Takehiro Ema

A technique of scatter-glare correction using a digital filtration

A scatter-glare correction technique for x-ray images acquired with an antiscatter grid was developed. In the technique, the scatter-glare image was estimated from exposure conditions and subtracted from the acquired image. The basic procedure in the estimation of the scatter-glare image is convolution filtering; however, the novel aspects of the technique are as follows: (1) To estimate the scatter-glare intensity, a formula that does not include the term of object thickness was used. With this formula, the correction can be performed, even for nonuniform phantoms; (2) To estimate the scatter-glare distribution, the experimental scatter-glare point spread function (PSF) was directly used as a convolution kernel. Although the shape of the PSF changed slightly for water thicknesses of 5-25 cm, we applied the PSF measured at a water thickness of 15 cm to the correction experiments. For the stepped water phantom (10-20 cm), scatter-glare estimation produced an average error of 10%, with respect to the lead bar data. Furthermore, the improvement of image quality and quantitative accuracy resulting from the correction was examined.