International Journal of Radiation Research
Volume:4 Issue: 4, Oct 2006

This study was carried out to observe the radioprotective effects of Rosemarinus officinalis leaves extract (ROE) against radiation-induced histopathological alterations in liver of mice. Adult Swiss albino mice were exposed to 6 Gy gamma radiation in the presence (experimental) or absence (control) of ROE to study the qualitative and quantitative alterations in the liver. Normal hepatocyte counts were found to be declined up to day 10th post-irradiation in both the groups but thereafter such cells increased reaching to near normal level at the last autopsy interval, only in experimental group. Contrary, frequency of abnormal hepatocytes increased up to day 10th after irradiation in both the groups. Binucleate hepatic cells showed a biphasic mode of elevation after irradiation, first at 12 hrs and second on day 10th in control group; whereas in experimental group, the elevation was comparatively less marked and even the second peak was not evident. Irradiation of animals resulted in an elevation in lipid peroxidation (LPx) and a significant decrease in glutathione (GSH) concentration in liver as well as in blood. Conversely, experimental group showed a significant decline in LPx and an elevation in GSH concentration. These results indicate that Rosemarinus officinalis leaves extract (ROE) is able to protect the liver of Swiss albino mice against radiation induced histopathological alterations.

Radon and its short-lived decay products are considered as the important sources of public exposure to natural radioactivity. The synergistic interaction between tobacco smoking and radon is known to be an actual problem. This study has provided a mathematical description and prognosis of the carcinogenic effects after combined action of radon with smoking. A simple mathematical model was adjusted for the optimization and prognosis of the synergistic interaction of radon with smoking. The model postulates that the occurrence of synergism is to be expected as a result of additional carcinogenic damage arising from the interaction of sublesions induced by the two agents under consideration. The predictions of the model were verified by comparison with experimental data published by other researchers. The model appears to be appropriate and the predictions valid. The suggested mathematical model predicts the greatest level of synergistic effect and condition under which this level is reached. The synergistic effect appeared to decline with any deviation from the optimal value of the ratio of carcinogenic effective damages produced by each agent alone.

Various variance reduction techniques such as forced detection (FD) have been implemented in Monte Carlo (MC) simulation of nuclear medicine in an effort to decrease the simulation time while keeping accuracy. However most of these techniques still result in very long MC simulation times for being implemented into routine use. Convolution-based forced detection (CFD) method as a variance reduction technique was implemented into the well known SIMIND MC photon simulation software. A variety of simulations including point and extended sources in uniform and non-uniform attenuation media, were performed to compare differences between FD and CFD versions of SIMIND modeling for I131 radionuclide and camera configurations. Experimental measurement of system response function was compared to FD and CFD simulation data. Different simulations using the CFD method agree very well with experimental measurements as well as FD version. CFD simulations of system response function and larger sources in uniform and non-uniform attenuated phantoms also agree well with FD version of SIMIND. CFD has been modeled into the SIMIND MC program and validated. With the current implementation of CFD, simulation times were approximately 10-15 times shorter with similar accuracy and image quality compared with FD MC.

Several landmine detection methods, based on nuclear techniques, have been suggested during the recent years. Neutron energy moderation, neutron-induced gamma emission, neutron and gamma attenuation, and fast neutron backscattering are nuclear-based methods used for landmine detection. The aim of this study is to use backscattered neutron for landmine detection. MCNP code, a well-known Monte Carlo particle-transport code, was theoretically used for backscattered neutron counts. An Am-Be neutron source and a single thermal neutron detector were experimentally applied to detect the buried sample. The experimental results obtained in this way have been in good agreement with the theoretical results obtained by MCNP. Therefore, the shield of neutron source plays an important role on landmine detection. Hydrogenous material such as polyethylene and boric acid can be used as suitable shields. They can increase neutron counts in detector and facilitate detection process

In order to obtain an anti-CD20 conjugate to be used in future therapeutic studies with therapeutic radioisotopes, 67Ga-labeled antibody was prepared as a model of metal chelated immunoconjugate for preliminary dosimetric and biodistribution studies. Rituximab was labeled with [67Ga]-gallium chloride after residulation with freshly prepared cyclic DTPAdianhydride. The best results of the conjugation were obtained by the addition of 1 ml of a rituximab pharmaceutical solution (5 mg/ml, in phosphate buffer, pH=8) to a glass tube pre-coated with DTPAdianhydride (0.01 mg) at 25|o|C with continuous mild stirring for 30 min. The final isotonic 67Ga-DTPArituximab complex was checked by gel electrophoresis for radiolysis/chemolysis control. Radio-TLC was performed to ensure the formation of only one species. Preliminary in vivo studies in normal rat model were performed to determine the biodistribution of the radioimmunoconjugate up to 6 hours. Radio-thin layer chromatography showed an overall radiochemical purity of 96-99% at optimized conditions (specific activity =300-500 MBq/mg, labeling efficiency 77%). Gel electrophoresis showed no protein cleavage after radiolabeling. Preliminary in vivo studies in normal rat model showed [67Ga]-DTPA-rituximab is a good probe for bio-dosimetry of therapeutic rituximab conjugates.

Radiation dose knowledge through Xray examinations and their distribution in Iran provides useful guidance on patient dose reduction. The results of the entrance skin dose (ESDs) of five common radiographies in all radiology centers in Yazd province were reported in our previous study (2003). In the present study we have evaluated the collective effective dose of conventional X-ray examinations, as well as the annual per caput of Yazd population. The annual frequencies of 18 different types of conventional radiology examinations during April 2005 to March 2006 were recorded from all 35 radiology centers in Yazd province. The exposure conditions consisted of kVp, mAs, and Focus surface distance (FSD) of the examinations for the mode of exposure in each X-ray unit. 620 ESD were measured by diode dosimeter in 35 hospitals and clinics. The real exposure kVp for each radiology unit was measured by a Molt-O-Meter. The conversion coefficient (effective dose - ESD ratio) for each radiology examination was determined by using SR262 tables. Finally, the patients'' effective dose was calculated by multiplying the conversion factor to the ESD. The patients'' annual collective effective dose due to the conventional radiology examinations was 31.159 man-Sv (0.03 mSv per inhabitant). The frequency of examinations was 311813 i.e. 0.36 examinations per head of the population for one year. According to our findings, the effective per caput dose seems to be optimally relative to HCL-II countries, which may be due to low mean effective dose that could obscure high examination frequency. The number of radiology conventional examinations and frequency of radiologist per1000 population of Yazd was more and lower than HCL-II countries respectively. Thus the justification of radiography requests in this province must be revised.

Some Particular areas contain natural radionuclide at levels much higher than those usually present in earth''s crust. The radiological impact of the use of zirconium ore in zirconium industry is due to internal exposure of the lung by alpha particles and external exposure of the body by the gamma rays. The result of gamma spectrometry measurement of the concentrations of the natural radionuclide in zirconium industry is described. Gamma spectrometry system with a shielded high pure germanium (HPGe) detector connected to multi channel analyzer (MCA) was used to determine concentrations of natural radionuclide in about 45 samples of imported zirconium minerals, tiles, stone ware and waste sludge''s of Iranian ceramic industry. The 238U concentration in the samples, ranging from 3000 to 10000 Bq Kg-1, is higher than the concentration of both 232Th (500-1800 Bq Kg-1), and 40K (50-800 Bq Kg-1). The measured specific activities in the mineral showed that specific activity of baddeleyite is higher than that of zircon. The results of ceramic tiles show that the tiles usually contain small amount of zirconium compound. Due to relatively high concentration level of uranium in imported zirconium samples, specific regulations is necessary for zirconium compound used in ceramic industry.

Exposure conditions in CT examinations are quite different from conventional Xray. In CT examination higher dose is given to patient in comparison with the dose in other diagnostic examinations. In order to calculate organ effective dose in chest CT, Monte Carlo simulation has been used in this study. The Impact survey data were used to determine the parameters related to patient dose. This was done by correlating the measurements from the NRPB scanners with the effective dose calculated, using the CTDOSE software. Patient dose index in air (CTDIair) was measured as function of tube exposure ranged from 90 to 225mAs at constant kVp and slice thickness, using a stack of TLD chips which was long enough to fully encompass the dose profile that could have been used. Dose profile of each exposure was measured with approximately Gaussian distribution shape. The full width at half maximum (FWHM) of these profiles was nearly equal, and on average it was equal to 8 cm. Also the maximum CTDIair for these profiles, as expected increased with mAs ranging from 29.2 to 50.606 mGy. CTDIair was measured by two methods using conversion coefficient established by using software, based on Monte Carlo simulations (CTDOSE) and the other was measured in the area under the dose profile distribution. The slice thickness measured from FWHM and those thicknesses set by the operator were nearly equal proving that the measurements using TLD were accurate. The effective dose for chest increased with increasing mAs. By these measurements, it was also noted that the maximum equivalent dose and sharpest slope variation were for lungs, heart and breast respectively, whereas the minimum equivalent dose with lowest slope variation was related to thyroid, liver, spleen, stomach wall and kidneys respectively.