ABSTRACT
Nuclear imaging portrays distribution of radionuclides inside the patient’s body by the external measurement of γ-rays emanating from the body, thus its alternate generic name γ-imaging or gammagraphy. The only difference in the character of rays, besides the different mechanism of generation, is in the photon flux density, several orders lower in nuclear imaging than in x-ray imaging. The positron emission-based imaging utilizes the production of the photon pair to improve substantially the collimation definition of the measured beam. When imaging periodically moving organs such as the heart, it may be necessary to provide a sequence of images corresponding to different phases of its movement. The typical values for modern systems are in the range of several millimeters to centimeters in the maximum practical depth. Positron emission tomography is a sophisticated imaging method enabling the provision of relatively precise two-dimensional or three-dimensional data on spatial distribution of a radionuclide inside the object.
