International Journal of Radiation Research
Volume:4 Issue: 3, Jul 2006

Knowledge of radioactivity levels in human diet is of particular concern for the estimation of possible radiological hazards to human health. However, very few surveys of radioactivity in food have been conducted in Iran; therefore the baseline values of the natural radionuclides concentration (40K, 226Ra and 232Th), and man made radionuclide, 137Cs, were determined in twenty six samples of imported foodstuff in Iran. Twenty six samples of different kinds of imported foodstuff were selected for analysis. These samples, after pretreatment and washing (if necessary), were measured by a low level gamma spectrometry system. All samples were found to contain detectable 40K content in range 6.4 to 778.4 Bq.kg-1 fresh weights (fw). 137Cs, 226Ra and 232Th were detectable in most of the samples. The maximum concentration of 40K, 226Ra and 232Th were found in tea sample, equal to 778.4±23.4, 2.9±0.1 and 5.4±0.2 Bq.kg-1 (fw), respectively, where as for 137Cs it was 3.2±0.1 Bq.kg-1 (fw) in milk powder. The concentrations of 40K and 137Cs in different imported foodstuff are comparable with those from the other countries yet 232Th concentration is higher than the reported values. Also, 226Ra results appear to be higher than the reported values in some cases.

Measurement of gross, gross activities, and cosmogenic beryllium-7 (7Be) concentrations were made both daily and weekly during the years 2001- 2004 from samples of atmospheric aerosols filtered from the air at Tehran Nuclear Research Center (35 41'' N) and Zahedan (28 29'' N). Weekly aerosol samples were collected with the high-volume air samplers on cellulose filters to determine the 7Be contents of samples, using a semiconductor gamma spectrometer. Airborne dust samples were collected on daily basis on fiber glass filters and used to determine the gross and gross activities with automatic beta analyzer and a ZnS(Ag) counter, respectively. In this study, the concentration and meteorological data were used to determine models for gross, gross and 7Be. The air concentrations of gross and gross activities and 7Be concentrations displayed lognormal distributions during the study period. Both and 7Be had maximum activity concentrations during warm mid-year months. The models can be used to estimate the part of the trend in gross and in 7Be levels that can be accounted for by-trends in local meteorology. There has been a satisfactory agreement between the results of the model and the measurements.

Radiolabeled polyclonal human immunoglubins are useful in the detection of inflammations. In this work a novel approach has been presented to use thallium-201 as a comlexed nuclide for the development of radioimmunoconjugates. Thallium-201 (T1/2=3.04 d) in Tl+ form was converted to Tl3+ cation in presence of O3 in 6M HCl, controlled by RTLC/gel electrophoresis methods and used in the labeling of human polyclonal antibody (HIgG) after residulation with freshly prepared cyclic DTPA-dianhydride. The best results of the conjugation were obtained by the addition of 1 ml of a HIgG pharmaceutical solution (5 mg/ml, in phosphate buffer, pH=7) to a glass tube, which was pre-coated with DTPA-dianhydride (0.01 mg) at 25C with continuous mild stirring for 30 min. The final isotonic [201Tl](III)-DTPA-HIgG complex was checked by radio-TLC using several solvent systems to ensure the formation of only one species, and it was followed by filtration through a 0.22 µm filter (specific activity= 33.7 TBq/mM, radiochemical purity95%). Preliminary bio-distribution studies in normal and inflammation-bearing rats were performed. The target/skin and target/blood ratios were 4 and 6 after 28h, respectively, showing the selectivity of the radiopharmaceutical for the inflammatory lesions. The incorporation of Tl(III) cation into a immunoconjugate was performed using the known methods. The biodistribution of the immunocomplex was shown to be consistent with a stable complex for the detection of inflammations. Significant inflammation detection was observed for the final complex in rats with turpentine oil-induced inflammation.

High-velocity carbon ion beams represent the most advanced tool for radiotherapy of deep-seated tumors. Currently, the superiority of carbon ion therapy is more prominent on lung cancer or hepatomas. The data for lateral straggling and projected range of monoenergetic 290 MeV/u (3.48 GeV) carbon ions in muscle tissue were obtained from the stopping and range of ions in matter (SRIM) computer code. The data were transformed to determine the carbon ion trajectories in tissue by means of the Monte Carlo method. Consequently, the lateral dose distributions in the Bragg peak as well as the thickness of a thin disc-shaped tumor in the lateral direction were computed. The absorbed dose in the tissue was obtained as a function of the diameter of a carbon ion pencil beam. More than 90% of the radiation dose in the lateral direction is deposited in the Bragg peak. The simulation results are in agreement with the existing data. It was confirmed that this method is reliable for estimation of dose deposited in human tissue by carbon ion beams.

With the introduction of computed tomography in diagnostic radiology a new and fundamentally different imaging modality has become available. Meanwhile, it is clear that the absorbed doses by the patients during CT were relatively high in comparison with those of other diagnostic radiology techniques. The aim of this survey was to determine the average absorbed dose in Yazd province by CT examinations, and to survey the potential risks per year by these examinations. This study was conducted in CT centers of Yazd during 2005-2006. The examination frequencies from 3 CT scanners were collected from all types of examinations. Effective dose were determined by CT Dose program (ImPACT CT patient dosimetry calculator). To use of this software, CTDIair, mAs and the thickness and number of slices in each type of CT examinations should have been measured. CTDIair was measured by pencil diode detector. It was estimated that the annual collective dose and caput dose were about 32.48 Person-Sv and 0.038 mSv, respectively for the Yazd population, which is lower than that reported for other countries. The numbers of examinations per 1000 people of Yazd was 18 which were equal to many other countries such as UK and New Zealand. The mean effective dose of each CT examinations was also lower than that of other countries. Using the ICRP risk factors, radiation dose from CT could be induced to about 1 fatal cancer per year in Yazd. Therefore choosing CT imaging must be completely justified.

Study of vascular and its secretory profile changes is an important issue in pathogenesis of radiation myelopathy. This paper reports the prostacyclin concentration changes after low-moderate doses of X-irradiation within a short period of time. Cervical cords of Wistar rats were irradiated to doses of 0.5, 1, 2, 4 and 6 Gy X-rays. After 24 hours, 2 and 13 weeks post-irradiation, prostacyclin contents were quantified and cords specimens were also stained routinely for histological studies. Twenty four hours post-irradiation, showed a decrease in the content of prostacyclin after doses of 0.5 and 1 Gy 91.67±1.47% 96.80±2.17% of respectively age-matched control group. After 2 weeks the concentration of prostacyclin showed significant decreases after 6 Gy. After 13 weeks irradiation shows marked differences even after a small dose of 2 Gy (p<0.001), and after doses of the low dose group. The differences between concentration values at doses of 4 Gy and 6 Gy were significant in comparison with the control (p<0.001 and p<0.002, respectively). Results suggested that the response of the vascular tissues to low and moderate doses of radiation occurs prior to that of the nervous tissue of the spinal cord. It means that the asymptomatic interval after radiation is characterized by sequential physiological changes which are imperfectly reflected in routine histological study and that even in the histologically unaffected spinal cord; severe impairment is present in substructures and biochemistry of irradiated spinal cord.

The fatal effect of ionizing radiation on cells depends on Linear Energy Transfer (LET) level. The distribution of ionizing radiation is sparse and homogeneous for low LET radiations such as X or γ, but it is dense and concentrated for high LET radiation such as heavy-ions radiation. Chinese hamster ovary cells (CHO-K1) were exposed to 4 Gy Fe-ion 2000 keV/m. The CR-39 is a special and sensitive plastic used to verify exact position of heavy-ions traversal. Terminal deoxynucleotidyl transferase (TdT) is an enzyme labeled with [3H] dATP for detection of cellular DNA damage by autoradiography assay. The track of heavy ions traversals presented by pit size was almost similar for all different doses of radiation. No pits to show the track of traversal were found in 20% of the cell nuclei of the irradiation. Apparently these fractions of cells wave not hit by heavy ions. This study indicated the possible usefulness of both the CR-39 plastics and DNA labeling with TdT method for evaluating the biological effect of heavy-ions in comparison with low LET ionizing radiation.

Depleted Uranium (DU) is uranium with low content of U 235 produced as a result of uranium enrichment. DU has high density (19.05 g /cm3), which is 2.54 more than Iron, so it’s high penetrating power makes it preferable as emanations with high penetration power. It was used in second Gulf ware in 1991 for first time. The radioactivity of soil, plants, fruit, meat, milk and water is measured using gamma ray spectroscopy. One hundred samples of soil, plants and tomato fruit were selected from the tomato farms near Basra city south of Iraq and 6 control samples from other farms not contaminated with depleted uranium (DU). Also samples of meats, milk and water were collected in January 2003. Radioactivity of these samples was measured using Gamma-ray spectrograph system with high purity Germanium detector with resolution of 2.2 keV at the energy of 1332.3 keV of Co-60. The system is connected to PC Pentium 111 with PCA program. The measurements show that radiation equilibrium between 234Th and 226R existed with the range between (0.86-1.16) in uncontaminated soil samples. For contaminated soil samples radiation equilibrium between 234Th and Pa-234m existed with the range between (0.928- 0.956). The mathematical equations of Kosovo team were used. Results show that the soils of two farms were contaminated with (DU). The radioactivity of 226R for plants ranging from 5.97 to 7.26 and for tomato fruits samples between 9.16 to 12.4Bq/kg. Comparing these values with the control radioactivity which range between 6.25 to 7.34 for fruits and 13.3 to 13.9 Bq/kg for plants indicate that these samples were not contaminated with DU. The soil samples of two farms were contaminated with DU but the fruit of these farms was not contaminated with DU may be due to its high molecular weight and not being water soluble. The radioactivity of 226Ra for different kinds of meat and milk for animal grazing near destroyed tanks contaminated with DU, ranges between (0.02-1.1) and (0.01-.0.2) Bq/kg respectively. These values indicated that meat and milk are uncontaminated with DU. The water samples collected from wells in the same region are below the detection limit of the system. All these results indicated that the food chain was not contaminated with DU at the time of measurements.