利用肺部模体研究肺癌在螺旋断层放射治疗计划中靶区间空间关系对肺组织的剂量学影响

Dosimetric Impact of Spatial Relationship of Radiation Targets in Tomotherapy on Lung Cancer by Using a Lung Phantom

目的:通过螺旋断层放射治疗(tomotherapy,TOMO)计划系统及肺部模体模拟肺癌中两个靶区的多种相对空间位置关系,研究各种相对空间位置关系的靶区对肺组织剂量的影响。方法:模拟肺癌中两个靶区的情况,分别改变这两个靶区的相对空间位置关系及体积大小,并设计相应的TOMO治疗计划,统计肺组织被5Gy剂量辐照体积V_5,20Gy剂量辐照体积V_(20)及平均剂量辐照体积V_(mean),并利用matlab软件进行数学统计。结果:靶区大小与肺V_5、V_(20)及V_(mean)呈正相关关系,而靶区大小不变时,肺V_5、V_(20)及V_(mean)与靶区间距离呈正相关关系,但会在距离到达一定值时出现极大值且不再随距离变大而变大。结论:TOMO计划系统中肺组织的所受剂量不但与肺组织自身和肿瘤大小有关,还与肿瘤间的空间相对位置有关。

Objective: To study the impact of several spatial relationships of two targets on absorbed dose received by lung Phantom in the tomotherapy (TOMO) treatment planning system. Methods: On a lung phantom, two targets were contoured in various targets sizes or spatial relationships. Then for each individual way a treatment plan was respectively optimized with relevant prescription dose in each TOMO treatment plan. At last, the V5,V20 and Vmean of lung in each plan were collected and then analyzed by MATLAB. Results: A positive correlation was found between target size and V5,V20, Vmean. Wlien the target size was constant, V5, V20 and Vmean increased with the growth of the distance between two targets till the distance reached a certain threshold beyond which the V5, V20 and Vmean would not increase anymore. Conclusion: The dose for lung is related to not only the size of lung and that of the tumor but also the relative position of between tumors.