Evaluation of radiation safety in¹⁷⁷Lu-PSMA therapy and development of outpatient treatment protocol

Abstract

The aim of this study is to investigate the outpatient treatment protocol and radiation safety of a new-emerging lutetium-177 ((177)Lu) prostate specific membrane antigen (PSMA) therapy. This work analyzed the dose rate of 23 patients treated with 7400 MBq (177)Lu-PSMA at different distances (0, 0.25, 0.50, 1.0 and 2.0 m) and variable time marks (0, 1, 2, 4, 18, 24, 48 and 120 h) after the termination of infusion. Blood samples were withdrawn from 17 patients within the same group at 3, 10, 20, 40, 60 and 90 min and 2, 3, 24 h after termination of infusion. Seven different patients were asked to collect urine for 24 h and a gamma well counter was used for counting samples. Family members were invited to wear an optically stimulated luminescence dosimeter whenever they were in the proximity of the patients up to 4-5 d. The total dose of the medical team including the radiopharmacist, physicist, physician, nurse, and nuclear medicine technologist was estimated by an electronic personnel dosimeter. The finger dose was determined using a ring thermoluminescent dosimeter for the radiopharmacist and nurse. The mean dose rate at 1 m after 4 h and 6 h was 23 ± 6 μSv h(-1) and 15 ± 4 μSv h(-1) respectively. The mean total dose to 23 caregivers was 202.3 ± 42.7 μSv (range: 120-265 μSv). The radiation dose of the nurse and radiopharmacist was 6 and 4 μSv per patient, respectively, whereas the dose of the physicist and physician was 2 μSv. The effective half life of blood distribution and early elimination was 0.4 ± 0.1 h and 5 ± 1 h, respectively. Seven patients excreted a mean of 45% (range: 32%-65%) from the initial activity in 6 h. Our findings demonstrate that (177)Lu-PSMA is a safe treatment modality to be applied as an outpatient protocol, since the dose rate decreases below the determined threshold of <30 μSv h(-1) after approximately 5 h and degrades to 20 μSv h(-1) after 6 h.

Lu-177-PSMA-617 Prostate-Specific Membrane Antigen Inhibitor Therapy in Patients with Castration-Resistant Prostate Cancer: Stability, Bio-distribution and Dosimetry

“…In accordance with the previous bio-distribution and dosimetry studies, the highest radiation absorbed dose was observed in salivary glands due to high uptake of the radiopharmaceutical and it seems to be the critical organ at risk rather than the kidney and bone marrow (11,12,13,14,15). Xerostomia is a frequent side effect of radiation therapy after exceeding 40 Gy of radiation doses, which decreases patient’s quality of life (16,17).…”

“…During the first 24 hours, good hydration and frequent urination may protect the bladder from high radiation-absorbed dose. Due to its rapid excretion, it seems that Lu-177-PSMA-617 therapy can be given in an outpatient protocol according to national regulations, since 6 h after administration of the radiopharmaceutical the dose rate decreases to 20 μSv/h and the radiation exposure of caregivers remains below 5 mSv (14). …”

Lutetium 177 PSMA radionuclide therapy for men with prostate cancer: a review of the current literature and discussion of practical aspects of therapy

“…However in our institution, patients were recorded to be below the recommended guideline of 25  μ Sv/h by 1 h post‐injection and all were recorded to be below 25  μ Sv/h at the time of discharge. The safety of 177 Lu PSMA administration to staff and caregivers was emphasised in a recent publication 31. The authors measured radiation doses delivered both to administering staff and family in 23 patients who received a mean dose of 7500Mbq 177 Lu PSMA per injection.…”

“…The safety of 177 Lu PSMA administration to staff and caregivers was emphasised in a recent publication. 31 The authors measured radiation doses delivered both to administering staff and family in 23 patients who received a mean dose of 7500Mbq 177 Lu PSMA per injection. They found that the mean dose rate at 1 m after 4 and 6 h was…”

Functional Optimization of Radionuclide Pairs in Theranostics of Prostate Cancer

“…Интересно, что точно такой же критерий по мощности дозы 30 мкГр/ч при выписке пациентов был получен и в работе [23], хотя расчетные формулы там не приводятся. об ограничениях на обращение с жидкими радиоактивными отходами -еще одним важным аспектом радиационно-гигиенического сопровождения радионуклидной терапии.…”