Technical Principle of SPECT (Single Photon Emission Computed Tomography)
SPECT is a nuclear medicine technique used to create a three-dimensional representation of the distribution of an administered radio-pharmaceutical. SPECT cameras detect only radio-nuclides that produce a cascaded emission of single photons. SPECT radio-nuclides do not require an on-site cyclotron. However, the isotopes of Tc,TI,In,and Xe are generally not found in the body. For example, it is extremely difficult to label a biologically active pharmaceutical with Tc-99m without altering its biochemical behavior. Presently, SPECT has been used mainly in the detection of tumors and other lesions, as well as in the evaluation of myocardial function using TI-201. However, certain pharmaceuticals have been labeled with iodine and technetium and provide information on blood perfusion within the brain and the heart. The largest category of SPECT systems uses a single gamma camera mounted on a specialized mechanical gantry that automatically rotate...