[Usefulness of Copper Filter Addition and Potential for Dose Reduction in Hip-joint Radiography].

Purpose: In this study, we evaluated image quality and radiation dose reduction when a Copper (Cu) filter was added to hip joint X-ray imaging.

Methods: We measured effective energy without (0 mm) and with (0.1/0.2 mm) Cu-added filter at 70 kV, and we calculated soft tissue-bone contrast and signal-difference-to-noise-ratio (SDNR) under constant entrance surface dose. After that, we estimated the dose reduction rate.

Results: The effective energy was 32.07 keV for 0 mm Cu, 37.59 keV for 0.1 mm Cu, and 40.91 keV for 0.2 mm Cu. As the thickness of the Cu-added filter was increased, contrast decreased, but SDNR increased. The dose reduction rate in bone calculated measuring SDNR was 34% for 0.1 mm Cu and 47% for 0.2 mm Cu in max.

Conclusion: It was suggested that adding Cu filter to hip-joint X-ray imaging could reduce entrance surface dose while maintaining the image quality based on SDNR.