Final answer:
For a radiologic exam of the fetus, the patient is typically placed in the supine position. Ultrasounds are the safest imaging modality to use during pregnancy as they do not involve ionizing radiation, unlike CT and PET scans, and X-rays.
Step-by-step explanation:
If a radiologic exam of the fetus is required, the preferred position for the patient is typically supine, meaning lying on their back, face-up. This orientation facilitates the examination and minimizes discomfort. However, in some cases, alternative positions such as lateral or semi-Fowler's might be employed based on the specific requirements of the examination or the comfort of the patient. The semi-Fowler's position involves the patient being semi-upright at an angle of 30-45 degrees, which can sometimes be helpful in radiology.
When considering the safest imaging study for use during pregnancy, ultrasounds are commonly used as they don't involve ionizing radiation, which can be harmful to the developing fetus. CT scans, PET scans, and X-rays involve radiation, hence are used cautiously during pregnancy.