Purpose : This study was aimed to evaluate the image qulity and the amount of radiation dose on the patients by collimating the window of uneffected site with Dyna CT scan which is frequently used in TACE procedure.
Targets and Methods : We compared entrance surface dose, DAP and air kerma value by attatching glass dosimeter to the abdomen surface of rando phantom model and collimating to 0, 4, and 8 cm with 6sDCT body and 5s DCT body care mode of Dyna CT of Axiom artis Q equipment. In order to quantitatively evaluate the change of the image quality before and after collimation application, we measured the signal-to-noise ratio and the contrast-to-noise ratio. Paired smaple T-test and Pearson correlation analysis was used to analyze the data.
Result : In the TACE procedure with 6s DCT body mode with the full field of 0cm, ESD, DAP and air Kerma were measured as 4465.5uGy, 4385.0uGym2, and 145mGy. In case of 4cm collimation, the values of ESD, DAP and Air Kerma were 3840.1, 3978.7, and 142mGy. With the 8cm collimation, ESD, DAP and Air Kerma were measured as 3714.1, 3476.8, and 173 in each. The dose reduction rate was 14% at 4 cm for ESD, 8 cm decreased by 16.8% , The DAP value was 9.5% when 4cm collimation was applied, decreased by 20.9% when 8cm collimation was applied. 5s DCT Body Care mode when the full field is Non Collimation ESD was 2055.35μGy, DAP was 1854.0μGym², Air Kerma was measured at 60.1 mGy, When applying 4cm Collimation ESD was 1921.35μGy, DAP is 1851.1μGym², Air Kerma was measured at 60.2 mGy. For 8cm Collimation, ESD is 1469.95μGy, DAP는 1497.3μGym², Air Kerma was measured at 74.6 mGy, At this time, the reduction rate of ESD dose was 6.5%, And 28.5% at 8 cm, DAP was 0.16% when 4cm collimation was applied, When applied 8cm, it showed a decrease of 19%. The SNR and CNR values of the Rando phantom obtained before and after the collimation were significantly smaller than the p-values of 0.05 (p <0.001).
Conclusion : Dyna CT in TACE procedure fields other than the region of interest are collimated to reduce the dose received by the patient, The 5s DCT Body Care mode can significantly reduce ESD and DAP, which can significantly reduce unnecessary exposure doses that patients receive during testing and treatment.
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