en Radiobiology Radiobiology تحقيق بديع Original Research <div style="text-align: justify;">Background: Since the radionuclides concentration in teeth is a good indicator of the human body&rsquo;s radioactive contamination, the purpose of this study was to measure the track density of alpha particles emitted from the human teeth and to assess the resulting cancer risk. Material and Methods: In this cross-section study, 93 permanent and unfilled tooth samples were collected from the patients residing in Khorramabad, Iran, and visiting dental clinics in this city. The alpha track density for the tooth samples was measured using CR-39 nuclear track detector. Annual effective dose (AED) and excess lifetime cancer risk (ELCR)&nbsp;were estimated based on the recommendations made by ICRP and&nbsp;UNSCEAR. Results: The mean alpha track density from ²²²Rn in patients&rsquo; teeth was410.15 tracks cm^-2, whereas the mean for women and men equaled 441.42 and 378.20, respectively. This difference was not statistically significant (P=0.22), but there&nbsp;was a statistically significant difference&nbsp;between the track densities in different age groups (P˂0.001).In this study, the average radon activity concentration was 40.62 Bq m^-3.&nbsp;Also, the mean annual&nbsp;effective&nbsp;dose and the mean ELCR&nbsp;were calculated as 1.02 mSvy^-1and 3.59 &times;10^-3, respectively. Conclusion: The AED value was higher than&nbsp;the&nbsp;permissible&nbsp;dose limit and also the mean ELCR was higher than the global average. Based on the results, it is necessary to perform periodical monitoring to detect pollution sources.</div> Human tooth, alpha particle, cancer risk, CR-39 detector. 607 613 http://ijrr.com/browse.php?a_code=A-10-2188-35&slc_lang=en&sid=1 N. Hassanpour 7900319475328460020260 7900319475328460020260 No Department of Radiology and Radiotherapy, Allied Medical Sciences School, Tehran University of Medical Sciences V. Changizi 7900319475328460020261 7900319475328460020261 No Department of Technology of Radiology and Radiotherapy, Allied Medical Sciences School, Tehran University of Medical Sciences M. Gholami Gholami.mehrdad@lums.ac.ir 7900319475328460020262 7900319475328460020262 Yes Department of Medical Physics, School of Allied Medical Sciences, Lorestan University of Medical Sciences, Khorramabad, Iran