Final answer:
The technique that uses radioactive materials to evaluate brain activity is PET (Positron Emission Tomography). It uses a tracer to monitor blood flow and physiological activity, helping to diagnose various conditions. The correct option is b.
Step-by-step explanation:
The imaging technique that uses radioactive material and emphasizes evaluating the activity of the brain rather than its structure is b) PET (Positron Emission Tomography). A PET scan uses radiopharmaceuticals to create images of active blood flow and physiological activity within the targeted organ or organs. This is distinctive from other imaging techniques like MRI and CT scans that provide static images of the brain's structure.
PET scans are particularly useful for illustrating metabolic processes and blood flow, which help in diagnosing conditions such as heart disease, cancer, brain abnormalities, and more. During a PET scan, a tracer is introduced into the body which allows the monitoring of the tracer's amount in different regions of the brain, with a computer creating a map of active and inactive areas of the brain during certain behaviors or functions. Hence, b is the correct option.