Kawahara Daisuke, Ozawa Syuichi, Nakashima Takeo, Aita Masamichi, Kawai Shintarou, Ochi Yusuke, Okumura Takurou, Masuda Hirokazu, Ohno Yoshimi, Kimura Tomoki, Nagata Yasushi
Section of Radiation Therapy, Department of Clinical Support, Hiroshima University Hospital.
Nihon Hoshasen Gijutsu Gakkai Zasshi. 2014 Jan;70(1):51-6. doi: 10.6009/jjrt.2014_jsrt_70.1.51.
Liver image guided radiation therapy (IGRT) based on bone matching risks generating serious target positioning errors for reasons of lack of reproducibility of expiration breath hold. We therefore investigated the feasibility of 3D image matching between planning CT images and pretreatment cone-beam computed tomography (CBCT) images based on diaphragm surface matching.
27 liver stereotactic body radiotherapy (SBRT) cases in whom trancecatheter arterial chemoembolization (TACE) had been performed in advance of radiotherapy were manually image-matched based on contrast, Lipiodol used in the TACE as the marker of the tumor, and the relative coordinates of the isocenter obtained by contrast matching, defined as the reference coordinate. The target positioning difference between diaphragm matching and bone matching were evaluated by using relative coordinates of the isocenter from the reference obtained for each matching technique.
The target positioning error using diaphragm matching and bone matching was 1.31±0.83 and 3.10±2.80 mm in the cranial-caudal (C-C) direction, 1.04±0.95 and 1.62±1.02 mm in the anterior-posterior (A-P) direction, and 0.93±1.19 and 1.12±0.94 mm in the left-right (L-R) direction, respectively. The positioning error due to diaphragm matching was significantly smaller than for bone matching in the C-C direction (p<0.05).
IGRT based on diaphragm matching has potential as an alternative image matching technique for the positioning of liver patients.
基于骨匹配的肝脏图像引导放射治疗（IGRT）因呼气屏气缺乏可重复性而有产生严重靶区定位误差的风险。因此，我们研究了基于膈肌表面匹配的计划CT图像与治疗前锥形束计算机断层扫描（CBCT）图像之间三维图像匹配的可行性。
对27例在放疗前已先行经导管动脉化疗栓塞术（TACE）的肝脏立体定向体部放疗（SBRT）病例，基于对比度、TACE中使用的碘油作为肿瘤标志物以及通过对比度匹配获得的等中心相对坐标（定义为参考坐标）进行手动图像匹配。通过使用每种匹配技术从参考中获得的等中心相对坐标来评估膈肌匹配和骨匹配之间的靶区定位差异。
在头脚（C-C）方向上，使用膈肌匹配和骨匹配的靶区定位误差分别为1.31±0.83和3.10±2.80mm，在前后（A-P）方向上分别为1.04±0.95和1.62±1.02mm，在左右（L-R）方向上分别为0.93±1.19和1.12±0.94mm。在C-C方向上，膈肌匹配导致的定位误差明显小于骨匹配（p<0.05）。
基于膈肌匹配的IGRT作为肝脏患者定位的替代图像匹配技术具有潜力。
