The effect of collimator geometrical characteristics on image quality in GAMMA CAMERA

Abstract

Collimator is one of the main parts in the structure of most of the diagnostic or therapeutic devices in nuclear medicine. It is used to reduce the amount of the radiation dose deposited in the body of the patient, for example in CT scan devices, to redirecting the radiation arrays coming from the radionuclide source in gamma camera, and to absorb some of the high energy photons since a part of the camera head consists of sensitive crystal material like NaI (Sodium Iodide). Collimator also determines the spatial resolution and the sensitivity of the system, which are most important factors in determining the efficiency and accuracy of the image in gamma camera in nuclear imaging. The physical and geometrical properties of collimators used in gamma camera are determined by the purpose of the imaging. The pharmaceutical energy limit and the size or the position of the organs is also important to decide the type of collimator to be used in the imaging. The common type of collimator used with gamma camera is low energy general purpose (LEGP) due to its acceptable values of both resolution and sensitivity. The focus in the current study is to compare the performance of various design demonstrated and tested in gamma camera. Parallel multi-hole collimator is found to be the best type to be used in medical nuclear imaging provided it fulfills the radiation protection requirements, and is valid for most of the low level energy radio-nuclides. The LEGP is the most common collimator type used in most of diagnosis cases, but if a more accurate information from the image is needed the most suitable design of collimator need to be used.