What computerized body scanning technique uses a radioactive substance injected into a patient?

The computerized body scanning technique that relies on a radioactive substance injected into a patient is Positron Emission Tomography (PET). In PET scans, a small amount of radioactive material, known as a radiotracer, is introduced into the body. This substance emits positrons, which collide with electrons in the body, resulting in the emission of gamma rays. The PET scanner detects these gamma rays and uses the data to create detailed images and functional information about various processes in the body, helping to diagnose conditions like cancer, heart disease, and brain disorders.

Other scanning techniques, while also valuable, do not employ a radioactive substance. For instance, Computed Tomography (CT) utilizes X-rays to create cross-sectional images, while Ultrasound Imaging employs sound waves to visualize structures within the body. Magnetic Resonance Imaging (MRI) relies on strong magnetic fields and radiofrequency waves rather than radiation. Each of these methods serves distinct purposes in medical imaging, but only PET specifically involves the injection of a radioactive tracer to visualize physiological activity in tissues.