¹⁷⁷Lu-DOTATATE (Lutathera) enables targeted radionuclide therapy of neuroendocrine tumors expressing somatostatin receptor type 2. Though patient-specific dosimetry estimates may be clinically important for predicting absorbed dose-effect relationships, there are multiple relevant dosimetry paradigms which are distinct in terms of clinical effort, numerical output and added-value. This work compares three different approaches for ¹⁷⁷Lu-DOTATATE dosimetry, including 1) an organ-level approach based on reference phantom MIRD S-values scaled to patient-specific organ masses (MIRDcalc), 2) an organ-level approach based on Monte Carlo simulation in a patient-specific mesh phantoms (PARaDIM), and 3) a 3D approach based on Monte Carlo simulation in patient-specific voxel phantoms. Method. Serial quantitative SPECT/CT images for two patients receiving ¹⁷⁷Lu-DOTATATE therapy were obtained from archive in the Deep Blue database. For each patient, the serial CT images were co-registered to the first time point CT using a deformable registration technique aided by virtual landmarks placed in the kidney pelves and the lesion foci. The co-registered SPECT images were integrated voxel-wise to generate time-integrated activity maps. Lesions, kidneys, liver, spleen, lungs, compact bone, spongiosa, and rest of body were segmented at the first imaging time point and overlaid on co-registered integrated activity maps. The resultant segmentation was used for three purposes: 1) to generate patient-specific phantoms, 2) to determine organ-level time-integrated activities, and 3) to generate dose volume histograms from 3D voxel-based calculations. Results. Mean absorbed doses were computed for lesions and 48 tissues with MIRDcalc software. Mean organ absorbed doses and dose volume histograms were obtained for lesions and 6 tissues with the voxel Monte Carlo approach. Lesion- and organ-level absorbed dose estimates agreed within 26% for the lesions and 13% for the critical organs, among the different methods tested. Overall good agreement was observed with the dosimetry estimates from the NETTER-1 trial. Conclusions. For personalized ¹⁷⁷Lu-DOTATATE dosimetry, a combined approach was determined to be valuable, which utilized two dose calculation methods supported by a single image processing workflow. In the absence of quantitative imaging limitations, the voxel Monte Carlo method likely provides valuable information to guide treatment by considering absorbed dose non-uniformity in lesions and organs at risk. The patient-scaled reference phantom method also provides valuable information, including absorbed dose estimates for non-segmented organs, and more accurate dose estimates for complex radiosensitive organs including the active marrow.

^第177章) 能够对表达 2 型生长抑素受体的神经内分泌肿瘤进行靶向放射性核素治疗。尽管特定患者的剂量测定估计对于预测吸收的剂量-效应关系在临床上可能很重要，但有多种相关的剂量测定范式在临床工作、数值输出和附加价值。^{这项工作比较了177} Lu-DOTATATE 剂量测定的三种不同方法，包括 1) 基于与患者特定器官质量 (MIRDcalc) 缩放的参考体模 MIRD S 值的器官水平方法，2) 基于 Monte 的器官水平方法患者特定网格模型 (PARaDIM) 中的 Carlo 模拟，以及 3) 基于患者特定体素模型中的 Monte Carlo 模拟的 3D 方法。方法. 两名接受¹⁷⁷ Lu-DOTATATE 治疗的患者的系列定量 SPECT/CT 图像来自Deep Blue中的档案数据库。对于每位患者，使用可变形配准技术将连续 CT 图像共同配准到第一个时间点 CT，该技术由放置在肾盂和病变灶的虚拟标志辅助。将共同注册的 SPECT 图像以体素方式集成以生成时间集成的活动图。在第一个成像时间点对病变、肾脏、肝脏、脾脏、肺、致密骨、海绵体和身体其他部位进行分割，并覆盖在共同注册的综合活动图上。产生的分割用于三个目的：1) 生成特定于患者的模型，2) 确定器官水平的时间积分活动，以及 3) 从基于 3D 体素的计算中生成剂量体积直方图。结果. 使用 MIRDcalc 软件计算病变和 48 个组织的平均吸收剂量。使用体素蒙特卡罗方法获得病变和 6 个组织的平均器官吸收剂量和剂量体积直方图。在所测试的不同方法中，病变和器官水平的吸收剂量估计值一致在 26% 范围内，对于关键器官，在 13% 范围内。与 NETTER-1 试验的剂量测定估计值总体一致。结论。个性化¹⁷⁷Lu-DOTATATE 剂量测定法是一种被确定为有价值的组合方法，它利用了由单个图像处理工作流程支持的两种剂量计算方法。在没有定量成像限制的情况下，体素蒙特卡罗方法可能通过考虑病变和危险器官的吸收剂量不均匀性来提供有价值的信息来指导治疗。患者比例的参考体模方法还提供了有价值的信息，包括对非分段器官的吸收剂量估计，以及对包括活动骨髓在内的复杂放射敏感器官的更准确的剂量估计。