Comparison of image quality obtained with optical and radiographic magnification techniques in fine-detail skeletal radiography: effect of object thickness.

Abstract

High-resolution radiography may be done using either optical or radiographic magnification. In the former technique, industrial Type M film was used without screens and the image was viewed with 4-10X optical magnification. In the latter technique, RP film was used with Detail screens and 4X geometric magnification together with a microfocus x-ray tube having a nominal focal spot size of 50 mum. The imaging properties of both techniques were evaluated by means of H & D curves, modulation transfer functions, and Wiener spectra. It was found that for thin objects such as the hand, optical magnification provides better bone images than radiographic magnification; whereas for thicker parts such as the knee, radiographic magnification is superior.