State the term - rCBF

In rCBF, the participant inhales a small amount of a radioactive gas such as xenon, which is absorbed into the bloodstream and thus transported around the body. The participant sits in a piece of apparatus that looks a little like dryer seen in hair-saloons! This has a series of sensors that detect the radioactivity from the transported xenon, and because more blood is required by 'active' brain regions, a computer can built up an image of areas of greater (and lesser) activity based on the detection rates.