Determination of reference dose levels among selected X-ray centers in Lagos State, South-West Nigeria

Abstract

Background: With increasing use of diagnostic X-ray machines across Lagos, South-West Nigeria, relevant international bodies have proposed the use of reference dose levels (RDLs) to help manage radiation dose to patients without compromising image quality. Objectives: The purpose of this study was to determine the entrance surface dose (ESD) at third quartile (75 th percentile) in Lagos metropolis for normal adult radiographic examinations and to compare them with national and international established reference dose guidelines. Materials and Methods: One dedicated X-ray unit in each diagnostic center was used for this study denoted as H1-H10. A noninvasive Unfors ThinX RAD kilovoltage (kVp) meter which served as the phantom (mimicked patient) was used for measurements. The ESDs were determined by placing the Unfors ThinX RAD kVp meter on the patient′s table bucky at a source to image distance (SID) of 100 cm and at the erect bucky at a SID of 180 cm. The peak tube kVp was varied at different milliampere seconds (mAs). Results : The mean ESD for adult postero-anterior (PA) chest, antero-posterior (AP) Abdomen and (AP) lumbar spine X-ray examination were 0.603, 2.57, and 2.57 mGy, respectively. While the ESD for the third quartile for adult (PA) chest, (AP) abdomen, and (AP) lumbar spine X-ray examination among the ten X-ray centers were 0.93, 2.74, and 2.47 mGy, respectively. Conclusion: Third quartile ESD which translate to RDL for adult (PA) chest examination for this study was higher compared to other national and international RDLs but adult (AP) abdomen and lumbar spine examinations were within accepted national and international range.

Keywords

• Entrance surface dose
• milliampere seconds
• peak tube kilovoltage
• reference dose levels
• technical factor
• third quartile