Final answer:
In radiographic imaging, to halve the exposure time necessary for an X-ray in the presence of involuntary motion, the kilovoltage peak (kVp) should be increased by 15 percent. This allows for maintaining image quality while minimizing motion blur, especially important in involuntary movements such as heartbeats or breathing.
Step-by-step explanation:
When considering the factors that affect X-ray exposure, the inverse square law and the relationship between kilovoltage peak (kVp) and radiation exposure are key. It is known that by increasing the kVp, one can increase the energy of the X-ray photons, which in turn increases their ability to penetrate through tissue. A higher kVp can reduce the exposure time needed to achieve the desired image quality because the greater penetration requires less time for the radiation to interact with the image receptor.
In the context of involuntary motion, such as heartbeats or breathing that cannot be controlled by the patient, reducing the exposure time is crucial to minimize motion blur in the resulting images. The question relates to how much the kVp must be increased if the exposure time is to be halved, while still obtaining the same quality of image. The correct answer, based on the knowledge of radiographic imaging principles, is deemed to be (B) increased by 15 percent. This is a well-established rule in radiographic imaging that a 15% increase in kVp is equivalent to doubling the exposure (mAs), allowing for a reduction in exposure time by half without losing image quality.