Methods used to estimate the collective dose in Denmark from diagnostic radiology

According to EU directive 97/43/Euratom all member states must estimate doses to the public from diagnostic radiology. In Denmark the National Institute of Radiation Hygiene (NIRH) is about to finish a project with the purpose of estimating the collective dose in Denmark from diagnostic radiology. In this paper methods, problems and preliminary results will be presented. Patient doses were obtained from x-ray departments, dentist and chiropractors. Information about the frequencies of examination was collected from each of the Danish hospitals or counties. It was possible to collect information for nearly all of the hospitals. The measurements were done by means of dose area product meters in x-ray departments and by termoluminescens dosimetry at chiropractors and solid-sate detectors at dentists. Twenty hospitals, 3.200 patients and 23.000 radiographs were measured in this study. All data were stored in a database for quick retrieval. The DAP measurements was done "automatically" controlled by PC based software. Later these recordings could be analysed by means of specially designed software and transferred to the database. Data from the chiropractors were obtained by mail. NIRH sent each chiropractor TLD's and registration form. The chiropractor did the measurements him self and returned afterwards the TLD's and registration forms. On the registration form height, weight, age etc. of the patient was noted and so was information about applied high-tension, current-time product and projection. Calculation of the effective dose from the DAP values and the surface entrance dose were done by Monte Carlo techniques. For each radiographs two pictures of the mathematical phantom were generated to ensure that the x-ray field where properly placed. The program ”diagnostic dose” developed by NIRH did the Monte Carlo calculations. INTRODUCTION According to EU Directive 97/43/Euratom (1) all member states must estimate doses to the public from diagnostic radiology. In Denmark the National Institute of Radiation Hygiene (NIRH) is about to finish a project with the purpose of estimating the yearly collective dose in Denmark from diagnostic radiology. In this paper, methods, problems and preliminary results will be presented. MATERIAL AND METHODS When estimating the collective dose to the public, one needs to know the number of various xray examinations performed annually and the mean effective dose for each type of examination. The collective effective dose (CED) can be calculated by means of the following equation: