Comparison of Entrance Surface Doses and Radiographic Techniques in the West Midlands (UK) with the CEC Criteria, Specifically for Lateral Lumbar Spine Radiographs

Abstract

The technique factors used by hospitals for five common examinations (skull, thoracic spine, lumbar spine, abdomen and pelvis) were compared with the CEC criteria and calculated doses were assessed. A more detailed survey was undertaken for lateral lumbar spine radiographs, including direct entrance surface dose measurements. This showed that: (1) 11 (39%) departments used nominal film-screen speed classes below 400. (2) 5 (18%) departments used a mean focus-film distance of less than 100 cm. (3) 18 (64%) departments used kilovoltages less than 90 kV. (4) 5 (18%) departments exceeded the reference dose of 30 mGy. A mean TLD dose of 19.9 mGy (s=12.2 mGy, n=245) was obtained for patients whose individual weights were within the range 50-90 kg. The considerable variation between the mean calculated/direct dose ratio for each department demonstrates the importance of direct dose measurements. The overall mean dose ratio was 1.0 (s-0.47, n=217).