Relationship between Patient Anatomical Thickness and Radiographic Exposure Factors for Selected Radiologic Examinations

Abstract

The most common cause of errors in radiographic examinations is inappropriate selection of exposure factors, which depends on the patient’s anatomical thickness. Inappropriate selection of exposure factors could lead to either underexposed or overexposed radiographs and unnecessary radiation exposure to the patient. The study sought to assess the relationship between patient anatomical thickness and their corresponding radiographic exposure factors used in the selected examinations. Anatomical thicknesses of patients aged 18 years and above, who presented for chest, lumbar spine or pelvis radiographic examinations at the Korle-Bu Polyclinic, from April to May 2014, were measured and recorded using a calliper of least count 0.1cm. The corresponding exposure factors (kVp and mAs) used for each examination were recorded as well as the demographic data of the patients. The study established a correlation between patient anatomical thickness and exposure factors. The results revealed a positive correlation between kVp, mAs and anatomical thickness in almost all the examinations under study. A low-negative correlation between mAs and kVp was recorded for lumbar spine lateral examinations. As mAs increases, kVp reduced marginally.

KEYWORDS: kVp, mAs, anatomical thickness