Poster - Thur Eve - 68: Computed Tomography Patient Dose and National Diagnostic Reference Levels in Iran

Abstract

Objective: To measure radiation doses from Computed Tomography(CT) in the head, chest and abdomen techniques and compare them with the international diagnostic reference levels, as part of National Research project, attempting to establish National Diagnostic Reference Levels (NDRL's). Materials and Methods: 50 CTscanners from all private and none private hospitals or clinics around the country were selected. All scanners were conventional or helical single‐slice or multi— detectors row CT systems. Five thousand patients undergoing above mentioned techniques were included. Collected data included patient height, weight, sex, and age; tube voltage and tube current—time product settings; pitch; slice thickness; number of slices. Weighted or volumetric CT dose index (CTDI); and dose‐length product (DLP) were measured using a pencil shape ionizing chamber with standard rod Plexiglas's with16, 32 cm in diameters for head and body respectively. Results: Mean volumetric CT dose index and DLP values were below the European diagnostic reference levels: 31 mGy and 1135 mGy‐ cm, respectively, at head CT; 12.8 mGy and 514 mGy‐cm, respectively, at chest CT; and 13.4 mGy and 537 mGy‐ cm, respectively, at abdominal CT. Estimated effective doses were 2.61, 8.74, and 8.06 mSv, respectively. Conclusion: NDRL's for CT is going to be established in the country and comparison of our results with EU revealed that we are in a good conditions but we have to reconsider CT techniques parameters for children.