JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY
Year:2004 | Volume:- | Issue:(30)|Papers Count:11

Selenium-75 was prepared in no-carrier-added elemental form by proton bombardment of a compressed natural arsenous trioxide disc. The chemical separation process was performed using solvent-solvent extraction method, which resulted in the extraction of selenium in organic phase. After the initial spectroscopic analysis, elemental selenium was oxidized to [75Se] selenium dioxide and reacted with ethyl acetoacetate semicarbazone in acetic acid as the solvent to produce [75Se]- 5- ethoxycarbonyl - 4- methyl-1, 2, 3- selenadiazole as a prototype. The labeled compound was purified by chemical methods and quality control tests (radionuclidic, radiochemical, chemical purity and apyrogenicity-sterility tests) were performed, which confirmed the optimum purity of the final product.

Dosimetry of ionizing radiations are based on standard methods issued by competent national and international organizations. Establishment of reference radiations at standard dosimetry laboratories are essential to transfer measurement standards to radiation users. This paper presents attempts made at Ionizing Radiation Division of PTB to produce a reference 20 MeV electron beam based on the German standard DIN 6800-2. The quality of the 20 MeV electron beam of a Philips SL75-20 linear accelerator (linac) is determined by a well designed plane-parallel ionization chamber, in terms of mean energy of the electron beam at the surface of a water phantom. Three types of cylindrical ionization chambers are calibrated against the primary standard of absorbed dose to water at PTB in Co-60 gamma radiation. Based on DIN 6800-2, independent measurements of absorbed dose to water are then carried out by these three calibrated chambers at a reference depth in water phantom and with reference to the dose monitoring system of the linac which consists of two other ionization chambers located in water phantom. The results are compared and a mean calibration factor for the monitor chambers with a combined standard uncertainty is determined.

Meta-iodobenzylguanidine (MIBG) is used for the diagnostic scintigraphy and therapy of adrenal tumors such as pheaeochromocytoma and neuroblastoma, as well as for the scintigrphic assessment of cardiac sympathetic neuronal integrity. This paper reviews the Cu+1 assisted nucleophilic exchange radioiodination of meta-iodobenzylguanidine (MIBG). In this study a kit formulation of meta-iodobenzylguanidine ready to be labeled with 131I without purification step is presented. Radioiodination had involved a nucleophilic exchange assisted by Cu (I) generated "in situ" and excess of reducing agents. An acceptable radiochemical yield ≥90% is obtained between 95-100oC within 30 min. The pH was adjusted by citrate buffer. Chemical and radiochemical purity of 131I -MIBG were determined by tin layer chromatography (TLC). The developed kit followed by a simple radiochemical manipulation allows preparing 131I-MIBG at medical centers.

Identification of irradiated potatoes (Alpha variety) by the electrical impedance measurements has been carried out. Experiments were performed by passing ~3mA alternating current through the potato tubers that were punctured with the galvanized metallic electrodes. The parameters Z0/Z180 (impedance ratio at 50Hz, zero to 180 seconds post puncturing), Z50k/Z5k, Z50k/Z0.5k, Z50k/Z0.05k(impedance ratio at 50kHz to 5kHz, 0.5kHz and 0.05kHz,respectively) were determined at various temperatures and the best temperature for the measurement was obtained. The selection of the identification parameter was based on its constancy over the post irradiation storage time (six months), as well as, its dependency on the magnitude of the absorbed dose. Based on the above criteria, the impedance ratio of Z50k/Z5k was determined to be the best identification parameter. The obtained empirical formulas allow to estimate the applied dose and also to differentiation between the irradiated and unirradiated potatoes at the temperature of the (20-35°C).

For performing rapid Thyroid test, the best approach is to reduce the steps of the experiments which are usually made by the manufacturers. The sequential steps in a typical Radioimunoassay (RIA) are: Adding Standards, Adding Tracer, and Adding Ab. So, if we can eliminate one of these steps, the test rapidity will be increased. During the past few years many research studies have been carried out in the Department of Radioisotopes at the NRC (NRC, R. D.) of the AEOI in order to eliminate the Adding Ab step in the RIA by coating the Ab on the inner surface of the local tubes. During these studies all physical and chemical conditions experimented for polypropylene and polystyrene tubes (both local and imported) were used and for each condition, QC tests were performed. Finally, the ready for use kits were tested by some creditable Medical Laboratories and the accuracy and precision of kits were confirmed. The final results of these studies were shown the ability of NRC, R. D. for producing T3 and T4 Coated Tubes for RIA Kits by using modified local made tubes.

Underground exploration, in particular in places with no outcrops is a very important task. The only indirect way for defining shape, dimensions and depth of ore bodies which are buried underground is the quantitative interpretation of the geophysical data. Also finding a best point for drilling is defined mainly by quantitative interpretation of the relevant geophysical data. In this way, a software package entitled "QuantInt" including about 10,000 lines programming by Visual Basic language was prepared for quantitative interpretation of geomagnetic and gravity data. This package also has the ability for calculation of terrain correction and average density of rocks. As an example for application of this package, exploration of uranium ore has been demonstrated.

Uranium mine in Saghand area can be mined and exploited using different underground methods. In order to achieve this goal, two vertical shafts each 350m in length were sunk and equipped. In this article two methods which have been applied by Russian and china experts will be explained and then they will be compared with each other. Based on the advantages and disadvantages of the applied methods, a third method has been derived from their comparisons. This last method was found to have many advantages and was accepted as an selected method for the Saghand Uranium exploitation.