Establishment of local diagnostic reference levels for CT colonography at a tertiary hospital

Filip M Kozłowski; Christoffel J van Reenen; Christoph J Trauernicht

doi:10.4102/sajr.v28i1.2809

Establishment of local diagnostic reference levels for CT colonography at a tertiary hospital

SA J Radiol. 2024 Jan 31;28(1):2809. doi: 10.4102/sajr.v28i1.2809. eCollection 2024.

Authors

Filip M Kozłowski^{1

2}, Christoffel J van Reenen^{1

2}, Christoph J Trauernicht^{1

2}

Affiliations

¹ Division of Medical Physics, Tygerberg Hospital, Cape Town, South Africa.
² Department of Medical Physics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.

Abstract

Background: Diagnostic reference levels (DRLs) are an important metric in identifying abnormally high radiation doses in diagnostic examinations. National DRLs for CT colonography do not currently exist in South Africa, but there are efforts to collect data for a national DRL project.

Objectives: This study investigated radiation doses for CT colonography in adult patients at a large tertiary hospital in South Africa with the aim of setting local DRLs.

Method: Patient data from two CT scanners (Philips Ingenuity and Siemens Somatom go.Top) in the period March 2020 - March 2023 were obtained from the hospital's picture archiving and communication system (PACS) (n = 115). Analysis involved determining the median computed tomography dose index-volume (CTDI_vol) and dose-length product (DLP) values. The findings were compared with DRLs established internationally.

Results: Ingenuity median CTDI_vol was 20 mGy and DLP was 2169 mGy*cm; Somatom median CTDI_vol was 6 mGy and DLP was 557 mGy*cm. Ingenuity exceeded the United Kingdom's (UK) recommended DRLs by 82% and 214%, respectively. Somatom median CTDI_vol and DLP were 45% and 19% lower than UK NDRLs.

Conclusion: Somatom's tin filter and other dose reduction features provided significant dose reduction. These data were used to set DRLs for CT colonography at the hospital; CTDI_vol: 6 mGy and DLP: 557 mGy*cm.

Contribution: In addition to informing radiation protection practices at the level of the institution, the established local DRLs contribute towards implementing regional and national DRLs.

Keywords: CT; colonography; computed tomography; computed tomography dose index-volume; diagnostic reference level; dose optimisation; dose-length product.

Grants and funding

Funding information This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.