The Development of Local Diagnostic Reference Levels for Common Adult Computed Tomography Examinations at Mzuzu...

Diagnostic reference level (DRL) is an important tool used to identify abnormally high radiation doses, aid dose audits, and trigger investigations in diagnostic radiological imaging. This study aimed to develop local DRLs for the adult head, chest, and abdomen computed tomography (CT) examinations without contrast material at Mzuzu Central Hospital (MCH).

This retrospective study was conducted at MCH radiology department using a NeuViz 16-slice Essence CT scanner from September 2023 to March 2024. The consecutive sampling method was used to extract data from patients' head, chest, and abdominal images from advanced visualization workspace (AVW) and Picture Archiving and Communication Systems (PACS) using a checklist. All images were anonymized, and the data was kept in password-locked folders. Data was exported into SPSS version 26.0 software for analysis. Continuous variables were expressed as means and medians. Categorical variables were presented in form of tables as frequencies. The local DRLs were obtained by calculating the median radiation dose values by anatomical region.

Out of 802 patients enrolled in this study, 361 (45%) had head CT examinations, 187 (23%) had chest CT examinations, and 254 (32%) had abdomen CT examinations without contrast. Local DRLs obtained by calculating the median of volume CT dose index (CTDIvol) and dose length product (DLP) for the head, chest, and abdomen CT examinations were 31 mGy, 5 mGy, 7 mGy, and 699 mGy.cm, 227 mGy.cm, and 331 mGy.cm, respectively.

Local DRLs for the head, chest, and abdomen have been developed for a NeuViz 16 Essence multi-detector CT scanner at MCH. The CTDIvol and DLP median values were lower or comparable to other single-facility, regional, and international values. This study should serve as a baseline for developing national adult CT DRLs for Malawi.