Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Radiation Oncology, Peking University Cancer Hospital and Institute, 52 Fucheng Road, Beijing, 100142, China.
Institute of Medical Technology, Peking University Health Science Center, 38 Huayuan Road, Beijing, 100191, China.
Radiat Oncol. 2022 Jun 4;17(1):104. doi: 10.1186/s13014-022-02077-4.
To propose a specific surface guided stereotactic radiotherapy (SRT) treatment procedure with open-face mask immobilization and evaluate the initial clinical experience in improving setup accuracy.
The treatment records of 48 SRT patients with head lesions were retrospectively analyzed. For each patient, head immobilization was achieved with a double-shell open-face mask. The anterior shell was left open to expose the forehead, nose, eyes and cheekbones. The exposed facial area was used as region-of-interest for surface tracking by AlignRT (VisionRT Inc, UK). The posterior shell provided a sturdy and personalized headrest. Patient initial setup was guided by 6DoF real-time deltas (RTD) using the reference surface obtained from the skin contour delineated on the planning CT images. The endpoint of initial setup was 1 mm in translational RTD and 1 degree in rotational RTD. CBCT guidance was performed to derive the initial setup errors, and couch shifts for setup correction were applied prior to treatment delivery. CBCT couch shifts, AlignRT RTD values, repositioning rate and setup time were analyzed.
The absolute values of median (maximal) CBCT couch shifts were 0.4 (1.3) mm in VRT, 0.1 (2.5) mm in LNG, 0.2 (1.6) mm in LAT, 0.1(1.2) degree in YAW, 0.2 (1.4) degree in PITCH and 0.1(1.3) degree in ROLL. The couch shifts and AlignRT RTD values exhibited highly agreement except in VRT and PITCH (p value < 0.01), of which the differences were as small as negligible. We did not find any case of patient repositioning that was due to out-of-tolerance setup errors, i.e., 3 mm and 2 degree. The surface guided setup time ranged from 52 to 174 s, and the mean and median time was 97.72 s and 94 s respectively.
The proposed surface guided SRT procedure with open-face mask immobilization is a step forward in improving patient comfort and positioning accuracy in the same process. Minimized initial setup errors and repositioning rate had been achieved with reasonably efficiency for routine clinical practice.
提出一种采用开放式面罩固定的特定表面引导立体定向放射治疗（SRT）的治疗方案，并评估其在提高摆位精度方面的初步临床经验。
回顾性分析了 48 例头部病变 SRT 患者的治疗记录。每位患者均采用双壳开放式面罩进行头部固定。前壳保持打开状态，以暴露额头、鼻子、眼睛和颧骨。暴露的面部区域用作 AlignRT（英国 VisionRT 公司）表面跟踪的感兴趣区域。后壳提供坚固且个性化的头枕。使用从计划 CT 图像上勾画的皮肤轮廓获得的参考表面，通过 6DoF 实时差值（RTD）引导患者初始摆位。初始摆位的终点为平移 RTD 为 1mm，旋转 RTD 为 1 度。进行锥形束 CT（CBCT）引导以获得初始摆位误差，并在治疗前进行治疗床调整以纠正摆位。分析了 CBCT 治疗床的调整、AlignRT RTD 值、重新定位率和摆位时间。
VRT、LNG、LAT、YAW、PITCH 和 ROLL 方向的 CBCT 治疗床调整的绝对值中位数（最大值）分别为 0.4（1.3）mm、0.1（2.5）mm、0.2（1.6）mm、0.1（1.2）度、0.2（1.4）度和 0.1（1.3）度。除 VRT 和 PITCH 方向外（p 值<0.01），治疗床调整与 AlignRT RTD 值高度一致，差异可忽略不计。我们没有发现任何因摆位误差超出允许范围而需要重新定位的患者，即 3mm 和 2 度。表面引导摆位时间范围为 52-174s，平均和中位数时间分别为 97.72s 和 94s。
采用开放式面罩固定的特定表面引导 SRT 治疗方案在提高患者舒适度和定位精度方面向前迈进了一步。在提高初始摆位精度和降低重新定位率方面取得了进展，同时保持了合理的临床效率。
