When decreasing the kilovoltage peak (kVp) in an anteroposterior (AP) abdomen radiograph, which change can be expected?

When decreasing the kilovoltage peak (kVp) in an anteroposterior (AP) abdomen radiograph, it can be expected that the exposure time will need to be increased to achieve adequate image density and contrast.

Lowering the kVp reduces the penetrating power of the x-rays. This means that fewer x-rays will be able to pass through the patient and reach the radiographic receptor. Therefore, to maintain the same level of receptor exposure and image quality, the exposure time must be increased to allow a greater number of x-rays to be produced and reach the receptor.

In clinical practice, adjusting the kVp is a balancing act; decreasing the kVp results in a need for compensatory changes in other exposure parameters, such as time, to ensure that the final image retains proper density and contrast. Thus, increasing the exposure time becomes a necessary adjustment in response to a drop in kVp.