Final answer:
Orbital cellulitis is best diagnosed with a CT scan, as it provides detailed images of the soft tissue and bone structures of the orbit. For pregnancy monitoring, ultrasounds are safest because they are non-invasive and radiation-free. PET scans are suitable for studying nutrient uptake by cancer cells.
Step-by-step explanation:
To diagnose orbital cellulitis, a CT scan would be the most appropriate choice among the imaging options provided. A CT scan of the head can provide detailed successive transverse sections, which are particularly helpful in evaluating soft tissue and bone structures within the orbit, making it very useful for diagnosing infections like orbital cellulitis. In contrast, while MRI also offers detailed images without radiation exposure, it is generally more time-consuming and may not be as readily available as CT in acute settings. X-rays have limited usefulness in soft tissue evaluation and ultrasounds are typically not used for imaging of the orbit.
Regarding safety during pregnancy, ultrasound technology is considered the safest imaging technique to monitor pregnancies as it is the least invasive and uses no ionizing radiation. Ultrasounds are frequently used for checking the fetus's development within the womb.
When it comes to assessing the uptake of nutrients by rapidly multiplying cancer cells, PET scans are highly effective. PET scans use radiopharmaceuticals to create images of active blood flow and physiological activity, which includes watching how cancer cells metabolize nutrients.