International Journal of Radiation Research
Volume:5 Issue: 3, Jul 2007

The aim of the present study was to evaluate the radioprotective effect of Grewia asiatica fruit pulp extract (GAE) on Swiss albino mice exposed to gamma radiation. In the present study radioprotective efficacy of Grewia asiatica (rich in anthocyanin, carotenes, vitamin C, etc.) was studied against radiation induced biochemical alterations in mice cerebrum. For experimental study, healthy Swiss Albino mice were selected from an inbred colony and divided into four groups. Group I (normal) did not receive any treatment. Group II was orally supplemented (GAE) once daily at the dose of 700 mg/kg.b.wt/day for fifteen consecutive days. Group III (control) received distilled water orally equivalent to GAE for fifteen days than exposed to 5 Gy of gamma radiation. Group IV (IR+Drug) was administered orally (GAE) for 15 consecutive days once daily after exposed to single dose of 5Gy of gamma radiation respectively. Mice were sacrificed at different autopsy intervals viz. 1, 3, 7, 15 and 30 days and brain were removed for various biochemical estimations viz. glutathione (GSH), lipid peroxidation (LPO) and protein. GAE post treatment renders protection against various biochemical changes in mice brain. Radiation induced augmentation in the levels of LPO was significantly ameliorated by GAE post-treatment. Radiation-induced depletion in the level of GSH, protein was checked significantly by GAE administration. These results indicate that Grewia asiatica fruit extract (GAE) is able to protect the brain of Swiss albino mice against radiation induced biochemical alterations.

A study has been conducted to assess two useful radiation protection indices, the annual per-capita effective dose equivalent (AED) and the genetically significant dose (GSD), from conventional diagnostic radiography in 10 counties with more than 1,886,000 inhabitants in Khorasan province in Iran. The health centre authorities of Khorasan province were asked to record data of their patients (sex, age, weight and height) who had undergone radiography during one month starting October 2002, with the radiography specifications (kVp, mAs, FSD, field size) and conditions of the X-ray machines (filtration, model and performance). Based on the gonad absorbed dose level, the radiography data were first divided into 5 groups. Then, the average gonad and effective dose of the radiography groups were estimated using ODS-60 software, and finally, GSD and AED of each county were calculated. Average number of radiography per thousand inhabitant was 34.5 in this study, which varied from 9.4 (Kashmar) to 109.4 (Ferdos). Number of X-ray units per 1000 population was 0.008. The GSD and AED of inhabitants in 10 counties in Khorasan province is 0.012 and 0.014 mGy/y/person respectively. The GSD and AED of 10 counties in Khorasan province were much lower than those in most of other countries, which would have been due to lower number of X-ray units and examinations per 1000 inhabitants. Although this would reduce the risk of radiation absorbed dose from medical diagnostic, but it also showed need to improve and expand the health care facility and services in those cities.

Over the last decade, exposure to non-ionizing electromagnetic waves due to base station antenna has increased. This in vivo study was planned for evaluating the effects of whole-body exposure to 950 MHz field of GSM mobile phone system on rat dentate gyrus long-term potentiation. 24 naive male Wistar rats (3 month old, 225|¡|25 g) were randomly divided in the three groups (sham-exposed, GSM and continuous field exposed). The exposure program was planned for 10 sessions at 3 days. Animals were exposed to electromagnetic field for 45 minutes in a circular plastic chamber (mean power density=0.835 mW/cm2). Immediately after end exposure, anesthesia was induced for long term potentiation (LTP) induction. Field potentials were recorded and analyzed using the population spike amplitude and EPSP slope for 60- min. There were no significant differences in population spike amplitude, EPSP slope and EPSP slope maintenance among the three groups. This study provides no evidence indicating that long-term potentiation can be affected by the whole-body exposure to low-power density of 950 MHz field of GSM mobile phone system.

In the present investigation radiation and cadmium induced biochemical changes in the kidney of Swiss albino mice have been studied. For this purpose, adult male Swiss albino mice (6-8 weeks old) were divided into four groups. Group I (sham-irradiated), Group II (treated with CdCl2 solution 20 ppm), Group III (irradiated with 1.25, 2.5 and 5.0 Gy gamma rays), Group IV (both irradiated with 1.25, 2.5 and 5.0 Gy gamma rays and treated with CdCl2 solution). The animals were autopsied after 1, 2, 4, 7, 14 and 28 days of treatment. The kidney was taken out and different biochemical parameters, such as total proteins, glycogen, cholesterol, acid phosphatase activity, alkaline phosphatase activity, DNA and RNA were estimated. In irradiated animals, the values of total proteins, glycogen, acid phosphatase, alkaline phosphatase activity and RNA increased continuously up to day-7 and decreased thereafter up to day-28. The changes were dose dependent. In CdCl2 treated animals, the values of glycogen and total proteins decreased during the early intervals and increased thereafter whereas the values of acid and alkaline phosphatase activity and RNA increased during early intervals and decreased thereafter. The values of cholesterol and DNA showed decrease in all the experimental groups (except group I) up to day-7 and increase thereafter up to day-28. After combined treatment also, the parameters followed the same pattern of increase and decrease, but the changes were more pronounced indicating their synergistic effect. The biochemical parameters showed highly significant values (P<0.001) as compared to normal ones. These results indicate that combined treatment of cadmium and gamma radiations causes synergistic or additive effect.

A dressing often covers the wound to accelerate its healing. Hydrocolloid-type dressing to give better conditions for healing has been developed consisting of gelatin, pectin, water and hydrophilic polymer which promote healing. In recent years, much attention has been focused on the research and development of polymer hydrogels as biomaterials, such as contact lenses, wound dressing and drugdelivery systems. Hydrogels, as wound dressing were prepared with composite poly (N-vinyl-2-pyrolidone) (PVP) with several additives such as agar and polyethylenglycol (PEG) and by electron-beam. Electron beam was applied as a tool for initiation of crosslinking and sterilization of these materials. The effects of irradiation dose at the range of 10-40 KGy and various concentration of components on the characterizes of hydrogel such as gel content, degree of swelling (DS), equilibrium water content (EWC) and dehydration properties, transparency and microbial test were investigated. After irradiation, the achieved gel content of hydrogels was obtained higher than 25%. Gels'' degree of swelling with different concentrations was changed from 35 to 20 at the range of irradiation dose of 10-40 KGy. Also, at the same range of irradiation and concentration, EWC of gels was found to be 98 to 94 %. The dehydration results did not show variation with the tested parameters. Results showed that hydrogels membrane with composition PVP (10% w/w), agar and PEG (1-3%w/w) at the dose of 25 KGy had the amount of gel content 80-85%. Their DS and EWC were respectively obtained 30% and 96.5%. They were elastic, transparent, flexible, sterile and impermeable for bacteria. They absorbed a high capacity of water, attached to healthy skin, and they were easy to remove. It was concluded that the network was solely composed of crosslinked PVP plasticized by other compounds.

Several landmine detection methods, based on nuclear techniques, have been suggested up to now. Neutron-induced gamma emission, neutron and gamma attenuation, and fast neutron backscattering are the nuclear methods used for landmine detection. In this paper an optimized (safe and effective) moderating structure using an 241Am-Be neutron source for detecting landmines has been investigated by experiment and MCNP simulation. The experimental set up was composed of a lead (Pb) cylindrical shell enclosing the neutron source, embedded in a fixed size high-density polyethylene (HDPe) cylinder with the variable thickness of the upper and lower moderator/reflector. Some experimental groups were used to measure several moderator configurations'' responses by replacing a thermal neutron detector with the mine and counting the neutron capture events. the total experimental results led to the introduction of optimum moderator geometry for landmine detection. A safe landmine detection system was obtained which enabled the operator to use it for 950 h/year, regarding the dose limit recommended by ICRP. The novel method for optimization applied in this work is more applicable than the usual approach that is based on measuring the prompt gamma rays emitted by the landmine. Results showed that the method can be optimized in short time, without the usual difficulties of the other methods.

In megavoltage radiotherapy rooms, ordinary concrete is usually used due to its low construction costs, although higher density concrete are sometimes used, as well. The use of high-density concrete decreases the required thickness of the concrete barrier; hence, its disadvantage is its high cost. In a nuclear reactor, neutron radiation is the most difficult to shield. A method for production of economic high-density concrete with appropriate engineering properties would be very useful. Galena (PbS) mineral was used to produce of a high-density concrete. Galena can be found in many parts of Iran. Two types of concrete mixes were produced. The water-to-concrete (w/c) ratios of the reference and galena concrete mixes were 0.53 and 0.25, respectively. To measure the gamma radiation attenuation of Galena concrete samples, they were exposed to a narrow beam of gamma rays emitted from a cobalt-60 therapy unit. The Galena mineral used in this study had a density of 7400 kg/m3. The concrete samples had a density of 4800 kg/m3. The measured half value layer thickness of the Galena concrete samples for cobalt- 60 gamma rays was much less than that of ordinary concrete (2.6 cm compared to 6.0 cm). Furthermore, the galena concrete samples had significantly higher compressive strength (500 kg/cm2 compared to 300 kg/cm2). The Galena concrete samples made in our laboratories had showed good shielding/engineering properties in comparison with all samples made by using high-density materials other than depleted uranium. Based on the preliminary results, Galena concrete is maybe a suitable option where high-density concrete is required in megavoltage radiotherapy rooms as well as nuclear reactors.

For an effective treatment planning in brachytherapy, it is necessary to know the accurate source dosimetric information such as air kerma strength, exposure rate constant, dose rate constant and redial dose distribution. The usual method to determine these factors is thermo luminescent dosimeter (TLD) dosimetry. Nowadays, another more accurate method is known to be the Monte Carlo simulation, and it is widely used in determining of brachytherapy sources dosimetric factors. The aim of the present study has been determine to dose distribution of 137Cs sources configuration used in interacavitary low dose rate (LDR) Selectron brachytherapy by Monte Carlo simulation method. Simulation has been performed for 137Cs stainless-steel encapsulated source in 2.5 mm in diameter of Selectron system. Six different combinations of 137Cs sources were simulated and each combination was put into different applicator. The Monte Carlo MCNP4C code was used for simulation. The number of history was taken 1 million for the calculation of air kerma strength and exposure rate constant and 0.1 million for calculating dose rate constant and redials dose distribution. Maximum air kerma strength was obtained for the combination with fourteen active sources and found to be 919.3 |µ|Gym2h-1 while its minimum value was 133.9 µ|Gym2h-1 for the case with two active sources. Maximum and minimum dose rate constant of 4.3 cGyh-1mCi-1 and 2.1 cGyh-1mCi-1 were obtained for the combination with eight and fourteen active sources, respectively. The results indicated that the Monte Carlo simulation method may be useful to determine dosimetric characteristics of brachytherapy sources.