Gamma-emitting radioisotope

Various computed tomography CT- scanners for industrial applications have been designed and constructed) They use as radiation sources X-ray tubes or gamma emitting radioisotopes and as detectors NaI(Tl)-scintillators for gamma rays and image intensifiers for X-rays. 

Radioimmunoassay (RIA) is used in nuclear medicine for measuring very low levels (concentrations below 10 g/mL) of some biological compounds in corporal fluids, by means of the combination of radioisotopes and antibodies. The most common radioisotope used in this technique is 1, a gamma-emitting radioisotope with a half-life of 60 days, which is used for labelling compounds of interest. 

Radioactive tracer techniques have long been used to study particle motion in solids fluidization systems. The advantage of this technique is that the flow field is not disturbed by the measurement facility and, therefore, the measurement of the motion of the tracers represents the actual movement of particles in the system. The tracer particles are usually made of gamma-emitting radioisotopes, and their gamma radiation is measured directly by scintillation detectors. Factors that affect gamma radiation measurement were identified as the characteristics of the radiation source, interactions of gamma rays with matter, the tracer s position relative to the detector, detector efficiency, and dead time of the measurement system. 

Arsenic (atomic number 33, atomic mass 74.9216) is the 20th most abundant element in the earth s crust. It belongs to the elements of the P block of the Periodic System where it is placed below phosphorus and above antimony. The mass numbers of its isotopes range from 68 to 80 however, only the natural isotope 75 is stable. The gamma-emitting radioisotopes As (half-life 26.4 h), As (half-life 17.77 d), and As ( half-life 80.3 d) are commercially available and often used for method development and control (Krivan, 1987 Krivan and Arpadjan, 1989). Elemental arsenic exists at room temperature as metallic or gray arsenic, and yellow arsenic. As a center element of the P block it can be found both in metallic and covalent compounds. The oxidation states are -III, 0, -i-lll, and -I- V. Arsenic trihydride (arsine, AsHa) is a colourless, very poisonous, neutral gas with a characteristic garlic odour. 

Polonium (ii) The radioisotopes of polonium (usually Po) have been difficult to analyze with accuracy using the conventional methods. The procedure outlined here is, however, simple, rapid, and accurate. With the sample in solution, add 3 to 5 mL of concentrated phosphoric acid and evaporate to remove other acids. Transfer this phosphoric acid solution to a small equilibration vessel using 3 to 5 mL of water. Add 1 mL of 0.1 M HCl. Add a measured volume, 1.2 to 1.5 mL, of a solution of TOPO, 0.1 to 0.2 M, in toluene and equilibrate. This is a highly selective separation of polonium from other radionuclides with the possible exception of the beta/gamma emitting bismuths. Quantitative stripping and transfer of the polonium to a plate is difficult but the use of an extractive scintillator and counting on a PERALS spectrometer is rapid and simple and the results are quite accurate. Because of the minimal chemical manipulations required, the accuracy of this determination can easily be better than 1%. 

Positron-emitting radioisotope and gamma ray detector system. 

Absorptive reactions are (n, a), (n, p), in,y), or (n, fission). In the case of an (n, y) reaction, the neutron may be detected through the interactions of the gamma emitted at the time of the capture, or it may be detected through the radiation emitted by the radioisotope produced after the neutron is captured. The radioisotope may emit /3 or or y or a combination of them. By counting the activity of the isotope, information is obtained about the neutron flux that produced it. This is called the activation method. If the reaction is fission, two fission fragments are emitted being heavy charged particles, these are detected easily. 

Applications of gamma rays are used both in medicine and in industry. In medicine, gamma rays are used for cancer treatment, diagnoses, and prevention. Gamma ray emitting radioisotopes are used as tracers. In industry, gamma rays are used in the inspection of castings, seams, and welds. 

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