Out-of-field photon dosimetry study between 3-D conformal and intensity modulated radiation therapy in the management of prostate cancer
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T. Siji Cyriac , M.M. Musthafa , R. Ganapathi Raman , K. Abdul Haneefa , Saju Bhasi |
Department of Physics, Noorul Islam Centre for Higher Education, Kumaracoil, Thuckalay, Kanyakumari District, 629 180, Tamilnadu, India , sijicyriacsanju@gmail.com |
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Abstract: (8113 Views) |
Background: The present work aims to study the out-of-field photon calculation accuracy of a commercial treatment planning system (TPS), Oncentra, for three-dimensional conformal radiotherapy (3D-CRT) and intensity modulated radiation therapy (IMRT) treatment techniques from Elekta Synergy medical linear accelerator. Materials and Methods: Accuracy of individual out-of-field dose components was studied by defining a square field of 10 x 10 cm2 in our TPS and it is verified by using ionization chamber and TLDs (Thermoluminescent dosimeter) at 5 cm depth. Using 3D-CRT and IMRT techniques Ca (carcinoma) prostate treatment plans were created using 6 MV photon beam and calculated in Oncentra Masterplan v4.3 planning systems for out-of-field and further compared the same with TLD measurements. Results: Individual components study shows the poor out-of-field calculations in TPS, with respect to that obtained from TLD measurements. Underestimation increases from 10 % to 80 % as a contribution from various components while moving far from field edge. Complex IMRT plans resemble this underestimation of TPS calculations in greater extend. Conclusion: This study quantifies the poor accuracy for out-of-field dose calculations in TPS. No significant difference in 3D-CRT and IMRT plans is found at near field edge. While, as distance from field edge increases, underestimation of TPS in IMRT plan is higher. 10 % – 60 % difference in out-of-field dose was found as distance move from 2 cm to 7.5 cm far from field edge between TPS estimations and the measurements. |
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Keywords: TPS, TLD, out-of-field dose, 3D-CRT, IMRT |
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Full-Text [PDF 1402 kb]
(2596 Downloads)
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Type of Study: Original Research |
Subject:
Radiation Biology
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