Objective Image Quality Measurements and the EC Quality Criteria for Lumbar Spine Radiographs

A series of AP lumbar spine radiographs taken in four different hospitals were examined and compared with EC Quality Criteria for radiographic technique and film density. Two of the hospitals assessed had modern X ray equipment installed within the last five years and two hospitals had much older X ray equipment. Individual patient doses were measured using thermoluminescence dosemeters calibrated following the UK National Dose Protocol. All the radiographs were reported as being clinically acceptable. The radiographic techniques used mostly complied with the EC quality criteria. Mean doses were less than 50% of the recommended levels. The films were digitised using a Lumisys film digitiser. The mean density of the AP radiographs was 1.24 which compared well with the density measured using a 20 cm water phantom and was within the target range 1.0 to 1.4 recommended in the Quality Criteria. The mean density of the lateral films was 1.4. The spread of mean density was much narrower in the two hospitals with AEC devices. Densities of four anatomical regions were measured and differences between adjacent regions were calculated and found to be small.