Final answer:
We measure the absorption of radio frequency waves in a patient through MRI and SAR. MRI uses radio frequencies to map tissue density, whereas SAR quantifies RF energy absorbed by the body from devices like cell phones. Both methods evaluate the effects of electromagnetic radiation on tissues.
Step-by-step explanation:
The way we measure the absorption of radio frequency waves in a patient is through various techniques including Magnetic Resonance Imaging (MRI) and the concept of Specific Absorption Rate (SAR). In MRI, radio frequencies are absorbed and reemitted by nuclei in a magnetic field. This helps build a tissue map by receiving radio waves as a function of frequency, giving position information and assessing the concentration of nuclear types. The SAR, on the other hand, is used for cell phones to measure the RF energy absorbed by the user's body. SAR levels must comply with safety regulations, such as those set by the Federal Communications Commission (FCC).
Absorbed dose is another method and is measured in either grays or rads, which is an indicator of the amount of radiation energy absorbed from a source. It is crucial in evaluating the potential damage that absorbed radiation may cause to the tissues. The absorption spectrum can also be employed as it denotes a specific pattern of absorption for substances that absorb electromagnetic radiation.