Background: Electronic portal imaging devices (EPIDs) are applied to measure the dose and verify patients’ position. Objective: The present study aims to evaluate the performance of EPID for measuring dosimetric parameters in small photon fields. Material and Methods: In this experimental study, the output factors and beam profiles were obtained using the amorphous silicon (a-Si) EPID for square field sizes ranging from 1×1 to 10×10 cm2 at energies 6 and 18 mega-voltage (MV). For comparison, the dosimetric parameters were measured with the pinpoint, diode, and Semiflex dosimeters. Additionally, the Monaco treatment planning system was selected to calculate the output factors and beam profiles. Results: There was a significant difference between the output factors measured using the EPID and that measured with the other dosimeters for field sizes lower than 8×8 cm2. In the energy of 6 MV, the gamma passing rates (3%/3 mm) between EPID and diode profile were 98%, 98%, 95%, 94%, 93%, and 94% for 1×1, 2×2, 3×3, 4×4, 5×5, and 10×10 cm2, respectively. The measured penumbra width with EPID was higher compared to that measured by the diode dosimeter for both energies. Conclusion: The EPID can measure the dosimetric parameters in small photon fields, especially for beam profiles and penumbra measurements. |
- Wang K, Tepper JE. Radiation therapy-associated toxicity: Etiology, management, and prevention. CA Cancer J Clin. 2021;71(5):437-54. doi: 10.3322/caac.21689. PubMed PMID: 34255347.
- Castelli J, Simon A, Acosta O, Haigron P, Nassef M, Henry O, et al. The role of imaging in adaptive radiotherapy for head and neck cancer. 2014;35(1):33-40. doi: 10.1016/j.irbm.2013.12.003.
- Taylor A, Powell ME. Intensity-modulated radiotherapy--what is it? Cancer Imaging. 2004;4(2):68-73. doi: 10.1102/1470-7330.2004.0003. PubMed PMID: 18250011. PubMed PMCID: PMC1434586.
- Eekers DBP, Roelofs E, Cubillos-Mesías M, Niël C, Smeenk RJ, Hoeben A, et al. Intensity-modulated proton therapy decreases dose to organs at risk in low-grade glioma patients: results of a multicentric in silico ROCOCO trial. Acta Oncol. 2019;58(1):57-65. doi: 10.1080/0284186X.2018.1529424. PubMed PMID: 30474448.
- Parwaie W, Geraily G, Shirazi A, Yarahmadi M, Shakeri A, Ardekani MA. Evaluation of lung heterogeneity effects on dosimetric parameters in small photon fields using MAGIC polymer gel, Gafchromic film, and Monte Carlo simulation. Appl Radiat Isot. 2020;166:109233. doi: 10.1016/j.apradiso.2020.109233. PubMed PMID: 32836165.
- Palmans H, Andreo P, Huq MS, Seuntjens J, Christaki KE, Meghzifene A. Dosimetry of small static fields used in external photon beam radiotherapy: Summary of TRS-483, the IAEA-AAPM international Code of Practice for reference and relative dose determination. Med Phys. 2018;45(11):e1123-e45. doi: 10.1002/mp.13208. PubMed PMID: 30247757.
- Aspradakis MM, Byrne JP, Palmans H, Duane S, Conway J, Warrington AP, Rosser K. IPEM Report 103: Small field MV photon dosimetry. Report Number, IAEA-CN--182; International Atomic Energy Agency (IAEA); 2010.
- Parwaie W, Refahi S, Ardekani MA, Farhood B. Different Dosimeters/Detectors Used in Small-Field Dosimetry: Pros and Cons. J Med Signals Sens. 2018;8(3):195-203. doi: 10.4103/jmss.JMSS_3_18. PubMed PMID: 30181968. PubMed PMCID: PMC6116321.
- Würfel JU. Dose measurements in small fields. Med Phys. 2013;1(1):81-90.
- Eklund K, Ahnesjö A. Modeling silicon diode dose response factors for small photon fields. Phys Med Biol. 2010;55(24):7411-23. doi: 10.1088/0031-9155/55/24/002. PubMed PMID: 21098913.
- Kumar AS, Sharma SD, Ravindran BP. Characteristics of mobile MOSFET dosimetry system for megavoltage photon beams. J Med Phys. 2014;39(3):142-9. doi: 10.4103/0971-6203.139002. PubMed PMID: 25190992. PubMed PMCID: PMC4154181.
- Ford EC, Chang J, Mueller K, Sidhu K, Todor D, Mageras G, Yorke E, Ling CC, Amols H. Cone-beam CT with megavoltage beams and an amorphous silicon electronic portal imaging device: Potential for verification of radiotherapy of lung cancer. Medical Physics. 2002;29(12):2913-24. doi: 10.1118/1.1517614.
- Van Elmpt W, McDermott L, Nijsten S, Wendling M, Lambin P, Mijnheer B. A literature review of electronic portal imaging for radiotherapy dosimetry. Radiother Oncol. 2008;88(3):289-309. doi: 10.1016/j.radonc.2008.07.008. PubMed PMID: 18706727.
- Celi S, Costa E, Wessels C, Mazal A, Fourquet A, Francois P. EPID based in vivo dosimetry system: clinical experience and results. J Appl Clin Med Phys. 2016;17(3):262-76. doi: 10.1120/jacmp.v17i3.6070. PubMed PMID: 27167283. PubMed PMCID: PMC5690938.
- Vial P, Greer PB, Hunt P, Oliver L, Baldock C. The impact of MLC transmitted radiation on EPID dosimetry for dynamic MLC beams. Med Phys. 2008;35(4):1267-77. doi: 10.1118/1.2885368. PubMed PMID: 18491519.
- Olaciregui-Ruiz I, Vivas-Maiques B, Kaas J, Perik T, Wittkamper F, Mijnheer B, Mans A. Transit and non-transit 3D EPID dosimetry versus detector arrays for patient specific QA. J Appl Clin Med Phys. 2019;20(6):79-90. doi: 10.1002/acm2.12610. PubMed PMID: 31083776. PubMed PMCID: PMC6560233.
- Grządziel A, Smolińska B, Rutkowski R, Ślosarek K. EPID dosimetry–configuration and pre-treatment IMRT verification. Reports of Practical Oncology & Radiotherapy. 2007;12(6):307-12. doi:10.1016/S1507-1367(10)60069-7.
- Charles PH, Cranmer-Sargison G, Thwaites DI, Crowe SB, Kairn T, Knight RT, Kenny J, Langton CM, Trapp JV. A practical and theoretical definition of very small field size for radiotherapy output factor measurements. Med Phys. 2014;41(4):041707. doi: 10.1118/1.4868461. PubMed PMID: 24694127.
- Godson HF, Ravikumar M, Sathiyan S, Ganesh KM, Ponmalar YR, Varatharaj C. Analysis of small field percent depth dose and profiles: Comparison of measurements with various detectors and effects of detector orientation with different jaw settings. J Med Phys. 2016;41(1):12-20. doi: 10.4103/0971-6203.177284. PubMed PMID: 27051165. PubMed PMCID: PMC4795411.
- Pappas E, Maris TG, Zacharopoulou F, Papadakis A, Manolopoulos S, Green S, Wojnecki C. Small SRS photon field profile dosimetry performed using a PinPoint air ion chamber, a diamond detector, a novel silicon-diode array (DOSI), and polymer gel dosimetry. Analysis and intercomparison. Med Phys. 2008;35(10):4640-8. doi: 10.1118/1.2977829. PubMed PMID: 18975710.
- Chand B, Kumar M, Kumar M. Comprehensive Review of Small Field Dosimetry. European Journal of Molecular & Clinical Medicine. 2020;7(7):3595-607.
- Agarwal A, Rastogi N, Maria Das KJ, Yoganathan SA, Udayakumar D, Kumar S. Investigating the Electronic Portal Imaging Device for Small Radiation Field Measurements. J Med Phys. 2017;42(2):59-64. doi: 10.4103/jmp.JMP_131_16. PubMed PMID: 28706350. PubMed PMCID: PMC5496271.
- Ding A, Xing L, Han B. Development of an accurate EPID-based output measurement and dosimetric verification tool for electron beam therapy. Med Phys. 2015;42(7):4190-8. doi: 10.1118/1.4922400. PubMed PMID: 26133618. PubMed PMCID: PMC4474956.
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