Film Scanning

Written by Helen Glenn Court
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Because so many medical records are film--whether x-rays, MRIs, or CT-scans--film scanning plays an especially big role in document management in the health care industry. It's particularly important during a migration from a paper-based system to an electronic one. While only five percent of physician's offices in the United States today use a digitized medical records system, it's a fair assumption that that number will change soon enough.

Specialized service bureaus are always a good choice for film scanning. This is especially true if you're planning for a large-scale conversion of archived files. Optimal scanning results call for capable and appropriate technology--specialty high resolution scanner and dedicated software--as well as a skilled expert in film imaging.

Film Scanning: The Process
Though scanning predates digital photography, that's essentially what it is. Working on the principle of refractive light, scanners take a snapshot of analog data--ultrasound, mammography, bone density scans, EKG, MRI, or CT-scan, for example--and convert it to digital format. The formats, depending on whether the image needs to be rendered as a three-dimensional or a flat image, include TIF, DICOM, JPEG, VRML, DXL, and more. The computer maps the data onto a rectangular grid, or series of these, which is nothing more than electronic graph paper.

For flat raster files, the program then assigns each square of the grid a tonal value, whether grayscale or color. Three-dimensional vector images include plane values, surfacing rendering, and the like. The finer the resolution, the higher the quality of the digital image is. Resolution is measured in dots per inch (dpi), also known as pixels--that is, grid squares per inch. Film scanning in medical records applications runs to resolutions of perhaps 4,000 dpi. To put this number in perspective, screen resolution is 72 dpi, and typical four-color printing 150 dpi.


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