The uncertainty associated with the relative biological effectiveness (RBE) in proton therapy, particularly near the Bragg peak (BP), has led to the shift towards biological-based treatment planning. Proton RBE uncertainty has recently been reported as a possible cause for brainstem necrosis in pediatric patients treated with proton therapy. Despite this, in vivo studies have been limited due to the complexity of accurate delivery and absolute dosimetry. The purpose of this investigation was to create a precise and efficient method of treating the mouse spinal cord with various portions of the proton Bragg curve and to quantify associated uncertainties for the characterization of proton RBE. Mice were restrained in 3D printed acrylic boxes, shaped to their external contour, with a silicone insert extending down to mold around the mouse. Brass collimators were designed for parallel opposed beams to treat the spinal cord while shielding the brain and upper extremities of the animal. Up to six animals may be accommodated for simultaneous treatment within the restraint system. Two plans were generated targeting the cervical spinal cord, with either the entrance (ENT) or the BP portion of the beam. Dosimetric uncertainty was measured using EBT3 radiochromic film with a dose-averaged linear energy transfer (LETd) correction. Positional uncertainty was assessed by collecting a library of live mouse scans (n = 6 mice, two independent scans per mouse) and comparing the following dosimetric statistics from the mouse cervical spinal cord: Volume receiving 90% of the prescription dose (V90); mean dose to the spinal cord; and LETd. Film analysis results showed the dosimetric uncertainty to be ±1.2% and ±5.4% for the ENT and BP plans, respectively. Preliminary results from the mouse library showed the V90 to be 96.3 ± 4.8% for the BP plan. Positional uncertainty of the ENT plan was not measured due to the inherent robustness of that treatment plan. The proposed high-throughput mouse proton irradiation setup resulted in accurate dose delivery to mouse spinal cords positioned along the ENT and BP. Future directions include adapting the setup to account for weight fluctuations in mice undergoing fractionated irradiation.

与质子治疗中的相对生物有效性 (RBE) 相关的不确定性，特别是在布拉格峰 (BP) 附近，导致了向基于生物的治疗计划的转变。最近有报道称，质子 RBE 不确定性是接受质子治疗的儿科患者脑干坏死的可能原因。尽管如此，体内由于准确递送和绝对剂量测定的复杂性，研究受到限制。本研究的目的是创建一种精确有效的方法，用质子布拉格曲线的各个部分治疗小鼠脊髓，并量化质子 RBE 表征的相关不确定性。小鼠被限制在 3D 打印的亚克力盒子中，盒子的形状与它们的外部轮廓相符，硅胶插入物向下延伸以在鼠标周围成型。黄铜准直器设计用于平行的相对光束来治疗脊髓，同时保护动物的大脑和上肢。在约束系统内最多可容纳六只动物进行同时治疗。生成了两个针对颈脊髓的计划，分别是光束的入口 (ENT) 或 BP 部分。使用具有剂量平均线性能量转移 (LETd) 校正的 EBT3 放射变色薄膜测量剂量学不确定性。通过收集活小鼠扫描库（n = 6 只小鼠，每只小鼠进行两次独立扫描）并比较小鼠颈脊髓的以下剂量统计数据来评估位置不确定性：接受 90% 处方剂量 (V90) 的体积；脊髓的平均剂量；和 LETd。胶片分析结果显示 ENT 和 BP 计划的剂量学不确定性分别为 ±1.2% 和 ±5.4%。小鼠库的初步结果显示，BP 计划的 V90 为 96.3 ± 4.8%。由于该治疗计划的固有稳健性，未测量耳鼻喉科计划的位置不确定性。提议的高通量小鼠质子照射设置导致向位于耳鼻喉和 BP 的小鼠脊髓准确传递剂量。未来的方向包括调整设置以解决接受分次照射的小鼠的体重波动。