Evaluation of the respiratory gated radiotherapy system

• Main Authors: Hsu Shu-Hui, 許淑惠
• Other Authors: Chi-Shiun Chiang
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/52331117548067804727

碩士 === 國立清華大學 === 原子科學系 === 89 === The goal of radiotherapy is to deliver as much dose to the tumor as possible while sparing surrounding normal tissues from radiation toxicity. The goal can be achieved by the continuous advancement of new treatment technology. On the other hand, these developments would also lead to increasing sensitivity to treatment uncertainties, mainly due to setup error and organ motion. Setup error is also called patient positioning error, deriving from everyday treatment variation. Organ motion could be caused by breathing, heartbeat, swallowing, and peristaltic motion. Organ motion caused by breathing has the largest impact on treatment accuracy. To solve this problem, a respiratory gating device which could deliver radiation treatment synchronized with patient breathing to reduce radiation toxicity to normal tissues is developed. The main objectives of this project are divided into three parts: developing new image processing software, finding the relation between skin movement and diaphragm displacement, and evaluating the feasibility of clinical respiratory gated radiotherapy by means of normal tissue complication probability and tumor control probability. The difference of the traced position of diaphragm between the automatic image tracing software and manual tracing was 1.06±1.25 mm and was much smaller than the average displacement caused by breathing. The result suggested that image processing system can be used in clinical settings. Time delay was observed when comparing the respiratory patterns of skin movement and diaphragm displacement. However, due to insufficient patient data, the relationship between these two movements is still indecisive. In evaluating the clinical feasibility of the respiratory gating system, one patient with lung cancer was taken as a demonstrative case. The result showed that respiratory gating treatment can diminish safe margin and normal tissue complication probability. This example has demonstrated the feasibility of clinical application of this system.