Radiation dose and diagnosticity of barium enema examinations by radiographers and radiologists: a comparative study

A review of factors affecting patient doses for barium enemas and meals

A study of patient doses for barium enema and meal examinations has been carried out for hospitals in the West of Scotland to assess the impact of dose reduction facilities on new X-ray equipment. Dose-area product (DAP) information has been collected on examinations for groups of patients at 20 hospitals and results reviewed together with data on equipment performance measurements. Median DAPs for barium enemas and meals were 15.7 Gy cm(2) and 4.8 Gy cm(2), respectively, and effective doses estimated from the results are 3.5+/-0.7 mSv and 1.5+/-0.5 mSv, respectively. These doses are lower than those reported in earlier studies and in previous surveys in the West of Scotland. The reduction in dose is linked primarily to the low dose facilities available on newer X-ray equipment, such as low dose pulsed fluoroscopy, digital imaging facilities and use of copper filtration. Use of the image intensifier for decubitus images on C-arm units employed for barium enemas also gives a significantly lower dose. Equipment with copper filtration had the lowest doses. The reduction in effective dose will be significantly less than the reduction in DAP for units in which a copper filter is included and the adoption of lower diagnostic reference levels is proposed for units with this facility. It is important that the operators are aware of the low dose imaging options on their equipment in order that techniques can be fully optimized.

Barium enema: use of increased copper filtration to optimize dose and image quality

The purpose of this study was to determine and validate the optimum copper filtration for adult double contrast barium enema examinations. Entrance surface dose rates to polymethyl methacrylate slabs and corresponding image intensifier input kermas, were measured for various added copper filters. Image contrast was assessed using a Leeds TO.10 test object. Copper filter thickness of 0.3 mm was chosen, as this reduced entrance surface dose rate by 56%, without substantially degrading image contrast due to kV and mA saturation. 20 sets of clinical films taken with each of 0.3 mm copper, 0.1 mm copper and no copper were reviewed following randomization, by a specialist gastrointestinal radiologist. Each set of digital spot and conventional films was allocated a score for each of three regions of the bowel, on a scale of 0-3 for perceived barium coating. The Kruskal-Wallis test showed no significant difference in perceived coating between the three groups (Digital spot: sigmoid colon p=0.207, splenic flexure p=0.103, hepatic flexure p=0.894. Screen-film: left colon p=0.803, right colon p=0.487, transverse colon p=0.905). All examinations but one were classified as diagnostic. The remaining one was classified indeterminate, due to poor distension of the colon. On adding 0.3 mm copper filtration, the mean dose-area product per examination was reduced by 57%, from 17.7 Gy cm(2) to 7.6 Gy cm(2). The estimated reduction in effective dose was 11%, from 3.0 mSv to 2.7 mSv. X-ray tube loading increased by 30%, but this caused no overheating with our local examination protocol and schedule. Additional filtration of 0.3 mm copper for adult double contrast barium enemas has now been implemented in routine clinical use at our hospital.