An approach to develop a diagnostic reference level in gamma camera imaging for bone scan

Background: In a Gamma Camera Unit, bone scans are the most commonly performed imaging procedure. Diagnostic reference levels (DRLs) play a crucial role in optimizing radiation exposure for patients and staff, while maintaining high-quality diagnostic images.
Objective: The objective of this study is to optimize the patient radiation dose by establishing a DRL for gamma camera imaging for bone scan performed at two hospitals in Colombo, Sri Lanka.
Methods: A total of 134 imaging procedures were sourced and compiled from the hospital database for this study. 84 gamma camera imaging procedures were selected from Apeksha Hospital, Maharagama (Hospital No.1) and 50 procedures were selected from Asiri Surgical Hospital, Colombo (Hospital No.2), from September 2022 to November 2022. According to the recommendation of the International Commission of Radiological Protection (ICRP), the median value of the administered activity value was considered to develop DRL.
Results: The median values of the administered activity for the two hospitals were 587 MBq for Hospital No.1and 586 MBq for Hospital No.2. The developed DRL values for bone scan in gamma camera imaging are 587 MBq (15.865 mCi) for Hospital No.1 and 586 MBq (15.839 mCi) for Hospital No.2. There is a 0.026 mCi difference in administered activity observed between two institutes.
Conclusions: There were significant correlations observed between the administered activity and patient’s body mass index, and between the administered activity and patient’s clinical indication.