Estimation of effective dose using the dose length product in chest computed tomography procedures

Background: approximation of radiation risks in computed tomography (ct) requires knowledge of specific organ doses. a rando phantom and thermoluminescent dosimeters (tlds) provide a proxy for in-vivo measurements. in this study, measured chest ct doses were used to calculate dose length product (dlp), a dosimetric needed for estimation of effective dose (e). method and materials: ninety-five calibrated tlds embedded at peripheral and central positions of rando phantom chest slice measured chest ct dose during imaging using phillips brilliance 64-slice ct scanner. three measurements were conducted each with new tlds. irradiated tlds were read with a harshaw tld reader (model 3500). one-way anova test verified statistical significance of tld measurements. tld doses were used to calculate chest ct dose given as dose length product (dlp), a product of chest slice ct dose measured by volumetric ct dose index (ctdiv) multiplied by scan length. consequently, e was calculated as the product of dlp and k, an adult chest conversion factor published by international commission on radiological protection publication 103. results: differences in mean tlds measurements were statistically significant (p=0.032). the mean chest slice peripheral and center doses were 3.61 ± 0.6 and 4.60 ± 0.31 mgy respectively. adult chest ct dose was 178.8 ± 15 mgy. e was estimated as 2.5 ± 0.21 msv. it is than the range (5.6 – 9.3 msv) found in literature. conclusion: e relates radiation exposure to stochastic effects. the estimated value (e = 2.5±0.21 msv), reveals that chest ct protocol used was optimized.