Patient dose due to colon examination: Dose assessment and results from a survey in the Netherlands

PURPOSE: To determine the effective dose to the patient during radiographic colon examination. MATERIALS AND METHODS: The integral dose-area product was measured during colon examination in 1,733 patients aged 18-94 years. The effective dose was estimated from the dose-area product through computer simulations of radiation transport in anthropomorphic phantoms. The relation between patient dose and imaging or radiographic technique was considered. Patient dose from a biphasic colon examination was compared to that from a double-contrast examination. RESULTS: The factors for converting dose-area product to effective dose were 0.29 mSv . Gy(-1) . cm(-2) and 0.27 mSv . Gy(-1) . cm(-2) for the biphasic and the double-contrast studies, respectively. The average dose-area product for the biphasic colon examination was 21 Gy . cm(2), of which 13 Gy . cm(2) was attributed to the double-contrast views. The average dose-area product was 29 Gy . cm(2) (range, 18-53 Gy . cm(2)); the average effective dose was 4.7 mSv (range, 2.7-8.4 mSv). CONCLUSION: Careful selection of the radiologic technique resulted in a surprisingly low dose during the biphasic colon examination. It is recommended that additional filtration of at least 0.1-mm copper be applied and that a screen-film combination with a speed class of at least 400 be used. Dose reduction when using digital techniques is often not realized in clinical practice.