Wang Gang, Zhu Xiwen, Zhang Fan, Liu Jing, Yue Lu, Deng Lihua, Zhou Mi
Department of Radiotherapy, Qingdao Municipal Hospital, Qingdao, China.
Transl Cancer Res. 2020 Nov;9(11):7227-7235. doi: 10.21037/tcr-20-2800.
To study the feasibility of target contouring and the potential benefits to radiotherapy of four-dimensional computed tomography (4D-CT) for early stage lung cancer.
We applied Brilliance CT to scan 24 lung cancer patients for 4D localization. Treatment plannings based on different breath phase CT images were designed in the Monaco 5.2 treatment planning system. Different planning was compared to find the difference of target volume, center, and dose.
Target volume composed of 10-breath phases (Sum) was considered as the reference volume, which was slightly larger than the volume contouring obtained by the maximum intensity projection (Mip) and extreme phase images (Exs). Target centers for Sum, Mip and Exs of CT images showed little deviation in the X, Y and Z directions. The V20 and V5 for the 4D-CT-based treatment plan showed a markedly lower dose delivered to normal tissues than those based on 3D-CT.
For target contouring, a target contouring by 10-breath phases was superior to Mip and Exs. As the gross target volume (GTV) contouring obtained by the maximum intensity projection and extreme phase were similar to that of the reference target, they can support the contouring target and reduce the time and work. Treatment plan comparisons indicated that normal lung tissues received a remarkably lower dose when a 4D-CT-based plan was used.
研究早期肺癌四维计算机断层扫描（4D-CT）进行靶区勾画的可行性及对放射治疗的潜在益处。
应用飞利浦Brilliance CT对24例肺癌患者进行4D定位扫描。在Monaco 5.2治疗计划系统中基于不同呼吸相位的CT图像设计治疗计划。比较不同计划以找出靶区体积、中心及剂量的差异。
将由10个呼吸相位组成的靶区体积（总和）视为参考体积，其略大于通过最大密度投影（Mip）和极端相位图像（Exs）获得的体积勾画。CT图像的总和、Mip和Exs的靶区中心在X、Y和Z方向上显示出微小偏差。基于4D-CT的治疗计划的V20和V5显示，与基于3D-CT的计划相比，正常组织接受的剂量明显更低。
对于靶区勾画，10个呼吸相位的靶区勾画优于Mip和Exs。由于通过最大密度投影和极端相位获得的大体肿瘤体积（GTV）勾画与参考靶区相似，它们可辅助靶区勾画并减少时间和工作量。治疗计划比较表明，使用基于4D-CT的计划时，正常肺组织接受的剂量明显更低。
