Department of Radiation Oncology, Yamagata University Faculty of Medicine, 2-2-2, Iida-Nishi, Yamagata, Japan.
Department of Heavy Particle Medical Science, Yamagata University Faculty of Medicine, 2-2-2, Iida-Nishi, Yamagata, Japan.
Radiat Oncol. 2019 Nov 21;14(1):207. doi: 10.1186/s13014-019-1411-0.
The purpose of this study was to compare carbon-ion (C-ion), proton and photon radiotherapy (RT) plans with regard to dose reduction of the gastrointestinal (GI) tract by using a greater omentum spacer (GO spacer).
We retrospectively retrieved data for ten patients who received the GO spacer as surgical spacer placement for abdominal and pelvic tumors. Simulation plans were created on pre-spacer Computed Tomography (CT) and post-spacer CT for C-ion RT, proton RT and photon RT to compare the dose of the GI tract. The plans were normalized so that at least 95% of the planning target volume (PTV) received 70 Gy (relative biological effectiveness equivalent) delivered in 35 fractions. All plans were created with the lowest possible dose to the GI tract under conditions that meet the dose constraints for the PTV and spinal cord (maximum dose < 45 Gy). The part of the GI tract to be evaluated was defined as that most adjacent to the PTV. C-ion RT plans and proton RT plans were calculated by a spot scanning technique, and photon RT plans were calculated employing by fixed-field intensity-modulated radiation therapy.
D2 cc and V10-70 of the GI tract were significantly lower on post-spacer plans than on pre-spacer plans for all three RT modalities. Regarding post-spacer plans, D2 cc of the GI tract was significantly lower on C-ion RT plans and proton RT plans than on photon RT plans (C-ion vs photon p = 0.001, proton vs photon p = 0.002). However, there was no significant difference between C-ion RT plans and proton RT plans for D2 cc of the GI tract (C-ion vs proton p = 0.992). In the photon RT plan for one patient, D2 cc of the GI tract did not meet < 50 Gy.
The GO spacer shows a significant dose reduction effect on the GI tract.
本研究旨在比较碳离子（C 离子）、质子和光子放疗（RT）计划，通过使用更大的网膜间隔物（GO 间隔物）减少胃肠道（GI）的剂量。
我们回顾性地检索了 10 名接受 GO 间隔物作为腹部和盆腔肿瘤手术间隔物放置的患者的数据。在预间隔物 CT 和后间隔物 CT 上为 C 离子 RT、质子 RT 和光子 RT 创建模拟计划，以比较 GI 道的剂量。计划进行了归一化处理，以使至少 95%的计划靶体积（PTV）接受 70Gy（等效相对生物学效应），分 35 次给予。在满足 PTV 和脊髓（最大剂量<45Gy）剂量限制的情况下，所有计划均以 GI 道最低剂量进行创建。要评估的 GI 道部分被定义为最接近 PTV 的部分。C 离子 RT 计划和质子 RT 计划通过点扫描技术计算，光子 RT 计划通过固定野强度调制放疗计算。
对于所有三种 RT 模式，GI 道的 D2 cc 和 V10-70 在间隔后计划中均明显低于间隔前计划。对于间隔后计划，GI 道的 D2 cc 在 C 离子 RT 计划和质子 RT 计划中明显低于光子 RT 计划（C 离子与光子比较 p=0.001，质子与光子比较 p=0.002）。然而，C 离子 RT 计划和质子 RT 计划之间的 GI 道 D2 cc 无显著差异（C 离子与质子比较 p=0.992）。在一名患者的光子 RT 计划中，GI 道的 D2 cc 未达到<50Gy。
GO 间隔物对 GI 道具有显著的剂量减少作用。
