A Comprehensive Study on Radiological Risk Analysis During 99m Tc-MDP Bone Scintigraphy: Highlighting Monte Carlo Simulation of Organ-Specific Absorbed Doses

Handling patients and processing radiopharmaceuticals during bone scintigraphy procedures causes potential radiation exposure risk to working personnel. The current study focuses on a detailed radiological risk investigation due to occupational radiation exposure during 99mTc- methylene diphosphonate (MDP) bone scintigraphy at the Institute of Nuclear Medicine and Allied Sciences, Chattogram, Bangladesh. A digital radiation survey meter was used to measure the occupational dose rates resulting from exposure to 20 mCi of 99mTc-MDP given to 30 patients undergoing bone scintigraphy at the facility. Measurements were carried out from the patient’s anterior, posterior, left lateral and right lateral anatomical positions for both head, chest and foot level at different distances (30, 50, 100, and 200 cm) and time points (5, 120, and 180 min). The maximum mean dose rate of 26.68 µSv/h was determined at the chest level for 5 min time point and 30 cm distance from the posterior position, exceeding the occupational dose rate limit of 25 µSv/h. Applying the visual Monte Carlo simulation approach, it was investigated that the whole eye, breast and testes were the maximum dose receiving organs with a dose value of 10.94 μGy, 9.19 μGy and 2.10 μGy, respectively, positioning a 20 mCi 99mTc source at the voxel phantom’s head, chest and foot level for the same time point and distance. Thus, concerning overexposure threats at the identified anatomical position, time point, distance and organs during the diagnostic procedure, every employee must attempt consciously to undertake required protective measures and follow the ALARA principle properly.