Storage Phosphor Technology

To date, computed radiography (CR) has been the most commercially successful form of digital radiography. CR relies on storage phosphor technology for recording and storing a latent x-ray image. Storage phosphors differ from phosphor screens used in conventional radiography in that rather than promptly fluorescing in response to x-ray exposure, they store a portion of the x-ray energy in the form of trapped electrical charge in the phosphor material. The spatial distribution of these trapped charges is representative of the pattern of the x-ray intensity that exposed the image plate.

When an exposed storage phosphor imaging plate is irradiated with light of appropriate wavelengths, the trapped charges recombine, emitting visible light in the process. By systematically stimulating the recombination of the trapped charge and collecting the emitted light, an image of the x-ray exposure is formed.

The concept of using of storage phosphors in medical imaging was first presented by Kodak. Fuji pursued its practical implementation and introduced the first storage phosphor readers in the 1980's. Others have further developed technology in storage phosphor image plates, readers, and image processing software. With advances in computing power, data storage, and networks, and accompanying cost reductions, the infrastructure necessary to widely implement CR can now be put in place in many facilities that could not consider it just a few years ago.

Despite the development of other approaches to digital radiography, CR continues to be an important means of generating digital radiographic images because of its portability, affordability, ease of use, and its ability to be easily integrated into existing x-ray facilities. For these reasons, use of CR will continue to expand for many years to come as more and more facilities make the shift from film-based to digitally-based radiography.

Alara Inc. has a successful history of developing high quality, affordable, and reliable imaging products based on storage phosphor technology. For more product-specific information, please visit the following links on our website:

DenOptix - a family of devices for dental radiography

MetriScan - estimates bone density and risk of osteoporosis

CRystalView - general medical radiology applications

X-Ray for NDT - security, industrial applications