Duan Yanhua, Cao Hongbin, Wu Boheng, Wu Yinghui, Liu Dong, Zhou Lijun, Feng Aihui, Wang Hao, Chen Hua, Gu Hengle, Shao Yan, Huang Ying, Lin Yang, Ma Kui, Fu Xiaolong, Fu Hong, Kong Qing, Xu Zhiyong
Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China.
Department of Radiation Oncology, Renji Hospital, Shanghai Jiao Tong University, Shanghai, China.
Front Oncol. 2021 Aug 5;11:716152. doi: 10.3389/fonc.2021.716152. eCollection 2021.
This study aimed to show the advantages of each stereotactic radiosurgery (SRS) treatment option for single small brain metastasis among Gamma Knife (GK), Cone-based VMAT (Cone-VMAT), and MLC-based CRT (MLC-CRT) plans.
GK, Cone-VMAT, and MLC-CRT SRS plans were retrospectively generated for 11 patients with single small brain metastasis whose volume of gross tumor volume (GTV) ranged from 0.18 to 0.76 cc (median volume 0.60 cc). Dosimetric parameters, treatment efficiency, and biological parameters of the three techniques were compared and evaluated. The metric variation with the planning target volume (PTV) was also studied.
The conformity index (CI) was similar in GK and MLC-CRT plans, higher than Cone-VMAT. Cone-VMAT achieved comparable volume covered by 12 Gy (V12) and gradient index (GI) as GK, lower than MLC-CRT. The heterogeneity index (HI) of GK, Cone-VMAT, and MLC-CRT decreased sequentially. GK gave the lowest volume covered by 3 Gy (V3) and 6 Gy (V6), while MLC-CRT got the highest. The beam-on time and treatment time of GK, Cone-VMAT, and MLC-CRT decreased in turn. Tumor control probability (TCP) of all three SRS plans was greater than 98%, and normal tissue complication probability (NTCP) of all organs at risk (OARs) was below 0.01%. GK and Cone-VMAT resulted in superior TCP and NTCP of the normal brain tissue than MLC-CRT. The relative value of Cone-VMAT and GK for all metrics hardly changed with the target volume. Except for the unchanged HI and TCP, the other results of MLC-CRT with respect to GK improved as the target volume increased. MLC-CRT could produce higher CI than GK and Cone-VMAT when the target volume increased above 2 and 1.44 cc, respectively.
For single small brain metastases, Cone-VMAT may be used as an alternative to GK-free centers. In addition to the advantage of short treatment time, MLC-CRT showed superiority in CI as the target volume increased. Treatment centers can choose appropriate SRS technique on a case-by-case basis according to institutional conditions and patients' individual needs.
本研究旨在展示伽玛刀（GK）、基于锥形束的容积调强弧形放疗（Cone-VMAT）和基于多叶准直器的调强适形放疗（MLC-CRT）计划在治疗单个小脑转移瘤时各自立体定向放射外科（SRS）治疗方案的优势。
对11例单个小脑转移瘤患者进行回顾性分析，这些患者的大体肿瘤体积（GTV）范围为0.18至0.76立方厘米（中位体积0.60立方厘米），分别生成GK、Cone-VMAT和MLC-CRT的SRS计划。比较并评估了这三种技术的剂量学参数、治疗效率和生物学参数。还研究了与计划靶体积（PTV）相关的指标变化。
GK和MLC-CRT计划的适形指数（CI）相似，高于Cone-VMAT。Cone-VMAT实现的12 Gy覆盖体积（V12）和梯度指数（GI）与GK相当，低于MLC-CRT。GK、Cone-VMAT和MLC-CRT的不均匀性指数（HI）依次降低。GK的3 Gy覆盖体积（V3）和6 Gy覆盖体积（V6）最小，而MLC-CRT的最大。GK、Cone-VMAT和MLC-CRT的照射时间和治疗时间依次减少。所有三种SRS计划的肿瘤控制概率（TCP）均大于98%，所有危及器官（OAR）的正常组织并发症概率（NTCP）均低于0.01%。GK和Cone-VMAT在正常脑组织的TCP和NTCP方面优于MLC-CRT。Cone-VMAT和GK在所有指标上的相对值随靶体积变化不大。除HI和TCP不变外，MLC-CRT相对于GK的其他结果随着靶体积增加而改善。当靶体积分别增加到2立方厘米和1.44立方厘米以上时，MLC-CRT可产生比GK和Cone-VMAT更高的CI。
对于单个小脑转移瘤，Cone-VMAT可作为无GK设备中心的替代方案。除治疗时间短的优势外，MLC-CRT在靶体积增加时CI方面表现出优越性。治疗中心可根据机构条件和患者个体需求，逐案选择合适的SRS技术。
