呼吸运动对4DCT扫描下靶区体积及位移的影响  

Effects of respiratory motion on target volume and center shift in 4DCT scan

作　　者：陈衎 杨振[2] 曹瑛 李书舟 张子健[2] 杨晓喻[2] 邵其刚 雷明军[2] 唐杜 龚学余[1] CHEN Kan;YANG Zhen;CAO Ying;LI Shuzhou;ZHANG Zijian;YANG Xiaoyu;SHAO Qigang;LEI Mingjun;TANG Du;GONG Xueyu(School of Nuclear Science and Technology,University of South China,Hengyang 421001,China;Department of Oncology,Xiangya Hospital,Central South University,Changsha 410008,China)

机构地区：[1]南华大学核科学技术学院,湖南衡阳421001 [2]中南大学湘雅医院肿瘤科,湖南长沙410008

出　　处：《中国医学物理学杂志》2022年第3期277-282,共6页Chinese Journal of Medical Physics

基　　金：国家自然科学基金青年科学基金(61906215,12005306)。

摘　　要：目的:探讨基于4DCT扫描图像勾画的靶区体积和位移与呼吸运动状态下肿瘤运动频率及幅度的关系。方法:使用自制的人体胸部模体及呼吸运动平台驱动直径为2 cm的小球做正弦运动(周期分别为3.0、3.8、6.0 s,幅度分别为1、2 cm)以模拟肺部肿瘤运动,再进行4DCT扫描。对每组4DCT图像中的10个时相进行大体肿瘤体积(GTV)靶区勾画并对每组4DCT图像中10个时相的GTV进行融合得到内靶区(ITV)。基于平均密度投影(AIP)和最大密度投影(MIP)进行自动靶区勾画,分别获得ITV_(AIP)及ITV_(MIP)。分析GTV体积与小球实际体积的关系,GTV体积和GTV中心位移与小球运动频率和幅度的关系,以及ITV_(P)、ITV_(MIP)及ITV_(AIP)与小球运动范围的体积VP(理论ITV体积)的关系。结果:GTV体积与对应时相小球运动速度无相关性,但GTV中心偏差与小球运动速度呈弱相关性,小球运动速度越快,GTV中心位移的偏差越大。ITV和PTV体积与肿瘤运动周期无关,仅与运动幅度有关。ITV_(MIP)和ITV_(P)的体积与ITVAIP相比更接近理论ITV体积,而ITV_(AIP)体积比理论ITV体积小。结论:对于胸腹部放疗的患者使用适当的呼吸管理手段控制患者呼吸或引导患者平稳呼吸有利于提高放疗精准度;基于MIP勾画的ITV靶区能够更好地反映肿瘤的运动。Objective To study the changes in target volume and center shift in 4DCT image caused by the frequency and amplitude of tumor motion.Methods A small ball with a diameter of 2 cm was driven by a homemade human thorax model and respiratory platform to move sinusoidally,with the periods of 3.0,3.8,6.0 s,and the amplitudes of 1,2 cm,for simulating the tumor motion in lung,and then 4DCT scan was carried out.The gross target volume(GTV) from 10 phases of each group of 4DCT image was segmented,and the obtained GTV was fused to obtain internal gross target volume(ITV).Furthermore,ITVAIPand ITVMIPwere obtained by the automatic target segmentation based on maximum intensity projection(MIP) and average intensity projection(AIP).The relationships between GTV and the actual volume of the ball,between the GTV or GTV center shift and the frequency or amplitude of ball motion,between ITVP,ITVMIPor ITVAIPand the volume covering ball motion scope VP(theoretical ITV) were analyzed.Results There was no correlation between GTV and the velocity of the small ball at the corresponding phase,but the center shift was weakly correlated to the velocity of the small ball.The larger velocity of small ball was,the larger GTV center shift was.ITV and PTV were only related to the amplitude of tumor motion,and had no correlation with the period of tumor motion.Compared with ITVAIPwhich was smaller than the theoretical ITV,ITVMIPand ITVPwere closer to the theoretical ITV.Conclusion Respiratory training and deep inspiration breath-hold or other respiratory management methods for the patient scheduled for thoracoabdominal tumor radiotherapy are conducive to improve the accuracy of radiotherapy.ITV segmented based on MIP can reflect the motion of tumor better.

关 键 词：肺癌 4DCT 呼吸运动曲线 模体 内靶区 平均密度投影 最大密度投影 

分 类 号：R318[医药卫生—生物医学工程] R815.6[医药卫生—基础医学]