Establishing Diagnostic Reference Levels for Single-Photon Emission Computed Tomography (SPECT) Imaging: A Preliminary Study in Indian Healthcare Settings.

Introduction In nuclear medicine, there is a critical need to balance the control and optimization of radiation doses to ensure patient safety while achieving high-quality diagnostic outcomes. However, diagnostic reference levels (DRLs) for nuclear medicine imaging studies have not been established in India. This study aims to fill this gap by establishing institutional DRLs and assessing radiation dose data specifically for Nuclear Medicine SPECT examinations. Methods This research was a cross-sectional observational study conducted in a single tertiary care setting, involving 1,250 patients. Data on the administered activity for 18 common single photon emission computed tomography (SPECT) procedures were gathered from 2019 to 2021. The 75th percentile (Q3) was established as the baseline for the institutional DRLs. Furthermore, the study conducted comparative analyses with established international DRLs. Results The study proposed institutional DRLs based on 18 SPECT nuclear medicine imaging examinations. The highest Q3 DRLs were identified for 99mTc-sestamibi (1193 MBq), followed by 99mTc-methylene diphosphonate (747 MBq) and 99mTc-ethyl cysteinate dimer (608 MBq). The lowest DRL was recorded for 99mTc gastric emptying imaging (37 MBq). Comparisons with international DRLs indicated close alignment with European Association of Nuclear Medicine Medical Internal Radiation Dose guidelines, while DRLs set by the National Council on Radiation Protection and Measurements (NCRP) were identified as distinct in several key aspects when compared to other established DRLs. Conclusion This research marks a significant step toward standardizing SPECT procedure doses in India, contributing to improved patient safety and care in nuclear medicine. The established DRLs will enhance the optimization of administered activities, ensure adherence to international standards, and improve diagnostic quality while reducing radiation exposure. These institutional DRLs will serve as the foundation for developing a roadmap to establish national DRLs.