In medical imaging, particularly in Magnetic Resonance Imaging (MRI), microwaves themselves are not directly used. Instead, radio waves (which are lower frequency than microwaves) play the key role. However, microwaves are related in the broader electromagnetic spectrum context.
Here’s how it works:
- MRI uses radio frequency (RF) pulses, typically in the megahertz (MHz) range, which is lower than microwaves, to excite hydrogen nuclei (protons) in the body’s water and fat molecules.
- When these RF pulses are applied inside a strong magnetic field, the protons absorb energy and then release it as they relax back to their original alignment.
- The MRI sensors detect these emitted signals, and the system processes them to create detailed images of tissues.
So, the direct role of microwaves in MRI is limited—MRI primarily relies on radio waves (RF). However, in related medical technologies:
- Microwave imaging is an emerging technique for detecting certain cancers (like breast cancer) by analyzing how microwaves scatter off tissues.
- Microwave diathermy uses microwaves for therapeutic heating of deep tissues.