Purpose : This study aims to compare the image quality and dose in accordance with the changes of magnification power of standard dose and low dose protocol in angiography to utilize it as clinical index.
Matrials and method : This study used SIEMENS equipment, NEMA phantom, Unfors Xi meter. The study conducted comparison on average value after examining accumulated dose during 30 seconds for 5 times by giving variation to magnification power of image when using standard and low dose protocol. An independent sample t-test was performed to verify the statistical significance of the mean dose difference between the two protocols. To compare the image quality in accordance with magnification power, the study measured spatial resolution, low contrast resolution, wire resolution.
Result : As the result of comparing accumulated amount of dose, the low dose had decrease rate of dose compared to standard dose(48cm 27.88%, 42cm 39.92%, 32cm 29.68%, 28cm 38.72%, 16cm 11.71%, 11cm 0.83%). Excluding 11cm, all variables were statistically very significant as p<0.001. As for the image quality, there was no image quality difference in 48cm. spatial resolution showed decrease in 42cm, 32cm and 22cm. There was no image quality difference in 16cm and 11cm.
Conclusion : When low dose showed average decrease rate of dose about 34.05±6.14% in 48cm, 42cm, 32cm, 22cm compared to standard dose protocol, 16cm had decrease rate as low as 11.71% and 11cm had decrease rate of 0.83% which was similar. However, compared to decrease rate of dose, in image quality comparison using NEMA Phantom, only 42cm, 32cm and 22cm had spatial resolution, and other magnification power did not show difference in image quality. In conclusion, the low dose protocol in NEMA Phantom with 20cm thickness did not have significant difference in image quality with standard dose compared to decrease rate of dose.
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