Establishment of facility reference level in computed tomography in selective examinations in a single institution in South Australia: A preliminary study

Introduction: The objective of this study is to provide preliminary data for the establishment of LDRL or FRL for CTDIvol and DLP for one scanner in our institution.Methods: Data was retrospectively collected from one CT scanner (Toshiba Aquilion One Vision 320-slice, installed in 2015) in our institution from 26 December 2016 to 26 June 2017. Examinations were separated as contrast and non-contrast studies, and single phasic for single acquisition or multiphasic for more than one acquisition. The common CT examinations, including chest, chest abdomen/pelvis, and abdomen/pelvis were reported. Examinations such as CT colonoscopy, CT pulmonary angiogram, CT gating angiography, CT chest and abdomen/pelvis non-contrast, CT high resolution lung and CT renal colic were excluded from the study. This is mostly due to a low number of examinations and the use of different exposure factors and/or techniques. The median mean (50th percentile), and 75th percentile for the dose spread were calculated according to the examination.Results: There was a total of 1571 CT examinations performed between 26 December 2016 and 26 June 2017 using the Toshiba scanner in our institution. 262 examinations met the inclusion and exclusion criteria. The examinations and our institutional DRLs for our Toshiba scanner (established as median value of CTDIvol and DLP), were distributed as CT chest contrast (n=67, 25.6%, 6mGy, 219.1mGy.cm), CT chest non-contrast (n=41, 15.6%, 5.7mGy, 190.6 mGy), CT abdomen/pelvis contrast (single phase) (n=49, 18.7%, 6.5 mGy, 330.5 mGy.cm), CT abdomen/pelvis contrast (multi-phase) (n=33, 12.6%, 8.93 mGy, 1037.5 mGy.cm), CT abdomen/pelvis non-contrast (n=12, 4.6%, 10.1 mGy, 289.9 mGy.cm) and CT chest and abdomen/pelvis (n=60, 22.9%, 7.15 mGy, 619.4mGy.cm).Conclusions: The preliminary data provided information that our own institution and others can use for quality improvement activities. Future research is required to allow for further analysis to include more CT examinations in various scanners.