No abstract

A detailed study of radiation doses received by 168 patients who underwent coronary angiography (CAG) and 102 patients who underwent percutaneous transluminal coronary angioplasty (PTCA) in two Greek hospitals is presented. Radiation dose was measured in terms of dose-area product (DAP). The contribution of fluoroscopy and cineradiography to the total DAP was examined separately for each radiological projection used in both procedures. Effective dose and doses to various organs were estimated with the help of the ODS-60 software. Total DAP was found to correlate linearly to fluoroscopy time and cine film length. Mean DAP values were found to be 80.8 +/- 28.0 Gy cm2 for CAG and 86.2 +/- 65.6 Gy cm2 for PTCAs, whereas the estimated mean values of effective dose were 20.9 +/- 7.5 and 23.2 +/- 18.1 mSv respectively. DAP to effective dose conversion coefficients were estimated to be 0.26 mSv/Gy cm2 for CAG and 0.27 mSv/Gy cm2 for PTCAs.

CT has become the major source of population exposure to diagnostic X-rays. CT dose index (CTDI) and dose-length product (DLP) have been proposed as the appropriate dose quantities for the establishment of diagnostic reference levels for optimizing patient exposure. Dose measurements on 27 CT scanners in Northern Greece involving six routine CT examinations have been performed in order to compare their performance with the currently proposed European reference dose values and to produce a preliminary set of data for the establishment of local diagnostic reference levels. All measurements were performed using a pencil shaped ionization chamber introduced into polymethyl methacrylate cylindrical head and body phantoms. The results revealed significant discrepancies in dose values among the CT scanners, which can be mainly attributed to variations in the examination protocols and the different kinds of scanners. Significant overdosing compared with the European reference levels has not been observed, with the exception of the routine head examination, where 47% of the scanners exceeded the corresponding CTDI(w) value. CT scans in the trunk region result in the higher effective doses, which can reach estimated maximal values of the order of 15 mSv.

The aim of this study was to measure the absorbed dose to seven organs other than the breast in mammography in order to calculate their contribution to the effective dose. The absorbed dose to these organs was measured using a lucite upper body anthropomorphic phantom containing thermoluminescent dosimeters (TLD) at appropriate locations, exposed as in a mammographic examination. In addition, the dependence of the absorbed dose on kVp, mAs and breast thickness was examined. The absorbed dose due to scattered radiation was found to be negligible to all organs except to the sternum red bone marrow (SRBM) and the thyroid. The mean doses to the SRBM and the thyroid, for a set of four exposures, one craniocaudal and one 90 degrees mediolateral per breast, simulating a complete breast screening examination, varied between 0.40 and 1.27 and 0.05-0.17 microGy mAs(-1), respectively, depending on the breast thickness and the kVp selection. Effective dose from mammography was also calculated based on the absorbed dose to the breast, the SRBM and the thyroid and tissue-weighting factors. The effective dose was found to vary between 0.66 and 0.85 microSv mAs(-1) depending on the breast thickness and the kVp value selected. The radiation dose to the breast contributes over 98% to the effective dose.