations have now been made using graphite produced commercially in the form of 50 μm thick sheets. Focusing on the relationship between absorbed radiation energy and induced material changes, investigations have been made of thermo- and photoluminescence dose dependence, also of alterations in Raman spectroscopic features. Photoluminescence studies have focused on the degree of structural order of the samples when exposed to incident MeV energy gamma-radiation, supported by crystallite size evaluations. The results are consistent and evident of structural alterations, radiation-driven thermal annealing also being observed. The results, supportive of previous TL, Raman and photoluminescence studies, are readily understood to arise from irradiation changes occurring at the microscopic level. Notwithstanding the non-linearities observed in the conduct of Raman and photoluminescence studies there is clear potential for applications in use of the defect-dependent methods herein, providing sensitive detection of radiation damage in graphite and from it dose determination. Most specifically, the readily available thin graphite sheets can provide the basis of a low-cost yet highly effective system for studies of radiation-driven changes in carbon (and/or carbon based composites), also as a dosimetric probe of skin dose, its atomic number closely matching with the effective atomic number of soft tissues.
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Affiliation(s)
- D A Bradley
- Centre for Applied Physics and Radiation Technologies, Sunway University, 46150, Petaling Jaya, Malaysia; Department of Physics, University of Surrey, Guidlford, GU2 7XH, UK.
| | - Lam Siok Ee
- Centre for Applied Physics and Radiation Technologies, Sunway University, 46150, Petaling Jaya, Malaysia
| | - Siti Nurasiah Mat Nawi
- Centre for Applied Physics and Radiation Technologies, Sunway University, 46150, Petaling Jaya, Malaysia
| | - Siti Fairus Abdul Sani
- Department of Physics, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Mayeen Khandaker
- Centre for Applied Physics and Radiation Technologies, Sunway University, 46150, Petaling Jaya, Malaysia
| | - Khalid Alzimami
- Department of Radiological Sciences, College of Applied Medical Sciences, King Saud University, PO Box 10219, Riyadh, 11433, Saudi Arabia
| | - Layal Jambi
- Department of Radiological Sciences, College of Applied Medical Sciences, King Saud University, PO Box 10219, Riyadh, 11433, Saudi Arabia
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43
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Sanchez-Parcerisa D, Sanz-García I, Ibáñez P, España S, Espinosa A, Gutiérrez-Neira C, López A, Vera JA, Mazal A, Fraile LM, Udías JM. Radiochromic film dosimetry for protons up to 10 MeV with EBT2, EBT3 and unlaminated EBT3 films. Phys Med Biol 2021; 66. [PMID: 33910190 DOI: 10.1088/1361-6560/abfc8d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 04/28/2021] [Indexed: 11/12/2022]
Abstract
Passive dosimetry with radiochromic films is widely used in proton radiotherapy, both in clinical and scientific environments, thanks to its simplicity, high spatial resolution and dose-rate independence. However, film under-response for low-energy protons, the so-called linear-energy transfer (LET) quenching, must be accounted and corrected for. We perform a meta-analysis on existing film under-response data with EBT, EBT2 and EBT3 GAFchromic™ films and provide a common framework to integrate it, based on the calculation of dose-averaged LET in the active layer of the films. We also report on direct measurements with the 10 MeV proton beam at the Center for Microanalysis of Materials (CMAM) for EBT2, EBT3 and unlaminated EBT3 films, focusing on the 20-80 keVμm-1LET range, where previous data was scarce. Measured film relative efficiency (RE) values are in agreement with previously reported data from the literature. A model on film RE constructed with combined literature and own experimental values in the 5-80 keVμm-1LET range is presented, supporting the hypothesis of a linear decrease of RE with LET, with no remarkable differences between the three types of films analyzed.
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Affiliation(s)
- Daniel Sanchez-Parcerisa
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain.,Sedecal Molecular Imaging, Algete, Madrid, Spain
| | - Irene Sanz-García
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain
| | - Paula Ibáñez
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
| | - Samuel España
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain.,Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Andrea Espinosa
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
| | - Carolina Gutiérrez-Neira
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.,Centro de Microanálisis de Materiales (CMAM), Universidad Autónoma de Madrid, Spain.,ALBA Synchrotron Light Source (CELLS-ALBA), Cerdanyola del Vallès, Barcelona, Spain
| | - Alfonso López
- Dept. de Radiofísica y Protección Radiológica, Hospital de Fuenlabrada, Madrid, Spain
| | - Juan Antonio Vera
- Centro de Protonterapia de Quirónsalud, Pozuelo de Alarcón, Madrid, Spain
| | - Alejandro Mazal
- Centro de Protonterapia de Quirónsalud, Pozuelo de Alarcón, Madrid, Spain
| | - Luis Mario Fraile
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
| | - José Manuel Udías
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
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44
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Guardiola C, Márquez A, Jiménez-Ramos MC, López JG, Baratto-Roldán A, Muñoz-Berbel X. Dosimetry with gafchromic films based on a new micro-opto-electro-mechanical system. Sci Rep 2021; 11:10414. [PMID: 34001941 PMCID: PMC8129144 DOI: 10.1038/s41598-021-89602-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 04/26/2021] [Indexed: 11/26/2022] Open
Abstract
This work presents the first tests performed with radiochromic films and a new Micro‒Opto‒Electro-Mechanical system (MOEMS) for in situ dosimetry evaluation in radiotherapy in real time. We present a new device and methodology that overcomes the traditional limitation of time-delay in radiochromic film analysis by turning a passive detector into an active sensor. The proposed system consists mainly of an optical sensor based on light emitting diodes and photodetectors controlled by both customized electronic circuit and graphical user interface, which enables optical measurements directly. We show the first trials performed in a low‒energy proton cyclotron with this MOEMS by using gafchromic EBT3 films. Results show the feasibility of using this system for in situ dose evaluations. Further adaptation is ongoing to develop a full real‒time active detector by integrating MOEM multi‒arrays and films in flexible printed circuits. Hence, we point to improve the clinical application of radiochromic films with the aim to optimize radiotherapy treatment verifications.
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Affiliation(s)
- C Guardiola
- Université Paris‒Saclay, CNRS/IN2P3, IJCLab, 91405, Orsay, France.
| | - A Márquez
- Instituto de Microelectrónica de Barcelona, (IMB-CNM, CSIC), 08193, Bellaterra, Spain
| | | | - J García López
- Centro Nacional de Aceleradores, 41092, Sevilla, Spain.,Department of Atomic, Molecular and Nuclear Physics, Universidad de Sevilla, 41012, Sevilla, Spain
| | - A Baratto-Roldán
- Centro Nacional de Aceleradores, 41092, Sevilla, Spain.,Department of Atomic, Molecular and Nuclear Physics, Universidad de Sevilla, 41012, Sevilla, Spain
| | - X Muñoz-Berbel
- Instituto de Microelectrónica de Barcelona, (IMB-CNM, CSIC), 08193, Bellaterra, Spain
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45
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Prikhodko VV, Alexeyev AS, Guskov PA, Novikov SG, Somov AI, Svetukhin VV. Technical Note: ID-card-size dosimeter based on radiochromic films for continuous personnel monitoring. Med Phys 2021; 48:3216-3222. [PMID: 33893658 DOI: 10.1002/mp.14893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 04/06/2021] [Accepted: 04/06/2021] [Indexed: 11/08/2022] Open
Abstract
PURPOSE This paper is aimed at investigating the feasibility of developing a personal dosimeter of cumulative radiation dose which would incorporate the following features: 1) a small size compared to that of a proximity ID card; 2) instant dose readout; 3) no power source; 4) moderate cost. The dosimeter is proposed as a potential replacement for TLD and OSL dosimeters used by nuclear industry workers and some medical staff groups. METHODS An original detector design is developed containing a two-color LED, two photodetectors located in one plane covered with a mirror coating. The power necessary for the operation comes from an RFID reader. A small (5x5 mm) piece of Gafchromic EBT3 photochromic film sensitive to both X-ray and gamma radiation is used as a sensor. Irradiation of samples under X-ray and gamma radiation is carried out in the dose range of 0.1 cGy-1 Gy. The transmittance spectra are measured in the 300 nm-1100 nm spectral range. RESULTS Several prototypes of the dosimeter are presented, the distinctive features of which are the absence of the power source, easy transmitting of the dosimetric data via a RF channel, and a slim form factor. Several sources of dose uncertainties are analyzed and ways to eliminate them are outlined. The average dose confidence interval (α = 0.05) calculated from the response curve is shown to equal 0.02 cGy. This makes it possible to reliably measure doses as low as 0.1 cGy, which corresponds to the minimum value claimed for Gafchromic EBT3. CONCLUSIONS The proposed idea of an ID-card-size dosimeter is feasible and has a number of advantages over TLD and OSL dosimeters, in particular, instant reading of the dose data using RFID/NFC readers, and a possibility of integrating into ERP systems.
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Affiliation(s)
- Victor V Prikhodko
- S.P. Kapitsa Research Institute of Technology of Ulyanovsk State University, Ulyanovsk, Russia
| | - Alexander S Alexeyev
- S.P. Kapitsa Research Institute of Technology of Ulyanovsk State University, Ulyanovsk, Russia
| | - Pavel A Guskov
- S.P. Kapitsa Research Institute of Technology of Ulyanovsk State University, Ulyanovsk, Russia
| | - Sergey G Novikov
- S.P. Kapitsa Research Institute of Technology of Ulyanovsk State University, Ulyanovsk, Russia
| | - Andrey I Somov
- S.P. Kapitsa Research Institute of Technology of Ulyanovsk State University, Ulyanovsk, Russia
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46
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Mutsakanyi S, du Plessis F. Characterization and dosimetry of photon multileaf collimated electron beams using Gafchromic film measurements. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2020.109266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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47
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Development and dosimetric characterization of novel amide substituted diacetylene based radiochromic films for medical radiation dosimetry. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2021.109391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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48
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Axford A, Dikaios N, Roberts DA, Clark CH, Evans PM. An end-to-end assessment on the accuracy of adaptive radiotherapy in an MR-linac. Phys Med Biol 2021; 66:055021. [PMID: 33503604 DOI: 10.1088/1361-6560/abe053] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE To develop and demonstrate an end-to-end assessment procedure for adaptive radiotherapy (ART) within an MR-guided system. METHODS AND MATERIALS A 3D printed pelvic phantom was designed and constructed for use in this study. The phantom was put through the complete radiotherapy treatment chain, with planned internal changes made to model prostate translations and shape changes, allowing an investigation into three ART techniques commonly used. Absolute dosimetry measurements were made within the phantom using both gafchromic film and alanine. Comparisons between treatment planning system (TPS) calculations and measured dose values were made using the gamma evaluation with criteria of 3 mm/3% and 2 mm/2%. RESULTS Gamma analysis evaluations for each type of treatment plan adaptation investigated showed a very high agreement with pass rates for each experiment ranging from 98.10% to 99.70% and 92.60% to 97.55%, for criteria of 3%/3 mm and 2%/2 mm respectively. These pass rates were consistent for both shape and position changes. Alanine measurements further supported the results, showing an average difference of 1.98% from the TPS. CONCLUSION The end-to-end assessment procedure provided demanding challenges for treatment plan adaptations to demonstrate the capabilities and achieved high consistency in all findings.
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Affiliation(s)
- A Axford
- The Centre for Vision Speech and Signal Processing (CVSSP), University of Surrey, Guildford, Surrey, United Kingdom. Metrology for Medical Physics (MEMPHYS), National Physical Laboratory, Teddington, United Kingdom
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49
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Santos T, Ventura T, Capela M, Mateus J, Lopes MDC. A protocol for absolute dose verification of SBRT/SRS treatment plans using Gafchromic™ EBT-XD films. Phys Med 2021; 82:150-157. [PMID: 33618154 DOI: 10.1016/j.ejmp.2021.01.082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/09/2021] [Accepted: 01/29/2021] [Indexed: 10/22/2022] Open
Abstract
PURPOSE To provide a practical protocol for absolute dose verification of stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS) treatment plans, based on our clinical experience. It aims to be a concise summary of the main aspects to be considered when establishing an accurate film dosimetry system. METHODS Procedures for film calibration and conversion to dose are described for a dosimetry system composed of Gafchromic™ EBT-XD films and a flatbed document scanner. Factors that affect the film-scanner response are also reviewed and accounted for. The accuracy of the proposed methodology was assessed by taking a set of strips irradiated to known doses and its applicability is illustrated for ten SBRT/SRS treatment plans. The film response was converted to dose using red and triple channel dosimetry. The agreement between the planned and measured dose distributions was evaluated using global gamma analysis with criteria of 3%/2mm 10% threshold (TH), 2%/2mm 10% TH, and 2%/2mm 20% TH. RESULTS The differences between the expected and determined doses from the strips analysis were 0.9 ± 0.6% for the red channel and 1.1 ± 0.7% for the triple channel method. Regarding the SBRT/SRS plans verification, the mean gamma passing rates were 99.5 ± 1.0% vs 99.6 ± 1.0% (3%/2mm 10% TH), 96.9 ± 3.5% vs 99.1 ± 1.3% (2%/2mm 10% TH) and 98.4 ± 1.8% vs 98.8 ± 1.5% (2%/2mm 20% TH) for red and triple channel dosimetry, respectively. CONCLUSIONS The proposed protocol allows for accurate absolute dose verification of SBRT/SRS treatment plans, applying both single and triple channel methods. It may work as a guide for users that intend to implement a film dosimetry system.
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Affiliation(s)
- Tania Santos
- Physics Department, University of Coimbra, Coimbra, Portugal; Medical Physics Department, IPOCFG, E.P.E., Coimbra, Portugal.
| | - Tiago Ventura
- Medical Physics Department, IPOCFG, E.P.E., Coimbra, Portugal
| | - Miguel Capela
- Medical Physics Department, IPOCFG, E.P.E., Coimbra, Portugal
| | - Josefina Mateus
- Medical Physics Department, IPOCFG, E.P.E., Coimbra, Portugal
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50
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Fiedler DA, Hoffman S, Roeske JC, Hentz CL, Small W, Kang H. Dosimetric assessment of brass mesh bolus and transparent polymer-gel type bolus for commonly used breast treatment delivery techniques. Med Dosim 2021; 46:e10-e14. [PMID: 33536152 DOI: 10.1016/j.meddos.2021.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/08/2020] [Accepted: 01/05/2021] [Indexed: 11/29/2022]
Abstract
We investigated skin dose enhancements of brass mesh bolus (BMB) and a recently developed transparent polymer-gel bolus (PGB) for clinically relevant breast treatment delivery techniques. The dose enhancement of the breast surface with BMB and PGB were compared to that of tissue-equivalent bolus. Three breast treatment plans were generated on CT scans of an anthropomorphic chest phantom: tangential step-and-shoot 3D conformal (3DCRT) planned using Field-in-Field (FiF), tangential sliding-window 3DCRT using Electronic Compensator (EC), and volumetric modulated arc therapy (VMAT). All plans were created using 6 MV photons and a prescription dose (Rx) of 180 cGy per fraction. Skin doses of all 3 plans were measured with radiochromic films, separately delivered in triplicate. Each plan was delivered to the phantom without bolus, and then with BMB (1 or 2 layers; 3 or 10 mm tissue-equivalent), PGB, and Superflab (3, 5, and 10 mm tissue-equivalent). Doses were determined by reading the radiochromic films with a flatbed scanner, and analyzing the images using a calibration curve for each specific batch. For all bolus types and plans, surface doses averaged over the 3 measurements were between 88.4% and 107.4% of Rx. Without bolus, average measured skin doses were between 51.2% and 64.2% of Rx. Skin doses with BMB and PGB were comparable to that with tissue-equivalent bolus. Over all 3 treatment delivery techniques, using BMB resulted in average skin doses of 92.8% and 102.1% for 1- and 2 layers, respectively, and using PGB results in average skin doses of 94.8%, 98.2%, and 99.7% for 3, 5, and 10-mm tissue-equivalent, respectively. The average measured skin doses with BMB and PGB agreed within ± 3% compared to the tissue-equivalent thickness bolus. We concluded that BMB and PGB are clinically equivalent in skin dose enhancement for breast treatment as the 3, 5, and 10 mm tissue-equivalent bolus.
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Affiliation(s)
- Derek A Fiedler
- Department of Radiation Oncology, Loyola University Medical Center, Maywood, IL, 60637 USA
| | - Sabrina Hoffman
- Department of Radiation Oncology, Loyola University Medical Center, Maywood, IL, 60637 USA
| | - John C Roeske
- Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernardine Cancer Center, Loyola University Chicago, Maywood, IL, 60637 USA
| | - Courtney L Hentz
- Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernardine Cancer Center, Loyola University Chicago, Maywood, IL, 60637 USA
| | - William Small
- Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernardine Cancer Center, Loyola University Chicago, Maywood, IL, 60637 USA
| | - Hyejoo Kang
- Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernardine Cancer Center, Loyola University Chicago, Maywood, IL, 60637 USA.
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