Simulation measurement and analysis of dose received by the personnel during ¹²⁵I seed implantation

Objective: To simulate and measure the exposure dose of workers during ¹²⁵I seed implantation treatment, and to provide radiation dosimetry data for the protection of workers. Methods: According to the contacting processes seed source in the field investigation, the ¹²⁵I seed implantation operation process was simulated. Before and after implantation, the ambient dose equivalent rate levels were measured respectively at 0.05 m and 1.0 m from the source. During implantation, 10, 50, 100, and 150 ¹²⁵I seeds were placed on the treatment bed and covered with 0 mm, 1 mm, 10 mm, 20 mm thick solid water and 0.25 mmPb lead pads, respectively. The level of dose equivalent rates around the head, chest and abdomen were detected at 10 cm from the bed and 155 cm, 125 cm, and 105 cm from the ground, respectively. The hand represents 0.05 m from the radiation source. Results: The ambient dose equivalent rate at 0.05 m from the well-type ionization chamber was 0.46 ∼ 0.64 μ Sv/h during measuring the activity of the seed source. After the seeds are loaded into the implant gun, the ambient dose equivalent rate on its surface was 15.7 ∼ 16.3 μSv/h, and the ambient dose equivalent rates of the other tested stages were the background radiation level. In the process of seed implantation, with the increase of the number of implanted seeds, the level of the ambient dose equivalent rate at the staff operating positions increased with the order of head, abdomen, chest and hands. However, with the increase of thickness of the solid water, the level of the ambient dose equivalent rate of each operating position decreases sequentially. When the seed source was covered with a lead pad, the ambient dose equivalent rate on its surface was at the background radiation level. Conclusion: Although the radiation dose received by the staff during ¹²⁵I operations did not exceed the requirements of relevant national laws and regulations, it was at a relatively high level, and should be paid enough attention. (authors)