Radation distribution in head & thorax computerized tomography

Determination of the exposure levels in the computerized tomography (CT) practices is necessary to define the respected national reference levels، quality control of CT centers and the risk assessment for radiation induced cancers. On the basis of this necessity، the radiation exposure distribution due to common CT practices has been investigated at Razi Hospital CT center in Rasht using tissue-equivalent phantoms and the thermoluminescent dosimeters (TLD). The Head and Thorax phantoms were used with the standard dimensions incorporating holes at the center and edges for TLD placement. Dosimetry was carried out using LiF; Mg، Cu، P small chips due to their relatively tissue equivalence، high sensitivity convenient annealing procedure and the non-complex glow curve. Results showed that CTDI for Head is 52. 85 mGy and for Body is 68. 15mGy. CTDLW for Head is 13. 67 mGy and for Body is 16. 94mGy. In comparison with other radiographical procedures، patient absorbed doses in CT imaging are usually very high. Content of dose is increased by increase of mAs.