Radiology Course page 5 – Film Speed-DoctorSpiller.com

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Note: This page relates nearly exclusively to the technology of radiographic film.  As the popularity of digital sensors grows, more and more dentists are abandoning film for computerized images.  Many offices, however, are still wedded to film and its processing.  Thus, it is still essential that anyone involved in radiographic technique understand this material.

Film Speed

One of the biggest misconceptions in dentistry today is that slower speed films are always a better choice for dental x-ray imaging than faster speed films. Early generations of film did require users to trade off between speed and image quality. An E or F-speed film will look “grainer” than a D-speed film when examined side-by-side. However, this has been proven by independent research not to negatively affect the diagnostic efficacy of the film. In recent years the technology has improved even more.

Film speed is a term that refers to how efficiently the light-sensitive agents in a film emulsion react to energy (e.g., e-rays or light) exposure. The two film speeds most commonly used in dental imaging today are D-speed and E-speed. Recently, however, Kodak introduced a true F-speed film. D-speed is the slowest film of the three, and F-speed is the fastest.

Faster radiographic films detect the image-forming element (light for photographic films, or x-rays for intraoral x-ray films) more efficiently than slower films.

In dental imaging, that means that when you use a faster film, you can reduce the amount of radiation required to expose the film and obtain a usable image. For example, Kodak InSight, an F-Speed dental film, lets you reduce radiation exposure by up to 60 percent as compared to Kodak Ultra-Speed dental film, a D-speed product.  F-speed film is beginning to become more and more popular in dental offices.

One of the biggest breakthroughs in film design was the development of T-Grain emulsions. The radiation-sensitive compound in dental x-ray film is silver halide, a salt of silver. Silver halide crystals, in their naturally occurring form, are pebble-shaped.  However, Kodak scientists have discovered a method of manufacturing the crystals in a flatter shape.  These flat crystals intercept more light but the total amount of silver does not increase.  This allows for an increase in speed with less noticeable grain. Kodak incorporated this T-Grain emulsion breakthrough into its E-speed dental x-ray film, Ektaspeed plus. As a result, Ektaspeed plus film delivers excellent image quality while at the same time allowing dental professionals to reduce radiation exposures significantly.

Dentistry is in the process of discarding older chemically processed film technology for digital tech. Film packets, however still have one distinct advantage over their newer competitor.  The film packets are much thinner than the bulky digital sensors and are thus much easier for patients to tolerate.

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