Nano-Phosphor Grid Screens for Mammography
Abstract
The goal of this research is to fabricate X-ray mammography screens with dramatically increased contrast/resolution capabilities. A conventional X-ray phosphor screen has a thickness of about 50 to 200 microns and consists of phosphor particles with a mean size between 3 to 10 microns. The light generated in the phosphor screen by the incident X-rays scatters over the thickness of the screen material. As the light scatters, it spreads out which results in loss of spatial resolution and contrast. To overcome the severe light scattering that stems from the phosphor screen thickness, without compromise in X-ray absorption, two approaches have been rigorously investigated. The first approach is to manufacture screens based on a novel type of efficient phosphors: nanocrystalline phosphors. The second approach is to fill microchannel plates with nanocrystalline or micron-sized phosphors. The X-ray-induced light is now transmitted and confined within the microchannel, which operates like an optical-fiber waveguide. Under X-ray excitation, the nanocrystalline phosphors exhibited luminescence efficiency that is 25% of the standard phosphors. Line-pair-phantom images, obtained from standard-phosphor-filled microchannel-plates of 10 microns diameter size, exhibited a resolution of 40-lp/mm. This resolution is twice that of analog screen/film systems currently used in mammography.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1999
- Accession Number
- ADB264544
Entities
People
- Rameshwar N. Bhargava