N-isopropylacrylamide Gel Dosimeters for Dose Verification of IMRT Treatment using 3D Gamma evaluation and Dose-volume Histogram

• Main Authors: Huang, Tsung-Chieh, 黃琮傑
• Other Authors: Hsieh, Ling-Ling
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/87994149062416856080

碩士 === 中臺科技大學 === 醫學影像暨放射科學系暨研究所 === 103 === Polymer gel dosimeters can record integrated absorbed dose in 3D. In addition, polymer gel dosimeters can exhibit 3D dose distribution of patients. In this study, N-isopropylacrylamide (NIPAM) gel dosimetry with magnetic resonance imaging (MRI) was employed to measure 3D dose distributions in clinical radiation treatment of eye tumor patients. This study comprised the following two stages. Stage one: NIPAM gels results were compared with measurement results obtained using EBT3 dosimetry films. Both dosimeters were evaluated using an isodose curve and 2D gamma evaluation with the criteria of 3% dose and 3 mm DTA. The results obtained using the NIPAM gel dosimeter and films were highly consistent for the ≥70% dose region. However, the film measurements and treatment planning system-calculated distribution were different at the low-dose region (<70%). The gamma passing rate of the NIPAM gel was 96.969%, which was higher than that of the film (57.599%). Stage two: NIPAM gel dosimetry was investigated using dose–volume histograms (DVHs) and 3D gamma evaluation. The long-term stability of irradiated NIPAM gel dosimeter was also investigated. Results show that the gamma values exceeded 98% 12 h post-irradiation and the DVHs were consistent for the ≥30% dose region, which became evident through the NIPAM gel method. Gamma passing rates and DVH had no considerable changes two months post-irradiation, which indicated the high stability of NIPAM gels. NIPAM gel dosimetry with MRI successfully estimated the 3D dose distribution during clinical radiation treatment. Therefore, NIPAM gel can serve as a 3D tool for verification of dose distribution during clinical radiation treatment.