Portal de Periódicos da CAPES

I. Apparatus and Method of Use

1955; Wiley; Volume: 28; Issue: 334 Linguagem: Inglês

10.1259/0007-1285-28-334-543

1748-880X

W D Oliphant,

Advanced X-ray and CT Imaging

In 1937 Chester F. Carlson described and patented a new photographic process which was based entirely on physical processing. This new method of image reproduction depended on electrostatics and tribo-electricity and was in direct contrast to other methods, such as silver halide photography, which require wet chemical processing for image development and fixation. In view of the essentially dry nature of the process, it was named xerography. It was first fully described by Schaffert and Oughton in 1948. The application of xerography to radiography, known as xeroradiography, followed naturally in the development of xerography and the early work has been described by McMaster (1951). Xerography depends fundamentally on the properties of thin films of certain photoconductive insulating materials such as anthracene, sulphur and amorphous selenium. These materials, whilst possessing high insulating properties in the dark, become conductive on exposure either to light or to X rays and it is this photoconduction process which enables the materials to be used photographically. Of the materials mentioned amorphous selenium is the best. It is near black in colour, is comparatively stable physically and has enamel-like properties so that it can be handled quite easily. A xerographic plate consists essentially of a mechanically rigid backing plate, which must also possess a certain amount of electrical conductivity, on one surface of which is deposited uniformly a film of amorphous selenium 50 to 100 μ thick.