| 摘要 |
<p>The appts. uses a conventional X-ray tube to send X-rays through the patient onto an anti-diffusion grid (2). The fluorescent screen (3) is placed on the anti-diffusion grid (2) and scanned by a television camera (4) fitted with a low level light analysing tube (5) (e.g. silicon intensification target type). In order to reduce the light diffusion and the fluorescent scintillation, the upper fluorescent face of the screen is covered by an anti-diffusion lamellar grid; its lower face is covered by optical surfaces (micro-lens, micro-prismatic surface or Fresnel lenses). The anti-diffusion grid, fluorescent screen and camera are mounted inside a lead screened light-tight protective casing (6). The appts. is much cheaper than the classical X-ray appts. using large diameter brightness amplifier, and provides a similar images quality on a larger field of vision.</p> |
