呼吸運動對肝內腫瘤調控放射治療的影響

• Main Authors: Kuo, Hsiang-Chi, 郭祥吉
• Other Authors: 莊克士
• Format: Others
• Language: en_US
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/68417653870018959698

博士 === 國立清華大學 === 生醫工程與環境科學系 === 98 === This dissertation investigates the dosimetric and radiobiological impact of respiratory organ motion on the delivery of IMRT techniques for intra-hepatic tumor. There are two methods applied in two different IMRT techniques. Convolution incorporated motion trajectory was performed to study motion impact in fixed-beam IMRT technique. A method incorporated 4DCT data was utilized to evaluate motion impact in rotational IMRT technique. The 4DCT method used a diffeoremorphic registration as framework to construct deformation field in three dimensions. The convolution method generates effective fluence which is the fluence distorted by the motion function. By analyzing 108 fluence generated from fixed field IMRT, this study found there are strong correlation of intensity error with motion displacement d (0.6), fluence gradient G (0.56), and their multiplication d*G (0.9). To keep the average intensity error below 0.05 and 0.03, the maximum motion displacement should be smaller than 1.3 cm and 0.7 cm, respectively. With 4DCT data, dosimetric error due to deformation is intrinsically included. Study from two cases showed that the dosimetric error due depth changes alone were 3% and 1%, respectively. Comparing the motion effect on the delivered dose between the moderately modulated plans and the highly modulated plans for the two cases in this study, the latter only increases the maximum dose deviation from the expected dosimetric error by 2% (from 1% to 3%). Method was applied at single-arc IMAT in this study, the same scheme can be applied at multiple-arc IMAT as well. Radiobiological impact of the respiratory motion was evaluated with the concept of equivalent uniform dose. Through the correlation between the survival fraction and different clinical cell type or stage of intra-hepatic tumor, appropriate margins were designed to account for the biological impact from respiratory motion in IMRT delivery.