Correct option is D
Explanation:
Statement A: "The PET scanner is a positron ray detector."
- This statement is incorrect. A PET scanner is not a positron ray detector, but rather a detector for gamma rays emitted when a positron interacts with an electron. These annihilation events generate two gamma photons which are detected by the scanner. Therefore, a PET scanner detects gamma rays, not positron rays.
Statement B: "The PET scanner cannot determine the location of collision between positron and electron in the brain."
- This is incorrect. The PET scanner can indeed determine the location of the collision between a positron and an electron in the brain. When a positron emitted from a radioactive tracer interacts with an electron in the body, they annihilate each other, resulting in the emission of two gamma rays. The PET scanner detects these gamma rays and uses them to construct an image showing the location of the annihilation events, thus providing spatial information about brain activity.
StatementC:"The typical PET activation studies can measure the absolute metabolic activity of the brain."
· This is incorrect. PET scans do provide data on metabolic activity, but they are generally used to measure relative metabolic activity, rather than absolute metabolic rates, under certain conditions.
Statement D: "In PET, a radioactive isotope is introduced into blood as 'tracer' that rapidly decays by emitting a positron from their atomic nuclei."
- This statement is correct. In PET, a radioactive tracer is introduced into the body, usually by injection into the bloodstream. The tracer consists of a molecule that contains a radioactive isotope, which decays by emitting positrons. These positrons then interact with electrons in the body, resulting in annihilation events that produce gamma rays. The PET scanner detects these gamma rays to create an image that can be used for diagnostic purposes.
