Patient dose audit for patients undergoing six common radiography examinations: Potential dose reference levels

Abstract

The purpose of this study was to determine radiation doses for patients undergoing six general radiography examinations at the main x-ray department of Charlotte Maxeke Johannesburg Academic Hospital (CMJAH). In addition, for the first time, a baseline for potential dose reference levels (DRLs) in South Africa was established for the selected examinations. Patient data and technical parameters related to the x-ray examinations were collected. The study involved the following examinations: chest posterior-anterior (PA), chest lateral (LAT), pelvis anterior-posterior (AP), abdomen AP, lumbar spine AP and thoracic spine AP. Entrance surface air kerma was calculated based on the x-ray tube output of the unit used and the exposure parameters used for the actual examination. Descriptive statistics were generated from the data using Microsoft Excel 2007. Diagnostic reference levels (DRLs) were established based on the third quartile of the entrance surface air kerma (ESAK) values. This study involved two x-ray rooms, 117 patients and a total of 166 ESAK calculations. Based on the mean ESAK values from the individual rooms, the following DRLs were established: 0.1 mGy for chest PA, 0.22 mGy for chest LAT, 2.98 mGy for pelvis AP, 4.19 mGy for abdomen AP, 5.30 mGy for lumbar spine AP and 3.28 mGy for thoracic spine AP. The established DRLs were compared with previously published DRLs from other countries. Since the data presented in this study is an initial attempt at establishing local DRL values, it provides a benchmark for the statutory authorities to establish dose reference levels for diagnostic radiology in South Africa.