RAS question
Which imaging technique uses strong magnetic fields and radio waves to produce detailed body images?
Correct answer: (B) MRI (Magnetic Resonance Imaging).
MRI, or Magnetic Resonance Imaging, uses strong magnetic fields and radio waves to produce detailed images of the body's internal structures.
Explanation
MRI is the imaging technique built around strong magnetic fields and radiofrequency pulses. These pulses excite hydrogen nuclei in body tissues; the signals then create detailed cross-sectional images without ionising radiation. The NSF describes MRI as a non-invasive technique that uses a strong magnetic field and radio waves to image internal structures such as the brain, spinal cord, organs, nervous system, muscles and blood vessels. That is why MRI is especially useful for soft tissue imaging, including the brain, joints and organs, and why it differs from X-ray-based methods.
Why the other options are wrong
- (A) Ultrasound is not based on magnetic fields or radio waves; it uses sound waves to form images.
- (C) X-ray imaging uses ionising radiation, whereas MRI creates images without exposing patients to that radiation.
- (D) A CT scan uses X-rays from multiple angles, so it belongs to the X-ray-based imaging group rather than the magnetic-field-and-radio-wave method.
Concept
Medical imaging in Science and Technology depends on the physical principle behind each diagnostic technique. RAS candidates are expected to distinguish everyday technologies by mechanism, use and safety feature.