Fiorentino Alba, Giaj-Levra Niccolò, Tebano Umberto, Mazzola Rosario, Ricchetti Francesco, Fersino Sergio, Di Paola Gioacchino, Aiello Dario, Ruggieri Ruggero, Alongi Filippo
Radiation Oncology, Sacro Cuore Don Calabria Cancer Care Center, Via Don Sempreboni 5, Negrar, 37034, Verona, Italy.
Statistic Science Faculty, University of Palermo, Palermo, Italy.
Radiol Med. 2017 Sep;122(9):676-682. doi: 10.1007/s11547-017-0768-0. Epub 2017 Apr 26.
For selected patients with brain metastases (BMs), the role of stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (SFRT) is well recognized. The recent introduction of flattening filter free (FFF) delivery during linac-based SRS or SFRT allows shorter beam-on-time, improving patients' comfort and facility workflow. Nevertheless, limited experiences evaluated the impact of FFF linac-based SRS and SFRT in BMs treatment. Aim of the current study was to analyze SRS/SFRT linac-based FFF delivery for BMs in terms of dosimetric and early clinical results.
Patients with life expectancy >3 months, number of BMs <5, diameter <3 cm, and controlled or synchronous primary tumor received SRS/SFRT. The prescribed total dose and fractionation, based on BMs size and proximity to organs at risk, ranged from 15 Gy in 1 fraction to 30 Gy in 5 fractions. A FFF volumetric modulated arc therapy (VMAT) plan was generated with one or two coplanar partial arcs. Toxicity was assessed according to CTCAE v4.0.
From April 2014 to February 2016, 45 patients (89 BMs) were treated with SRS/SFRT linac-based FFF delivery. The mean beam-on-time was 140 s for each lesion (range 90-290 s) and the average brain Dmean was 1 Gy (range 0.1-4.8 Gy). At the time of analysis, local control was reported in 93.2% (83/89 BMs). With a median follow-up time of 12 months (range 1-27 months), the median overall survival was 14 months and the 6-month overall survival was 77%. Finally, the median intracranial disease control was 11 months. Acute and late toxicities were acceptable without severe events (no adverse events ≥G2 were recorded).
These preliminary results highlighted the feasibility and safety of linac-based SRS/SFRT with FFF mode for BMs patients. A longer follow-up is necessary to confirm the efficacy of this treatment modality in BM patients.
对于部分脑转移瘤（BMs）患者，立体定向放射外科治疗（SRS）或分次立体定向放射治疗（SFRT）的作用已得到充分认可。近期在基于直线加速器的SRS或SFRT中引入的无 flattening 滤过器（FFF）技术可缩短射束开启时间，提高患者舒适度并改善设备工作流程。然而，仅有有限的经验评估了基于FFF直线加速器的SRS和SFRT在脑转移瘤治疗中的影响。本研究的目的是从剂量学和早期临床结果方面分析基于直线加速器的FFF技术在脑转移瘤SRS/SFRT治疗中的应用。
预期生存期>3个月、脑转移瘤数量<5个、直径<3 cm且原发肿瘤得到控制或与脑转移瘤同时存在的患者接受SRS/SFRT治疗。根据脑转移瘤大小和与危及器官的距离，规定的总剂量和分割方式为1次分割15 Gy至5次分割30 Gy。采用一或两个共面部分弧生成FFF容积调强弧形治疗（VMAT）计划。根据CTCAE v4.0评估毒性。
2014年4月至2016年2月，45例患者（89个脑转移瘤）接受了基于直线加速器FFF技术的SRS/SFRT治疗。每个病灶的平均射束开启时间为140秒（范围90 - 290秒），脑平均剂量（Dmean）平均为1 Gy（范围0.1 - 4.8 Gy）。在分析时，报告局部控制率为93.2%（83/89个脑转移瘤）。中位随访时间为12个月（范围1 - 27个月），中位总生存期为14个月，6个月总生存率为77%。最后，中位颅内疾病控制时间为11个月。急性和晚期毒性均可接受，未发生严重事件（未记录到≥2级不良事件）。
这些初步结果突出了基于直线加速器的FFF模式SRS/SFRT治疗脑转移瘤患者的可行性和安全性。需要更长时间的随访来证实这种治疗方式对脑转移瘤患者的疗效。
