Tomography by emission of positrons (pet) system dedicated to examinations of human body parts such as the breast, axilla, head, neck, liver, heart, lungs, prostate region and other body extremities which is composed of at least two detecting plates (detector heads) with dimensions that are optimized for the breast, axilla region, brain and prostrate region or other extremities; motorized mechanical means to allow the movement of the plates under manual or computer control, making it possible to collect data in several orientations as needed for tomographic image reconstruction; an electronics system composed by a front-end electronics system, located physically on the detector heads, and a trigger and data acquisition system located off-detector in an electronic crate; a data acquisition and control software; and an image reconstruction and analysis software that allows reconstructing, visualizing and analyzing the data produced during the examination.