Wyniki wyszukiwania - Biblioteka Nauki

1

Computer simulation of temperature distribution on a solid target for 201Tl production

100%

Aboudzadeh Rovais M. R. , Yousefi K. , Ardaneh K. , Mirzaii M.

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tom Vol. 56, No. 4

283-289

EN

Thallium-201 is of great interest in nuclear medicine for diagnostic purposes. It is produced by the 203Tl(p,3n)201Pb nuclear reaction. Since the target for 201Tl production is a solid target and the maximum beam current for the irradiation has a direct relation with its temperature surface, therefore, the control of temperature during the irradiation is essential. Designing a proper cooling system is one of the important and determining parameters in radionuclide production efficiency. Non-controlled temperature would cause melting and consequently loss of target materials that could be very costly especially when an isotopically enriched material is used. In this study, the heat transfer and temperature distribution on the target has been simulated based on a computational fluid dynamics (CDF) code for the thermal behavior of the target during the irradiation and under the different beam currents, cooling flow rates and target designing. The results on the routinely used target for the production of 201Tl in AMIRS, showed that there was a good linearity between proton beam currents (in the range of 100–350 mi A) and maximum temperature on the thallium target (345–458 K). The results also showed that the flow rate of the cooling water can be brought down (from routinely used 45 L/min) to 15 L/min without any risk of melting of target material.

2

Assessment of the staff absorbed dose related to cyclotron operation and service in the production of 18F radiopharmaceuticals

100%

Sadat-Eshkevar S. M. , Karimian A. , Mirzaii M.

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tom Vol. 57, No. 3

407-410

EN

Cyclotron accelerators are used to produce medical radioisotopes. One of the most important problems which may be encountered is malfunction of a part of the target or beam line which requires stopping of the bombardment and making a repair. The decision about doing the repair depends on the whole body dose rate in a target room. In this work, dosimetric conditions related to the production of 18FDG radiopharmaceutical were simulated by the Monte Carlo (MC) method. Independently, the dose rates were measured by 7 ICRU spherical body phantoms placed inside the liquid target room and the maze of the cyclotron. The radiation dose rate inside the target room depends on the duration of the bombardment and the time passed after stopping the bombardment. The correlation between duration of the bombardment and required time after stopping the bombardment to reach the absorbed dose rate less than 25 mi Sv/h, was calculated for the presence and absence of the irradiated target. The results showed that the repair can be started immediately after stopping of the proton bombardment only if the target has been ejected from the target room and the duration of bombardment has not taken more than 10 min.

3

Production of [18F] fluoride with a high-current two layer spherical gold target

88%

Mirzaii M. , Afarideh H. , Hadji-Saeid S. , Aslani G. , Ensaf M.

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tom Vol. 49, nr 1

23--27

EN

A new automated target for high yield production of aqueous [18F] fluoride at high beam currents has been constructed for a cyclotron at NRCAM in Karaj (Cyclone 30). It consists of one small golden sphere inside another target chamber, mounted into a special holder, which provides rapid cooling by water flow around and inside the sphere. The target is irradiated with 28 MeV protons. The incident energy on the target chamber is 18 MeV. This target is operated without external overpressure and has been tested for beam currents up to 60 ěA. The measured target yield is 80% of the theoretically calculated yield of 18F, which is used for the synthesis of [18F] 2-fluoro-2-deoxy-D-glucose.

4

Biological evaluation of [18F]-nifedipine as a novel PET tracer for L-type calcium channel imaging

75%

Sadeghpour H. , Jalilian A. R. , Akhlaghi M. , Shafiee A. , Mirzaii M. , Miri R. , Saddadi F.

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tom Vol. 53, No. 4

151-154

EN

Due to interesting role of dihydropyridines in cardiovascular diseases and drug resistance studies and lack of a fluorine-18 labeled imaging agent for L-type calcium channel studies, this study was designed. [18F]Dimethyl 2-(fluoromethyl)-6-methyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate 2 was prepared in no-carrier-added (n.c.a.) form from a starting brominated compound in one step at 80°C in Kryptofix2.2.2/[18F]. Compound 2 was administered to normal rats via their tail veins for preliminary biodistribution studies and the ID/g% of the labeled compound was determined up to 3 h post injections. Coincidence images were obtained in rats 5 to 120 min. Radiofluorination on bromo precursor gave a fluorinated compound in 95% radiochemical purity and a 8% yield shown by RTLC and HPLC. Biodistribution studies showed that the tracer is accumulated in the heart in the first few minutes, followed by metabolism resulting in very soluble 18F-containing metabolites eliminated through the urinary tract. In coincidence images, the target organ was shown to be the heart. Lung had high accumulation possibly due to the presence of Ca2+ channels and/or hydrolyzing enzymes showing a significant myocardial uptake at 120 min. The data demonstrates a significant agreement with the reported L-type calcium channels throughout the animal body. To our knowledge, this is the first example of 18F-DHPs in the literature.

5

Investigating the prevalence of intestinal parasites with an emphasis on Strongyloides stercoralis infection in hospitalized patients: a regional report from Iran

75%

Norouzi P. , Mohaghegh M. A. , Ghorbani M. , Mirzaii M. , Abolhassani M. , Mirbadie S. R.

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