Patient and occupational dosimetry in double contrast barium enema examinations

A new and relatively simple method is presented to distribute total dose-ar ea product (DAP) over a number of projections that model exposure during do uble contrast barium enema (DCBE) examinations. In addition, hitherto unava ilable entrance and effective doses to the physician performing the DCBE ex amination have been determined. DAP, fluoroscopy time, number of images as well as some patient data were collected for 150 DCBE examinations. For a s ubset of 50 examinations, the distribution of DAP over 12 hypothetical but representative projections was estimated by measuring the entrance dose in the centre of each of these projections during the complete procedure. Effe ctive dose to the patient was obtained using DAP to effective dose conversi on coefficients calculated for each of the 12 projections. Exposure of the worker was quantified by measuring the entrance dose at the forehead, neck, arms, right hand and legs. The sex-averaged effective dose to the patient per examination was 6.4 +/-2.1 mSv (mean +/- SD; n=50) and the correspondin g DAP was 44 +/- 22 Gy cm(2). The effective dose to the worker per examinat ion was 0.52 mu Gy (n=50), whereas the highest entrance dose of 30 +/- 25 m u Gy was found for the right arm. The proposed method for deriving the dist ribution of total DAP over a set of representative projections is much less time consuming than visual observation of patient exposure, whilst accurac y seems acceptable. Entrance and effective doses per examination for worker s in DCBE examinations are very low. For a normal workload, doses remain fa r below the legally established dose limits.