Medical Physics Service, Radiation Oncology Department, Humanitas Clinical and Research Hospital, Rozzano-Milan, Italy.
Radiation Oncology Department, Humanitas Clinical and Research Hospital, Rozzano-Milan, Italy.
Pract Radiat Oncol. 2021 Jan-Feb;11(1):e98-e105. doi: 10.1016/j.prro.2020.02.012. Epub 2020 Mar 8.
A body frame dedicated to total marrow (lymph node) irradiation (TMI/TMLI) could minimize patient motion during the potentially extended beam-on time with this technique. We present the development of a dedicated immobilization system for TMI/TMLI using volumetric modulated arc therapy.
Since 2010, 59 adult patients were treated with TMI/TMLI using a multi-isocenter volumetric modulated arc therapy technique. Two computed tomographies (CTs) were required (1 head-first supine and 1 feet-first supine) to cover the whole volume. For the first 10 patients, 2 standard commercial frames with personalized masks (with/without personalized vacuum cushion for the lower extremities) were used without specific interfixation (frame A). For the next 49 patients a homemade 3-frame immobilization system was adopted (frame B), where each frame was interlocked with the next one and thermoplastic masks used to fix the patient. The effectiveness of the 2 immobilization systems was assessed by offline/online matching between daily cone beam CT of each isocenter and the simulation CTs.
Mean offline shifts for frame A were 3 to 12 mm in anterior-posterior, 2 to 5 mm in cranilal-caudal, and 2 to 6 mm in left-right directions. Larger shifts were found for feet-first supine series (shifts up to 23 mm). In frame B, mean offline shifts were 1 to 4 mm in anterior-posterior, 1 to 4 mm in cranial-caudal, and 1 to 4 mm in left-right directions. Mean online adjustments were -1 ± 4 mm in anterior-posterior, 0 ± 2 mm in cranial-caudal, and 0 ± 4 mm in left-right directions.
The patient positioning shifts for TMI/TMLI irradiation were mitigated by a homemade immobilization system and the use of individualized masks.
专门用于全骨髓（淋巴结）照射（TMI/TMLI）的体架可以最大限度地减少患者在接受这种技术治疗时的潜在延长照射时间内的运动。我们介绍了一种使用容积调强弧形治疗技术为 TMI/TMLI 开发的专用固定系统。
自 2010 年以来，59 例成人患者接受了 TMI/TMLI 治疗，采用多等中心容积调强弧形治疗技术。需要进行 2 次计算机断层扫描（CT）（1 次头高脚低位仰卧位和 1 次脚高脚低位仰卧位）以覆盖整个体积。在前 10 例患者中，使用了 2 个带有个性化面罩的标准商用框架（带有/不带有下肢个性化真空垫），没有特定的固定装置（框架 A）。对于接下来的 49 例患者，采用了自制的 3 框架固定系统（框架 B），每个框架都与下一个框架联锁，并用热塑面罩固定患者。通过对每个等中心点的每日锥形束 CT 与模拟 CT 进行离线/在线匹配，评估了这两种固定系统的有效性。
框架 A 的平均离线移位为前后方向 3 至 12 毫米，头脚方向 2 至 5 毫米，左右方向 2 至 6 毫米。头高脚低位仰卧位系列的移位更大（最大移位 23 毫米）。在框架 B 中，平均离线移位为前后方向 1 至 4 毫米，头脚方向 1 至 4 毫米，左右方向 1 至 4 毫米。平均在线调整为前后方向-1 ± 4 毫米，头脚方向 0 ± 2 毫米，左右方向 0 ± 4 毫米。
通过自制的固定系统和个体化面罩的使用，减轻了 TMI/TMLI 照射的患者定位移位。
