Ⅰ Study On The Kinetics And Thermal Stability Of Metalorganic Thin Films Ⅱ Radiation Dose And Protection In PET Center

Part 1:Great attention was paid in metalorganic complexes in recent years due to then-special optical and electric properties, in which M (Ag, Cu)-TCNQ complexes are one kind of model materials of great importance. M-TCNQ is one of the candidate materials for high-desity information storage because of their bistable and photochromic properties. The thin films of this type of materials with high quality are usually prepared by solid diffusive reaction between the metal and organic after successive vacuum evaporation. As one of the important properties, transport study was focused on inorganic materials while little on organic amterials, especially when there exist chemical potential gradient. Therefore, it is of great scientific importance to understand the special properties in the organic.In this part, Ag and TCNQ were selected as the evaporation materials and the transport behavior in Ag/TCNQ thin films was studied, including the transport mechanism during the formation process of Ag-TCNQ complex from Ag/TCNQ bilayer thin films, the calculation of activation energy, and the thermal stability of Ag-TCNQ complex.The results are as follows:(1) Ag/TCNQ bi-layer thin films with good molar ratio between Ag and TCNQ are prepared on glass by successive vacuum evaporation of Ag and TCNQ with the measurement of the optical transmittance spectra of Ag/TCNQ thin films.(2) The tracer method was established because of the similar properties of Ag and Cu when they react with TCNQ. The diffusion behavior in Ag/TCNQ is studied using Cu as a tracer, in combination with profile analyses by secondary ion mass spectroscopy (SIMS). The results show that the diffusion mechanism in Ag-TCNQ thin film is Ag ion diffusion accompanied by ion exchange.(3) The transport behavior of Ag-TCNQ was studied at different temperature (60～110℃) with different thickness. The results showed that the transport distance (x) and transport time (t) accord with parabola law (x² = 2k't) at 90℃. And the transport coefficient k' andthe temperature T accord with Arrhenius Law, which could be expressed And the transport mechanism was discussed, which was believed to be interstitialcy mechanism.(4) The thermal stability of TCNQ films and Ag-TCNQ complex thin films with different thickness were studied at different temperatures. The activation energy of evaporation for both TCNQ and Ag-TCNQ was calculated, which were 0.74eV and 0.81eV, respectively.Part 2:The development of science and technology pushes the process of cyclotron miniaturization, which supply the development of PET (Positron Emission Tomography) and PET/CT with pharmaceutical support. In recent years, the quantities of PET centers in China increased dramastically, and more than 30 PET centers were established, in which cyclotrons, hotcell and PET (or PET/CT) scanners were included. Up to now, the number of PET and PET/CT scanners is more than 60, while the number of cyclotrons is more than 30.As there is much radiation in PET centers, it is necessary to monitor and analyze the radiation systematically and in detail, and put forward reasonable suggestions to strengthen the radiation protection to make all the staff safe. Although there are a few literatures about the radation dose and radiation protection, radiation data are not fully and systematically included.In this part, the radiation dose and dose rate were monitored and evaluated, including the points inside/outside of the cyclotron room and around the hotcell. The factors affecting the radiation dose rate aroud the cyclotron were analyzed, and the annual radiation doses of staff were calculated. After that, the methods of radiation protection were discussed.The results are as fellows:(1) During the production of ¹¹, ¹³N, ¹⁵O and ¹⁸F with target current of 40μA, the radiation dose rate of most of the measuring points in the cyclotron room was less than 15μSv/h except one point, and the radiation dose rate of all the measuring points outside the cyclotron room was less than 0.5μSv/h.(2) The linear relationship between the radiation dose rate and the target current showed that the higher beam current, the higher radiation dose rate.(3) The Gamma radiation dose rate around the hotcell is less than 0.39μSv/h.(4) The annual radiation doses of occupational people were no more than 5.22mSv, which is less than the safety standard of our country (20mSv for occupational people).(5) The annual radiation dose of occupational people is related to the examinees. The more examinees, the higher radiation dose.