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Petrucci E, Radici L, Borca VC, Ferrario S, Paolini M, Pasquino M. Delta 4 Discover transmission detector: A comprehensive characterization for in-vivo VMAT monitoring. Phys Med 2021; 85:15-23. [PMID: 33945949 DOI: 10.1016/j.ejmp.2021.04.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 04/13/2021] [Accepted: 04/18/2021] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE To investigate the dosimetric behaviour, influence on photon beam fluence and error detection capability of Delta4 Discover transmission detector. METHODS The transmission detector (TRD) was characterized on a TrueBeam linear accelerator with 6 MV beams. Linearity, reproducibility and dose rate dependence were investigated. The effect on photon beam fluence was evaluated in terms of beam profiles, percentage depth dose, transmission factor and surface dose for different open field sizes. The transmission factor of the 10x10 cm2 field was entered in the TPS's configuration and its correct use in the dose calculation was verified recalculating 17 clinical IMRT/VMAT plans. Surface dose was measured for 20 IMRT fields. The capability to detect different delivery errors was investigated evaluating dose gamma index, MLC gamma index and leaf position of 15 manually modified VMAT plans. RESULTS TRD showed a linear dependence on MU. No dose rate dependence was observed. Short-term and long-term reproducibility were within 0.1% and 0.5%. The presence of the TRD did not significantly affect PDDs and profiles. The transmission factor of the 10x10 cm2 field size was 0.985 and 0.983, for FF and FFF beams respectively. The 17 recalculated plans met our clinical gamma-index passing rate, confirming the correct use of the transmission factor by the TPS. The surface dose differences for the open fields increase for shorter SSDs and greater field size. Differences in surface dose for the IMRT beams were less than 2%. Output variation ≥2%, collimator angle variations within 0.3°, gantry angle errors of 1°, jaw tracking and leaf position errors were detected. CONCLUSIONS Delta4 Discover shows good linearity and reproducibility, is not dependent on dose rate and does not affect beam quality and dose profiles. It is also capable to detect dosimetric and geometric errors and therefore it is suitable for monitoring VMAT delivery.
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Affiliation(s)
| | - Lorenzo Radici
- Medical Physics Department, A.S.L. TO4, 10015 Ivrea, TO, Italy
| | | | | | - Marina Paolini
- Radiotherapy Department, A.S.L. TO4, 10015 Ivrea, TO, Italy
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Nguyen THT, Yokoyama H, Kojima H, Isomura N, Takemura A, Ueda S, Noto K. Effect of an integral quality monitor on 4-, 6-, 10-MV, and 6-MV flattening filter-free photon beams. J Appl Clin Med Phys 2020; 22:76-91. [PMID: 33270985 PMCID: PMC7856493 DOI: 10.1002/acm2.13106] [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: 06/01/2020] [Revised: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 12/04/2022] Open
Abstract
Purpose To investigate the effect of an integral quality monitor (IQM; iRT Systems GmbH, Koblenz, Germany) on 4, 6, 10, and 6‐MV flattening filter‐free (FFF) photon beams. Methods We assessed surface dose, PDD20,10, TPR20,10, PDD curves, inline and crossline profiles, transmission factor, and output factor with and without the IQM. PDD, transmission factor, and output factor were measured for square fields of 3, 5, 10, 15, 20, 25, and 30 cm and profiles were performed for square fields of 3, 5, 10, 20, and 30 cm at 5‐, 10‐, and 30‐cm depth. Results The differences in surface dose of all energies for square fields of 3, 5, 10, 15, 20, and 25 cm were within 3.7% whereas for a square field of 30 cm, they were 4.6%, 6.8%, 6.7%, and 8.7% for 4‐MV, 6‐MV, 6‐MV‐FFF, and 10‐MV, respectively. Differences in PDD20,10, TPR20,10, PDD, profiles, and output factors were within ±1%. Local and global gamma values (2%/2 mm) were below 1 for PDD beyond dmax and inline/crossline profiles in the central beam region, respectively. The gamma passing rates (10% threshold) for PDD curves and profiles were above 95% at 2%/2 mm. The transmission factors for 4‐MV, 6‐MV, 6‐MV‐FFF, and 10‐MV for field sizes from 3 × 3 to 30 × 30 cm2 were 0.926–0.933, 0.937–0.941, 0.937–0.939, and 0.949–0.953, respectively. Conclusions The influence of the IQM on the beam quality (in particular 4‐MV X‐ray has not verified before) was tested and introduced a slight beam perturbation at the surface and build‐up region and the edge of the crossline/inline profiles. To use IQM in pre‐ and intra‐treatment quality assurance, a tray factor should be put into treatment planning systems for the dose calculation for the 4‐, 6‐, 10‐, and 6‐MV flattening filter‐free photon beams to compensate the beam attenuation of the IQM detector.
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Affiliation(s)
- Trang Hong Thi Nguyen
- Division of Health Sciences, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
| | - Haruna Yokoyama
- Department of Radiological Technology, Kanazawa University Hospital, Kanazawa, Japan
| | - Hironori Kojima
- Department of Radiological Technology, Kanazawa University Hospital, Kanazawa, Japan
| | - Naoki Isomura
- Department of Radiological Technology, Kanazawa University Hospital, Kanazawa, Japan
| | - Akihiro Takemura
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Shinichi Ueda
- Department of Radiological Technology, Kanazawa University Hospital, Kanazawa, Japan
| | - Kimiya Noto
- Department of Radiological Technology, Kanazawa University Hospital, Kanazawa, Japan
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C M, F C P DP. X-Ray Beam Segment Size and Entrance Location Effects on the Integral Quality Monitor (IQM®) Signal and Usefulness in Predicting Complex Segment Output Signals. J Biomed Phys Eng 2020; 10:395-410. [PMID: 32802788 PMCID: PMC7416101 DOI: 10.31661/jbpe.v0i0.1162] [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: 04/15/2019] [Accepted: 06/12/2019] [Indexed: 11/16/2022]
Abstract
Background: The Integral Quality Monitor (IQM®) is an independent online dosimetry device attached to the treatment machine to monitor the accuracy of radiation delivery. Objective: This study investigates the influence of beam segment size and displacement as projected onto the IQM chamber on the signals and determine how individual signals can be added to get a combined segment signal made up of smaller segments. Material and Methods: This is an experimental original research type of study. IQM response maps were generated by irradiating the IQM sensitive area with small elementary segments and measuring their corresponding signals per monitor unit (MU). The output signal/MU was measured for regular and irregular fields and compared with the predicted signal/MU obtained from decomposing the open segment into a set of smaller regular segments and summing their signals from their respective response maps. The dependence of signals on segment size, shape, location and combination was investigated. Results: Predicted signals were calculated within 95-98 % accuracy for regular fields and 90-98% for irregular fields. More uniform fluence contain distribution for larger segments was observed. Response maps were consistent with the geometrical symmetry in the chamber’s wedge shape and the symmetry in the linac fluence. Conclusion: The field decomposition method allows the pre-calculation of known segment output signals per MU within 2% error, although the accuracy drops significantly for smaller, irregular fields. A method of correcting predicted signals in smaller segments needs to be laid down to get a better match with measured signals.
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Affiliation(s)
- Mahuvava C
- PhD, Department of Medical Physics, Faculty of Health Sciences, University of the Free State, P.O. Box 339, Bloemfontein, 9300 South Africa
| | - Du Plessis F C P
- PhD, Department of Medical Physics, Faculty of Health Sciences, University of the Free State, P.O. Box 339, Bloemfontein, 9300 South Africa
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Esposito M, Villaggi E, Bresciani S, Cilla S, Falco MD, Garibaldi C, Russo S, Talamonti C, Stasi M, Mancosu P. Estimating dose delivery accuracy in stereotactic body radiation therapy: A review of in-vivo measurement methods. Radiother Oncol 2020; 149:158-167. [PMID: 32416282 DOI: 10.1016/j.radonc.2020.05.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 05/08/2020] [Accepted: 05/10/2020] [Indexed: 12/25/2022]
Abstract
Stereotactic body radiation therapy (SBRT) has been recognized as a standard treatment option for many anatomical sites. Sophisticated radiation therapy techniques have been developed for carrying out these treatments and new quality assurance (QA) programs are therefore required to guarantee high geometrical and dosimetric accuracy. This paper focuses on recent advances on in-vivo measurements methods (IVM) for SBRT treatment. More specifically, all of the online QA methods for estimating the effective dose delivered to patients were compared. Determining the optimal IVM for performing SBRT treatments would reduce the risk of errors that could jeopardize treatment outcome. A total of 89 papers were included. The papers were subdivided into the following topics: point dosimeters (PD), transmission detectors (TD), log file analysis (LFA), electronic portal imaging device dosimetry (EPID), dose accumulation methods (DAM). The detectability capability of the main IVM detectors/devices were evaluated. All of the systems have some limitations: PD has no spatial data, EPID has limited sensitivity towards set-up errors and intra-fraction motion in some anatomical sites, TD is insensitive towards patient related errors, LFA is not an independent measure, DAMs are not always based on measures. In order to minimize errors in SBRT dose delivery, we recommend using synergic combinations of two or more of the systems described in our review: on-line tumor position and patient information should be combined with MLC position and linac output detection accuracy. In this way the effects of SBRT dose delivery errors will be reduced.
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Affiliation(s)
- Marco Esposito
- S.C. Fisica Sanitaria Firenze-Empoli, Azienda Sanitaria USL Toscana Centro, Italy.
| | | | - Sara Bresciani
- Medical Physics, Candiolo Cancer Institute - FPO IRCCS, Turin, Italy
| | - Savino Cilla
- Medical Physics Unit, Gemelli Molise Hospital, Campobasso, Italy
| | - Maria Daniela Falco
- Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Cristina Garibaldi
- Radiation Research Unit, European Institute of Oncology IRCCS, Milan, Italy
| | - Serenella Russo
- S.C. Fisica Sanitaria Firenze-Empoli, Azienda Sanitaria USL Toscana Centro, Italy
| | - Cinzia Talamonti
- University of Florence, Dept Biomedical Experimental and Clinical Science, "Mario Serio", Medical Physics Unit, AOU Careggi, Florence, Italy
| | - Michele Stasi
- Medical Physics, Candiolo Cancer Institute - FPO IRCCS, Turin, Italy
| | - Pietro Mancosu
- Medical Physics Unit of Radiotherapy Dept., Humanitas Clinical and Research Hospital - IRCCS, Rozzano, Italy
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Mahuvava C, Du Plessis FCP. External beam patient dose verification based on the integral quality monitor (IQM ®) output signals. Biomed Phys Eng Express 2020; 6:035014. [PMID: 33438659 DOI: 10.1088/2057-1976/ab5f55] [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
BACKGROUND The Integral Quality Monitor (IQM®) can essentially measure the integral fluence through a segment and provide real-time information about the accuracy of radiation delivery based on comparisons of measured segment signals and pre-calculated reference values. However, the present IQM chamber cannot calculate the dose in the patient. AIM This study aims to make use of IQM field output signals to calculate the number of monitor units (MUs) delivered through an arbitrary treatment field in order to convert Monte Carlo (MC)-generated dose distributions in a patient model into absolute dose. METHODS XiO and Monaco treatment planning systems (TPSs) were used to define treatment beam portals for cervix and esophagus conformal radiotherapy as well as prostate intensity-modulated radiotherapy for the translation of patient and beam setup information from DICOM to DOSXYZnrc. The planned beams were simulated in a patient model built from actual patient CT images and each simulated integral field/segment was weighted with its MUs before summation to get the total dose in the plan. The segment beam weights (MUs) were calculated as the ratio of the open-field IQM measured signal and the calculated signal per MU extracted from chamber sensitivity maps. These are the actual MUs delivered not just MUs set. The beam weighting method was evaluated by comparing weighted MC doses with original planned doses using profile and isodose comparisons, dose difference maps, γ analysis and dose-volume histogram (DVH) data. RESULTS γ pass rates of up to 98% were found, except for the esophagus plan where the γ pass rate was below 45%. DVH comparisons showed good agreement for most organs, with the largest differences observed in low-density lung. However, these discrepancies can result from differences in dose calculation algorithms or differences in MUs used for dose weighting planned by the TPS and MUs calculated using IQM field output signals. To test this, a 4-field box DOSXYZnrc MC simulation weighted with planned (XiO) MUs was compared with the same simulation weighted with IQM-based MUs. Dose differences of up to 5% were found on the isocentre slice. For XiO versus MC, up to 7% dose differences were found, indicating additional error due to limitations of XiO's superposition algorithm. Dose differences between MC Monaco and MC EGSnrc were less than 3%. CONCLUSIONS The most valuable comparison was MC versus MC as it eliminated algorithm discrepancies and evaluated dose differences precisely according to beam weighting. For XiO TPS, care must be taken as dose differences may also arise due to limitations in XiO's planning software, not merely due to differences in MUs. Overall, the IQM was successfully used to compute beam dose weights to accurately reconstruct the patient dose using unweighted MC beams. Our technique can be used for pre-treatment QA provided each segment output is known and an accurate linac source model is available.
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Affiliation(s)
- Courage Mahuvava
- Medical Physics Department, Faculty of Health Sciences, University of the Free State, P O Box 339, Bloemfontein 9300, South Africa
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Utitsarn K, Biasi G, Stansook N, Alrowaili ZA, Petasecca M, Carolan M, Perevertaylo VL, Tomé WA, Kron T, Lerch MLF, Rosenfeld AB. Two-dimensional solid-state array detectors: A technique for in vivo dose verification in a variable effective area. J Appl Clin Med Phys 2019; 20:88-94. [PMID: 31609090 PMCID: PMC6839376 DOI: 10.1002/acm2.12744] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 07/25/2019] [Accepted: 09/16/2019] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We introduce a technique that employs a 2D detector in transmission mode (TM) to verify dose maps at a depth of dmax in Solid Water. TM measurements, when taken at a different surface-to-detector distance (SDD), allow for the area at dmax (in which the dose map is calculated) to be adjusted. METHODS We considered the detector prototype "MP512" (an array of 512 diode-sensitive volumes, 2 mm spatial resolution). Measurements in transmission mode were taken at SDDs in the range from 0.3 to 24 cm. Dose mode (DM) measurements were made at dmax in Solid Water. We considered radiation fields in the range from 2 × 2 cm2 to 10 × 10 cm2 , produced by 6 MV flattened photon beams; we derived a relationship between DM and TM measurements as a function of SDD and field size. The relationship was used to calculate, from TM measurements at 4 and 24 cm SDD, dose maps at dmax in fields of 1 × 1 cm2 and 4 × 4 cm2 , and in IMRT fields. Calculations were cross-checked (gamma analysis) with the treatment planning system and with measurements (MP512, films, ionization chamber). RESULTS In the square fields, calculations agreed with measurements to within ±2.36%. In the IMRT fields, using acceptance criteria of 3%/3 mm, 2%/2 mm, 1%/1 mm, calculations had respective gamma passing rates greater than 96.89%, 90.50%, 62.20% (for a 4 cm SSD); and greater than 97.22%, 93.80%, 59.00% (for a 24 cm SSD). Lower rates (1%/1 mm criterion) can be explained by submillimeter misalignments, dose averaging in calculations, noise artifacts in film dosimetry. CONCLUSIONS It is possible to perform TM measurements at the SSD which produces the best fit between the area at dmax in which the dose map is calculated and the size of the monitored target.
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Affiliation(s)
- Kananan Utitsarn
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
- Department of Medical ServicesLopburi Cancer HospitalLopburiThailand
| | - Giordano Biasi
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
| | - Nauljun Stansook
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
- Department of RadiologyFaculty of MedicineMahidol UniversityBangkokThailand
| | - Ziyad A. Alrowaili
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
- Physics DepartmentCollege of ScienceJouf UniversitySakakaSaudi Arabia
| | - Marco Petasecca
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
| | - Martin Carolan
- Illawarra Cancer Care Centre (ICCC)Wollongong HospitalWollongongNSWAustralia
| | | | - Wolfgang A. Tomé
- Department of Radiation OncologyAlbert Einstein College of MedicineNew York CityNYUSA
| | - Tomas Kron
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
- Department of Physical SciencesPeter MacCallum Cancer CentreMelbourneVic.Australia
- Sir Peter MacCallum Cancer InstituteUniversity of MelbourneMelbourneVic.Australia
| | - Michael L. F. Lerch
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
| | - Anatoly B. Rosenfeld
- Centre for Medical Radiation Physics (CMRP)University of WollongongWollongongNSWAustralia
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Turgeon V, Kertzscher G, Carroll L, Hopewell R, Massarweh G, Enger SA. Characterization of scintillating fibers for use as positron detector in positron emission tomography. Phys Med 2019; 65:114-120. [PMID: 31450121 DOI: 10.1016/j.ejmp.2019.08.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 07/15/2019] [Accepted: 08/11/2019] [Indexed: 10/26/2022] Open
Abstract
PURPOSE Manual and automatic blood sampling at different time intervals is considered the gold standard to determine the arterial input function (AIF) in dynamic positron emission tomography (PET). However, blood sampling is characterized by poor time resolution and is an invasive procedure. The aim of this study was to characterize the scintillating fibers used to develop a non-invasive positron detector. METHODS The detector consists of a scintillating fiber coupled at each end to transmission fiber-optic cables that are connected to photo multiplier tubes in a dual readout setup. The detector is designed to be wrapped around the wrist of the patient undergoing dynamic PET. The attenuation length and bending losses were measured with excitation from gamma radiation (137Cs) and ultraviolet (UV) light. The response to positron-emitting radio-tracers was evaluated with 18F and 11C. RESULTS The attenuation length for a 3.0 m and 1.5 m long scintillating fiber both coincides with the attenuation length given by the manufacturer when excited with the 137Cs source, but not with the UV source due to the differences in scintillation mechanisms. The bending losses are smaller than the measurement uncertainty for the 137Cs source irradiation, and increase when the bending radius decrease for the UV source irradiation. The signal-to-noise ratio for 18F and 11C solutions are 1.98 and 22.54 respectively. The measured decay constant of 11C agrees with its characteristic value. CONCLUSION The performed measurements in the dual readout configuration suggest that scintillating fibers may be suitable to determine the AIF non-invasively.
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Affiliation(s)
- Vincent Turgeon
- Medical Physics Unit, McGill University, Montreal, Quebec, Canada; Jewish General Hospital, Montreal, Quebec, Canada.
| | | | - Liam Carroll
- Medical Physics Unit, McGill University, Montreal, Quebec, Canada
| | - Robert Hopewell
- Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada
| | - Gassan Massarweh
- Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada
| | - Shirin A Enger
- Medical Physics Unit, McGill University, Montreal, Quebec, Canada; Department of Oncology, McGill University, Montreal, Quebec, Canada; Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
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Sarkar V, Paxton A, Kunz J, Szegedi M, Nelson G, Rassiah‐Szegedi P, Zhao H, Huang YJ, Su F, Salter BJ. A systematic evaluation of the error detection abilities of a new diode transmission detector. J Appl Clin Med Phys 2019; 20:122-132. [PMID: 31385436 PMCID: PMC6753730 DOI: 10.1002/acm2.12691] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 06/19/2019] [Accepted: 07/20/2019] [Indexed: 02/02/2023] Open
Abstract
Transmission detectors meant to measure every beam delivered on a linear accelerator are now becoming available for monitoring the quality of the dose distribution delivered to the patient daily. The purpose of this work is to present results from a systematic evaluation of the error detection capabilities of one such detector, the Delta4 Discover. Existing patient treatment plans were modified through in‐house‐developed software to mimic various delivery errors that have been observed in the past. Errors included shifts in multileaf collimator leaf positions, changing the beam energy from what was planned, and a simulation of what would happen if the secondary collimator jaws did not track with the leaves as they moved. The study was done for simple 3D plans, static gantry intensity modulated radiation therapy plans as well as dynamic arc and volumetric modulated arc therapy (VMAT) plans. Baseline plans were delivered with both the Discover device and the Delta4 Phantom+ to establish baseline gamma pass rates. Modified plans were then delivered using the Discover only and the predicted change in gamma pass rate, as well as the detected leaf positions were evaluated. Leaf deviations as small as 0.5 mm for a static three‐dimensional field were detected, with this detection limit growing to 1 mm with more complex delivery modalities such as VMAT. The gamma pass rates dropped noticeably once the intentional leaf error introduced was greater than the distance‐to‐agreement criterion. The unit also demonstrated the desired drop in gamma pass rates of at least 20% when jaw tracking was intentionally disabled and when an incorrect energy was used for the delivery. With its ability to find errors intentionally introduced into delivered plans, the Discover shows promise of being a valuable, independent error detection tool that should serve to detect delivery errors that can occur during radiotherapy treatment.
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Affiliation(s)
| | | | | | | | | | | | - Hui Zhao
- University of UtahSalt Lake CityUTUSA
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Razinskas G, Wegener S, Greber J, Sauer OA. Sensitivity of the IQM transmission detector to errors of VMAT plans. Med Phys 2018; 45:5622-5630. [DOI: 10.1002/mp.13228] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 09/28/2018] [Accepted: 09/28/2018] [Indexed: 11/09/2022] Open
Affiliation(s)
- Gary Razinskas
- Radiation Oncology University of Wuerzburg Josef‐Schneider‐Str. 11 97080 Wuerzburg Germany
| | - Sonja Wegener
- Radiation Oncology University of Wuerzburg Josef‐Schneider‐Str. 11 97080 Wuerzburg Germany
| | - Johannes Greber
- Radiation Oncology University of Wuerzburg Josef‐Schneider‐Str. 11 97080 Wuerzburg Germany
| | - Otto A. Sauer
- Radiation Oncology University of Wuerzburg Josef‐Schneider‐Str. 11 97080 Wuerzburg Germany
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11
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Thermoplastic wrapped lead sheet to reduce cardiac device cumulative dose. Med Dosim 2018; 44:93-101. [PMID: 29598925 DOI: 10.1016/j.meddos.2018.02.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 02/13/2018] [Accepted: 02/16/2018] [Indexed: 11/21/2022]
Abstract
The objective of this project is to evaluate the percentage dose reduction in cardiac implantable electronic devices (CIEDs) using a thermoplastic wrapped lead sheet. The dose to CIED is evaluated in various situations with and without a lead shield. The efficiency of this type of shielding is supported by measurements made with a commercial plastic scintillation detector (PSD). Percentage depth dose (PDD) curve and lateral dose measurements (LDMs) were made with and without shielding for photon and electron beams. Photon LDMs were made at a depth of 0.5 cm. PSD measurements were compared with dose calculation from the treatment planning system (TPS). The benefit of shielding is greater at 23 MV than at 6 MV, with an average reduction of 71% and 59% of dose, respectively, for out-of-field distance range between 3 and 15 cm. Measurement of posterior beams shows there is no significant increase in skin dose due to backscatter from the lead sheet even when the field intercepts it. Large deviations between TPS calculation and measurements have been observed. The use of lead shielding with an anterior field is advised and provides an easy way to decrease the cumulative dose to CIEDs. Interception of shielding by an electron beam would increase significantly the cumulative dose to CIED for high energies or decrease the quality of the treatment. For a posterior out-of-field, shielding does not have a significant impact on CIED dose.
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Development of Optical Fiber Based Measurement System for the Verification of Entrance Dose Map in Pencil Beam Scanning Proton Beam. SENSORS 2018; 18:s18010227. [PMID: 29342941 PMCID: PMC5796397 DOI: 10.3390/s18010227] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 01/11/2018] [Accepted: 01/13/2018] [Indexed: 11/28/2022]
Abstract
This study describes the development of a beam monitoring system for the verification of entrance dose map in pencil beam scanning (PBS) proton therapy based on fiber optic radiation sensors (FORS) and the validation of this system through a feasibility study. The beam monitoring system consisted of 128 optical fibers optically coupled to photo-multiplier tubes. The performance of the beam monitoring system based on FORS was verified by comparing 2D dose maps of square-shaped fields of various sizes, which were obtained using conventional dosimeters such as MatriXX and EBT3 film, with those measured using FORS. The resulting full-width at half maximum and penumbra were compared for PBS proton beams, with a ≤2% difference between each value, indicating that measurements using the conventional dosimetric tool corresponded to measurements based on FORS. For irregularly-shaped fields, a comparison based on the gamma index between 2D dose maps obtained using MatriXX and EBT3 film and the 2D dose map measured by the FORS showed passing rates of 96.9 ± 1.3% and 96.2 ± 1.9%, respectively, confirming that FORS-based measurements for PBS proton therapy agreed well with those measured using the conventional dosimetric tools. These results demonstrate that the developed beam monitoring system based on FORS is good candidate for monitoring the entrance dose map in PBS proton therapy.
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Hoffman D, Chung E, Hess C, Stern R, Benedict S. Characterization and evaluation of an integrated quality monitoring system for online quality assurance of external beam radiation therapy. J Appl Clin Med Phys 2016; 18:40-48. [PMID: 28291937 PMCID: PMC5689870 DOI: 10.1002/acm2.12014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 09/10/2016] [Indexed: 11/16/2022] Open
Abstract
Purpose The aim of this work was to comprehensively evaluate a new large field ion chamber transmission detector, Integral Quality Monitor (IQM), for online external photon beam verification and quality assurance. The device is designed to be mounted on the linac accessory tray to measure and verify photon energy, field shape, gantry position, and fluence before and during patient treatment. Methods Our institution evaluated the newly developed ion chamber's effect on photon beam fluence, response to dose, detection of photon fluence modification, and the accuracy of the integrated barometer, thermometer, and inclinometer. The detection of photon fluence modifications was performed by measuring 6 MV with fields of 10 cm × 10 cm and 1 cm × 1 cm “correct” beam, and then altering the beam modifiers to simulate minor and major delivery deviations. The type and magnitude of the deviations selected for evaluation were based on the specifications for photon output and MLC position reported in AAPM Task Group Report 142. Additionally, the change in ion chamber signal caused by a simulated IMRT delivery error is evaluated. Results The device attenuated 6 MV, 10 MV, and 15 MV photon beams by 5.43 ± 0.02%, 4.60 ± 0.02%, and 4.21 ± 0.03%, respectively. Photon beam profiles were altered with the IQM by < 1.5% in the nonpenumbra regions of the beams. The photon beam profile for a 1 cm × 1 cm2 fields were unchanged by the presence of the device. The large area ion chamber measurements were reproducible on the same day with a 0.14% standard deviation and stable over 4 weeks with a 0.47% SD. The ion chamber's dose–response was linear (R2 = 0.99999). The integrated thermometer agreed to a calibrated thermometer to within 1.0 ± 0.7°C. The integrated barometer agreed to a mercury barometer to within 2.3 ± 0.4 mmHg. The integrated inclinometer gantry angle measurement agreed with the spirit level at 0 and 180 degrees within 0.03 ± 0.01 degrees and 0.27 ± 0.03 at 90 and 270 degrees. For the collimator angle measurement, the IQM inclinometer agreed with a plum‐bob within 0.3 ± 0.2 degrees. The simulated IMRT error increased the ion chamber signal by a factor of 11–238 times the baseline measurement for each segment. Conclusions The device signal was dependent on variations in MU delivered, field position, single MLC leaf position, and nominal photon energy for both the 1 cm × 1 cm and 10 cm × 10 cm fields. This detector has demonstrated utility repeated photon beam measurement, including in IMRT and small field applications.
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Affiliation(s)
- David Hoffman
- Department of Radiation Medicine and Applied Sciences, University of California, San Diego, CA, USA
| | - Eunah Chung
- Department of Radiation Oncology, Samsung Medical Center, Seoul, South Korea
| | - Clayton Hess
- Pediatric Radiation Oncology, Harvard Medical School, Boston, MA, USA
| | - Robin Stern
- Department of Radiation Oncology, University of California, Davis, Sacramento, CA, USA
| | - Stanley Benedict
- Department of Radiation Oncology, University of California, Davis, Sacramento, CA, USA
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Beaulieu L, Beddar S. Review of plastic and liquid scintillation dosimetry for photon, electron, and proton therapy. Phys Med Biol 2016; 61:R305-R343. [DOI: 10.1088/0031-9155/61/20/r305] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Li T, Wu QJ, Matzen T, Yin FF, O'Daniel JC. Diode-based transmission detector for IMRT delivery monitoring: a validation study. J Appl Clin Med Phys 2016; 17:235-244. [PMID: 27685115 PMCID: PMC5874094 DOI: 10.1120/jacmp.v17i5.6204] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 06/02/2016] [Accepted: 05/02/2016] [Indexed: 11/23/2022] Open
Abstract
The purpose of this work was to evaluate the potential of a new transmission detector for real‐time quality assurance of dynamic‐MLC‐based radiotherapy. The accuracy of detecting dose variation and static/dynamic MLC position deviations was measured, as well as the impact of the device on the radiation field (surface dose, transmission). Measured dose variations agreed with the known variations within 0.3%. The measurement of static and dynamic MLC position deviations matched the known deviations with high accuracy (0.7–1.2 mm). The absorption of the device was minimal (∼ 1%). The increased surface dose was small (1%–9%) but, when added to existing collimator scatter effects could become significant at large field sizes (≥30×30 cm2). Overall the accuracy and speed of the device show good potential for real‐time quality assurance. PACS number(s): 87.55.Qr
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Noel CE, Santanam L, Parikh PJ, Mutic S. Process-based quality management for clinical implementation of adaptive radiotherapy. Med Phys 2015; 41:081717. [PMID: 25086527 DOI: 10.1118/1.4890589] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Intensity-modulated adaptive radiotherapy (ART) has been the focus of considerable research and developmental work due to its potential therapeutic benefits. However, in light of its unique quality assurance (QA) challenges, no one has described a robust framework for its clinical implementation. In fact, recent position papers by ASTRO and AAPM have firmly endorsed pretreatment patient-specific IMRT QA, which limits the feasibility of online ART. The authors aim to address these obstacles by applying failure mode and effects analysis (FMEA) to identify high-priority errors and appropriate risk-mitigation strategies for clinical implementation of intensity-modulated ART. METHODS An experienced team of two clinical medical physicists, one clinical engineer, and one radiation oncologist was assembled to perform a standard FMEA for intensity-modulated ART. A set of 216 potential radiotherapy failures composed by the forthcoming AAPM task group 100 (TG-100) was used as the basis. Of the 216 failures, 127 were identified as most relevant to an ART scheme. Using the associated TG-100 FMEA values as a baseline, the team considered how the likeliness of occurrence (O), outcome severity (S), and likeliness of failure being undetected (D) would change for ART. New risk priority numbers (RPN) were calculated. Failures characterized by RPN ≥ 200 were identified as potentially critical. RESULTS FMEA revealed that ART RPN increased for 38% (n = 48/127) of potential failures, with 75% (n = 36/48) attributed to failures in the segmentation and treatment planning processes. Forty-three of 127 failures were identified as potentially critical. Risk-mitigation strategies include implementing a suite of quality control and decision support software, specialty QA software/hardware tools, and an increase in specially trained personnel. CONCLUSIONS Results of the FMEA-based risk assessment demonstrate that intensity-modulated ART introduces different (but not necessarily more) risks than standard IMRT and may be safely implemented with the proper mitigations.
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Affiliation(s)
- Camille E Noel
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Lakshmi Santanam
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Parag J Parikh
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Sasa Mutic
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110
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Goulet M, Rilling M, Gingras L, Beddar S, Beaulieu L, Archambault L. Novel, full 3D scintillation dosimetry using a static plenoptic camera. Med Phys 2015; 41:082101. [PMID: 25086549 DOI: 10.1118/1.4884036] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Patient-specific quality assurance (QA) of dynamic radiotherapy delivery would gain from being performed using a 3D dosimeter. However, 3D dosimeters, such as gels, have many disadvantages limiting to quality assurance, such as tedious read-out procedures and poor reproducibility. The purpose of this work is to develop and validate a novel type of high resolution 3D dosimeter based on the real-time light acquisition of a plastic scintillator volume using a plenoptic camera. This dosimeter would allow for the QA of dynamic radiation therapy techniques such as intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT). METHODS A Raytrix R5 plenoptic camera was used to image a 10 × 10 × 10 cm(3) EJ-260 plastic scintillator embedded inside an acrylic phantom at a rate of one acquisition per second. The scintillator volume was irradiated with both an IMRT and VMAT treatment plan on a Clinac iX linear accelerator. The 3D light distribution emitted by the scintillator volume was reconstructed at a 2 mm resolution in all dimensions by back-projecting the light collected by each pixel of the light-field camera using an iterative reconstruction algorithm. The latter was constrained by a beam's eye view projection of the incident dose acquired using the portal imager integrated with the linac and by physical consideration of the dose behavior as a function of depth in the phantom. RESULTS The absolute dose difference between the reconstructed 3D dose and the expected dose calculated using the treatment planning software Pinnacle(3) was on average below 1.5% of the maximum dose for both integrated IMRT and VMAT deliveries, and below 3% for each individual IMRT incidences. Dose agreement between the reconstructed 3D dose and a radiochromic film acquisition in the same experimental phantom was on average within 2.1% and 1.2% of the maximum recorded dose for the IMRT and VMAT delivery, respectively. CONCLUSIONS Using plenoptic camera technology, the authors were able to perform millimeter resolution, water-equivalent dosimetry of an IMRT and VMAT plan over a whole 3D volume. Since no moving parts are required in the dosimeter, the incident dose distribution can be acquired as a function of time, thus enabling the validation of static and dynamic radiation delivery with photons, electrons, and heavier ions.
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Affiliation(s)
- Mathieu Goulet
- Département de physique, de génie physique et d'optique and Centre de recherche sur le cancer, Université Laval, Québec, Québec G1V 0A6, Canada and Département de radio-oncologie and CRCHU de Québec, CHU de Québec, 11 Côte du Palais, Québec, Québec G1R 2J6, Canada
| | - Madison Rilling
- Département de physique, de génie physique et d'optique and Centre de recherche sur le cancer, Université Laval, Québec, Québec G1V 0A6, Canada; Département de radio-oncologie and CRCHU de Québec, CHU de Québec, 11 Côte du Palais, Québec, Québec G1R 2J6, Canada; and Department of Physics, McGill University, Montréal, Québec H3A 0G4, Canada
| | - Luc Gingras
- Département de physique, de génie physique et d'optique and Centre de recherche sur le cancer, Université Laval, Québec, Québec G1V 0A6, Canada and Département de radio-oncologie and CRCHU de Québec, CHU de Québec, 11 Côte du Palais, Québec, Québec G1R 2J6, Canada
| | - Sam Beddar
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 94, Houston, Texas 77030
| | - Luc Beaulieu
- Département de physique, de génie physique et d'optique and Centre de recherche sur le cancer, Université Laval, Québec, Québec G1V 0A6, Canada and Département de radio-oncologie and CRCHU de Québec, CHU de Québec, 11 Côte du Palais, Québec, Québec G1R 2J6, Canada
| | - Louis Archambault
- Département de physique, de génie physique et d'optique and Centre de recherche sur le cancer, Université Laval, Québec, Québec G1V 0A6, Canada and Département de radio-oncologie and CRCHU de Québec, CHU de Québec, 11 Côte du Palais, Québec, Québec G1R 2J6, Canada
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Chang J, Heaton RK, Mahon R, Norrlinger BD, Jaffray DA, Cho YB, Islam MK. A method for online verification of adapted fields using an independent dose monitor. Med Phys 2014; 40:072104. [PMID: 23822448 DOI: 10.1118/1.4811204] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Clinical implementation of online adaptive radiotherapy requires generation of modified fields and a method of dosimetric verification in a short time. We present a method of treatment field modification to account for patient setup error, and an online method of verification using an independent monitoring system. METHODS The fields are modified by translating each multileaf collimator (MLC) defined aperture in the direction of the patient setup error, and magnifying to account for distance variation to the marked isocentre. A modified version of a previously reported online beam monitoring system, the integral quality monitoring (IQM) system, was investigated for validation of adapted fields. The system consists of a large area ion-chamber with a spatial gradient in electrode separation to provide a spatially sensitive signal for each beam segment, mounted below the MLC, and a calculation algorithm to predict the signal. IMRT plans of ten prostate patients have been modified in response to six randomly chosen setup errors in three orthogonal directions. RESULTS A total of approximately 49 beams for the modified fields were verified by the IQM system, of which 97% of measured IQM signal agree with the predicted value to within 2%. CONCLUSIONS The modified IQM system was found to be suitable for online verification of adapted treatment fields.
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Affiliation(s)
- Jina Chang
- Department of Radiation Physics, Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario M5G 2M9, Canada
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Goulet M, Archambault L, Beaulieu L, Gingras L. 3D tomodosimetry using long scintillating fibers: A feasibility study. Med Phys 2013; 40:101703. [DOI: 10.1118/1.4819937] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Beaulieu L, Goulet M, Archambault L, Beddar S. Current status of scintillation dosimetry for megavoltage beams. ACTA ACUST UNITED AC 2013. [DOI: 10.1088/1742-6596/444/1/012013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Goulet M, Archambault L, Beaulieu L, Gingras L. High resolution 2D dose measurement device based on a few long scintillating fibers and tomographic reconstruction. Med Phys 2012; 39:4840-9. [PMID: 22894410 DOI: 10.1118/1.4736526] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Patient-specific QA of highly conformal radiotherapy treatments are usually conducted using 2D or 3D dosimetry of the incident dose distribution in a water-equivalent phantom. However, dosimeters typically used for this task usually lack in either spatial resolution or dose accuracy. The purpose of this work is to develop and validate a novel type of high resolution 2D dosimeter based on the tomographic reconstruction of the dose projections obtained using long scintillating fibers for the quality assurance of modern radiotherapy techniques such as IMRT. METHODS Fifty parallel scintillating fibers were aligned in a 30 cm diameter cylindrical masonite phantom with a 95 cm source-to-surface distance and a 100 cm source-to-fibers distance. The fibers were disposed so that the effective detection area of the scintillating fibers was a 20 cm diameter disk. Both ends of each scintillating fiber were coupled to clear optical fibers to enable light collection by a single CCD camera. Seven IMRT segments and two square fields were acquired using 18 projections over a 170° rotation of the device. Computation of the dose integrals was made for each scintillating fiber using the irradiation of known rectangular reference fields. Dose reconstructions were conducted using a total-variation minimization iterative reconstruction algorithm. Eight monitor units were programmed for each projection and the reconstructed dose grid pixel resolution was set to 1 × 1 mm(2). RESULTS 3%∕3 mm gamma tests conducted between the reconstructed IMRT dose distributions and the dose calculated with the treatment planning system Pinnacle(3) were on average successful for 99.6% of the dose pixels with a predicted dose of at least 10% of the maximum dose. The dose profiles for both square fields and IMRT segments agreed within 2% to the dose calculated with Pinnacle(3) except in high dose gradient regions, and were comparable to the dose measured using an ionization chamber array (IBA MatriXX) and radiographic films (Kodak XV2). CONCLUSIONS Using tomographic reconstruction on the projections acquired with rotating scintillating fibers, we were able to perform water-equivalent 2D dosimetry of square fields and IMRT segments with acceptable accuracy and high spatial resolution. The underlying concept of tomographic dosimetry and the small number of fibers needed to reconstruct a given 2D dose distribution offer new dosimetric possibilities, both applicable to 2D and 3D dosimetry.
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Affiliation(s)
- Mathieu Goulet
- Département de Radio-Oncologie et Centre de Recherche en Cancérologie, Hotel-Dieu de Québec, 11 Cote du Palais, Québec, Québec G1R 2J6, Canada
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