International Journal of Radiation Research
Volume:11 Issue: 3, Jul 2013

Ghrelin is a hormone related to food intake in rodents and humans, mainly produced in stomach. This study aimed to determine the effect of irradiation on ghrelin concentration in the gastric mucosa of rats. Twenty-five rats were exposed to 15 Gy of whole-abdominal irradiation. Gastric tissue samples were obtained 1, 3, 7, 30, and 90 days after irradiation. Five non-irradiated rats were used as controls. The number of ghrelin cells that reacted with anti-ghrelin antibody was counted. Moreover, ghrelin mRNA expression was determined. Food intake and body weight changes were measured simultaneously. Compared to the controls, irradiated rats showed a significantly decreased gastric ghrelin cell count, i.e., 29%, 30%, 32%, and 32% at 1, 3, 30, and 90 days, respectively, after irradiation (p < 0.05). Irradiated rats also showed decreased ghrelin mRNA expression; the expression decreased by 54.1%, 58.8%, 52.0%, and 52.7% at 1, 3, 30, and 90 days, respectively (p < 0.05). Food intake of irradiated rats decreased continuously compared with the control rats, except at 90 days. Body weight of the irradiated rats was lower than that of the controls at 7 and 30 days. This study demonstrated that abdominal irradiation can reduce gastric ghrelin concentration. Though decrease of food intake and body weight was observed simultaneously, further evaluation needs to find out the relationship between gastric ghrelin level and food intake after exposure to irradiation.

Development of safe radioprotector is a challenging task. In this study radioprotective effect of sucrose has been demonstrated in calf thymus DNA (CtDNA). Sucrose is a free radical scavenger and also acts as osmolyte and therefore can influence the water activity around DNA and effects of radiation on DNA. Hoechst 33258 was used to probe the possible alteration in physicochemical properties due to altered hydration induced by sucrose in irradiated CtDNA. Calf thymus DNA (CtDNA), sucrose and Hoechst 33258 were obtained from Sigma Chemicals, USA. 60Co Gamma source (Gamma5000, BRIT India) was used for irradiation. Radiation induced structural destabilization was monitored spectrophotometrically (Cary Bio 100, Varian, Australia) by measuring CtDNA melting temperature. Changes in physicochemical properties (altered water activity, minor groove binding characteristics) were investigated using absorption and fluorescence spectroscopic properties of Hoechst 33258-CtDNA interactions in presence of sucrose. The CtDNA melting temperature data suggest that sucrose reduced the effect of γ-irradiation on CtDNA. Thermodynamics of binding interaction of Hoechst 33258 with irradiated CtDNA suggested favorable energetics accompanied by displacement of water molecules. Binding affinity in presence of sucrose was altered marginally at low concentration (<0.5Osm). The marginal changes in absorption and fluorescence spectroscopic properties of Hoechst 33258-CtDNA interactions at higher concentration of sucrose suggested unaltered functional capability of CtDNA. This study suggests that sucrose can provide structural protection in γ irradiated CtDNA. Both scavenging and altered water activities by sucrose contributed in the observed radioprotection. These physicochemical properties of sucrose can be considered for designing better radioprotector. The observations at low concentrations of sucrose appears important lead for further validation studies.

In high-intensity, mixed and pulsed neutron fields the use of spectrometers or area monitors with active detectors is useless; in these conditions neutron measuring devices must have a passive detector. Here a passive neutron area monitor with CR39 track detector was designed and the response was calculated. The response of a passive neutron area monitor with CR39 track detector has been calculated with the MCNPX code. To increase the detection efficiency a 10B converter was included. The response was calculated using 47 monoenergetic neutron sources. A passive neutron area monitor using a CR39 with 10B converter was designed where fluence and H*(10) responses were calculated. The shape of the responses is similar to responses reported for neutron monitors with active detectors.

The radioactivity levels in sediment and rock samples of İkizdere and Kaptanpaşa Valley have been determined. To our knowledge, there seems to be no information about radioactivity level in the İkizdere and Kaptanpaşa Valley sediments and rocks so far. The average radium equivalent activity (Raeq), the total absorbed dose rate (D), the external risk index (Hex) and the annual effective dose equivalent (AEDE) which will be defined later have been calculated and compared with the results in literature. Rock characterization was also investigated using thin section and X-ray diffraction (XRD) analysis. Also gross α and β activity concentrations were calculated for some rock samples. Their radiological implications were also calculated and compared with the international recommended values. The gross α activity is generally lower than the corresponding gross β activity for some rock samples. Rock characterization was also investigated using thin section and XRD analysis. This study can be used as a baseline for future investigations and the data obtained in this study may be useful for natural radioactivity mapping. It seems necessary to determine the radioactivity concentrations in sediments and rock of other parts of Turkey. The results may also be used as a reference data for monitoring possible radioactivity pollutions in future.

Whether exposure to common electromagnetic fields affects human health adversely has been a controversial issue. The main goal of this study was to assess the role of 900 MHz microwave radiations with different specific absorption rates (SARs), emitted from some widely used cell phones, on the induction of adaptive response in male Balb/c mice after receiving a lethal dose of gamma radiation. This study was conducted on 120 male Balb/c mice. The animals were divided into groups of 20 mice each (6 groups). Group one (the control group) received neither microwave radiation nor the lethal dose of gamma radiation. Group two was exposed only to the lethal dose of 8.8 Gy. The mice in group three were first exposed to low SAR 900 MHz microwave radiations emitted from a cell phone for six hours (3 hours in the morning and 3 hours in the afternoon) for 5 days and then were exposed to a lethal dose of 8.8 Gy on day six. The mice in group 4 were treated as those in group 3 but with a moderate SAR and the mice in group 5 were also treated as those in groups 3 and 4 but with a high SAR. The mice in group six were exposed only to high SAR 900 MHz microwaves. All groups were monitored for 12 days and their daily mortality rates were recorded. The results showed that there was a statistically significant difference between group two (the animals exposed only to lethal dose of gamma radiation) and the groups with a pre-exposure to microwave radiations before receiving the lethal dose. To the best of our knowledge, this is the first study that investigates the role of SAR on the induction of microwave-induced survival adaptive response. It can be concluded that 900 MHz microwaves emitted from cell phones, regardless of their SAR can induce adaptive responses which make the animals more resistant to subsequent lethal doses of ionizing radiation. These findings also confirm our preliminary findings obtained in a previous study.

Intraoperative radiation therapy (IORT) technique is used to treat a surgically exposed tumor or tumor bed in the treatment of locally advanced intraabdominal, retroperitoneal, pelvic, thoracic, breast and soft tissue tumors. One way to perform IORT is to use an existing linac and modify the treatment head using an applicator system. In this study the objectives were to design, and build an in-house IORT applicator system, perform an acquisition of dosimetry data and characterize the IORT radiation parameters. IORT applicator system developed in this research consists of three flat applicators with inner diameters (ф) of 3, 5 and 9 cm and one tube (ф =3 cm) with a 45-degree beveled end. Beam characteristics evaluated include percent depth dose distributions, beam profiles, and leakage dose distributions. Measurements were performed using a Scanditronix (p-si) diode field detector in a Scanditronix (RFAplus) 3-D water phantom. Compared to the standard applicator, depth dose curves for intra-operative cones are shallower; surface dose is higher and the maximum peripheral dose is in the order of 9.6%. Using a 10 MeV electron beam, the cone system developed in this study is suitable for treating tumors of width and depth ranges of 1.9-8.4 cm and 14-29 mm, respectively.

The concentrations of radionuclides like 226Ra, 232Th and 40K and the dose rate are measured in igneous and metamorphic rock formations in and around Chickmagalur. A total of 236 samples from 13 different locations around study area were analyzed. The activity concentrations of the three radioactive elements were determined for mean period of 25000 s using HPGe (GMX - 10190) detector and the dose calculations were made using standard formulae. The mean activity concentrations in igneous rocks recorded were 36.6 Bqkg-1, 73.2 Bqkg-1 and 992.3 Bqkg-1 for 226Ra, 232Th and 40K respectively. The mean activity concentrations in metamorphic rocks were 17.2 Bqkg-1, 28.1 Bqkg-1 and 617.8 Bqkg-1 for 226Ra, 232Th and 40K respectively. Assuming 20% occupancy factor, the corresponding mean annual effective dose due to igneous and metamorphic rocks were 169.6 µSv and 90 µSv respectively. The concentrations of radionuclides were found to be in similar with global and Indian average (1-3).

The effectiveness and safety of brachytherapy treatment is mainly concerned with the calibration of sources and their traceability to internationally accepted Standards. Secondary Standard Dosimetry Laboratory (SSDL) does not offer calibration of ionization chambers with gamma-ray spectrum of high dose rate source 192Ir. This work has been carried out to calibrate the high dose rate (HDR) 192Ir sources. An interpolation procedure, using calibrations above 1.25 MeV (60Co), and below 135 kV X-rays (61.1 keV), the exposure-weighted average energy 397 keV of 192Ir is employed. Using Farmer ionization chamber HDR 192Ir source has been calibrated by free in-air measurement technique and then the calibrated source has been used to calibrate well-type ionization chamber. Difference between in-air measurement and that of manufacturer’s remained within ± 3%, and the difference between in-air measurement and well-type chamber remained within ± 1%. Comparison between well-type measurements and manufacturer values shows differences less than ± 2%. All these differences are within the acceptable tolerance limits. The method presented shows good degree of accuracy so that the traceability of calibration is assured. Installation of a new brachytherapy source needs to be calibrated by in-air measurement technique and then this calibrated source should be used for well chamber calibration. Brachytherapy community is suggested to calibrate their sources with this method.

After curative treatment of Hodgkin’s lymphoma, increased risk of certain solid tumors has been reported. To best of our knowledge this is the first report of metachronous pancreatic adenocarcinoma which developed outside the previous radiation field in a patient with relapse Hodgkin’s lymphoma. Herein we present an 81-year-old female who developed pancreatic adenocarcinoma four years after the curative treatment of Hodgkin’s lymphoma.

As a member of the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS), Iran has a long-term space exploration program. Space radiation is one of the challenges facing humans when they go outside Earth''s protective atmosphere and magnetic field. Space is an environment that the cardinal principles of radiation protection; i.e. time, distance and shielding cannot be effectively applied. On the other hand, well-known limitations of physical shielding prompt us to explore biological methods for inducing radioresistance during space missions. Screening of the candidates of long-term space missions by ground-based in vitro adaptive response studies might be helpful. It has recently been shown that the detrimental effects of exposure to protons and HZE particles can be prevented by some dietary supplements. Interestingly, in contrast with radioprotectors, these dietary supplements can prevent radiation induced detrimental effects even when applied several days after exposure to radiation. It seems that finding appropriate radiation mitigators with a post-exposure time window in excess of 24 hours will be a critical goal in planning future manned space missions. In this paper, the advantages of biological shielding over current well defined physical shielding will be discussed.