Analysis on eye lens doses and hand doses of working operator in ¹²⁵I seed source implantation

Objective: To measure the doses to eye lens and hands of workers, using thermo luminescent dosimeter (TLD) and optically stimulated luminescence dosimeter (OSLD). Methods: TLDs in the same batch were annealed, packed and stuck to the flat abdomen of Alderson-Phantom at a distance of about 15 cm from ¹²⁵I seed source, while irradiated at different doses: 1.0, 1.5, 3.0, 5.0, 10.0, 12.0, 20.0, 25.0, 30.0, 50.0 and 60.0 μGy. And then TLDs were measured by dosimeters to establish a dose calibration curve. By implanting seed source into the selected lung for 14 cases, belly for 10 cases, pelvic for 5 case and neck for 6 cases while placing calibrated TLDs on the left, middle and right above eyes, left and right hands of the workers to obtain the location-specific kerma values. Finally, the conversion factors H_p (3) and H_p (0.07) were used to calculate the values of dose equivalent to eye lens and hands. Additionally, OSLDs were used to measure the doses to workers in the same way. Results: The TLD-measured eye lens dses to the operator and his assistant were 0.8 and 1.6 mSv in lungs, 1.3 and 1.2 mSv in bellies, 0.9 and 0.6 mSv in pelves, 0.3 mSv in necks, respectively. Meanwhile, hand doses to the operator and his assistant were 1.4 and 2.1 mSv in lungs, 1.2 and 1.0 mSv in bellies, 0.5 and 0.9 mSv in pelves, 0.1 mSv in necks, respectively. The maximum doses to eye lens and hands were 1.2 and 1.0 mSv, respectively in a single treatment. OSLD-measured dose equivalents from lung therapy were 0.2 and 0.1 mSv for eye lens of the operator and his assistant and 0.4 and 0.6 mSv for hands. For belly therapy, the accumulated dose equivalent to hands of the operator was 0.1 mSv while those for other types of therapy were 0 mSv. Conclusions: TLDs have the capability to measure not only accumulated dose but also dose equivalent from a single therapy According to ICRP 118 publication and as estimated in the present study, the number of therapy should be not more than 17 every year. OSLDs only give the accumulated dose, the accuracy of which needs to be studied in low-dose measurement. (authors)