Final answer:
In thallium SPECT, a lead collimator within an Anger or gamma camera system is used to direct gamma rays towards detectors, which then produce an image of the radiopharmaceutical distribution in the body.
Step-by-step explanation:
What Collimator Is Used for Thallium SPECT?
The collimator used for thallium Single-Photon Emission Computed Tomography (SPECT) is typically a lead collimator as part of an Anger or gamma camera system. This lead collimator has holes bored through it to restrict the direction of incoming gamma rays, thereby ensuring that the detectors receive gamma rays from specific directions only. After passing through the collimator, gamma rays interact with a scintillator material, producing light that is converted into an electrical signal by photomultipliers. A computer then constructs an image from these detector outputs.
SPECT imaging makes use of the physical properties of nuclear decay and electron-positron collisions. It shares similarities with the geometry of a CT scanner and provides the ability to form images of the concentration of radiopharmaceutical compounds within the human body. Notably, the isotope technetium-99m (Tc-99m) is used due to its properties, including a relatively short half-life of 6 hours which allows for convenient production and attachment to various compounds for imaging different body parts.