:: Volume 16, Issue 4 (10-2018) ::
Int J Radiat Res 2018, 16(4): 493-497 Back to browse issues page
Dosimetric verification of pre-treatment intensity modulated radiation therapy in the commissioning process
G. Esmaili, S.R. Mahdavi Dr. , A.R. Nikoofar, P. Fadavi, A. Ameri, V. Nazari
Radiation Biology Research Center & Medical Physics Department, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran , mahdavi.r@iums.ac.ir
Abstract:   (1334 Views)
Background: Commissioning tests are recommended before implementing Intensity Modulated Radiation Therapy. This study evaluated five different plans of IMRT mocks for different modulation indices. Materials and Methods: IMRT tests were done in slab phantom for both 6MV and 15 MV photon energies using a 2D array ion chamber dosimeter. Results: The acceptance criteria were based on 3% /3mm. All tests passed the gamma criteria except for the prostate test with 15 MV photon beams and C shape test for both 6 MV and 15 MV energies. The Ratio passing points for Multi target test in 6 MV and 15 MV plans were 93.1% and 91.5%, respectively. The results of the prostate tests with 3%/3mm was 92.3% for 6MV and 91.2% for 15 MV in 4%/4 mm tolerance limit. For Head and Neck test with the same gamma criteria, the percentages of the points were 93.2 and 94 for 6 MV and 15 MV plans, respectively. For C shape tests, the used gamma criteria were 4%/ 4 mm. The ratio passing points were 94.9% and 94.3% for 6MV and 15MV plans, respectively. However, C shape hard test could not pass the gamma criteria of 4%/ 4mm for 6MV. Conclusion: results showed that by increasing the complexity of the IMRT plan, the verification test must be done in a more strict-manner, because a small change in dose delivery can cause a large discrepancy between planned and real dosimetry and may produce hot spots in organs or a cold spot in the target volume.
Keywords: Pre- treatment IMRT, 2D array, IMRT mock, Gamma evaluation.
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Type of Study: Technical Note | Subject: Radiation Biology

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Volume 16, Issue 4 (10-2018) Back to browse issues page