Kurth J, Krause B J, Schwarzenböck S M, Stegger L, Schäfers M, Rahbar K
Department of Nuclear Medicine, Rostock University Medical Center, Gertrudenplatz 1, 18057, Rostock, Germany.
Department of Nuclear Medicine, University Hospital Muenster, Muenster, Germany.
EJNMMI Res. 2018 Apr 12;8(1):32. doi: 10.1186/s13550-018-0386-4.
Prostate-specific membrane antigen (PSMA)-targeted therapy with Lu-PSMA-617 is a therapeutic option for patients with metastatic castration-resistant prostate cancer (mCRPC). To optimize the therapy procedure, it is necessary to determine relevant parameters to define radiation protection and safety necessities. Therefore, this study aimed at estimating the ambient radiation exposure received by the patient. Moreover, the excreted activity was quantified.
In total, 50 patients with mCRPC and treated with Lu-PSMA-617 (mean administered activity 6.3 ± 0.5 GBq) were retrospectively included in a bi-centric study. Whole-body dose rates were measured at a distance of 2 m at various time points after application of Lu-PSMA-617, and effective half-lives for different time points were calculated and compared. Radiation exposure to the public was approximated using the dose integral. For the estimation of the excreted activity, whole body measurements of 25 patients were performed at 7 time points. Unbound Lu-PSMA-617 was rapidly cleared from the body. After 4 h, approximately 50% and, after 12 h, approximately 70% of the administered activity were excreted, primarily via urine. The mean dose rates were the following: 3.6 ± 0.7 μSv/h at 2 h p. i., 1.6 ± 0.6 μSv/h at 24 h, 1.1 ± 0.5 μSv/h at 48 h, and 0.7 ± 0.4 μSv/h at 72 h. The mean effective half-life of the cohort was 40.5 ± 9.6 h (min 21.7 h; max 85.7 h). The maximum dose to individual members of the public per treatment cycle was ~ 250 ± 55 μSv when the patient was discharged from the clinic after 48 h and ~ 190 ± 36 μSv when the patient was discharged after 72 h.
In terms of the radiation exposure to the public, Lu-PSMA is a safe option of radionuclide therapy. As usually four (sometimes more) cycles of the therapy are performed, it must be conducted in a way that ensures that applicable legal requirements can be followed. In other words, the radiation exposure to the public and the concentration of activity in wastewater must be sub-marginal. Therefore, in certain countries, hospitalization of these patients is mandatory.
使用镥-PSMA-617进行前列腺特异性膜抗原（PSMA）靶向治疗是转移性去势抵抗性前列腺癌（mCRPC）患者的一种治疗选择。为了优化治疗程序，有必要确定相关参数以明确辐射防护和安全要求。因此，本研究旨在估算患者所接受的环境辐射暴露。此外，还对排泄物中的活度进行了量化。
一项双中心研究回顾性纳入了总共50例接受镥-PSMA-617治疗的mCRPC患者（平均给药活度6.3±0.5GBq）。在注射镥-PSMA-617后的不同时间点，于距离患者2米处测量全身剂量率，并计算和比较不同时间点的有效半衰期。使用剂量积分估算公众所受的辐射暴露。为了估算排泄物中的活度，对25例患者在7个时间点进行了全身测量。未结合的镥-PSMA-617迅速从体内清除。4小时后，约50%的给药活度被排出，12小时后，约70%的给药活度被排出，主要通过尿液。平均剂量率如下：注射后2小时为3.6±0.7μSv/h，24小时为1.6±0.6μSv/h，48小时为1.1±0.5μSv/h，72小时为0.7±0.4μSv/h。该队列的平均有效半衰期为40.5±9.6小时（最小值21.7小时；最大值85.7小时）。当患者在48小时后出院时，每个治疗周期公众个体所受的最大剂量约为250±55μSv，当患者在72小时后出院时，约为190±36μSv。
就公众所受的辐射暴露而言，镥-PSMA是一种安全的放射性核素治疗选择。由于通常要进行四个（有时更多）周期的治疗，必须以确保能够遵循适用法律要求的方式进行。换句话说，公众所受的辐射暴露以及废水中的活度浓度必须低于临界值。因此，在某些国家，这些患者必须住院治疗。
