Background/Objectives: Red bone marrow irradiation is a major concern for patients with advanced prostate cancer undergoing [177Lu]Lu-PSMA therapy. However, low uptake in the red bone marrow and the presence of bone lesions complicate image-based red bone marrow dosimetry. This study aimed to investigate the general feasibility of image-based red bone marrow activity estimation for [177Lu]Lu-PSMA treatment and to develop a fully automated workflow for clinical implementation.Methods: In the first part of the study, 175 virtual patient phantoms with realistic177Lu activity distributions were generated based on 639 pre-therapeutic [18F]F-PSMA-1007 PET/CT scans. The SIMIND Monte Carlo tool was used to simulate the177Lu SPECT acquisitions (24 h post-injection (p.i.)), which were used to assess the uncertainty of red bone marrow activity estimation. In the second part, red bone marrow self- and cross-absorbed doses were estimated for four therapy cycles of 20 patients.Results: The simulation study shows a significant overestimation of activity in skeletal sites with bone lesions, with median recovery coefficients (RCs) across all phantoms yielding a median of 225% (range: 106–1015%). In contrast, the median RCs were markedly lower in skeletal sites neighboring or distant to lesion-carrying sites (105% [72–163%] and 107% [77–130%], respectively). The median total absorbed dose to the red bone marrow was 20.8 mGy/GBq (range: 5.6–297.9 mGy/GBq). Median blood levels decreased with an increasing median cumulative total absorbed dose.Conclusions: Reliable estimation of activity concentration in skeletal sites without bone lesion infiltration has been shown to be feasible. Based on this finding, an automated workflow for routine image-based red bone marrow dosimetry was developed.
背景/目的：对于接受[¹⁷⁷Lu]Lu-PSMA治疗的晚期前列腺癌患者，红骨髓照射是主要关注点。然而，红骨髓的低摄取及骨转移灶的存在使得基于影像的红骨髓剂量测定变得复杂。本研究旨在探讨基于影像的红骨髓活度估算在[¹⁷⁷Lu]Lu-PSMA治疗中的总体可行性，并开发适用于临床实施的自动化工作流程。 方法：研究第一部分基于639例治疗前[¹⁸F]F-PSMA-1007 PET/CT扫描数据，生成了175个具有真实¹⁷⁷Lu活度分布的虚拟患者模型。采用SIMIND蒙特卡洛工具模拟¹⁷⁷Lu SPECT采集（注射后24小时），用于评估红骨髓活度估算的不确定性。第二部分对20名患者四个治疗周期的红骨髓自吸收剂量与交叉吸收剂量进行了估算。 结果：模拟研究显示，存在骨转移灶的骨骼部位活度被显著高估，所有模型的中位恢复系数（RCs）中位值为225%（范围：106-1015%）。相比之下，邻近或远离骨转移灶的骨骼部位中位RCs显著降低（分别为105%[72-163%]和107%[77-130%]）。红骨髓中位总吸收剂量为20.8 mGy/GBq（范围：5.6-297.9 mGy/GBq）。随着中位累积总吸收剂量增加，中位血液活度水平呈下降趋势。 结论：研究证实对无骨转移浸润的骨骼部位进行可靠的活度浓度估算是可行的。基于此发现，开发了适用于常规影像学红骨髓剂量测定的自动化工作流程。
肿瘤(癌症)患者之家