Division, Nuclear Medicine Research, MedStar Health Research Institute, Hyattsville, MD, USA.
Division of Nuclear Medicine, MedStar Washington Hospital Center, Washington, DC, USA.
Ann Nucl Med. 2022 Mar;36(3):213-223. doi: 10.1007/s12149-021-01655-y. Epub 2022 Feb 4.
The objective of this study is to evaluate the lesion absorbed dose (AD), biological effective dose (BED), and equivalent uniform dose (EUD) to clinical-response relationship in lesional dosimetry for I therapy.
Nineteen lesions in four patients with metastatic differentiated thyroid cancer (DTC) were evaluated. The patients underwent PET/CT imaging at 2 h, 24 h, 48 h, 72 h, and 96 h post administration of ~ 33-65 MBq (0.89-1.76 mCi) of I before undergoing I therapy. The I PET/CT images were used to perform dosimetry calculations for I therapy. Lesion dose-rate values were calculated using the time-activity data and integrated over the measured time points to obtain AD and BED. The Geant4 toolkit was used to run Monte Carlo on spheres the same size as the lesions to estimate EUD. The lesion AD, BED, and EUD values were correlated with response data (i.e. change in lesion size pre- and post-therapy): complete response (CR, i.e. disappearance of the lesion), partial response (PR, i.e. any decrease in lesion length), stable disease (SD, i.e., no change in length), and progressive disease (PD, i.e., any increase in length).
The lesion responses were CR and PR (58%, 11/19 lesions), SD (21%, 4/19), and PD (21%, 4/19). For CR and PR lesions, the ADs, BEDs and EUDs were > 75 Gy for 82% (9/11) and < 75 Gy for 18% (2/11). The ADs and BEDs were < 75 Gy for SD and PD lesions.
By performing retrospective dosimetry calculations for I therapy based on I PET/CT imaging, we evaluated the correlation of three dosimetric quantities to lesional response. When lesion AD, BED, and EUD values were > 75 Gy, 47% (9/19) of the lesions had a CR or PR. The AD, BED, and EUD values for SD and PD lesions were < 75 Gy. The data presented herein suggest that the greater the lesion AD, BED, and/or EUD, the higher the probability of a therapeutic response to I therapy.
本研究旨在评估 I 治疗中病灶剂量学的病变吸收剂量（AD）、生物有效剂量（BED）和等效均匀剂量（EUD）与临床反应的关系。
对 4 例患有转移性分化型甲状腺癌（DTC）的患者的 19 个病灶进行评估。患者在接受 ~33-65MBq（0.89-1.76mCi）I 治疗前 2 小时、24 小时、48 小时、72 小时和 96 小时进行 PET/CT 成像，然后进行 I 治疗。使用 I PET/CT 图像为 I 治疗进行剂量计算。使用时间-活性数据计算病灶剂量率值，并在测量时间点上积分以获得 AD 和 BED。使用 Geant4 工具包对与病灶大小相同的球体进行蒙特卡罗模拟，以估算 EUD。将病变 AD、BED 和 EUD 值与反应数据（即治疗前后病变大小的变化）相关联：完全缓解（CR，即病变消失）、部分缓解（PR，即病变长度任何减小）、疾病稳定（SD，即长度无变化）和疾病进展（PD，即长度任何增加）。
病变反应为 CR 和 PR（58%，19 个病变中的 11 个）、SD（21%，19 个病变中的 4 个）和 PD（21%，19 个病变中的 4 个）。对于 CR 和 PR 病变，82%（9/11）的病变 AD、BED 和 EUD 值>75Gy，18%（2/11）的病变 AD、BED 和 EUD 值<75Gy。SD 和 PD 病变的 AD 和 BED 值<75Gy。
通过基于 I PET/CT 成像对 I 治疗进行回顾性剂量计算，我们评估了三种剂量学参数与病变反应的相关性。当病变 AD、BED 和/或 EUD 值>75Gy 时，19 个病变中有 47%（9/19）有 CR 或 PR。SD 和 PD 病变的 AD、BED 和 EUD 值<75Gy。本文的数据表明，病变 AD、BED 和/或 EUD 值越大，对 I 治疗的治疗反应的可能性就越高。
