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 radiogr aphic 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 produ ct through computer simulations of radiation transport in anthropomorp hic phantoms. The relation between patient dose and imaging or radiogr aphic technique was considered. Patient dose from a biphasic colon exa mination was compared to that from a double-contrast examination. RESU LTS: The factors for converting dose-area product to effective dose we re 0.29 mSv . Gy(-1) . cm(-2) and 0.27 mSv . Gy(-1) . cm(-2) for the b iphasic and the double-contrast studies, respectively. The average dos e-area product for the biphasic colon examination was 21 Gy . cm(2), o f 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). CONCLUS ION: Careful selection of the radiologic technique resulted in a surpr isingly low dose during the biphasic colon examination. It is recommen ded that additional filtration of at least 0.1-mm copper be applied an d that a screen-film combination with a speed class of at least 400 be used. Dose reduction when using digital techniques is often not reali zed in clinical practice.