RESEARCH OF SCINTILLATION DETECTORS USED IN DEVICES OF POINT RADIONUCLIDE DIAGNOSTICS OPERATIONALLY USED IN SURGICAL INTERVENTION

Abstract

Recurrence of cancer, arising from the remaining after surgery metastases and small tumors,
forcing surgeons to increase the volume of resection in surgical interventions. The paper
presents a procedure for selecting the optimal characteristics of the scintillation material for the
registration of gamma radiation from a radiopharmaceutical drug. Using interpolated data, the
dependence of the probability of interaction of a gamma quantum with a substance on the thickness of the scintillator for a radiopharmaceutical drug based on technetium 99mts radionuclide,
which most intensively emits gamma quanta with an energy of 140.5 keV, is estimated. The values
of the optimal length of sodium iodide scintillator doped with thallium NaI(Tl) for registration of
radiation from technetium-99 isomer were numerically estimated. It is established that in the process
of optimizing the size of the scintillator it is necessary to come to such a compromise that the
maximum absorption of γ quanta is provided and at the same time the optical losses in the volume
are minimal. The possibility of manufacturing detectors with a theoretically maximum sensitivity
limit in the form of a compact, suitable for manual use diagnostic device is shown. For scintillation
products, the factors influencing the light output index are given. It is established that it is
necessary to take into account not only the conversion efficiency and linear attenuation coefficient
for a given radiation energy, but also the transparency of the scintillation material to its own radiation,
which is directly affected by the chemical purity of materials and manufacturing technology
of crystal scintillators.