ABSTRACT
The collimator is an important part in an Anger-based gamma camera in that it makes it possible not only to detect a photon but also to determine an estimate of the origin of the emission. The most common collimator is the parallel-hole collimator. It is made of lead (Pb) or wolfram (W) and consists of a plate with a large number of parallel holes, with the hole-axis’s orthogonal of the camera crystal surface. The purpose of this design is to assure that only those photons that are emitted in a direction almost along the hole axis can pass through the collimator and contribute to the image formation by interactions in the crystal. This chapter will discuss in detail the design of this collimator but also of other types of collimators that are important for nuclear medicine applications, such as the pinhole collimator (single or multiple), slit-slat, and fan-beam collimators. Factors that will affect the geometrical sensitive, spatial resolution and septal penetration will be described. A section will also describe factors that need to be considered for an optimal choice for a particular study and radionuclide and that will affect the acquired image.
