Challenges experienced in establishing clinical indication based diagnostic reference levels: Pilot study

The objective of this study is to establish clinical-indication based Diagnostic Reference Levels (DRLs) for the Computed Tomography (CT) examinations of Head, Abdomen & Pelvis + Contrast, and Kidney Ureter Bladder (KUB). Further, is to investigate the cases that register high-end doses to enable dose optimization.

Dose length product total (tDLPs) and scan acquisition parameters of a total of 715 patients who underwent CT Head, CT Abdomen & Pelvis + Contrast, and CT KUB studies were obtained and retrospectively examined. An electronic patient radiation dose monitoring system DOSE-TQM linked with the existing PACS was used to randomly generate patient dose information. Patient's demographics, clinical indications and scan acquisitions were also collected. ANOVA and Tukey's multiple comparison tests were used to check statistical differences between tDLPs per clinical indications.

The data exhibited 341 CT Head, 109 patients for CT Abdomen & Pelvis + Contrast, and 265 CT KUB examinations. The DRLs proposed using total DLP (mGy.cm) for clinical indications; abdominal pain for both CT Abdomen & Pelvis + Contrast and CT KUB (441 and 311 mGy.cm, respectively), appendicitis /acute appendicitis (484 mGy.cm), head trauma (544 mGy.cm), stroke (544 mGy.cm) and renal colic (308 mGy.cm). These values were concluded to be below or in close proximity with the total DLP based indication reported internationally. Patient weight is a significant dose contributor.

DLP differences exists not only between the same anatomical based CT studies but also across the same clinical indications. DLPs based on clinical indications provide a tool for CT dose optimisation that is better adapted to clinical practices and to the variability of patient's morphology.