CAMRT Radiography Practice Exam

What adjustment in kVp is recommended for a plaster cast?

1. Increase by 2 - 4 kVp

2. Increase by 5 - 7 kVp

3. Decrease by 3 - 5 kVp

4. No adjustment

The correct answer is: Increase by 5 - 7 kVp

When dealing with radiographic imaging of a plaster cast, an increase in kilovolt peak (kVp) is necessary due to the increased density and thickness that the cast material adds to the area being imaged. Plaster casts are typically dense and can absorb more radiation than soft tissue, which means that to adequately penetrate the cast and provide a clear image of the underlying structures, an increase in the kVp setting is required. The recommended adjustment of 5 - 7 kVp is based on the typical attenuation properties of the plaster material, which is denser than soft tissue. This adjustment compensates for the higher absorption of X-rays, ensuring that sufficient penetration occurs. Failure to increase the kVp adequately might result in underexposed images that lack clarity or detail. Adjustments beyond this range may lead to overexposure, which could negatively impact the diagnostic quality of the images. Understanding these principles allows a radiographer to make the necessary technical adjustments for optimal imaging outcomes in circumstances where body composition changes, such as when a patient has a plaster cast.