A portable radiometric system (PRS) developed at the Ural Federal University can be used for low-cost local 2D-scanning, as well as for dynamic scintigraphy of various organs and systems. PRS has several small-size detector modules based on silicon photomultipliers and software for its operation in three modes: gamma probing, 2D-scanning and dynamic scintigraphy. The components of each PRS detection module are selected to ensure maximum radiation detection efficiency, and the overall capsule design protects it from damage and exposure to sterilizing solutions. The developed PRS detection modules make it possible to record gamma radiation in the energy range 100-250 keV with sufficient efficiency for diagnostics, in particular, due to the optimal selection of a silicon photomultiplier of the MicroFC-30035-SMT type and a CsI(Tl) scintillation crystal. PRS can be effectively used in scintigraphy studies, including the study of extended and small objects and systems, short and long-term processes, as well as 2D-visualization of the distribution of the injected radiopharmaceutical both with standard and with reduced initial activity. This paper describes the principles of constructing the developed portable radiometric system for medical radionuclide diagnostics and demonstrates its potential application in medical diagnostic procedures. A technique for selecting the optimal parameters of the collimators of the detection modules of a PRS for its use in various methods of radionuclide diagnostics is considered. Phantom models of the sentinel lymph node and lacrimal system were developed and tested. It is necessary for testing the PRS and the proposed methods, as well as for comparative studies carried out in conjunction with gamma camera. Phantom studies have been carried out on original biological tissue models to test the developed portable radiometric system. Based on the study, conclusions were drawn about the effectiveness of the use of PRS in research in nuclear medicine. In the future, PRS can be supplemented with specialized technical solutions for adaptation to scintigraphy studies of various organs and tissues. PRS can be used to create small departments for radionuclide diagnostics and mobile diagnostic points. In comparing with gamma camera, PRS in 2D-scanning and dynamic scintigraphy modes, allows to obtain similar information.