March 1980

The Many Advantages of Direct Microfocus Roentgenographic Magnification in Pediatric Radiology

Author Affiliations

Machine With a Uniquely Different X-ray Tube; Department of Radiology Cardinal Glennon Memorial Hospital for Children and St Louis University School of Medicine St Louis, MO 63104

Am J Dis Child. 1980;134(3):245-247. doi:10.1001/archpedi.1980.02130150003001

Direct radiographic magnification as a means of complementing diagnostic imaging is not a new concept.1 The technique has been used widely, but never applied generally because a "bigger" image was not necessarily a "better" image. The physics of direct roentgenographic imaging is a complex marriage of x-ray beam geometry and the physicochemistry of photon absorption within a cassette.

Until the time of development of the Radiological Sciences Inc (RSI) x-ray tube, virtually all medical x-ray tubes depended on a hot tungsten filament as the initial source of electrons for the generation of x-ray photons (ie, since 1913, when Coolidge2 introduced the first filament x-ray tube). Detail in magnification is adversely affected by imperfections in the beam source. The standard filament x-ray tubes usually produce two point sources and a trailing edge of radiation off their axes. The resultant images are blurred, and this blurring is amplified by magnification. Therefore, the