ESTIMATION OF RADIATION RISK AND ESTABLISHMENT OF DIAGNOSTIC REFERENCE LEVELS FOR PATIENTS UNDERGOING COMPUTED TOMOGRAPHY CHEST-ABDOMEN-PELVIC EXAMINATIONS IN SUDAN

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

BackgroundComputed tomography (CT) scans account for 60% of the total radiation dose in medical imaging. Literature has shown that patient dose varies across CT scanners, diagnostic protocols, and technical parameters at each site, suggesting an opportunity for starting an optimization process through establishing diagnostic reference levels (DRLs).PurposeTo establish local DRLs (LDRLs) for six Norwegian private diagnostic institutes for frequently performed CT protocols.Material and MethodsDose data from 900 patients were collected from six diagnostic facilities. Data were recorded from 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 were determined by the 75th percentile of median values from dose indicators of CT scanners.ResultsThe 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, for both national and international DRLs.ConclusionObserved dose variations from the scanners indicate a need for protocol optimization for some institutes, while the LDRLs demonstrate a potential for establishing newer national diagnostic reference levels (NDRLs) in Norway.

A survey of local diagnostic reference levels for the head, thorax, abdomen and pelvis computed tomography in Norway and Canada

Background

Computed tomography (CT) contributes to 60% of the collective dose in medical imaging. Literature has demonstrated that patient dose varies across regions and countries. Establishing diagnostic reference levels (DRLs) contributes to the optimization of clinical practices and radiation protection.

Purpose

To survey the dose indices (CTDIvol and dose-length product) for frequently performed CT examinations from the chosen hospitals in Norway and Canada and to determine local DRLs (LDRLs) based on the collected data.

Material and Methods

The survey included eight scanners from two Norwegian hospitals and four scanners from four Canadian hospitals. Dosimetry data were collected for the following routine CT examinations: head, contrast-enhanced thorax, and abdomen and pelvis. Overall 480 adult average-sized patients from Norway and 360 from Canada were included in the survey. The LDRLs were determined as the 75th percentile of distributions of median values of dose indicators from different CT scanners. The differences in dose between scanners were determined using single-factor ANOVA.

Results

The LDRLs determined in Norway were higher overall than in Canada. The obtained values were compared to the national DRLs. The dose from several scanners in Norway exceeded national Norwegian DRLs, while Canadian LDRLs were below the Canadian reference levels. The differences between the means of the dose distributions from each scanner were statistically significant (p < 0.05) for all examinations with exception of identical scanners located in the same hospital and using the same protocols.

Conclusion

Observed dose variations even in the same hospital, or from the same scanner model confirmed the need for CT protocol optimization.