Salman Ali, Maseeh-uz Zaman, Nosheen Fatima, Khalil Khan, Gufran Khan, Noreen Hameed, Sadaf Saleem, Mansoor Naqvi.
Temporal Trends in Exposure Rates from Bone Scan patients: Time Ensures Safety.
Pak J Radiol Jan ;25(1):18-21.

Background: Bone scintigraphy is one of the most frequently performed of nuclear medicine procedures and nuclear medicine technologists are prone to expose at time of administering the radiopharmaceutical and position the patient during imaging. The purpose of this research work was to find out the exposure rates from patients undergoing bone scan at various time interval after injection of radiopharmaceutical. Material and Methods: This was a prospective study conducted at Nuclear Medicine Section, Department of Radiology, Aga Khan University Hospital, Karachi from January 2015 till February 2015. After injection of radiopharmaceutical (700-740 MBq of Tc-99m MDP), exposure rates (milli-Roentgen/hour; mR/h) were estimated at 1 meter distance at 10 minutes (T0) and 1 hour (T1) after injection and time of leaving the department (T2). Results: During the study period, 71 patients were accrued with a mean age of 54 ±17 years. Male: Female 51%:49%. Mean dose of Tc-99m MDP injected was 705 ± 131 MBq intravenously. Mean exposure rates at 1 meter distance at T0, T1 and T2 were 13.103 ± 4.631, 10.980 ± 4.559 and 5.300 ± 3.186 mR/h respectively. There was a statistically significant temporal reduction in exposure rates which was 16% in 1st hour (T0 to T1) and 60% in next phase (T1-T2). Conclusion: We conclude that exposure rate at 1 meter from bone scan patients to nuclear medicine technologists at the time of imaging is significantly lower than at 1 hour after injection. To keep radiation exposure at minimum, NM technologists should adopt time and distance strategies of radiation protection.

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