The influence of field of view on radiation dose and resolution of digital substraction angiography

Objective: To investigate the influence of incident screen size on the representative and maximum value of air kerma rate of perspective body surface, air kerma rate of image receptor front screen, spatial resolution and low contrast resolution, by testing 9 PHILIPS Allura Xper FD 20 digital subtraction angiography systems. Methods: We tested the indexes of the nine radiography unit with the Specification for testing of quality control in medical X-ray diagnostic Equipment (WS 76 — 2017). The data were collected under auto exposure in perspective mode with the bed 100 cm far away from the ground, and image receiver 30 cm far away from the bed surface, moreover phantom and surveying instrument located at the center of radiation field. All data were analysed by SPSS 23.0. Data were done by Tamhane′ T2 test and Kruskal-Wallis test. Pearson correlation analysis was used for correlation analysis. The difference was statistically significant by P < 0.05. Results: The experimental results of the nine units showed that, reducing the field of view of digital subtraction angiography could significantly improve spatial resolution and low contrast resolution, and increase the representative value of air kerma rate of perspective body surface and air kerma rate of image receptor front screen, but had no effect on the maximum value of air kerma rate of perspective body surface. Conclusion: In this study, we found that changing the field of view of digital subtraction angiography could cause the influence of incident screen size on the representative value of air kerma rate of perspective body surface, air kerma rate of image receptor front screen, spatial resolution and low contrast resolution. And that result was closely related to the changes of kV and mA caused by FOV of digital subtraction angiography. (authors)