Why do you want to take pictures at high kV with a line filter?

According to Baidu Encyclopedia, because of the large energy of high kilovolts, it will scatter when passing through human tissues, resulting in gray images, and adding line filters will reduce scattered lines, so it is necessary to use line filters to assist photography.

High kV photography is a photography method that uses high-energy X-rays generated by tube voltage above 120kV to obtain rich X-ray photographic images in a small density range.