Local Reference Dose Level Evaluation in Chest Radiography in Yaounde

ABSTRACT

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