3种分次立体定向放射治疗技术在颅内寡转移瘤中剂量学研究

Three fractionated stereotactic radiotherapy techniques in treatment of intracranial oligometastases: a dosimetric study

摘要

目的：比较螺旋断层放射治疗（tomotherapy,TOMO）、容积旋转调强放射治疗（volumetric modulated arc therapy,VMAT）和射波刀（cyber Knife,CK）3种分次立体定向放射治疗技术在治疗颅内寡转移瘤中剂量学特性，评估其剂量分布、治疗效率及对危及器官受量差异。方法：采用回顾性分析方法，收集2021年至2023年在陆军军医大学第一附属医院接受分次立体定向放射治疗的54例颅内寡转移瘤患者的临床资料。在Varian Eclipse 16.1医生工作站中完成所有患者肿瘤靶区的勾画，在MANTEIA Acc Contour 3.2软件中完成危及器官（如脑干、脊髓、视神经等）勾画。将勾画好的结构和图像传输至TOMO、CK及Eclipse系统，并分别设计3种不同放射治疗技术治疗计划。为评估3种放射治疗技术剂量学特性，通过剂量体积直方图（dosevolume histogram,DVH）分析了以下关键参数：靶区适形度指数（conformity index,CI）、剂量均匀性指数（homogeneity index,HI）、出束时间（TIME）、机器跳数（monitor units,MU），以及危及器官的受照剂量。结果：TOMO、VMAT和CK计划均实现处方剂量要求。TOMO计划的CI为1.05，稍优于VMAT（1.09）和CK（1.17）(P<0.001)。VMAT计划的HI为1.15，优于CK（1.28）和TOMO（1.46）(P<0.001)。在计划执行效率上，VMAT计划出束时间（5 min,1 633 MU），小于TOMO计划出束时间（10 min,8 932MU）和CK计划出束时间（39 min,5 191 MU）(P<0.001)。在危及器官的受照剂量方面，CK对晶体保护最佳，右晶体和左晶体的最大剂量(D_max)分别为15 c Gy和17 c Gy,TOMO在右耳蜗剂量控制上具有优势，平均剂量(D_mean)为88 c Gy，而VMAT在脊髓剂量限制方面表现最优，D_max为31 c Gy（P<0.05）。结论：本研究表明，在治疗颅内寡转移瘤中，TOMO、VMAT和CK均能满足处方剂量要求并有效保护危及器官。临床应用中，可结合病灶特征和治疗目标，选择最适宜的技术以实现个性化治疗。

Abstract

Objective To compare the dosimetric characteristics of three fractionated stereotactic radiotherapy techniques，i.e.，tomotherapy（TOMO），volumetric-modulated arc therapy（VMAT），and CyberKnife（CK），in the treatment of intracranial oligometastases，and to assess their dose distribution，treatment efficiency，and difference in dose delivered to organs at risk（OARs）. Methods A retrospective analysis was performed for the clinical data of 54 patients with intracranial oligometastases who underwent fractionated stereotactic radiotherapy in The First Affiliated Hospital of Army Medical University in 2021-2023. Varian Eclipse 16.1 Physician Workstation was used to perform tumor target volume delineation，and MANTEIA AccContour 3.2 software was used to perform the delineation of OARs，such as brainstem，spinal cord，and optical nerves. The delineated structures and images were transmitted to TOMO，CK，and Eclipse treatment planning systems to design three different radiotherapy treatment plans. Related key parameters were analyzed using the dose-volume histogram to evaluate the dosimetric characteristics of these three radiotherapy techniques，including conformity index （CI） of the target，dose homogeneity index（HI），beam-on time，the number of monitor units（MU），and the exposure dose of OARs. Results All three treatment plans（TOMO，VMAT，and CK） met the requirements for prescribed dose. TOMO had a slightly better CI than VMAT and CK（1.05 vs. 1.09 and 1.17，P<0.001）. VMAT had a better HI than CK and TOMO（1.15 vs. 1.28 and 1.46，P<0.001）. In terms of execution efficiency，VMAT had a significantly shorter beam-on time than TOMO and CK（5 minutes，1 633 MU vs. 10 minutes，8 932 MU and 39 minutes，5 191 MU，P<0.001）. In terms of the exposure dose of OARs，CK provided the best protection for the lens，with a maximum dose of 15 cGy for the right lens and 17 cGy for the left lens，and TOMO had an advantage in dose control for the right cochlea，with a mean dose of 88 cGy，while VMAT had the best performance in limiting the dose for the spinal cord，with a maximum dose of 31 cGy（P<0.05）. Conclusion This study shows that TOMO，VMAT，and CK all meet the requirements for the prescribed dose and can effectively protect OARs in the treatment of intracranial oligometastases. In clinical practice，the most appropriate technique should be selected based on the features of lesions and treatment goals to achieve individualized treatment.

Graphical abstract

关键词

立体定向放射治疗 / 颅内寡转移瘤 / 螺旋断层放射治疗 / 容积旋转调强放射治疗 / 射波刀 / 剂量学

Key words

stereotactic radiotherapy / intracranial oligometastases / tomotherapy / volumetric-modulated arc therapy / CyberKnife / dosimetry

基金资助

重庆市科卫联合医学科研面上资助项目(2023MSXM040)