Biological effects of radiation and dosimetry in X-ray diagnostics of children

The chest radiograms represent the basic radiological examinations of thorax. The basis for radiation protection especially in pediatrics is the exact determination of doses. The risk estimation of genome damages can be received in human peripheral blood lymphocytes using alkaline version of Comet Assay. The aim of this work was assessment and quantification of the level of DNA damage in peripheral blood lymphocytes of children during airways X-ray examinations of chest and to compare data to the dose of exposure. Doses were determined using thermoluminescence (TL) dosimetry and radiophotoluminescent (RPL) glass dosimetry system. Twenty children with pulmonary diseases, ages between 5 and 14 years were assessed. Dose measurements were conducted for poster-anterior (PA) projection on the forehead, thyroid gland, gonads, chest and back. We used a 150 kV Shimadzu CH-200 M X-ray unit. Peripheral blood samples were taken from children after and prior to X-ray exposure and were examined with the alkaline Comet Assay. Comet Assay is one of the standard techniques for assessing genome damage with variety applications in genotoxicity testing as well as fundamental research in DNA damage and repair. As a measure of DNA damage tail length was used, calculated from the centre of the head and presented in micrometers (μm). Mean value of group after irradiation was 14.04 ± 1.74 as opposed to mean value of group before irradiation that was 13.15 ± 1.33. Differences between mean tail lengths were statistically significant (P<0.05, ANOVA). In addition, correlation was found between doses in primary beam (measured on the back) and the ratio of tail length (DNA damage) before and after irradiation. Doses measured with TL and RPL dosimeters showed satisfactory agreement and both dosimetry methods are suitable for dosimetric measurements in X-ray diagnostics. (author)