A survey of diagnostic reference levels for head, chest and abdomen and pelvis CT in several private diagnostic facilities in Norway

Abstract

Background: Computed Tomography (CT) scans account for 60% of the total radiation dose in medical imaging. Literature has shown that patient dose varies across CT scanner design, diagnostic protocols, and technical parameters at each site. Suggesting there is an opportunity for optimization through establishing diagnostic reference levels (DRLs).

Purpose: To collect, evaluate and compare local DRLs (LDRLS) for frequently performed CT protocols. Materials and Methods: Dose data from 1500 patients was collected from 10 diagnostic facilities and included non-contrast CT scans of the head and contrast-enhanced scans of the thorax and abdomen and pelvis from average-sized adult patients. An ANOVA test was performed to determine the variation in dose between scanners. LDRLS was determined by the 75th percentile of median values from dose indicators of CT scanners.

Results: The difference between the means of the dose distribution from each scanner was statistically significant (p < 0.05) for all examinations. The LDRLs determined were lower overall, for both national and international DRLs.

Conclusion: Observed dose variations from the scanners indicate a need for protocol optimization for some institutes, while the LDRLs demonstrate a potential for establishing newer NDRLs in Norway.