Depth resolution: a mechanism by which high kilovoltage improves visibility in chest films.

Depth resolution, a measure of the thinnest layer of tissue which will cast a detectable radiographic shadow, significantly limits visibility in conventional chest technique. Depth resolution, averaged over the chest area, improves with increasing kilovoltage, and thin, soft tissues can be seen more readily. The visibility of calcifications increases with kilovoltage in some areas of the chest and decreases in others, which is again explained by depth resolution. Densitometric data verify the mechanism involved: the latitude of the radiographic image matches that of the conventional film at high kilovoltages, so that more chest images are recorded at high contrast where visibility is best.