Radiological Accident and Acute Radiation Syndrome

In mass casualty situation due to radiological accidents, it is important to start aggressive management with rapid triage decisions. External contamination needs immediate decontamination and internal contamination should be treated with special expertise and equipment to prevent the rapid uptake of radionuclides by target organs. Acute radiation syndrome shows a sequence of events that varies with the severity of the exposure. More severe exposures generally lead to more rapid onset of symptoms and severe clinical findings. After the massive exposure, various systems of the body reflect their severe damages that can lead to death within hours or up to several months. The disease progression has classically been divided into four stages: prodromal, latent, manifest illness, and recovery or death. Three characteristic clusters of symptoms including the hematopoietic syndrome, the gastrointestinal syndrome and the cerebrovascular syndrome are all associated with the acute radiation syndrome. The standard medical management of the patients with a potentially survivable radiation exposure includes good medical, surgical and supportive measures. Specific treatment with cytokines and bone marrow transplantation should be considered. The management of internal contamination is much the same as the treatment of poisoning. The standard decontamination should be applied to reduce uptake, and the chelating agents can be administered to enhance the clearance of radioisotopes. Radioactive iodine (131I) as one of the nuclear fission products can increase the incidence of thyroid cancer in children. Potential benefit of potassium iodide prophylaxis is greater especially in neonates, infants and small children.

Production of Ga-66 from natural zinc

In this study, production of Gallium-66 by irradiation of natural zinc target with 15 MeV protons was verified.Gallium-66 is an intermediate-lived radioisotope that has potential for positron emission tomography (PET), along study of the biological processes with intermediate to slow target tissue uptake. 66Ga [t1/2 = 9.49 h; ß+ (56.5 percent), EC(43.5 percent)] can be used in a large number of labeled proteins, peptides, and small molecules. We have produced 66Ga by irradiation of natural Zinc with 15 MeV proton beam, using the cyclotron -30Cyclon- at nuclear research center for agriculture and medicine. A 400µm Zinc target with copper backing substrate was irradiated for 1.5 hours with total integrated current 250µAh. Gallium has been purified from irradiated targets by passing through the cation exchange column and diisopropyl ether extraction. The concentration of zinc and copper in 0.1 and 0.5 ppm were respectively measured by polarography. In order to detect impurities, gallium radioisotopes were detected by a Canberra HPGe gamma spectrometer. The production yield at EOB was 7mCi/µAh with total activity of 1.75 Ci for Gallium-66. The ratio of activity at 9 hours after the EOB for 66Ga(t 1/2=9.5h), 68Ga(t1/2=1.1h) and 67Ga(t1/2=78h) was 98.63 percent, 1.12 percent and 0.25 percent respectively. The amount of 64Ga(t1/2=0.04h), and 70Ga(t1/2=0.35h) was not detectable. Due to using natural zinc, this method could be considered as an inexpensive method for laboratories studies. The production process comparing the irradiation of natural copper has no impurity such as copper-61, 64 and 67. The purification including cation-exchange and ether extraction afforded high yield beside negligible concentrations of copper and stable zinc as chemical impurity.