Study of Ferric ion diffusion effects in NMR-Fricke-Agarose Gel dosimetry

• Main Authors: Yang Tso-Yuan, 楊左元
• Other Authors: Chu Woei-chyn
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/76840700910014137336

碩士 === 國立陽明大學 === 醫學工程研究所 === 90 === Ferrous-sulfate-doped agarose gel dosimetry is a useful tool for the measurement of three-dimensional absorbed radiation dose distribution. Because its true 3D nature and its good tissue-equivalence, apllication of MRI Fricke-infused gel dosimetry to the measurement of dose distribution for Gamma-knife radiosurgery、Brachytherapy、Linac etc. have been presented. Although, Fricke-infused gel dosimetry is an excellence tool, however diffusion of ferric ions causes degradation of dose distribution profile. In this study we compare the accuracy and applicability of the conventional MR R1-based method and Intensity-based method in three-dimensional dose measurement, elucidate the extend of ferric ion diffusion time scale and the degree of ferric ion diffusion, we also compare means of verifying the dose distributions from Gamma knife and Brachytherapy sources. Our results show that dose profile degradation is not significant if elapsed diffusion was kept less than 30 minutes. Due to significantly suppressed ferric ion diffusion, the image-based method provides more accurate result than R1-based approach.