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Ketabi A, Karbasi S, Faghihi R, Mosleh-Shirazi MA. A phantom-based experimental and Monte Carlo study of the suitability of in-vivo diodes and TLD for entrance in-vivo dosimetry in small-to-medium sized 6 MV photon fields. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Das IJ, Francescon P, Moran JM, Ahnesjö A, Aspradakis MM, Cheng CW, Ding GX, Fenwick JD, Saiful Huq M, Oldham M, Reft CS, Sauer OA. Report of AAPM Task Group 155: Megavoltage photon beam dosimetry in small fields and non-equilibrium conditions. Med Phys 2021; 48:e886-e921. [PMID: 34101836 DOI: 10.1002/mp.15030] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/06/2021] [Accepted: 06/02/2021] [Indexed: 12/14/2022] Open
Abstract
Small-field dosimetry used in advance treatment technologies poses challenges due to loss of lateral charged particle equilibrium (LCPE), occlusion of the primary photon source, and the limited choice of suitable radiation detectors. These challenges greatly influence dosimetric accuracy. Many high-profile radiation incidents have demonstrated a poor understanding of appropriate methodology for small-field dosimetry. These incidents are a cause for concern because the use of small fields in various specialized radiation treatment techniques continues to grow rapidly. Reference and relative dosimetry in small and composite fields are the subject of the International Atomic Energy Agency (IAEA) dosimetry code of practice that has been published as TRS-483 and an AAPM summary publication (IAEA TRS 483; Dosimetry of small static fields used in external beam radiotherapy: An IAEA/AAPM International Code of Practice for reference and relative dose determination, Technical Report Series No. 483; Palmans et al., Med Phys 45(11):e1123, 2018). The charge of AAPM task group 155 (TG-155) is to summarize current knowledge on small-field dosimetry and to provide recommendations of best practices for relative dose determination in small megavoltage photon beams. An overview of the issue of LCPE and the changes in photon beam perturbations with decreasing field size is provided. Recommendations are included on appropriate detector systems and measurement methodologies. Existing published data on dosimetric parameters in small photon fields (e.g., percentage depth dose, tissue phantom ratio/tissue maximum ratio, off-axis ratios, and field output factors) together with the necessary perturbation corrections for various detectors are reviewed. A discussion on errors and an uncertainty analysis in measurements is provided. The design of beam models in treatment planning systems to simulate small fields necessitates special attention on the influence of the primary beam source and collimating devices in the computation of energy fluence and dose. The general requirements for fluence and dose calculation engines suitable for modeling dose in small fields are reviewed. Implementations in commercial treatment planning systems vary widely, and the aims of this report are to provide insight for the medical physicist and guidance to developers of beams models for radiotherapy treatment planning systems.
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Affiliation(s)
- Indra J Das
- Department of Radiation Oncology, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Paolo Francescon
- Department of Radiation Oncology, Ospedale Di Vicenza, Vicenza, Italy
| | - Jean M Moran
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Anders Ahnesjö
- Medical Radiation Sciences, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Maria M Aspradakis
- Institute of Radiation Oncology, Cantonal Hospital of Graubünden, Chur, Switzerland
| | - Chee-Wai Cheng
- Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
| | - George X Ding
- Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - John D Fenwick
- Molecular and Clinical Cancer Medicine, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - M Saiful Huq
- Department of Radiation Oncology, University of Pittsburgh, School of Medicine and UPMC Hillman Cancer Center, Pittsburgh, PA, USA
| | - Mark Oldham
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
| | - Chester S Reft
- Department of Radiation Oncology, University of Chicago, Chicago, IL, USA
| | - Otto A Sauer
- Department of Radiation Oncology, Klinik fur Strahlentherapie, University of Würzburg, Würzburg, Germany
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Weber C, Kranzer R, Weidner J, Kröninger K, Poppe B, Looe HK, Poppinga D. Small field output correction factors of the microSilicon detector and a deeper understanding of their origin by quantifying perturbation factors. Med Phys 2020; 47:3165-3173. [PMID: 32196683 PMCID: PMC7496769 DOI: 10.1002/mp.14149] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 01/31/2020] [Accepted: 03/13/2020] [Indexed: 11/09/2022] Open
Abstract
PURPOSE The aim of this study is the experimental and Monte Carlo-based determination of small field correction factors for the unshielded silicon detector microSilicon for a standard linear accelerator as well as the Cyberknife System. In addition, a detailed Monte Carlo analysis has been performed by modifying the detector models stepwise to study the influences of the detector's components. METHODS Small field output correction factors have been determined for the new unshielded silicon diode detector, microSilicon (type 60023, PTW Freiburg, Germany) as well as for the predecessors Diode E (type 60017, PTW Freiburg, Germany) and Diode SRS (type 60018, PTW Freiburg, Germany) for a Varian TrueBeam linear accelerator at 6 MV and a Cyberknife system. For the experimental determination, an Exradin W1 scintillation detector (Standard Imaging, Middleton, USA) has been used as reference. The Monte Carlo simulations have been performed with EGSnrc and phase space files from IAEA as well as detector models according to manufacturer blueprints. To investigate the influence of the detector's components, the detector models have been modified stepwise. RESULTS The correction factors for the smallest field size investigated at the TrueBeam linear accelerator (equivalent dosimetric square field side length Sclin = 6.3 mm) are 0.983 and 0.939 for the microSilicon and Diode E, respectively. At the Cyberknife system, the correction factors of the microSilicon are 0.967 at the smallest 5-mm collimator compared to 0.928 for the Diode SRS. Monte Carlo simulations show comparable results from the measurements and literature. CONCLUSION The microSilicon (type 60023) detector requires less correction than its predecessors, Diode E (type 60017) and Diode SRS (type 60018). The detector housing has been demonstrated to cause the largest perturbation, mainly due to the enhanced density of the epoxy encapsulation surrounding the silicon chip. This density has been rendered more water equivalent in case of the microSilicon detector to minimize the associated perturbation. The sensitive volume itself has been shown not to cause observable field size-dependent perturbation except for the volume-averaging effect, where the slightly larger diameter of the sensitive volume of the microSilicon (1.5 mm) is still small at the smallest field size investigated with corrections <2%. The new microSilicon fulfils the 5% correction limit recommended by the TRS 483 for output factor measurements at all conditions investigated in this work.
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Affiliation(s)
- Carolin Weber
- PTW FreiburgFreiburg79115Germany
- TU Dortmund UniversityDortmund44227Germany
| | | | | | | | - Björn Poppe
- University Clinic for Medical Radiation PhysicsMedical Campus Pius HospitalCarl von Ossietzky UniversityOldenburg26121Germany
| | - Hui Khee Looe
- University Clinic for Medical Radiation PhysicsMedical Campus Pius HospitalCarl von Ossietzky UniversityOldenburg26121Germany
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Biasi G, Al Shukaili K, Petasecca M, Corde S, Guatelli S, Perevertaylo VL, Kron T, Rosenfeld AB. Today’s monolithic silicon array detector for small field dosimetry: the Octa. ACTA ACUST UNITED AC 2019. [DOI: 10.1088/1742-6596/1154/1/012002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Biasi G, Petasecca M, Guatelli S, Martin EA, Grogan G, Hug B, Lane J, Perevertaylo V, Kron T, Rosenfeld AB. CyberKnife ® fixed cone and Iris™ defined small radiation fields: Assessment with a high-resolution solid-state detector array. J Appl Clin Med Phys 2018; 19:547-557. [PMID: 29998618 PMCID: PMC6123130 DOI: 10.1002/acm2.12414] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/13/2018] [Accepted: 06/18/2018] [Indexed: 11/18/2022] Open
Abstract
Purpose The challenges of accurate dosimetry for stereotactic radiotherapy (SRT) with small unflattened radiation fields have been widely reported in the literature. In this case, suitable dosimeters would have to offer a submillimeter spatial resolution. The CyberKnife® (Accuray Inc., Sunnyvale, CA, USA) is an SRT‐dedicated linear accelerator (linac), which can deliver treatments with submillimeter positional accuracy using circular fields. Beams are delivered with the desired field size using fixed cones, the InCise™ multileaf collimator or a dynamic variable‐aperture Iris™ collimator. The latter, allowing for field sizes to be varied during treatment delivery, has the potential to decrease treatment time, but its reproducibility in terms of output factors (OFs) and dose profiles (DPs) needs to be verified. Methods A 2D monolithic silicon array detector, the “Octa”, was evaluated for dosimetric quality assurance (QA) for a CyberKnife system. OFs, DPs, percentage depth‐dose (PDD) and tissue maximum ratio (TMR) were investigated, and results were benchmarked against the PTW SRS diode. Cross‐plane, in‐plane and 2 diagonal dose profiles were measured simultaneously with high spatial resolution (0.3 mm). Monte Carlo (MC) simulations with a GEANT4 (GEometry ANd Tracking 4) tool‐kit were added to the study to support the experimental characterization of the detector response. Results For fixed cones and the Iris, for all field sizes investigated in the range between 5 and 60 mm diameter, OFs, PDDs, TMRs, and DPs in terms of FWHM measured by the Octa were accurate within 3% when benchmarked against the SRS diode and MC calculations. Conclusions The Octa was shown to be an accurate dosimeter for measurements with a 6 MV FFF beam delivered with a CyberKnife system. The detector enabled real‐time dosimetric verification for the variable aperture Iris collimator, yielding OFs and DPs consistent with those obtained with alternative methods.
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Affiliation(s)
- Giordano Biasi
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, 2522 NSW, Australia
| | - Marco Petasecca
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, 2522 NSW, Australia
| | - Susanna Guatelli
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, 2522 NSW, Australia
| | - Ebert A Martin
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, 2522 NSW, Australia.,Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia.,School of Physics and Astrophysics, University of Western Australia, Crawley, WA, Australia
| | - Garry Grogan
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
| | - Benjamin Hug
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia.,School of Physics and Astrophysics, University of Western Australia, Crawley, WA, Australia
| | - Jonathan Lane
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia
| | | | - Tomas Kron
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, 2522 NSW, Australia.,Peter MacCallum Cancer Centre, Melbourne, VIC, Australia.,Sir Peter MacCallum Cancer Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Anatoly B Rosenfeld
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, 2522 NSW, Australia
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Pimpinella M, Caporali C, Guerra AS, Silvi L, De Coste V, Petrucci A, Delaunay F, Dufreneix S, Gouriou J, Ostrowsky A, Rapp B, Bordy JM, Daures J, Le Roy M, Sommier L, Vermesse D. Feasibility of using a dose-area product ratio as beam quality specifier for photon beams with small field sizes. Phys Med 2018; 45:106-116. [DOI: 10.1016/j.ejmp.2017.12.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 12/13/2017] [Accepted: 12/15/2017] [Indexed: 01/17/2023] Open
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Wegener S, Sauer OA. Energy response corrections for profile measurements using a combination of different detector types. Med Phys 2017; 45:898-907. [DOI: 10.1002/mp.12706] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 11/21/2017] [Accepted: 11/25/2017] [Indexed: 12/25/2022] Open
Affiliation(s)
- Sonja Wegener
- Department of Radiation Oncology; University of Würzburg; Würzburg Germany
| | - Otto A. Sauer
- Department of Radiation Oncology; University of Würzburg; Würzburg Germany
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Biasi G, Petasecca M, Guatelli S, Hardcastle N, Carolan M, Perevertaylo V, Kron T, Rosenfeld AB. A novel high-resolution 2D silicon array detector for small field dosimetry with FFF photon beams. Phys Med 2017; 45:117-126. [PMID: 29472075 DOI: 10.1016/j.ejmp.2017.12.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 12/13/2017] [Accepted: 12/15/2017] [Indexed: 11/19/2022] Open
Abstract
PURPOSE Flattening filter free (FFF) beams are increasingly being considered for stereotactic radiotherapy (SRT). For the first time, the performance of a monolithic silicon array detector under 6 and 10 MV FFF beams was evaluated. The dosimeter, named "Octa" and designed by the Centre for Medical Radiation Physics (CMRP), was tested also under flattened beams for comparison. METHODS Output factors (OFs), percentage depth-dose (PDD), dose profiles (DPs) and dose per pulse (DPP) dependence were investigated. Results were benchmarked against commercially available detectors for small field dosimetry. RESULTS The dosimeter was shown to be a 'correction-free' silicon array detector for OFs and PDD measurements for all the beam qualities investigated. Measured OFs were accurate within 3% and PDD values within 2% compared against the benchmarks. Cross-plane, in-plane and diagonal DPs were measured simultaneously with high spatial resolution (0.3 mm) and real time read-out. A DPP dependence (24% at 0.021 mGy/pulse relative to 0.278 mGy/pulse) was found and could be easily corrected for in the case of machine specific quality assurance applications. CONCLUSIONS Results were consistent with those for monolithic silicon array detectors designed by the CMRP and previously characterized under flattened beams only, supporting the robustness of this technology for relative dosimetry for a wide range of beam qualities and dose per pulses. In contrast to its predecessors, the design of the Octa offers an exhaustive high-resolution 2D dose map characterization, making it a unique real-time radiation detector for small field dosimetry for field sizes up to 3 cm side.
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Affiliation(s)
- G Biasi
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - M Petasecca
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - S Guatelli
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - N Hardcastle
- Peter MacCallum Cancer Centre, Melbourne, Australia
| | - M Carolan
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia; Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, NSW, Australia
| | | | - T Kron
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia; Peter MacCallum Cancer Centre, Melbourne, Australia; Sir Peter MacCallum Cancer Institute, University of Melbourne, Australia
| | - A B Rosenfeld
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.
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Dechambre D, Baart V, Cucchiaro S, Ernst C, Jansen N, Berkovic P, Mievis C, Coucke P, Gulyban A. Commissioning Monte Carlo algorithm for robotic radiosurgery using cylindrical 3D-array with variable density inserts. Phys Med 2017; 33:152-158. [DOI: 10.1016/j.ejmp.2017.01.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 11/18/2016] [Accepted: 01/07/2017] [Indexed: 10/20/2022] Open
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