Background/Objectives:Advancements in radiotherapy technology now enable the delivery of ablative doses to targets in the upper urinary tract, including primary renal cell carcinoma (RCC) or upper tract urothelial carcinomas (UTUC), and secondary involvement by other histologies. Magnetic resonance imaging-guided linear accelerators (MR-Linacs) have shown promise to further improve the precision and adaptability of stereotactic body radiotherapy (SBRT).Methods:This single-institution retrospective study analyzed 34 patients (31 with upper urinary tract non-metastatic primaries [RCC or UTUC] and 3 with metastases of non-genitourinary histology) who received SBRT from August 2020 through September 2024 using a 1.5 Tesla MR-Linac system. Treatment plans were adjusted by using [online settings] for “adapt-to-position” (ATP) and “adapt-to-shape” (ATS) strategies for anatomic changes that developed during treatment; compression belts were used for motion management.Results:The median duration of treatment was 56 min overall and was significantly shorter using the adapt-to-position (ATP) (median 54 min, range 38–97 min) in comparison with adapt-to-shape (ATS) option (median 80, range 53–235 min). Most patients (77%) experienced self-resolving grade 1–2 acute radiation-induced toxicity; none had grade ≥ 3. Three participants (9%) experienced late grade 1–2 toxicity, potentially attributable to SBRT, with one (3%) experiencing grade 3.Conclusions:We conclude that MR-Linac-based SBRT, supported by online plan adaptation, is a feasible, safe, and highly precise treatment modality for the definitive management of select upper urinary tract lesions.
**背景/目的：** 放疗技术的进步现已能够对包括原发性肾细胞癌或上尿路尿路上皮癌在内的上尿路靶区，以及其他组织学类型的继发性受累病灶，实施消融剂量的照射。磁共振成像引导直线加速器在进一步提高立体定向体部放疗的精确性和适应性方面展现出潜力。 **方法：** 这项单中心回顾性研究分析了34例患者（31例为上尿路非转移性原发肿瘤[肾细胞癌或上尿路尿路上皮癌]，3例为非泌尿生殖系统组织学来源的转移瘤），这些患者在2020年8月至2024年9月期间使用1.5特斯拉磁共振引导直线加速器系统接受了立体定向体部放疗。针对治疗期间出现的解剖结构变化，治疗计划通过在线设置，采用“适应位置”和“适应形状”策略进行调整；并使用压迫带进行运动管理。 **结果：** 总体治疗中位时长为56分钟。与“适应形状”方案相比，“适应位置”方案的治疗时长显著缩短。大多数患者经历了可自行缓解的1-2级急性放射性毒性反应；无患者出现≥3级毒性反应。三名参与者出现了可能与立体定向体部放疗相关的晚期1-2级毒性反应，其中一名参与者出现3级毒性反应。 **结论：** 我们得出结论，在在线计划自适应支持下，基于磁共振引导直线加速器的立体定向体部放疗，对于特定上尿路病灶的根治性治疗是一种可行、安全且高度精确的治疗方式。
肿瘤(癌症)患者之家