EFFECTIVE DOSES ASSOCIATED WITH CT EXAMINATIONS AND RADIATION INDUCED LIFETIME CANCER RISK ESTIMATION

Abstract

Background

Computed Tomography (CT) examinations are increased significantly over the past three decades. However CT contributed substantially higher radiation doses as compared to conventional x-ray procedures. In this study, the radiation doses are estimated for head and chest CT procedures and calculated the cancer risks on the basis of measured doses.

Material and Methods

CT doses are estimated by using scanner derived parameters and thermo luminescent dosimeters (TLD) for head and chest CT procedure. TLD chips were placed on the exposed area of the selected patients and one TLD for each patient placed outside the field to measure the scattered radiation. Age, weight and height of all selected patients were recorded. To evaluate the TLD dose, exposed TLDs were read with TLD reader.

Results

Mean doses of male and female patient for head CT procedure measured with CT generated dose index and TLD were 57.59 ± 2.354 mGy and 47.1 ± 5.35 mGy respectively. Mean doses for chest scan generated with CT dose index was 8.82 ± 2.09 mGy and measured with TLD came out to be 15.73 ± 5.2 mGy. The mean effective doses calculated for CT and TLD were 2.0 ± 0.579 mSv and 0.443 ± 0.043 mSv during head CT procedure and 5.6 ± 0.913 mSv and 1.7 ± 0.754 mSv found for chest CT examination. Based on measured data lifetime excess cancer risks for head and chest CT were calculated.

Conclusion

Radiation doses measured from selected procedures in diagnostic CT examinations were lower than the recommended dose limits and variable within the same examinations. The calculated doses from CT derived parameters and TLD do not exceed the recommended safe limits for head and chest CT procedures.