ABSTRACT
The diagnostic reference levels (DRLs) are determined from dosimetry studies to compare and manage patient doses in medical imaging procedures. The aim of this work was to establish the first DRLs for pediatric patients during the most common computed tomography (CT) procedures in Yaoundé, Cameroon during routine head CT examinations to know how to improve our clinical practice tomorrow. The sample was classified per age group: ≤ 1-, 1-5-, 5-10- and 10-15-y-old. The retrospective study was used. The proposed DRLs were defined as 75th percentile of the median values of the distributions. In terms of Volume CT Dose Index (CTDIvol) and dose length product (DLP), the DRLs obtained for the ages groups were: 28.6 mGy and 545.8 mGy.cm, 32.6 mGy and 735 mGy.cm, 37.1 mGy and 761.6 mGy.cm and 44.2 mGy and 1081.2 mGy.cm, respectively. DRLs in Yaoundé for DLP were higher than those of comparison literatures. The Yaoundé CTDIvol was higher than the comparison literatures except for the IAEA (2015) values for the three older age groups. The DRLs reported in Yaoundé were compared to Morocco 2020, Switzerland 2018, IAEA 2015 and Iran 2020 values. The estimation of this first DRL for pediatric head CT scan in Yaoundé must be a starting point to spread this investigation towards other examinations and imaging modalities across the country. Therefore, optimization of the CT scan procedures and orderly updates of local DRLs are necessary to improve radioprotection.
Subject(s)
Diagnostic Reference Levels , Tomography, X-Ray Computed , Humans , Child , Aged , Retrospective Studies , Radiation Dosage , Reference Values , CameroonABSTRACT
Purpose: Patient radiation doses encountered during conventional X-ray examinations are not exactly known.This study aims to realize a radiation dose audit for chest posterior-anterior (PA) and chest lateral (LAT) examinations;analyze the procedures and establish local diagnostic reference level (LDRL).Method: A total number of 882 radiographs of 715 patients from seven selected hospitals in Yaounde were considered in this work.Entrance surface dose (ESD) ofadult patients undergoing chest PA and chest LAT examinations is estimated; using a mathematical algorithm and a standard backscatter factor.Results: Estimated mean ESDs in the hospitals range from 0.28 to 0.73mGy for chest PA and from 0.39 to 2.08 mGy for chest LAT. For each projection there is a wide variation in patientsESD within hospitals for individual patients and between hospitals.The third quartile ESD value 0.39 mGy for chest PA examinations was found to be above both the Diagnostic Reference Levels (DRLs)reported from similar studies in some African countries and the international established DRLs; while the value 1.33 mGy obtained for chest LAT was within the established international DRLs.Conclusion:The major contribution to the high dose has been identified in the use of shorter focus-film distance (FFD) and higher charge (mAs). Other factors are boththeabsence of quality control and the equipment performance.This study shows the need of the implementation of protocol and technics that can reduce patient dose and regular quality control and quality assurance
