适形放疗靶区确定的影响因素分析

目的探讨适形放疗靶区的计划靶体积的影响因素。方法分析经扫描仪输入的CT图像，计算图像重建偏差；由5位放射治疗科医生单独勾画大体肿瘤体积(GTV)，通过计算辐射线状测量差异(RLMV)值，比较与实际实施治疗计划在中心层面上的差异；分析手动多叶光栅(MLC)摆位及GTV模具制作过程，计算GTV模具误差及边缘剂量误差。结果由扫描仪输入CT图像引起的综合误差累计达1．5～2．5mm，非平行扫描误差达1～3mm；与实际实施计划GTV相比，在GTV中心层面上无一例完全吻合。结论直接通过数字化方式传输CT/MRI图像保证数据准确、不失真；确定适形放射治疗计划靶体积(GTV)应该由一组放射治疗医生共同确定；计算机控制的多叶光栅(MLC)能够避免GTV模具制作及摆位带来的误差。

Influence Factors of Determining the Target Area of Conformal Radiation Therapy

Objective To explore the influence factors o f determining the pla nning target volume of conformal radiation therapy (CRT). Methods The images obtaining from the scanning were analyzed and the reconstructi on bias of computer tomography images were calculate. The gross tumor volume (GTV) was determined b y five doctors. And the radial line measurement variation (RLMV) in center layer was calculated. The difference between the implement treatment planning and ima ge determined by five doctors was analyzed. The bias of marginal dose and GTV mo uld were evaluated by analyzing the process of conforming GTV mould and manual m ulti-leaf conformer (MLC). Results The resultant error resul ting from images o f the scanner was 1.5 to 2.5 mm in all. Nonparallel scanning error was from 1mm to 3mm. Comparing to the implement treatment planning. The GTVs in the center sl ide were different from each other. Conclusions Digitizing d irectly transporta tion of the CT/MRI images can eliminate the losing of images data. The GTVs shou ld be adumbrated by a group of doctors. The MLC could reduce the errors in the p rocesses of the conforming mould and body position.