Proton Medical Research Center, University of Tsukuba, Tsukuba, Japan.
Lung Cancer. 2012 Jul;77(1):83-8. doi: 10.1016/j.lungcan.2012.01.007. Epub 2012 Jan 26.
To investigate the geometrical accuracy in proton beam therapy (PBT) to the lung by comparing the location of the fibrosis after PBT and the tumor using less invasive method.
We examined 50 lung tumors that had been treated by respiratory-gated PBT (33-74 Gray equivalents). Image registration and re-slicing of computed tomography (CT) before and after PBT were performed using an image analysis software system. We investigated whether the location of fibrosis was accurate with the tumor site and which factor among the respiratory rhythm, tumor volume, location, fixation, beam direction and clinical outcome was affected with accuracy.
The area of fibrosis was accurate with the tumor in 45 tumors (Group A) and not accurate in 5 tumors (Group B). All lesions with a small irregularity of respiratory rhythm showed fibrosis in an area accurate with the tumor. This percentage (100%) was higher than that of the lesions with a large irregularity of respiratory rhythm (67%, p = 0.037). Radiation pneumonitis was found for 1 lesion in group A and 2 lesions in Group B (p = 0.0009).
The geometrical accuracy of beam delivery to the lung was higher in the patients with a regular respiratory rhythm in PBT. The patients of Group B had greater risk of pneumonitis.
通过对比质子放射治疗（PBT）后纤维化的位置与肿瘤位置，采用微创方法研究 PBT 治疗肺部的几何精度。
我们对 50 例接受呼吸门控 PBT（33-74 格雷等效剂量）治疗的肺部肿瘤进行了研究。使用图像分析软件系统对 PBT 前后的 CT 进行图像配准和重新切片。我们研究了纤维化的位置与肿瘤部位是否准确，以及呼吸节律、肿瘤体积、位置、固定、射束方向和临床结果等因素中哪一个会影响精度。
45 例肿瘤（A 组）的纤维化区域与肿瘤位置准确，5 例肿瘤（B 组）的纤维化区域不准确。所有呼吸节律不规则较小的病变，其纤维化区域均与肿瘤位置准确，这一比例（100%）高于呼吸节律不规则较大的病变（67%，p=0.037）。A 组中有 1 例、B 组中有 2 例出现放射性肺炎（p=0.0009）。
在 PBT 中，呼吸节律规则的患者的肺部射束传输几何精度更高。B 组患者发生肺炎的风险更大。
