Patient dose resulting from CT examinations in Yazd, Iran

With the introduction of computed tomography in diagnostic radiology a new and fundamentally different imaging modality has become available. Meanwhile, it is clear that the absorbed doses by the patients during CT were relatively high in comparison with those of other diagnostic radiology techniques. The aim of this survey was to determine the average absorbed dose in Yazd province by CT examinations, and to evaluate the potential risks per year by these examinations. Materials and Methods: This study was conducted in Yazd CT centers during 2005-2006. The examination frequencies from 3 CT scanners were collected from all types of examinations. The effective dose was determined by CT Dose program (ImPACT CT patient dosimetry calculator). To use of this software, CTDIair, mAs and the thickness and number of slices in each type of CT examinations should have been measured. CDTIair was measured by pencil diode detector. Results: The annual collective dose and caput dose were 32.48 Person-Sv and 0.038 mSv, respectively for the Yazd population, which is lower than that reported for other populations. The frequency of examinations per 1000 people of Yazd was 18 which were equal to many other populations such as UK and New Zealand. The mean effective dose of each CT examinations was also lower than that of other countries. Conclusion: According to the ICRP risk factors, radiation dose from CT examinations could lead to about 1.3 fatal cancer per year. 'Therefore request for CT examinations should be more justified