The ultrasound technique is used frequently in obstetrics instead of X-Rays based techniques. What is / are the principles behind this?
1. Ultrasound is a non-ionizing imaging technique
2. Ultrasound gives a clear picture of soft tissues, which do not show up in X-rays
3. Ultrasound causes almost no health problems (for a mother or unborn foetus)
Choose the correct option from the codes given below:

Answer: [C] 1, 2 & 3

Ultrasound, also called sonography, is another type of 3-D computerized imaging. Using brief pulses of ultrahigh frequency  acoustic waves (lasting 0.01 seconds), it can produce a sonar map of the imaged object. The technique is similar to the echolocation used by bats, whales, and dolphins. By measuring the echo waves, it is possible to determine the size, shape, location, and consistency (whether it is solid, fluid-filled, or both) of an object.

Why is ultrasound used frequently in obstetrics?

Ultrasound is a very safe, noninvasive imaging technique. Unlike X-rays, sonography does not use ionizing radiation to produce an image. It gives a clear  picture of soft tissues, which do not show up in X-rays. Ultrasound causes no health problems (for a mother or unborn fetus) and may be repeated as  often as necessary. Current evidence indicates that diagnostic ultrasound is safe for the unborn child, unlike radiographs, which employ ionizing  radiation. However, no randomized controlled trials have been undertaken to test the  safety of the technology, and thus ultrasound procedures are generally not done repeatedly unless medically indicated.

This question is a part of GKToday's Integrated IAS General Studies Module