A new high-definition microfocal X-ray unit.

A new microfocal unit is described with an operating range up to 170 kVp (limited to 125 kVp for medical use), 0-1 mA and a maximum output of 75-80 W. The unit comprises a lanthanum hexaboride (LaB6) cathode, a single electromagnetic lens and a stationary oil-cooled multifaced tungsten target. The estimated source size ranges from 6 to 20 microns between 14 and 77 W. The tube's output is x 3 to x 3.5 greater than that of a conventional X-ray unit. The use of fast rare-earth film-screen systems permits exposures of most views of the patient within 1 s. The spatial resolution within these film-screen systems is 40-30 microns diameter at magnifications of x 5-10. The tube is fixed so as to project a horizontal beam and the patient table is designed to position the patient close to the source (20-30 cm) with the film placed at a focus-film distance of 1-3 m. Stereopair macroradiographs permit greater accuracy in the identification and location of radiographic features. The large magnification and resolution of macroradiographs allow direct and accurate measurement of radiographic features.