COMPUTER-ASSISTED DETERMINATION OF THE DOSE-AREA PRODUCT IN RETROGRADE URETHROGRAPHY

Retrograde urethrography (RUG) is a dynamic radiological procedure in which the cumulative dose-area product (DAP comprises radiation doses derived from both fluoroscopy and radiography. In the present prospect ive study, digital retrograde urethrographs (Prestilix 1600X DRS. Gene ral Electric) are obtained in 40 consecutive male patients (mean age 6 0.6 years: range 23-88 years) presenting for evaluation of urinary pat hology. The radiation dose was recorded as the dose-area product. From these data. a. computer program (Diasoft 2.0, PTW, Freiburg, Germany) then determined the respective proportions of the total radiation dos e deriving from fluoroscopy and radiography, as well as the number of radiographic exposures. The average total radiation dose was 316 cGy c m(2). In five of the 40 patients examined (12.5%), the number of radio graphic exposures registered by the program and, hence the calculated DAPs were erroneous. In the remaining 35 patients, the average proport ion of the cumulative DAP resulting from fluoroscopy was 81% b. while that deriving from radiography was 19%. The computer program utilized in this study makes possible an intelligent evaluation of the DAP in d ynamic procedures such as RUG. Since fluoroscopy is responsible for 81 % of the cumulative DAP at RUG, a significant decrease in applied radi ation dose may be achieved by reducing fluoroscopy time or by using pu lsed fluoroscopy.