Final answer:
Fetometry is the measurement of a fetus, typically conducted using 3D ultrasound imaging during pregnancy to ensure fetal health and development. Ultrasound is favored because it is non-invasive and safe, utilizing high-frequency sound waves to create real-time imagery without exposing the fetus to radiation. Doppler-shifted ultrasound is particularly useful for monitoring the fetal heartbeat and blood flow. Thus, the option a is the correct answer.
Step-by-step explanation:
Fetometry refers to the measurement of a fetus. This process is important for assessing fetal growth and ensuring the health and development of the fetus during pregnancy. Ultrasonography, especially 3D ultrasound imaging, plays a significant role in fetometry by providing detailed views that can help with the detection of abnormalities and the reinforcement of parental bonds due to the visual connection established with the unborn child. Ultrasound is the method of choice for this as it is the least invasive and safest form of imaging during pregnancy, capable of real-time imagery while protecting the fetus from exposure to ionizing radiation which can be harmful. Additionally, Doppler-shifted ultrasound is utilized to monitor fetal heartbeat and blood velocity, as it allows for the detection of movement through changes in the frequency of the sound waves caused by motion.
The fetal stage extends from the beginning of the ninth week after fertilization to about 38 weeks, which is when birth commonly occurs. Therefore, fetometry is vital for tracking fetal development throughout this period. When compared to other imaging techniques such as CT scans, PET scans, and X-rays, ultrasonography is preferred because it poses no risk to the fetus, unlike the other modalities which involve exposure to harmful radiation. Ultrasonography's use in fetometry is an exemplary application of medical imaging technology in prenatal care.