Entrance surface dose measurements for routine X-ray examinations in Chaharmahal and Bakhtiari hospitals

Over the past hundred years or so, X-rays have been used for diagnostic purposes. The use of X-rays for imaging purposes, however, exposes patients to ionizing radiation. The increasing use of X-ray in hospitals has made medical exposure an important source of radiation in the population collective dose (1, 2). Ionizing radiation has the ability to break apart biologically important molecules such as DNA in exposed cells and can cause harm. As a result, the amount of radiation received by patients undergoing X-ray examinations needs to be quantified to estimate the possibility of harm. Patient doses in radiography primarily depend on the entrance surface dose and the sensitivity of the organs and tissues that are irradiated during the radiographic examination (3). The patient effective dose is proportional to the entrance surface exposure, and also depends on the X-ray penetrating power. The body region being examined is another important factor for determining the patient dose. The effective dose is a radiation dose parameter, which takes into account the absorbed dose received by each irradiated organ and the organ's relative sensitivity. Since the effective dose may be taken as an approximate measure of the stochastic radiation risk, it may be used to quantify the amount of radiation received by patients undergoing diagnostic examinations (4). Radiation protection is concerned with the control of the manner in which sources of ionizing radiation are used so that the user of the sources and also members of the public are not irradiated above acceptable levels recommended by the International Commission on Radiological Protection (2). Many studies have been proposed to measure entrance surface dose in different countries and their results were compared with dose levels recommended by relevant organizations. Also, organizations such as the National Radiological Protection Board and International Atomic Energy Agency (1, 5) recommended the use of dose constraints or *Corresponding author: Dr. Daryoush Shahbazi-Gahrouei, Department of Medical Physics and Medical Engineering, Isfahan University of Medical Sciences, Isfahan, Iran. Fax: +98 311 6688597 E-mail: [email protected] Background: There is not any report on the radiation doses received by patients in diagnostic radiology sections in hospitals under control of Chaharmahal and Bakhtiari Medical Sciences University, in the south west of Iran. The aim of this study is measurement of entrance surface doses (ESD) for the most routine types of X-ray procedures in radiology centers as part of ongoing dose reduction program. Materials and Methods: Geiger-Muller and thermoluminescence dosimeters (TLD), were used to measure entrance surface doses for four common radiographic views in six hospitals (7 X-ray machines). The entrance surface dose was measured on 20 randomly selected patients (male and female) for each X-ray examination. Patients were not exposed to any additional radiation and the radiographs were used for diagnostic purposes. Results: The entrance surface doses for the PA and lateral chest X-ray examinations were found to be in the range of 0.22-1.45 and 0.344.90 mGy, respectively. The ESD values for the AP or PA skull and LAT skull were in the range of 2.55-8.45 and 2.85-9.12 mGy, respectively. Most of the ESD measured doses were slightly greater than the ICRP and NRPB reference doses. Conclusion: The results of the present study indicate a need for quality assurance (QA) programs to be undertaken to avert considerable cost and high patient doses. The recommendations to avoid unnecessary radiation exposure are also given without lose of image quality. Iran. J. Radiat. Res., 2006; 4 (1): 29-33