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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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van den Dobbelsteen M, Hackett SL, van Asselen B, Oolbekkink S, Wolthaus JW, de Vries JW, Raaymakers BW. Experimental validation of multi-fraction online adaptations in magnetic resonance guided radiotherapy. Phys Imaging Radiat Oncol 2023; 28:100507. [PMID: 38035206 PMCID: PMC10685304 DOI: 10.1016/j.phro.2023.100507] [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] [Received: 05/31/2023] [Revised: 11/01/2023] [Accepted: 11/02/2023] [Indexed: 12/02/2023] Open
Abstract
Background and purpose Radiotherapy plan verification is generally performed on the reference plan based on the pre-treatment anatomy. However, the introduction of online adaptive treatments demands a new approach, as plans are created daily on different anatomies. The aim of this study was to experimentally validate the accuracy of total doses of multi-fraction plan adaptations in magnetic resonance imaging guided radiotherapy in a phantom study, isolated from the uncertainty of deformable image registration. Materials and methods We experimentally verified the total dose, measured on external beam therapy 3 (EBT3) film, using a treatment with five online adapted fractions. Three series of experiments were performed, each focusing on a category of inter-fractional variation; translations, rotations and body modifications. Variations were introduced during each fraction and adapted plans were generated and irradiated. Single fraction doses and total doses over five online adapted fractions were investigated. Results The online adapted measurements and calculations showed a good agreement for single fractions and multi-fraction treatments for the dose profiles, gamma passing rates, dose deviations and distances to agreement. The gamma passing rate using a 2%/2 mm criterion ranged from 99.2% to 99.5% for a threshold dose of 10% of the maximum dose (Dmax) and from 96.2% to 100% for a threshold dose of 90% of Dmax, for the total translations, rotations and body modifications. Conclusions The total doses of multi-fraction treatments showed similar accuracies compared to single fraction treatments, indicating an accurate dosimetric outcome of a multi-fraction treatment in adaptive magnetic resonance imaging guided radiotherapy.
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Affiliation(s)
- Madelon van den Dobbelsteen
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Sara L. Hackett
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Bram van Asselen
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Stijn Oolbekkink
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Jochem W.H. Wolthaus
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - J.H. Wilfred de Vries
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Bas W. Raaymakers
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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3
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Xu Q, Baldvinsson G, Piracha NZ, Logadóttir Á, Henrysdóttir HB. Patient-specific QA for the HyperArc technique using gafchromic film with multiple calibration methods. Acta Oncol 2023; 62:1215-1221. [PMID: 37672563 DOI: 10.1080/0284186x.2023.2254484] [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: 05/03/2023] [Accepted: 08/17/2023] [Indexed: 09/08/2023]
Abstract
PURPOSE This study aims to evaluate different methods for calibrating EBT-XD films to develop a precise pre-treatment verification method for stereotactic radiotherapy (SRT) patients using the HyperArc (HA, Varian Medical System) technique. METHODS Gafchromic EBT-XD films were calibrated using three different approaches: manual calibration, EDW calibration, and PDD calibration. Films were digitalized with an Epson V850 Pro scanner applying the local scanning protocol. Three clinical treatment plans were selected for evaluation. Patient-specific QA films were irradiated in the Mobius MVP phantom and the STEEV phantom. Scanned film images were converted into dose images using the calibration curves. Gamma analysis was performed to compare film dose and TPS calculated dose with various criteria. RESULTS The scan-to-scan variation was evaluated to be ≤ 0.2%. The accuracy of the calibration curves was verified and the deviation from the converted dose deviates ≤ 3% from the known delivered dose. The gamma passing rate for all calibration methods was found to be over 94% with clinically relevant criteria. EDW calibration demonstrated higher average gamma passing rates compared to the manual method for single target plans, which is 99% ± 1.2% and 98.8% ± 1.5%, respectively. PDD method demonstrated improved agreement for multiple targets with the result of 99.3% ± 0.8%. CONCLUSIONS The three calibration methods were validated, and they produced accurate calibration curves for EBT-XD films to enable pre-treatment patient-specific QA for stereotactic radiotherapy.
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Affiliation(s)
- Qiuyi Xu
- Department of Radiotherapy, Landspitali University Hospital, Reykjavik, Iceland
| | - Gauti Baldvinsson
- Department of Radiotherapy, Landspitali University Hospital, Reykjavik, Iceland
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Miura H, Ozawa S, Okazue T, Enosaki T, Nagata Y. Characterization of scanning orientation and lateral response artifact for EBT4 Gafchromic film. J Appl Clin Med Phys 2023:e13992. [PMID: 37086445 PMCID: PMC10402671 DOI: 10.1002/acm2.13992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/29/2023] [Accepted: 04/04/2023] [Indexed: 04/24/2023] Open
Abstract
The purpose of this study was to investigate the impact of scanning orientation and lateral response artifact (LRA) effects on the dose-response of EBT4 films and compare it with that of EBT3 films. Dose-response curves for EBT3 and EBT4 films in red-green-blue (RGB) color channels in portrait orientation were created for unexposed films and for films exposed to doses ranging from 0 to 1 000 cGy. Portrait and landscape orientations of the EBT3 and EBT4 films were scanned to investigate the scanning orientation effect in the red channel. EBT3 and EBT4 films were irradiated to assess the LRA in the red channel using a field size of 15 × 15 cm2 and delivered doses of 200, 400, and 600 cGy. Films were scanned at the edge of the scanner bed, and the measured doses were compared with the treatment planning system (TPS) calculated doses at a position 100 mm lateral to the scanner center. At a dose of 200 cGy, the differences in optical density (OD) in the red, green, and blue color channels between EBT3 and EBT4 films were 0.035 (24.8%), 0.042 (49.7%), and 0.022 (64.4%), respectively. The EBT4 film slightly improved the scanning orientation compared to the EBT3 film. The OD difference in the different scanning orientations for the EBT3 and EBT4 films was 0.015 (6.8%) and 0.007 (3.9%), respectively, at a dose of 200 cGy. This is equivalent to a 20 or 10 cGy variation at a dose of 200 cGy. Compared with the TPS calculation, the measurement doses for EBT3 and EBT4 films irradiated at 200 cGy were approximately 16% and 13% higher, respectively, at the 100 mm off-centered position. The EBT4 film showed an improvement concerning the impact of LRA compared with the EBT3 film. This study demonstrated that the response of EBT4 film to a dose in the blue channel was less sensitive and showed an improvement in the scanning orientation and LRA effects.
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Affiliation(s)
- Hideharu Miura
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Shuichi Ozawa
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Toshiya Okazue
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
| | - Tsubasa Enosaki
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
| | - Yasushi Nagata
- Hiroshima High-Precision Radiotherapy Cancer Center, Hiroshima, Japan
- Department of Radiation Oncology, Institute of Biomedical & Health Sciences, Hiroshima University, Hiroshima, Japan
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5
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Kamst O, Desai P. Evaluation of HyperArc™ using film and portal dosimetry quality assurance. Phys Eng Sci Med 2023; 46:57-66. [PMID: 36454430 DOI: 10.1007/s13246-022-01197-1] [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: 02/10/2022] [Accepted: 11/02/2022] [Indexed: 12/02/2022]
Abstract
HyperArc™ is a stereotactic radiotherapy modality designed for targeting multiple brain metastases using a single isocenter with multiple non-coplanar arcs. This study aimed to assess the efficacy of two patient-specific quality assurance methods, film and the Varian Portal Dosimetry System with Varian's HyperArc™ technique and raise important considerations in the customisation of patient-specific quality assurance to accommodate HyperArc™ delivery. Assessment criteria included gamma analysis and mean dose at full width half maximum. The minimum metastasis size, maximum off-axis distance and suitable energy were identified and validated. Patient-specific quality assurance procedures were applied to a range of clinically relevant brain metastasis plans. Initial investigation into energy selection showed no significant differences in gamma pass rates using 6MV, 6MV FFF, or 10MV FFF for metastasis sizes greater than 15 mm diameter at the isocenter. Gamma pass rates (2%/2mm) for 15 mm metastases at the isocenter for all energies were greater than 96.0% for portal dosimetry and greater than 98.7% for film. Fields of size 15 mm placed at various distances (10-70 mm) from the isocenter resulted in a maximum mean dose difference of 1.5% between film and planned. Clinically relevant plans resulted in a maximum mean dose difference for selected metastases of 1.0% between film and plan and a maximum point dose difference of 2.9% between portal dose and plan. Portal dose image prediction was a quick and convenient quality assurance tool for metastases larger than 15 mm near the isocenter but provided diminished geometrical relevance for off-axis metastases. Film QA required exacting procedures but offered the ability to assess the accuracy of geometrical targeting for off-axis metastases and provided dosimetric accuracy for metastases to well below 15 mm diameter.
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Affiliation(s)
- Onno Kamst
- ICON Cancer Care, Gold Coast University Hospital, Southport, Australia.
| | - P Desai
- ICON Cancer Care, Gold Coast University Hospital, Southport, Australia
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Van der Walt M, Marsh L, Baines J, Gibson S, Shoobridge A, de Vine G. Performance evaluation of an LED flatbed scanner for triple channel film dosimetry with EBT3 and EBT-XD film. Phys Eng Sci Med 2022; 45:901-914. [PMID: 35997925 DOI: 10.1007/s13246-022-01161-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 07/07/2022] [Indexed: 11/25/2022]
Abstract
We investigate the properties of a light emitting diode (LED) flatbed scanner for use with EBT3 and EBT-XD film types in a clinical radiochromic film (RCF) dosimetry program with modern treatment techniques. The flatbed scanner was characterised in terms of lateral and longitudinal response, X-Y scaling integrity, scanning reproducibility, scanner warm up dependence and film orientation dependence. The preferred lateral response artefact (LRA) corrections are investigated for the LED light source. Supporting evidence is provided regarding the dose independent nature of the corrections while also providing results suggesting a potential film type independence. Results from 2D gamma analysis of four patient treatments were compared between the new 12000XL and existing 10000XL model. Lastly, a dose uncertainty analysis was performed for the film-scanner system combination. It may be concluded that the lateral response variation requires correction while the longitudinal response variation is insignificant. The linear scaling in the lateral and longitudinal directions are within 0.5% and the scanner reproducibility is stable. Scanner warm up dependence no longer exists, and effort should be made to maintain all film orientation in a study set within 15°. The LRA corrections are as reported substantially dose independent and there is evidence to support film type independence. Comparative gamma analysis of patient specific dose maps between the EPSON 10000XL (xenon fluorescent lamp) and 12000XL (LED) scanners showed that results are indistinguishable for both film types across the two scanner models when the necessary corrections are applied. Dose uncertainty is in agreement with the literature and can be kept below 3% with necessary corrections applied.
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Affiliation(s)
- Marchant Van der Walt
- Department of Medical Physics, Townsville Hospital and Health Service, Townsville, 4814, Australia.
| | - Linda Marsh
- Department of Medical Physics, Townsville Hospital and Health Service, Townsville, 4814, Australia
| | - John Baines
- Department of Medical Physics, Townsville Hospital and Health Service, Townsville, 4814, Australia
| | - Stephen Gibson
- Department of Medical Physics, Townsville Hospital and Health Service, Townsville, 4814, Australia
| | - Ariadne Shoobridge
- Department of Medical Physics, Townsville Hospital and Health Service, Townsville, 4814, Australia
| | - Glenn de Vine
- Department of Medical Physics, Townsville Hospital and Health Service, Townsville, 4814, Australia
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7
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Muurholm CG, Ravkilde T, De Roover R, Skouboe S, Hansen R, Crijns W, Depuydt T, Poulsen PR. Experimental investigation of dynamic real-time rotation-including dose reconstruction during prostate tracking radiotherapy. Med Phys 2022; 49:3574-3584. [PMID: 35395104 PMCID: PMC9322296 DOI: 10.1002/mp.15660] [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: 11/07/2021] [Revised: 02/12/2022] [Accepted: 03/30/2022] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Hypofractionation in prostate radiotherapy is of increasing interest. Steep dose gradients and a large weight on each individual fraction emphasize the need for motion management. Real-time motion management techniques such as multi-leaf collimator (MLC) tracking or couch tracking typically adjust for translational motion while rotations remain uncompensated with unknown dosimetric impact. PURPOSE The purpose of this study is to demonstrate and validate dynamic real-time rotation-including dose reconstruction during radiotherapy experiments with and without MLC and couch tracking. METHODS Real-time dose reconstruction was performed using the in-house developed software DoseTracker. DoseTracker receives streamed target positions and accelerator parameters during treatment delivery and uses a pencil beam algorithm with water density assumption to reconstruct the dose in a moving target. DoseTracker's ability to reconstruct motion-induced dose errors in a dynamically rotating and translating target was investigated during three different scenarios: (1) no motion compensation and translational motion correction with (2) MLC tracking and (3) couch tracking. In each scenario, dose reconstruction was performed online and in real-time during delivery of two dual-arc volumetric modulated arc therapy (VMAT) prostate plans with a prescribed fraction dose of 7 Gy to the prostate and simultaneous intraprostatic lesion boosts with doses of at least 8 Gy, but up to 10 Gy as long as the organs-at-risk dose constraints were fulfilled. The plans were delivered to a pelvis phantom that replicated three patient-measured motion traces using a rotational insert with 21 layers of EBT3 film spaced 2.5 mm apart. DoseTracker repeatedly calculated the actual motion-including dose increment and the planned static dose increment since the last calculation in 84500 points in the film stack. The experiments were performed with a TrueBeam accelerator with MLC and couch tracking based on electromagnetic transponders embedded in the film stack. The motion-induced dose error was quantified as the difference between the final cumulative dose with motion and without motion using the 2D 2%/2mm γ-failure rate and the difference in dose to 95% of the clinical target volume (CTV ΔD95% ) and the gross target volume (GTV ΔD95% ) as well as the difference in dose to 0.1 cm3 of the urethra, bladder, and rectum (ΔD0.1CC ). The motion-induced errors were compared between dose reconstructions and film measurements. RESULTS The dose was reconstructed in all calculation points at a mean frequency of 4.7 Hz. The root-mean-square difference between real-time reconstructed and film measured motion-induced errors was 3.1%-points (γ-failure rate), 0.13 Gy (CTV ΔD95% ), 0.23 Gy (GTV ΔD95% ), 0.19 Gy (urethra ΔD0.1CC ), 0.09 Gy (bladder ΔD0.1CC ), and 0.07 Gy (rectum ΔD0.1CC ). CONCLUSIONS In a series of phantom experiments, online real-time rotation-including dose reconstruction was performed for the first time. The calculated motion-induced errors agreed well with film measurements. The dose reconstruction provides a valuable tool for monitoring dose delivery and investigating the efficacy of advanced motion-compensation techniques in the presence of translational and rotational motion. This article is protected by copyright. All rights reserved.
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Affiliation(s)
| | - Thomas Ravkilde
- Department of Medical Physics, Aarhus University Hospital, Aarhus, Denmark
| | - Robin De Roover
- Department of Oncology, KU Leuven, Leuven, Belgium.,Department of Radiation Oncology, University Hospitals Leuven, Leuven, Belgium
| | - Simon Skouboe
- Danish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Rune Hansen
- Department of Medical Physics, Aarhus University Hospital, Aarhus, Denmark
| | - Wouter Crijns
- Department of Oncology, KU Leuven, Leuven, Belgium.,Department of Radiation Oncology, University Hospitals Leuven, Leuven, Belgium
| | - Tom Depuydt
- Department of Oncology, KU Leuven, Leuven, Belgium.,Department of Radiation Oncology, University Hospitals Leuven, Leuven, Belgium
| | - Per R Poulsen
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark.,Danish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
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8
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Moncion A, Wilson M, Ma R, Marsh R, Burmeister J, Dryden D, Lack D, Grubb M, Mayville A, Jursinic P, Dess K, Kamp J, Young K, Dilworth JT, Kestin L, Jagsi R, Mietzel M, Vicini F, Pierce LJ, Moran JM. Evaluation of Dose Accuracy in the Near-Surface Region for Whole Breast Irradiation Techniques in a Multi-Institutional Consortium. Pract Radiat Oncol 2022; 12:e317-e328. [DOI: 10.1016/j.prro.2022.01.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 11/02/2021] [Accepted: 01/10/2022] [Indexed: 11/29/2022]
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Méndez I, Rovira-Escutia JJ, Casar B. A protocol for accurate radiochromic film dosimetry using Radiochromic.com. Radiol Oncol 2021; 55:369-378. [PMID: 34384012 PMCID: PMC8366735 DOI: 10.2478/raon-2021-0034] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 07/01/2021] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Radiochromic films have many applications in radiology and radiation therapy. Generally, the dosimetry system for radiochromic film dosimetry is composed of radiochromic films, flatbed scanner, and film analysis software. The purpose of this work is to present the effectiveness of a protocol for accurate radiochromic film dosimetry using Radiochromic.com as software for film analysis. MATERIALS AND METHODS Procedures for image acquisition, lot calibration, and dose calculation are explained and analyzed. Radiochromic.com enables state-of-the-art models and corrections for radiochromic film dosimetry, such as the Multigaussian model for multichannel film dosimetry, and lateral, inter-scan, and re-calibration corrections of the response. RESULTS The protocol presented here provides accurate dose results by mitigating the sources of uncertainty that affect radiochromic film dosimetry. CONCLUSIONS Appropriate procedures for film and scanner handling in combination with Radiochromic.com as software for film analysis make easy and accurate radiochromic film dosimetry feasible.
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Affiliation(s)
- Ignasi Méndez
- Department for dosimetry and quality of radiological procedures, Institute of Oncology Ljubljana, Ljubljana, Slovenia
| | | | - Bozidar Casar
- Department for dosimetry and quality of radiological procedures, Institute of Oncology Ljubljana, Ljubljana, Slovenia
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10
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Aldrovandi LG, Farías RO, Mauri MF, Mairal ML. Commissioning of a three-dimensional arc-based technique for total body irradiation. J Appl Clin Med Phys 2021; 22:123-142. [PMID: 34258860 PMCID: PMC8425872 DOI: 10.1002/acm2.13355] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 03/25/2021] [Accepted: 06/16/2021] [Indexed: 11/24/2022] Open
Abstract
The purpose of this study is to describe the commissioning of a novel three‐dimensional arc‐based technique for total body irradiation (TBI) treatments. The development and implementation of this technique allowed our institution to transition from a bilateral two‐dimensional (2D) technique to a methodology based on volumetric dose calculation. The methodology described in this work is a derivation from the MATBI technique, with the static fields being replaced by four contiguous arc‐fields for each anterior and posterior incidence. The reduced number of fields we employed makes it possible to reach a satisfactory dose uniformity through manual optimization in a straightforward process. We use the Eclipse anisotropic analytical algorithm (AAA) algorithm, commissioned with preconfigured beam data for a 6 MV photon beam, at standard SSD (100 cm). A thorough evaluation of the accuracy of the AAA algorithm at an extended distance (approximately 200 cm) was carried out. For the evaluation, we compared measured and calculated percentage depth–dose and profiles that included open‐field, penumbra, and out‐of‐field regions. The analysis was performed for both static and arc fields, taking into consideration unshielded fields and also in the presence of lung shielding blocks. End‐to‐end tests were carried out for our institutional template plan by two means: with a 2D ion chamber array detector in solid phantom and using Gafchromic films in an anthropomorphic phantom. The results obtained in this work demonstrate that the Eclipse AAA algorithm commissioned for standard treatments can be safely used with our TBI planning technique. Moreover, this technique proved to be a highly efficient path to replace conventional treatment techniques, providing a homogeneous dose distribution, dosimetric robustness, and shorter treatment times. In addition, as inherited from the MATBI technique, our methodology can be implemented in small treatment rooms, with no need for ancillary equipment.
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Affiliation(s)
- León G Aldrovandi
- Departamento de Física Médica, Mevaterapia Oncología Radiante, Ciudad Autónoma de Buenos Aires, Argentina
| | - Rubén O Farías
- Departamento de Física Médica, Mevaterapia Oncología Radiante, Ciudad Autónoma de Buenos Aires, Argentina
| | - María F Mauri
- Departamento de Física Médica, Mevaterapia Oncología Radiante, Ciudad Autónoma de Buenos Aires, Argentina
| | - María L Mairal
- Departamento de Física Médica, Mevaterapia Oncología Radiante, Ciudad Autónoma de Buenos Aires, Argentina
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11
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Akino Y, Shiomi H, Isohashi F, Suzuki O, Seo Y, Tamari K, Hirata T, Mizuno H, Ogawa K. Correction of lateral response artifacts from flatbed scanners for dual-channel radiochromic film dosimetry. JOURNAL OF RADIATION RESEARCH 2021; 62:319-328. [PMID: 33479768 PMCID: PMC7948896 DOI: 10.1093/jrr/rraa124] [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: 07/15/2020] [Revised: 10/14/2020] [Indexed: 06/12/2023]
Abstract
In this study, we evaluated the inter-unit variability of the lateral response artifact for multiple flatbed scanners, focusing on the dual-channel method, and investigated the correction method of the lateral non-uniformity. Four scanners with A3+ paper-size and five scanners with A4 paper-size were evaluated. To generate the dose-response curves, small pieces of the Gafchromic EBT3 and EBT-XD films were irradiated, and five of the pieces were repeatedly scanned by moving them on the scanner to evaluate the lateral non-uniformity. To calculate the dose distribution accounting for the lateral non-uniformity, linear functions of the correction factor, representing the difference between the pixel values at offset position and the scanner midline, were calculated for red and blue color channels at each lateral position. Large variations of the lateral non-uniformity among the scanners were observed, even for the same model of scanner. For high dose, red color showed pixel value profiles similar to symmetric curves, whereas the profiles for low dose were asymmetric. The peak positions changed with dose. With correction of the lateral non-uniformity, the dose profiles of the pyramidal dose distribution measured at various scanner positions and that calculated with a treatment planning system showed almost identical profile shapes at all high-, middle- and low-dose levels. The dual-channel method used in this study showed almost identical dose profiles measured with all A3+ and A4 paper-size scanners at any positions when the corrections were applied for each color channel.
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Affiliation(s)
- Yuichi Akino
- Corresponding author. Oncology Center, Osaka University Hospital, 2-2 (D10), Yamadaoka, Suita, Osaka, 565-0871, Japan. Tel: (+81) 6-6879-3482; Fax: (+81) 6-6879-3489;
| | - Hiroya Shiomi
- Osaka University Graduate School of Meidcine, Suita, Osaka 565-0871, Japan
| | - Fumiaki Isohashi
- Osaka University Graduate School of Meidcine, Suita, Osaka 565-0871, Japan
| | - Osamu Suzuki
- Osaka Heavy Ion Therapy Center, Osaka 540-0008, Japan
| | - Yuji Seo
- Osaka University Graduate School of Meidcine, Suita, Osaka 565-0871, Japan
| | - Keisuke Tamari
- Osaka University Graduate School of Meidcine, Suita, Osaka 565-0871, Japan
| | - Takero Hirata
- Osaka University Graduate School of Meidcine, Suita, Osaka 565-0871, Japan
| | | | - Kazuhiko Ogawa
- Osaka University Graduate School of Meidcine, Suita, Osaka 565-0871, Japan
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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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Santos T, Ventura T, Lopes MDC. A review on radiochromic film dosimetry for dose verification in high energy photon beams. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2020.109217] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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14
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Lozares S, Font JA, Gandía A, Campos A, Flamarique S, Ibáñez R, Villa D, Alba V, Jiménez S, Hernández M, Casamayor C, Vicente I, Hernando E, Rubio P. In vivo dosimetry in low-voltage IORT breast treatments with XR-RV3 radiochromic film. Phys Med 2021; 81:173-181. [PMID: 33465753 DOI: 10.1016/j.ejmp.2020.12.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 12/12/2020] [Accepted: 12/16/2020] [Indexed: 12/30/2022] Open
Abstract
PURPOSE The objectives of the study were to establish a procedure for in vivo film-based dosimetry for intraoperative radiotherapy (IORT), evaluate the typical doses delivered to organs at risk, and verify the dose prescription. MATERIALS AND METHODS In vivo dose measurements were studied using XR-RV3 radiochromic films in 30 patients with breast cancer undergoing IORT using the Axxent® device (Xoft Inc.). The stability of the radiochromic films in the energy ranges used was verified by taking measurements at different depths. The stability of the scanner response was tested, and 5 different calibration curves were constructed for different beam qualities. Six pieces of film were placed in each of the 30 patients. All the pieces were correctly sterilized and checked to ensure that the process did not affect the outcome. All calibration and dose measurements were analyzed using the Radiochromic.com software application. RESULTS The doses were measured for 30 patients. The doses in contact with the applicator (prescription zone) were 19.8 ± 0.9 Gy. In the skin areas, the doses were as follows: 1-2 cm from the applicator, 1.86 ± 0.77 Gy; 2-5 cm, 0.73 ± 0.14 Gy; and greater than 5 cm, 0.28 ± 0.17 Gy. The dose delivered to the pectoral muscle (tungsten shielding disc) was 0.51 ± 0.27 Gy. CONCLUSIONS The study demonstrated the viability of XR-RV3 films for in vivo dose measurement in the dose and energy ranges applied in a complex procedure, such as breast IORT. The doses in organs at risk were far below the tolerances for cases such as those studied.
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Affiliation(s)
- Sergio Lozares
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain.
| | - Jose A Font
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Almudena Gandía
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Arantxa Campos
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Sonia Flamarique
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Reyes Ibáñez
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - David Villa
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Verónica Alba
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Sara Jiménez
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Mónica Hernández
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Carmen Casamayor
- Endocrine, Bariatric and Breast Surgery Unit. General and Digestive Surgery Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Isabel Vicente
- Breast Unit. Gynaecology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Ernesto Hernando
- Endocrine, Bariatric and Breast Surgery Unit. General and Digestive Surgery Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Patricia Rubio
- Breast Unit. Gynaecology Department. Miguel Servet University Hospital Zaragoza, Spain
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Santos J, Silva S, Sarmento S. Optimized method for in vivo dosimetry with small films in pelvic IOERT for rectal cancer. Phys Med 2020; 81:20-30. [PMID: 33338728 DOI: 10.1016/j.ejmp.2020.11.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 11/09/2020] [Accepted: 11/15/2020] [Indexed: 11/28/2022] Open
Abstract
PURPOSE Intra-Operative Electron Radiation Therapy (IOERT) is used to treat rectal cancer at our institution, and in vivo measurements with Gafchromic EBT3® films were introduced as quality assurance. The purpose of this work was to quantify the uncertainties associated with digitization of very small EBT3 films irradiated simultaneously, in order to optimize in vivo dosimetry for IOERT. METHODS Film samples of different sizes - M1 (5×5cm2), M2 (1.5×1.5 cm2), M3 (1.0×1.5 cm2) and M4 (0.75×1.5 cm2) - were used to quantify typical variations (uncertainties) due to scanner fluctuations, misalignment, film inhomogeneity, long-term effect of film cutting, small rotations, film curling, edge effects and the influence of opaque templates. Fitting functions and temporal validity of sensitometric curves were also assessed. RESULTS Film curling, intra-film variability and scanner fluctuations are important effects that need to be minimized or considered in the uncertainty budget. Small rotations, misalignments and film cutting have little or no influence on the readings. Most fitting functions perform well, but the quantity used for dose quantification determines over- or under-valuation of dose in the long term. Edge effects and the influence of opaque templates need to be well understood, to allow optimization of methodology to the intended purpose. CONCLUSION The proposed method allows practical and simultaneous digitization of up to ten small irradiated film samples, with an experimental uncertainty of 1%.
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Affiliation(s)
- Joana Santos
- Physics and Astronomy Department, Faculty of Sciences, University of Porto, Portugal; Medical Physics, Radiobiology and Radiation Protection Group, IPO Porto Research Center (CI-IPOP), Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal
| | - Sofia Silva
- Medical Physics, Radiobiology and Radiation Protection Group, IPO Porto Research Center (CI-IPOP), Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal; Medical Physics Service, Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal
| | - Sandra Sarmento
- Management, Outcomes Research and Economics in Healthcare Group, IPO Porto Research Center (CI-IPOP), Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal; Medical Physics Service, Portuguese Oncology Institute of Porto (IPO Porto), Porto, Portugal.
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De Roover R, Hansen R, Crijns W, Muurholm CG, Poels K, Skouboe S, Haustermans K, Poulsen PR, Depuydt T. Dosimetric impact of intrafraction prostate rotation and accuracy of gating, multi-leaf collimator tracking and couch tracking to manage rotation: An end-to-end validation using volumetric film measurements. Radiother Oncol 2020; 156:10-18. [PMID: 33264640 DOI: 10.1016/j.radonc.2020.11.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 10/30/2020] [Accepted: 11/24/2020] [Indexed: 12/31/2022]
Abstract
BACKGROUND AND PURPOSE Both gating and tracking can mitigate the deteriorating dosimetric impact of intrafraction translation during prostate stereotactic body radiotherapy (SBRT). However, their ability to manage intrafraction rotation has not yet been thoroughly investigated. The dosimetric accuracy of gating, MLC tracking and couch tracking to manage intrafraction prostate rotation was investigated. MATERIALS AND METHODS Treatment plans for end-to-end tests of prostate SBRT with focal boosting were generated for a dynamic anthropomorphic pelvis phantom. The phantom applied internal lateral rotation (up to 25°) and coupled vertical and longitudinal translation of a radiochromic film stack that was used for dose measurements. Dose was delivered for each plan while the phantom applied motion according to three typical prostate motion traces without compensation (i), with gating (ii), with MLC tracking (iii) or with couch tracking (iv). Measured doses for the four motion compensation strategies were compared with the planned dose in terms of γ-index analysis, target coverage and organs at risk (OAR) sparing. RESULTS Intrafraction rotation reduced the 3%(global)/2mm γ-index passing rate (γPR) for the prostate target volume by median (range) -33.2% (-68.6%, -4.1%) when no motion compensation was applied. The use of motion compensation improved the γPR by 13.2% (-0.4%, 32.9%) for gating, by 6.0% (-0.8%, 27.7%) for MLC tracking and by 11.1% (1.2%, 22.9%) for couch tracking. The three compensation techniques improved the target coverage in most cases. Gating showed better OAR sparing than MLC tracking or couch tracking. CONCLUSIONS Compensation of intrafraction prostate rotation with gating, MLC tracking and couch tracking was investigated experimentally for the first time. All three techniques improved the dosimetric accuracy, but residual motion-related dose errors remained due to the lack of rotation correction.
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Affiliation(s)
- Robin De Roover
- Department of Oncology, KU Leuven, Belgium; Department of Radiation Oncology, University Hospitals Leuven, Belgium.
| | - Rune Hansen
- Department of Medical Physics, Aarhus University Hospital, Denmark.
| | - Wouter Crijns
- Department of Oncology, KU Leuven, Belgium; Department of Radiation Oncology, University Hospitals Leuven, Belgium.
| | | | - Kenneth Poels
- Department of Oncology, KU Leuven, Belgium; Department of Radiation Oncology, University Hospitals Leuven, Belgium.
| | - Simon Skouboe
- Department of Oncology, Aarhus University Hospital, Denmark.
| | - Karin Haustermans
- Department of Oncology, KU Leuven, Belgium; Department of Radiation Oncology, University Hospitals Leuven, Belgium.
| | - Per Rugaard Poulsen
- Department of Oncology, Aarhus University Hospital, Denmark; Danish Center for Particle Therapy, Aarhus University Hospital, Denmark.
| | - Tom Depuydt
- Department of Oncology, KU Leuven, Belgium; Department of Radiation Oncology, University Hospitals Leuven, Belgium.
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Niroomand‐Rad A, Chiu‐Tsao S, Grams MP, Lewis DF, Soares CG, Van Battum LJ, Das IJ, Trichter S, Kissick MW, Massillon‐JL G, Alvarez PE, Chan MF. Report of AAPM Task Group 235 Radiochromic Film Dosimetry: An Update to TG‐55. Med Phys 2020; 47:5986-6025. [DOI: 10.1002/mp.14497] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 09/15/2020] [Accepted: 09/17/2020] [Indexed: 12/12/2022] Open
Affiliation(s)
| | | | | | | | | | | | - Indra J. Das
- Radiation Oncology Northwestern University Memorial Hospital Chicago IL USA
| | - Samuel Trichter
- New York‐Presbyterian HospitalWeill Cornell Medical Center New York NY USA
| | | | - Guerda Massillon‐JL
- Instituto de Fisica Universidad Nacional Autonoma de Mexico Mexico City Mexico
| | - Paola E. Alvarez
- Imaging and Radiation Oncology Core MD Anderson Cancer Center Houston TX USA
| | - Maria F. Chan
- Memorial Sloan Kettering Cancer Center Basking Ridge NJ USA
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Capaldi DPI, Skinner LB, Dubrowski P, Yu AS. An integrated quality assurance phantom for frameless single-isocenter multitarget stereotactic radiosurgery. ACTA ACUST UNITED AC 2020; 65:115006. [DOI: 10.1088/1361-6560/ab8534] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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19
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Tien CJ, Pinkham DW, Chen ZJ. Feasibility of using multiple-dwell positions in 192Ir Leipzig-style brachytherapy surface applicators to expand target coverage and clinical application. Brachytherapy 2020; 19:532-543. [PMID: 32327342 DOI: 10.1016/j.brachy.2020.03.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 03/04/2020] [Accepted: 03/04/2020] [Indexed: 11/29/2022]
Abstract
PURPOSE Leipzig-style applicators for surface brachytherapy are traditionally used with a single-source dwell position. This study explores the feasibility of using multiple-source dwell positions ("multidwell") to improve the dose coverage and applicability of Leipzig-style applicators. METHODS AND MATERIALS A virtual model of the Leipzig-style applicator was commissioned for a model-based dose calculation algorithm (MBDCA) and compared against American Association of Physicists in Medicine working group 186 benchmarking data sets and ionization chamber point measurements. An absolute dosimetry technique based on radiochromic film was used to validate both single-dwell and multidwell plans. RESULTS Dose distributions generated from the MBDCA-based virtual model were consistent with working group data sets, ion chamber measurements, and radiochromic film analysis. In one multidwell configuration, at 3 mm prescription depth, the 80% isodose width was increased to 25 mm, compared with 15 mm in the same dimension for a single-dwell delivery. In the same multidwell configuration, the flatness, measured as >98% isodose line, was more than doubled to 8 mm, compared with 3 mm in the same dimension. For multidwell plans, 2-D planar agreement between radiochromic film and MBDCA exceeded 93% in gamma analysis (3%/1 mm criteria). Submillimeter positional agreement was found, with a total dosimetric uncertainty of 4.5% estimated for the entire system. CONCLUSIONS Leipzig-style surface applicators with multiple-source dwell positions have been benchmarked against radiochromic film dosimetry. Results show that the clinically viable coverage area can be increased significantly.
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Affiliation(s)
- Christopher J Tien
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT.
| | - Daniel W Pinkham
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT
| | - Zhe Jay Chen
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT
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20
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Ruiz-Morales C, Antonio Vera-Sánchez J, González-López A. Optimizing the recalibration process in radiochromic film dosimetry. ACTA ACUST UNITED AC 2020; 65:015016. [DOI: 10.1088/1361-6560/ab58dd] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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21
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Aldelaijan S, Devic S, Papaconstadopoulos P, Bekerat H, Cormack RA, Seuntjens J, Buzurovic IM. Dose-response linearization in radiochromic film dosimetry based on multichannel normalized pixel value with an integrated spectral correction for scanner response variations. Med Phys 2019; 46:5336-5349. [PMID: 31529516 DOI: 10.1002/mp.13818] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 09/02/2019] [Accepted: 09/05/2019] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To introduce a model that reproducibly linearizes the response from radiochromic film (RCF) dosimetry systems at extended dose range. To introduce a correction method, generated from the same scanned images, which corrects for scanner temporal response variation and scanner bed inhomogeneity. METHODS Six calibration curves were established for different lot numbers of EBT3 GAFCHROMIC™ film model based on four EPSON scanners [10000XL (2 units), 11000XL, 12000XL] at three different centers. These films were calibrated in terms of absorbed dose to water based on TG51 protocol or TRS398 with dose ranges up to 40 Gy. The film response was defined in terms of a proposed normalized pixel value ( n P V RGB ) as a summation of first-order equations based on information from red, green, and blue channels. The fitting parameters of these equations are chosen in a way that makes the film response equal to dose at the time of calibration. An integrated set of correction factors (one per color channel) was also introduced. These factors account for the spatial and temporal changes in scanning states during calibration and measurements. The combination of n P V RGB and this "fingerprint" correction formed the basis of this new protocol and it was tested against net optical density ( n e t O D X = R , G , B ) single-channel dosimetry in terms of accuracy, precision, scanner response variability, scanner bed inhomogeneity, noise, and long-term stability. RESULTS Incorporating multichannel features (RGB) into the normalized pixel value produced linear response to absorbed dose (slope of 1) in all six RCF dosimetry systems considered in this study. The "fingerprint" correction factors of each of these six systems displayed unique patterns at the time of calibration. The application of n P V RGB to all of these six systems could achieve a level of accuracy of ± 2.0% in the dose range of interest within modeled uncertainty level of 2.0%-3.0% depending on the dose level. Consistent positioning of control and measurement film pieces and integrating the multichannel correction into the response function formalism mitigated possible scanner response variations of as much as ± 10% at lower doses and scanner bed inhomogeneity of ± 8% to the established level of uncertainty at the time of calibration. The system was also able to maintain the same level of accuracy after 3 and 6 months post calibration. CONCLUSIONS Combining response linearity with the integrated correction for scanner response variation lead to a sustainable and practical RCF dosimetry system that mitigated systematic response shifts and it has the potential to reduce errors in reporting relative information from the film response.
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Affiliation(s)
- Saad Aldelaijan
- Department of Radiation Oncology, Dana Farber/Brigham and Women's Cancer Center, Harvard Medical School, Boston, MA, 02115, USA
- Department of Biomedical Engineering, Montreal Neurological Institute, McGill University, Montréal, QC, H3A 2B4, Canada
- Medical Physics Unit, McGill University, Montréal, QC, H4A 3J1, Canada
- Department of Radiation Oncology, SMBD Jewish General Hospital, Montréal, QC, H3T 1E2, Canada
- Biomedical Physics Department, King Faisal Specialist Hospital & Research Centre, Riyadh, 12713, Saudi Arabia
| | - Slobodan Devic
- Medical Physics Unit, McGill University, Montréal, QC, H4A 3J1, Canada
- Department of Radiation Oncology, SMBD Jewish General Hospital, Montréal, QC, H3T 1E2, Canada
| | | | - Hamed Bekerat
- Department of Radiation Oncology, SMBD Jewish General Hospital, Montréal, QC, H3T 1E2, Canada
| | - Robert A Cormack
- Department of Radiation Oncology, Dana Farber/Brigham and Women's Cancer Center, Harvard Medical School, Boston, MA, 02115, USA
| | - Jan Seuntjens
- Medical Physics Unit, McGill University, Montréal, QC, H4A 3J1, Canada
| | - Ivan M Buzurovic
- Department of Radiation Oncology, Dana Farber/Brigham and Women's Cancer Center, Harvard Medical School, Boston, MA, 02115, USA
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Makris DN, Pappas EP, Zoros E, Papanikolaou N, Saenz DL, Kalaitzakis G, Zourari K, Efstathopoulos E, Maris TG, Pappas E. Characterization of a novel 3D printed patient specific phantom for quality assurance in cranial stereotactic radiosurgery applications. Phys Med Biol 2019; 64:105009. [PMID: 30965289 DOI: 10.1088/1361-6560/ab1758] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In single-isocenter stereotactic radiosurgery/radiotherapy (SRS/SRT) intracranial applications, multiple targets are being treated concurrently, often involving non-coplanar arcs, small photon beams and steep dose gradients. In search for more rigorous quality assurance protocols, this work presents and evaluates a novel methodology for patient-specific pre-treatment plan verification, utilizing 3D printing technology. In a patient's planning CT scan, the external contour and bone structures were segmented and 3D-printed using high-density bone-mimicking material. The resulting head phantom was filled with water while a film dosimetry insert was incorporated. Patient and phantom CT image series were fused and inspected for anatomical coherence. HUs and corresponding densities were compared in several anatomical regions within the head. Furthermore, the level of patient-to-phantom dosimetric equivalence was evaluated both computationally and experimentally. A single-isocenter multi-focal SRS treatment plan was prepared, while dose distributions were calculated on both CT image series, using identical calculation parameters. Phantom- and patient-derived dose distributions were compared in terms of isolines, DVHs, dose-volume metrics and 3D gamma index (GI) analysis. The phantom was treated as if the real patient and film measurements were compared against the patient-derived calculated dose distribution. Visual inspection of the fused CT images suggests excellent geometric similarity between phantom and patient, also confirmed using similarity indices. HUs and densities agreed within one standard deviation except for the skin (modeled as 'bone') and sinuses (water-filled). GI comparison between the calculated distributions resulted in passing rates better than 97% (1%/1 mm). DVHs and dose-volume metrics were also in satisfying agreement. In addition to serving as a feasibility proof-of-concept, experimental absolute film dosimetry verified the computational study results. GI passing rates were above 90%. Results of this work suggest that employing the presented methodology, patient-equivalent phantoms (except for the skin and sinuses areas) can be produced, enabling literally patient-specific pre-treatment plan verification in intracranial applications.
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Affiliation(s)
- D N Makris
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Athens 115 27, Greece
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Spickermann H, Wegener S, Sauer OA. Evaluation of the reconstructed dose from the three-dimensional dose module of a helical diode array: factors of influence and error detection. Phys Med Biol 2018; 64:015010. [PMID: 30524066 DOI: 10.1088/1361-6560/aaf485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The 3D-dose module (3DVH) of the ArcCHECK-phantom reconstructs the dose distribution in the phantom volume and transfers it to the patient geometry. Our aim was to evaluate the 3DVH-reconstructed dose systematically building up from simple to complex cases. Therefore, the influence of different field sizes without and with blocking the isocenter was tested. The dose distributions of different radiation techniques, error-free and error-induced VMAT-plans were verified by measuring with films and other detectors in the phantom. It was checked how the inclusion of the dose measured separately in the ArcCHECK-isocenter affects the reconstruction. Thus it was also investigated which detector should be used for the dosimetry in the isocenter. Without including the isocentrically measured dose, the reconstruction for the smallest field (2 × 2 cm²) was 5% (6 MV) and 3.7% (10 MV) higher than measured with an ionization chamber. With increasing field size, the deviation decreased. For fields with blocked isocenters, the reconstructed dose was between -10.6% and -24% lower than determined with a microDiamond. Measurements with the Semiflex of the spinal plan resulted in higher doses than calculated by the treatment planning system (TPS) and measured with the film and the other detectors. Through the inclusion of the isocentric dose in the reconstruction its accordance with the film increased mostly. With exception of an error-induced head and neck plan, the induced errors in the reconstructed dose volume histogram became visible, but were underestimated. With the 3DVH-algorithm not every induced-error was detected. The 3DVH underestimated the dose in blocked areas. To protect organs at risk (OAR), these are often blocked. Consequently, there is a risk that a clinical decision is based on a 3DVH that underestimated the dose for the OAR. We recommend including the isocentric dose in the reconstruction. The detector used for the isocentric measurements should be carefully chosen.
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Affiliation(s)
- Heidi Spickermann
- University of Wuerzburg, Radiation Oncology, Josef-Schneider-Str. 11, 97080 Wuerzburg, Germany. TU Ilmenau, Institute of Biomedical Engineering and Informatics, Gustav-Kirchhoff Str. 2, 98693 Ilmenau, Germany. Krankenhaus Buchholz, Strahlentherapie, Steinbecker Straße 44, 21244 Buchholz, Germany
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Valdes-Cortez C, Niatsetski Y, Perez-Calatayud J, Ballester F, Vijande J. A Monte Carlo-based dosimetric characterization of Esteya®
, an electronic surface brachytherapy unit. Med Phys 2018; 46:356-369. [DOI: 10.1002/mp.13275] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 10/07/2018] [Accepted: 10/23/2018] [Indexed: 12/16/2022] Open
Affiliation(s)
- Christian Valdes-Cortez
- Department of Atomic, Molecular and Nuclear Physics; University of Valencia; Burjassot 46100 Spain
- Radiotherapy Department; Centro Oncológico de Antofagasta; Los Pumas 10255 Antofagasta Chile
| | - Yury Niatsetski
- R&D Elekta Brachytherapy; Waardgelder 1 3905 TH Veenendaal The Netherlands
| | - Jose Perez-Calatayud
- Unidad Mixta de Investigación en Radiofísica e Instrumentación Nuclear en Medicina (IRIMED); Instituto de Investigación Sanitaria La Fe (IIS-La Fe)-Universitat de Valencia (UV); E-46026 Valencia Spain
- Radiotherapy Department; La Fe Hospital; E-46026 Valencia Spain
| | - Facundo Ballester
- Department of Atomic, Molecular and Nuclear Physics; University of Valencia; Burjassot 46100 Spain
- Unidad Mixta de Investigación en Radiofísica e Instrumentación Nuclear en Medicina (IRIMED); Instituto de Investigación Sanitaria La Fe (IIS-La Fe)-Universitat de Valencia (UV); Burjassot 46100 Spain
| | - Javier Vijande
- Department of Atomic, Molecular and Nuclear Physics; University of Valencia; Burjassot 46100 Spain
- Unidad Mixta de Investigación en Radiofísica e Instrumentación Nuclear en Medicina (IRIMED); Instituto de Investigación Sanitaria La Fe (IIS-La Fe)-Universitat de Valencia (UV); Burjassot 46100 Spain
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Noorin ES, Feizi S, Dehaghi SM. Novel radiochromic porphyrin-based film dosimeters for γ ray dosimetry: investigation on metal and ligand effects. RADIOCHIM ACTA 2018. [DOI: 10.1515/ract-2018-3055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
As the utilizing of porphyrins and metalloporphyrins in high dose dosimetry becomes more prevalent, research on structural effects of these molecules on dosimetric characteristics and physicochemical properties of their film dosimeters becomes more and more essential. The present study emphasizes dosimetry (measuring radiolytic bleaching of two novel film dosimeters with spectrophotometric methods against 60Co γ-rays exposure in dose range of 0–100 kGy) and evaluating substituent effects on the radiation response of the film dosimeters (role of organic groups and changing the metal core of porphyrins). With casting of solutions of polycarbonate (PC) containing 0.5 wt.% 5,10,15,20-Tetrakis(2,4,6-trimethoxyphenyl) porphyrin (TTMPP) and 5,10,15,20-Tetraphenyl-21H,23H-porphine manganese (III) chloride (Mn-TPP), two novel radiochromic films with the thickness of 20 μm were fabricated. The presence of porphyrin fragments has been observed in the UV–Vis spectra after γ radiation. Due to the changes of the metal core and substituents of the dye ring, meaningful shifts of maximum absorbance of Soret bands of porphyrins and different radiation response of film-dosimeters were observed. The results were compared with the other polycarbonate/porphyrin film dosimeters. The results indicate that the radiation-induced decoloration of PC/Porphyrin films can be reliably tuned and used in high dose dosimetry.
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Affiliation(s)
- Eftekhar Sadat Noorin
- Department of Chemistry, Tehran North Branch , Islamic Azad University , Tehran , Iran
| | - Shahzad Feizi
- Radiation Application Research School, Nuclear Science and Technology Research Institute (NSTRI), AEOI , PO Box 11365-3486 , Tehran , Iran , E-mail:
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Méndez I, Polšak A, Hudej R, Casar B. The Multigaussian method: a new approach to mitigating spatial heterogeneities with multichannel radiochromic film dosimetry. Phys Med Biol 2018; 63:175013. [PMID: 30101754 DOI: 10.1088/1361-6560/aad9c1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The main objective of multichannel radiochromic film dosimetry methods is to correct, or at least mitigate, spatial heterogeneities in the film-scanner response, especially variations in the active layer thickness. To this end, films can also be scanned prior to irradiation. In this study, the abilities of various single channel and multichannel methods to reduce spatial heterogeneities, with and without scanning before irradiation, were tested. Red, green and blue single channel models, two additive channel independent perturbation (CHIP) models and two multiplicative CHIP models were compared with the Multigaussian method. The Multigaussian method is a new approach to multichannel dosimetry, based on experimental findings. It assumes that the probability density function of the response vector formed by the pixel values of the different color channels, including irradiated and non-irradiated scans, follows a multivariate Gaussian distribution. The Multigaussian method provided more accurate doses than the other models under comparison, especially when incorporating the information of the film prior to irradiation. The relative dose differences between reference doses measured with MatriXX and film doses were examined. After applying inter-scan and lateral corrections, the lowest mean absolute errors were 0.8% and 1.0% for the Multigaussian method with and without the information of the scan before irradiation, respectively. Followed by the uniform multiplicative CHIP and red single channel models, using pixel values and net optical density, respectively, both with 1.1%.
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Affiliation(s)
- I Méndez
- Department of Medical Physics, Institute of Oncology Ljubljana, Zaloška cesta 2, Ljubljana 1000, Slovenia
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Noorin ES, Feizi S, Dehaghi SM. Dosimetric characterization of novel polycarbonate/porphyrin film dosimeters for high dose dosimetry: study on complexation effect. RADIOCHIM ACTA 2018. [DOI: 10.1515/ract-2017-2839] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Abstract
Two novel radiochromic films with 20 μm thickness were made from casting of solutions of polycarbonate (PC) containing 0.5 wt.% tetra phenyl porphyrin (TPPH2) and 5,10,15,20-tetraphenyl-21H,23H-porphine iron(III) chloride (Fe-TPP). Dosimetric characterization of the films as routine dosimeters were studied by spectrophotometric method. On subjecting TPPH2/PC and Fe-TPP/PC film dosimeters to gamma radiation, radiolytic bleaching of films was observed. The effects of metal-complexation on the radiation response of the film dosimeters were studied under 60Co γ-rays exposure in dose range of 0–100 kGy. The results were also compared with the PC/TPPF20 (PC/tetrakis (pentafluorophenyl) porphyrin) dosimeter to evaluate the substituent effect (role of fluorine groups). Experimental parameters including humidity, temperature and pre-irradiation (shelf-life) and post-irradiation storage in dark and in indirect sunlight were examined. The maximum absorbance of Soret band of dyes had meaningful shifts and reduction which arose from complexation and substituents. The dyed films characteristics were found to be stable enough in media with high degrees of temperature and humidity. The results indicate that the radiation-induced decoloration of TPPH2/PC and Fe-TPP/PC films can be reliably tuned and used in high dose dosimetry.
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Comparison of dose response functions for EBT3 model GafChromic™ film dosimetry system. Phys Med 2018; 49:112-118. [DOI: 10.1016/j.ejmp.2018.05.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 05/10/2018] [Accepted: 05/11/2018] [Indexed: 11/24/2022] Open
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Gholizadeh Sendani N, Karimian A, Ferreira C, Alaei P. Technical Note: Impact of region of interest size and location in Gafchromic film dosimetry. Med Phys 2018; 45:2329-2336. [DOI: 10.1002/mp.12885] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 01/05/2018] [Accepted: 02/17/2018] [Indexed: 11/06/2022] Open
Affiliation(s)
- Neda Gholizadeh Sendani
- Department of Medical Radiation Engineering; University of Isfahan; Isfahan 81746 Iran
- Department of Radiation Oncology; University of Minnesota; Minneapolis MN 55455 USA
| | - Alireza Karimian
- Department of Biomedical Engineering; University of Isfahan; Isfahan 81746 Iran
| | - Clara Ferreira
- Department of Radiation Oncology; University of Minnesota; Minneapolis MN 55455 USA
| | - Parham Alaei
- Department of Radiation Oncology; University of Minnesota; Minneapolis MN 55455 USA
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30
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On the re-calibration process in radiochromic film dosimetry. Phys Med 2017; 42:67-75. [DOI: 10.1016/j.ejmp.2017.08.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 08/24/2017] [Accepted: 08/26/2017] [Indexed: 11/17/2022] Open
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31
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Dose comparison between TG-43–based calculations and radiochromic film measurements of the Freiburg flap applicator used for high-dose-rate brachytherapy treatments of skin lesions. Brachytherapy 2017; 16:1065-1072. [DOI: 10.1016/j.brachy.2017.06.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 06/24/2017] [Accepted: 06/26/2017] [Indexed: 11/19/2022]
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32
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Calvo-Ortega JF, Pozo M, Moragues S, Casals J. Fast protocol for radiochromic film dosimetry using a cloud computing web application. Phys Med 2017; 39:1-8. [DOI: 10.1016/j.ejmp.2017.05.072] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 05/22/2017] [Accepted: 05/31/2017] [Indexed: 11/29/2022] Open
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33
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Dahle TJ, Rykkelid AM, Stokkevåg CH, Mairani A, Görgen A, Edin NJ, Rørvik E, Fjæra LF, Malinen E, Ytre-Hauge KS. Monte Carlo simulations of a low energy proton beamline for radiobiological experiments. Acta Oncol 2017; 56:779-786. [PMID: 28464743 DOI: 10.1080/0284186x.2017.1289239] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
BACKGROUND In order to determine the relative biological effectiveness (RBE) of protons with high accuracy, radiobiological experiments with detailed knowledge of the linear energy transfer (LET) are needed. Cell survival data from high LET protons are sparse and experiments with low energy protons to achieve high LET values are therefore required. The aim of this study was to quantify LET distributions from a low energy proton beam by using Monte Carlo (MC) simulations, and to further compare to a proton beam representing a typical minimum energy available at clinical facilities. MATERIALS AND METHODS A Markus ionization chamber and Gafchromic films were employed in dose measurements in the proton beam at Oslo Cyclotron Laboratory. Dose profiles were also calculated using the FLUKA MC code, with the MC beam parameters optimized based on comparisons with the measurements. LET spectra and dose-averaged LET (LETd) were then estimated in FLUKA, and compared with LET calculated from an 80 MeV proton beam. RESULTS The initial proton energy was determined to be 15.5 MeV, with a Gaussian energy distribution of 0.2% full width at half maximum (FWHM) and a Gaussian lateral spread of 2 mm FWHM. The LETd increased with depth, from approximately 5 keV/μm in the entrance to approximately 40 keV/μm in the distal dose fall-off. The LETd values were considerably higher and the LET spectra were much narrower than the corresponding spectra from the 80 MeV beam. CONCLUSIONS MC simulations accurately modeled the dose distribution from the proton beam and could be used to estimate the LET at any position in the setup. The setup can be used to study the RBE for protons at high LETd, which is not achievable in clinical proton therapy facilities.
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Affiliation(s)
- Tordis J. Dahle
- Department of Physics and Technology, University of Bergen, Bergen, Norway
| | | | - Camilla H. Stokkevåg
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
| | - Andrea Mairani
- Centro Nazionale di Adroterapia Oncologica (CNAO Foundation), Pavia, Italy
- Heidelberg Ion Beam Therapy Center (HIT), Heidelberg, Germany
| | | | - Nina J. Edin
- Department of Physics, University of Oslo, Oslo, Norway
| | - Eivind Rørvik
- Department of Physics and Technology, University of Bergen, Bergen, Norway
| | - Lars Fredrik Fjæra
- Department of Physics and Technology, University of Bergen, Bergen, Norway
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
| | - Eirik Malinen
- Department of Physics, University of Oslo, Oslo, Norway
- Department of Medical Physics, Oslo University Hospital, Oslo, Norway
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Grid patterns, spatial inter-scan variations and scanning reading repeatability in radiochromic film dosimetry. Phys Med 2016; 32:1072-81. [DOI: 10.1016/j.ejmp.2016.08.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 07/21/2016] [Accepted: 08/03/2016] [Indexed: 11/23/2022] Open
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Vera Sánchez JA, Ruiz Morales C, González López A. Characterization of noise and digitizer response variability in radiochromic film dosimetry. Impact on treatment verification. Phys Med 2016; 32:1167-74. [PMID: 27595366 DOI: 10.1016/j.ejmp.2016.08.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 08/21/2016] [Accepted: 08/23/2016] [Indexed: 11/26/2022] Open
Abstract
PURPOSE To study how noise and scanner response variability affect radiochromic film dosimetry. METHODS Five treatment plans were analyzed in this work with two different multichannel protocols: the multichannel algorithm of Mayer et al. and the efficient protocol of Lewis et al. RESULTS AND CONCLUSION The multichannel protocol of Mayer et al. is not able to compensate variability in scanner response, which is an important issue for radiochromic film dosimetry. The efficient protocol compensates variations of scanner response, so dose values and gamma scores become more accurate and reproducible. The compensation of digitizer scan variability of the efficient protocol, together with time averaging improve radiochromic film dosimetry. Noise is related to selected resolution in the scanner, our results show that if high resolution measurements are required, de-noising should be considered.
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Morales JE, Butson M, Crowe SB, Hill R, Trapp JV. An experimental extrapolation technique using the Gafchromic EBT3 film for relative output factor measurements in small x-ray fields. Med Phys 2016; 43:4687. [DOI: 10.1118/1.4958679] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Tamponi M, Bona R, Poggiu A, Marini P. A new form of the calibration curve in radiochromic dosimetry. Properties and results. Med Phys 2016; 43:4435. [DOI: 10.1118/1.4954208] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Butson M, Pope D, Haque M, Chen T, Song G, Whitaker M. Build-up material requirements in clinical dosimetry during total body irradiation treatments. J Med Phys 2016; 41:149-52. [PMID: 27217628 PMCID: PMC4871005 DOI: 10.4103/0971-6203.181632] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Total body irradiation (TBI) treatments are mainly used in a preparative regimen for hematopoietic stem cell (or bone marrow) transplantation. Our standard clinical regimen is a 12 Gy/6 fraction bi-daily technique using 6MV X-rays at a large extended source to surface distance (SSD). This work investigates and quantifies the dose build-up characteristics and thus the requirements for bolus used for in vivo dosimetry for TBI applications. Percentage dose build-up characteristics of photon beams have been investigated at large extended SSDs using ionization chambers and Gafchromic film. Open field measurements at different field sizes and with differing scatter conditions such as the introduction of standard Perspex scattering plates at different distances to the measurement point were made in an effort to determine the required bolus/build-up material required for accurate determination of applied dose. Percentage surface dose values measured for open fields at 300 cm SSD were found to range from 20% up to 65.5% for fields 5 cm × 5 cm to 40 cm × 40 cm, respectively. With the introduction of 1 cm Perspex scattering plates used in TBI treatments, the surface dose values increased up to 83–90% (93–97% at 1 mm depth), depending on the position of the Perspex scattering plate compared to the measurement point. Our work showed that at least 5 mm water equivalent bolus/scatter material should be placed over the EBT3 film for accurate dose assessment for TBI treatments. Results also show that a small but measurable decrease in measured dose occurred with 5 mm water equivalent thick bolus material of areas '3 cm2. As such, we recommend that 3 cm × 3 cm × 5 mm bolus build-up is the smallest size that should be placed over EBT3 Gafchromic film when used for accurate in vivo dosimetry for TBI applications.
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Affiliation(s)
- Martin Butson
- Department of Radiation Oncology, Chris O'Brien Lifehouse, Chris O'Brien Lifehouse Centre, NSW, Australia; Institute of Medical Physics, University of Sydney, Camperdown, NSW, Australia
| | - Dane Pope
- Department of Radiation Oncology, Chris O'Brien Lifehouse, Chris O'Brien Lifehouse Centre, NSW, Australia
| | - Mamoon Haque
- Department of Radiation Oncology, Chris O'Brien Lifehouse, Chris O'Brien Lifehouse Centre, NSW, Australia; Institute of Medical Physics, University of Sydney, Camperdown, NSW, Australia
| | - Tom Chen
- Genesis Care - Mater Sydney Radiation Oncology, Sydney, NSW, Australia
| | - Guangli Song
- Department of Radiation Oncology, Chris O'Brien Lifehouse, Chris O'Brien Lifehouse Centre, NSW, Australia
| | - May Whitaker
- Department of Radiation Oncology, Chris O'Brien Lifehouse, Chris O'Brien Lifehouse Centre, NSW, Australia
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Strojnik A, Méndez I, Peterlin P. Reducing the dosimetric impact of positional errors in field junctions for craniospinal irradiation using VMAT. Rep Pract Oncol Radiother 2016; 21:232-9. [PMID: 27601956 DOI: 10.1016/j.rpor.2016.03.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Revised: 01/18/2016] [Accepted: 03/04/2016] [Indexed: 10/22/2022] Open
Abstract
AIM To improve treatment plan robustness with respect to small shifts in patient position during the VMAT treatment by ensuring a linear ramp-like dose profile in treatment field overlap regions. BACKGROUND Craniospinal irradiation (CSI) is considered technically challenging because the target size exceeds the maximal field size, which necessitates using abutted or overlapping treatment fields. Volumetric modulated arc therapy (VMAT) is increasingly being examined for CSI, as it offers both better dose homogeneity and better dose conformance while also offering a possibility to create field junctions which are more robust towards small shifts in patient position during the treatment. MATERIALS AND METHODS A VMAT treatment plan with three isocenters was made for a test case patient. Three groups of overlapping arc field pairs were used; one for the cranial and two for the spinal part. In order to assure a ramp-like dose profile in the field overlap region, the upper spinal part was optimised first, with dose prescription explicitly enforcing a ramp-like dose profile. The cranial and lower spinal part were done afterwards, taking into account the dose contribution of the upper spinal fields. RESULTS Using simple geometrical reasoning, we demonstrated that hot- and cold spots which arise from small displacement of one treatment field relative to the other treatment field can be reduced by taking two precautions: (a) widening the field overlap region, and (b) reducing the field gradient across the overlap region. The function with the smallest maximal gradient is a linear ramp. We present a treatment planning technique which yields the desired dose profile of the two contributing fields, and minimises dosimetric dependence on minor positional errors in patient set-up.
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Affiliation(s)
- Andrej Strojnik
- Institute of Oncology Ljubljana, Zaloška 2, SI-1000 Ljubljana, Slovenia
| | - Ignasi Méndez
- Institute of Oncology Ljubljana, Zaloška 2, SI-1000 Ljubljana, Slovenia
| | - Primož Peterlin
- Institute of Oncology Ljubljana, Zaloška 2, SI-1000 Ljubljana, Slovenia
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van Battum LJ, Huizenga H, Verdaasdonk RM, Heukelom S. How flatbed scanners upset accurate film dosimetry. Phys Med Biol 2015; 61:625-49. [PMID: 26689962 DOI: 10.1088/0031-9155/61/2/625] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Film is an excellent dosimeter for verification of dose distributions due to its high spatial resolution. Irradiated film can be digitized with low-cost, transmission, flatbed scanners. However, a disadvantage is their lateral scan effect (LSE): a scanner readout change over its lateral scan axis. Although anisotropic light scattering was presented as the origin of the LSE, this paper presents an alternative cause. Hereto, LSE for two flatbed scanners (Epson 1680 Expression Pro and Epson 10000XL), and Gafchromic film (EBT, EBT2, EBT3) was investigated, focused on three effects: cross talk, optical path length and polarization. Cross talk was examined using triangular sheets of various optical densities. The optical path length effect was studied using absorptive and reflective neutral density filters with well-defined optical characteristics (OD range 0.2-2.0). Linear polarizer sheets were used to investigate light polarization on the CCD signal in absence and presence of (un)irradiated Gafchromic film. Film dose values ranged between 0.2 to 9 Gy, i.e. an optical density range between 0.25 to 1.1. Measurements were performed in the scanner's transmission mode, with red-green-blue channels. LSE was found to depend on scanner construction and film type. Its magnitude depends on dose: for 9 Gy increasing up to 14% at maximum lateral position. Cross talk was only significant in high contrast regions, up to 2% for very small fields. The optical path length effect introduced by film on the scanner causes 3% for pixels in the extreme lateral position. Light polarization due to film and the scanner's optical mirror system is the main contributor, different in magnitude for the red, green and blue channel. We concluded that any Gafchromic EBT type film scanned with a flatbed scanner will face these optical effects. Accurate dosimetry requires correction of LSE, therefore, determination of the LSE per color channel and dose delivered to the film.
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Affiliation(s)
- L J van Battum
- Physics and Medical Technology, VU University Medical Center, Support Radiotherapy, PO Box 7057, 1007 MB Amsterdam, The Netherlands
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