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X-RAY IMAGE INTENSIFIERS

X-ray image intensifiers use advanced technologies to miniaturize pillar crystals with optical fiber structures. Computer controlled processing facilitates uniform growth of fine CsI pillar crystals that are 10µm or less in diameter and approximately 400µm thick. The resulting thick film improves MTF properties by coating the input screen with a fine guide light structure that reduces dispersion of light within the CsI phosphor.

 A new process technology was developed to make fine fluorescent particles that are more uniform in size and increase their density in the window coating, and this significantly reduces the structural mottle inherent to image intensifiers.
A direct phosphor coating method is used to prevent light scatter at the image surface and to improve transmittance of the glass output window. In addition, a special anti-reflection coating has been added to the window surface.
These technologies have realized an excellent output screen with a high contrast ratio.

X-ray image intensifiers were developed to minimize the amount of X-ray radiation patients and X-ray technicians were subjected to when using radioscopy and radiography for medical or industrial applications whilst maintaining image clarity.
Structurally, as illustrated in the diagram above, image intensifiers comprise an imaging tube with an input screen, a photocathode, a focusing electrode, an anode and an output screen, housed in a vacuum envelope.

  1. Photoelectrons from the input screen are accelerated by high voltage and focused by an electronic lens comprising a focusing electrode and an anode. Compressed to one-tenth in size, the focused electron beams make a visible image when they hit the output screen.
  2. High voltage acceleration and beam compression enable image intensifiers to produce images that are 5,000-10,000 times brighter than conventional fluorescent screens.

X-ray TV systems are gaining popularity in medical applications.
The brightness of images produced by X-ray image intensifiers enables them to be used in conjunction with an imaging device (CCD, CMOS) as an X-ray TV. This reduces the X-ray dosage patients are subjected to and facilitates transmission of images to other rooms for diagnosis or other remote locations.
In terms of industrial applications, X-ray TVs are widely used in nondestructive testing (NDT) to inspect welded metal joints and cast metal, non-metal plastics and food products, IC and other electrical parts. Moreover, use of X-ray TVs is expected to continue expanding into new fields.

With the aim of obtaining even clearer electronic images for both medical and industrial applications, conventional 400,000 pixel cameras are increasingly being replaced with cameras with one million pixels or more.