Peter Ekwulugwo Ojike - Radiography Unit, Department of Radiology, Federal University Teaching Hospital Owerri (Formerly, Federal Medical Center Owerri), Imo State Nigeria
Chikwendu Emenike Orji - Department of Physics, Federal University of Technology Owerri, Imo state, Nigeria
Kelechukwu Bierechi Okeoma - Department of Physics, Federal University of Technology Owerri, Imo state, Nigeria
Chinyere Ada Madu - Department of Physics, Federal University of Technology Owerri, Imo state, Nigeria
Usman Rilwan - Department of Physics, Nigerian Army University, Biu, Borno State, Nigeria

The work aimed at establishing DRLs for adult CT examination of the head in Rivers State, Nigeria. The dose report and scan parameters for adult Head examination was retrospectively surveyed during the study period of four months in three CT center. Sixty-nine patient folders, comprising twenty-five subjects for center A, twenty-three subjects for center B, and twenty-one subjects for center C were included. Data on CT dose index (CTDIvol) and dose length product (DLP) displayed on CT scanner console from three (۳) selected hospitals were recorded for each facility. The percentile (۷۵th) was assessed for all centers to set up center-unique DRLs. Lastly, a summed percentile (۷۵th) for mean of DLP and CTDIv in the entire centers was assessed to obtain DRLs in adult Head examinations across investigated area. Facts were analyzed with the aid of SPSS (version ۲۵.۰). The modern files (digital) of ۲۴ female and ۴۵ male patients with age bracket ۱۶-۱۰۰ years old were analyzed. Centre-unique percentile (۷۵th) of mean DLP and CTDIv of three centers A, B, and C were ۳۹ mGy and ۸۲۰ mGy.cm, ۷۰.۹ mGy, and ۱۳۳۰ mGy.cm, ۵۵ mGy, and ۱۱۵۸ mGy.cm, respectively. The head CT examination DRLs for the area was ۵۴.۹ mGy and ۱۱۰۳ mGy.cm. The Head CT examination’s DRLs for the state of Rivers has been obtained. Nonetheless, variation between CT scan center was noted, CTDIvol is lower than recommendations of European Commission (EC) of ۶۰mGy. The DLP is slightly supper than EC value of ۱۰۰۰ mGy.cm. Personnel training and more awareness on optimization of dosage may still aid to further guide down the dosage of radiation within the location compared to international values. Therefore, centers with fairly lower values than the state derived DRLs (LDRL) should retain their values, while those whose values are higher should implement dose optimization.

Dose Optimization, Computed tomography, Diagnostic Reference Levels, Volume Computed Tomography Dose index, Dose length product