Establishing typical diagnostic reference levels in a Peruvian nuclear medicine centre: a retrospective study.

Diagnostic reference levels (DRLs) are tools for optimizing medical exposures. We performed a retrospective analysis of 898 adult scintigraphic examinations acquired between 2018 and 2024 at a Peruvian hospital to establish institutional DRLs for eight procedures. Typical values were defined as the median administered activity, and the 75th percentiles were used as institutional action levels to trigger protocol review. Median weight-normalized activities ranged from 0.1 MBq·kg-1 for 131I thyroid uptake testing to 14.5 MBq·kg-1 for three-phase bone scintigraphy; corresponding derived effective dose estimates were ~1-45 mSv and are reported only for population-level benchmarking. Comparison with international DRLs showed broad concordance; however, bone scintigraphy exceeded several reference values by >25%, indicating opportunities for optimization. These results provide the first institutional DRLs reported in Peru, identify priorities for local quality improvement, and support periodic review within an optimization cycle.