Final answer:
Option B and D: The use of pointed PIDs is prohibited in medical imaging due to the increase in scatter radiation they cause, which can result in decreased image sharpness and higher radiation doses to the patient.
Step-by-step explanation:
The use of pointed PIDs is prohibited because their use results in scatter radiation. Scatter radiation is a type of secondary radiation that occurs when the primary x-rays collide with objects, such as body tissues, and change direction. It can lead to increased radiation exposure to the patient and decrease the image sharpness in medical imaging, thereby affecting the overall quality of the diagnostic images.
To mitigate this, radiographic equipment and protocols are designed to reduce scatter radiation and other potential negative effects, like overexposure which can increase the risk of cancer. It is also worth noting that some medical imaging techniques, like positron emission tomography (PET), utilize radioisotopes with short half-lives to limit radiation dose to the patient. While the PET technique provides improved image resolution, it is distinct from imaging methods involving x-rays, which can lead to scatter radiation when not appropriately managed.