Heart size in high-kilovoltage chest radiography.

High-kilovoltage (kV) radiography of the chest using an air gap results in magnification of the heart and thorax despite the use of a longer focus-to-film distance. One hundred patients had their recent high-kV chest radiograph compared with their previous low-kV film. There was a significant increase in all cardiac parameters. Geometric distortion of the cardiac shadow also occurred, resulting in magnification and elongation preferentially affecting the left side of the heart. We believe this causes an additional subjective impression of a large heart. Radiologists and clinicians should revalue their assessment of cardiac size when such a technique is used.