Radiation Medicine and Protection (Sep 2021)
Personalized radioprotection in tumor patients after 125I seed brachytherapy
Abstract
Objective: To investigate patient-specific radioprotection methods for people in close contact with cancer patients treated by 125I-seed implantation. Methods: The initial dose rates (Ḋ0) at distances of 30 and 100 cm from 80 patients who had undergone 125I-seed implantation were measured within 24 h of the procedure. The dose rate at t (Ḋt) and effective dose (E) were calculated according to the measured values of Ḋ0. The appropriate precaution times for general adult family members, spouses, coworkers, and children or pregnant women were determined, and the relationships between Ḋ0 and precaution time for different close-contact groups were derived by curve-fitting the corresponding data. Results: The mean Ḋ0 values of 80 patients at distances of 30 and 100 cm were (15.24 ± 11.25) μSv/h and (1.96 ± 2.63) μSv/h, respectively (P < 0.05). The mean values and range of precaution time for general adult family members, spouses, coworkers, and children or pregnant women were (4.17 ± 16.55), (102.93 ± 49.22), (51.00 ± 61.29), and (34.27 ± 56.90) d; (0–90.61), (0–234.01), (0–247.81), and (0–224.69) d, respectively. Furthermore, a logarithmic relationship between Ḋ0 and precaution time (Y) was observed for the different groups. The equations of these relationships were determined to be Y = −131.569 + 83.256 lnḊ0 for general adult family members, Y = −108.532 + 83.318 lnḊ0 for spouses, Y = 25.470 + 83.318 lnḊ0 for coworkers, and Y = 2.585 + 83.229 lnḊ0 for children or pregnant women. Conclusions: Some cancer patients treated by 125I-seed brachytherapy emit over-dose levels of γ-rays, necessitating radiation protection for their close contacts. However, appropriate patient-specific radiation protection for different close contacts can be determined based on the precaution time calculated using the Ḋ0 value.
