Nakamura Ryuji, Sugawara Jun, Yamaguchi Satoshi, Kakuhara Hisao, Kikuchi Koyo, Ariga Hisanori
Department of Radiology, Iwate Medical University, Morioka, Japan.
Department of Radiology, Iwate Prefectural Chubu Hospital, Kitakami, Japan.
BJR Case Rep. 2020 Jun 18;6(4):20190121. doi: 10.1259/bjrcr.20190121. eCollection 2020 Dec 1.
A 45-year-old male developed a second set of pulmonary metastases 5 years after surgery for extraskeletal mucinous chondrosarcoma of the left shoulder. He already underwent a lobectomy and two segmentectomies for a first set of pulmonary metastases 2 years ago. The closely grouped three nodules within the left lower lung formed a planning target volume (PTV) for stereotactic body radiotherapy (SBRT) with a single isocentre, which was focused on the centre of the largest nodule (the simultaneous plan). Dose-volume histogram analysis confirmed that the plan was superior to an alternative plan, in which SBRT plans would have been produced for each individual tumour (the individual plan). The mean, maximum and minimum PTV doses were 54.0, 57.5 and 47.3 Gy, respectively, in the simultaneous plan, and 65.6, 87.2 and 52.3 Gy, respectively, in the individual plan. The homogeneity index, conformity index, and the maximum dose delivered to the surrounding healthy lung were 1.21, 0.71, and 37.7 Gy, respectively, in the simultaneous plan and 1.66, 4.44, and 46.2 Gy, respectively, in the individual plan. The patient developed Grade two pneumonitis, but remained healthy until 4 years after the SBRT. When multiple closely grouped metastases are treated using SBRT, the use of a single isocentre should be considered.
一名45岁男性在左肩部骨外黏液性软骨肉瘤手术后5年出现了第二批肺转移瘤。两年前，他已经因第一批肺转移瘤接受了肺叶切除术和两次肺段切除术。左下肺内紧密聚集的三个结节形成了立体定向体部放疗（SBRT）的计划靶区（PTV），采用单一等中心，该等中心聚焦于最大结节的中心（同步计划）。剂量体积直方图分析证实，该计划优于另一种计划，即对每个单独的肿瘤制定SBRT计划（个体化计划）。同步计划中PTV的平均、最大和最小剂量分别为54.0、57.5和47.3 Gy，个体化计划中分别为65.6、87.2和52.3 Gy。同步计划中均匀性指数、适形指数和输送到周围健康肺组织的最大剂量分别为1.21、0.71和37.7 Gy，个体化计划中分别为1.66、4.44和46.2 Gy。该患者出现了二级肺炎，但在SBRT后4年一直保持健康。当使用SBRT治疗多个紧密聚集的转移瘤时，应考虑使用单一等中心。
