Department of Radiation Oncology and Therapy, Tianjin Medical University Cancer Institute and Hospital, 60 Weijin Road, Hexi, Tianjin, China.
Department of Radiotherapy, Konggang Branch of Tianjin Cancer Hospital, Dong Fifth Road, Dongli District, Tianjin, China.
BMC Cancer. 2020 Nov 25;20(1):1144. doi: 10.1186/s12885-020-07624-4.
In order to obtain a high dose conformal index of tumor and steep dose fall-off in healthy tissues for brain metastasis stereotactic radiosurgery (SRS), the aim of this study was to investigate SRS planning optimization by comparing one multiple-lesions plan (MLP) with multiple single-lesion plans (SLPs) for patients with multiple brain metastases using the Cyberknife (CK) system.
Fifty non-small cell lung cancer (NSCLC) patients (28 males and 22 females) with 2-4 brain metastases, inter-tumour distances less than 3 cm, were retrospectively replanned with the original prescription dose (12-32 Gy) in the original fractions (1-3). Two different clinical CK SRS plans (SLPs and MLP) were generated for the same patients with the same collimator and prescription isodose line (62-68%) by the CK Multiplan System. Both SLPs and MLP were able to achieve > 95% PTV volume covered prescription dose and met the Timmerman 2011 organs at risk (brainstem, optic nerve and pituitary) constraints.
Compared with those in the SLPs, the maximum dose (D) and mean dose (D) of brainstem in the MLP were reduced 0.22-3.13% (2.62%) and 2.71-12.56% (5.57%), respectively, all P < 0.05. Meanwhile, the volumes of the whole brain minus the tumors that received a single dose equivalent of 8-16 Gy (V8Gy-V16Gy) were effectively reduced in the MLP. The treatment time parameters, the total number of beams and monitor units, of the MLP were reduced by 3.31 and 1.47% (P < 0.05), respectively. Although there were a few differences in the conformity index (CI) and homogeneity index (HI) between the two treatment plans, the differences were not statistically significant (P = 2.94 and 1.08 > 0.05).
One multiple-lesions plan for brain metastases could achieve higher precision in the target and lower doses in healthy tissue while shortening the treatment time and improving the treatment efficiency over multiple single-lesion plans.
为了在脑转移立体定向放射外科（SRS）中获得高剂量适形指数的肿瘤和陡峭的健康组织剂量下降，本研究旨在通过比较使用 Cyberknife（CK）系统的多位点计划（MLP）和多个单病灶计划（SLP），来为多位脑转移患者进行 SRS 计划优化。
回顾性地对 50 名非小细胞肺癌（NSCLC）患者（28 名男性和 22 名女性）进行了重新规划，这些患者的脑转移灶数量为 2-4 个，肿瘤间距离小于 3cm，采用原始处方剂量（12-32Gy）和原始分次（1-3 次）。通过 CK Multiplan 系统为同一患者生成了两种不同的临床 CK SRS 计划（SLP 和 MLP），使用相同的准直器和处方等剂量线（62-68%）。SLP 和 MLP 均能够实现>95%PTV 体积覆盖处方剂量，并满足 Timmerman 2011 年危险器官（脑干、视神经和垂体）的限制。
与 SLP 相比，MLP 中脑干的最大剂量（D）和平均剂量（D）分别降低了 0.22-3.13%（2.62%）和 2.71-12.56%（5.57%），均 P<0.05。同时，MLP 有效地降低了整个肿瘤减去肿瘤体积的单剂量等效体积 8-16Gy（V8Gy-V16Gy）。MLP 的治疗时间参数，即总光束数和监测单位数，分别降低了 3.31%和 1.47%（P<0.05）。尽管两种治疗计划的适形指数（CI）和均匀性指数（HI）存在一些差异，但差异无统计学意义（P=2.94 和 1.08>0.05）。
对于脑转移，一个多位点计划可以在目标中实现更高的精度，同时在健康组织中降低剂量，缩短治疗时间，提高治疗效率，优于多个单点计划。
