What effect does increasing the kV have on a radiograph?

Increasing the kilovolt peak (kV) in radiography primarily affects the penetration power of the x-ray beam. A higher kV means that the x-rays produced have higher energy, which leads to more efficient penetration of the tissues being imaged. This results in increased exposure of the film or digital sensor, typically producing a radiograph that is lighter due to the increased penetration reducing contrast within the image.

Higher kV settings result in less differential absorption of the x-rays by various tissues, which effectively lowers contrast. Thus, while the image may be lighter, the range of greys between the light and dark areas becomes less pronounced. This is particularly important in certain types of imaging where a detailed distinction between tissues is required, as high contrast can help delineate boundaries better than low contrast settings.

While increasing kV can reduce the exposure time required for creating a radiograph, the primary direct impact of the change in kV is the alteration in contrast rather than exposure time. The sharpness of the image is more influenced by other factors such as movement and the quality of the imaging system.