Final answer:
To reduce motion from peristalsis in radiographic imaging, one should give the patient clear instructions and decrease exposure time; exposure during inspiration or expiration is not as relevant. Isotopes with short half-lives are used to limit radiation doses because they decay quickly, reducing radiation emission duration.
Step-by-step explanation:
To minimize motion due to peristalsis during radiographic imaging, the radiographer can employ several techniques. One effective method is to give the patient explicit instructions before the procedure to stay very still and to use calm and steady breathing. Another key technique is to decrease exposure time, which can be achieved by using fast films or other technologies that require less time to capture the image, hence reducing the chance for motion artifacts due to peristalsis. While exposing the radiograph on inspiration or expiration may be relevant for chest imaging to avoid motion due to breathing, peristalsis is independent of the breathing cycle and thus would not be affected by the timing of inspiration or expiration.
Regarding radiation protection, employing isotopes with short half-lives in medical imaging would limit the radiation dose as they decay more rapidly, which reduces the time during which radiation is emitted. This, coupled with radiation protection measures such as shielding, maintaining distance, and limiting time of exposure, ensures both patient and technician safety.