Back to the Basics January 16, 2009
Posted by CL in Technique Charts.add a comment
Producing a radiographic image is all about the right kind of radiation and the right amount of radiation. It’s really quite simple! Simple, that is, if you are willing to add method “to your madness.”
The right kind is controlled by kVp. KVp has to be high enough to produce x-rays with sufficient penetration and has to be chosen carefully when doing film/screen imaging to produce desirable contrast. This second point is of less concern in digital imaging. In fact, we can experiment with using higher kVp than we would have dreamed of doing in the film-based world for the advantage of reducing the dose to the patient.
The right amount of radiation is primarily controlled by mAS. There has to be enough with film-based images so the film is not too light and not too much to produce a film that is too dark. With digital imaging there has to be enough to avoid mottled or noisy images but only slightly more than that to avoid increasing the dose to the patient unnecessarily.
In both worlds, film-based and film-less, a systematic method of “fixing” the kVp by exam or body part and varying the mAS chosen according to patient or part thickness can yield great images with contolled radiation dose!
Connie
