Final answer:
The safest imaging study during pregnancy is an ultrasound, as it uses no ionizing radiation, unlike CT scans or PET scans, which carry risks due to radiation exposure.
Step-by-step explanation:
When considering the safest imaging study to be used during pregnancy, ultrasounds are the most appropriate option. Ultrasounds use sound waves to create images of the developing fetus and do not expose the mother or fetus to ionizing radiation. Unlike CT scans, which construct detailed X-ray images and expose patients to radiation, or PET scans that use radiopharmaceuticals posing potential risks, ultrasounds are the least invasive and carry no such risks. Therefore, for an expectant mother requiring diagnostic imaging, an ultrasound is the premier choice due to its safety profile.
It's worth noting that CT scans are particularly useful for soft tissue scanning and can offer highly detailed images. However, the significant exposure to radiation is a major disadvantage, particularly for pregnant women and children. The radiation from CT scans has been associated with an increased risk of developing cancer, which is an important consideration when deciding on imaging tests.