International Journal of Radiation Research
Volume:7 Issue: 3, Jul 2009

Tumor response after multimodality treatment using combination of radiation, chemotherapeutic drugs and hyperthermia usually assessed by parameters such as tumor growth delay, volume doubling time and regression response. The study herein was conducted to investigate the usefulness of micronucleus assay for assessing the multimodality treatment. The induction of micronuclei (MN) in a transplantable solid tumor grown in inbred Balb/c mice was analyzed after treating the tumors with cis-platin (cDDP), radiation (RT) and hyperthermia (HT). The MN frequency in tumor was measured at 1, 3, 5 and 7 days of post-treatment. On day 1, all the cDDP and RT groups, except HT treatment produced significantly higher MN counts from that of the untreated tumors. Cis-platin treatment resulted in a dose-dependent linear increase in the frequency of MN induction on day one. Combination of radiation with cDDP or HT, as bimodality treatment further increased the MN counts. In the tri-modality group (cDDP+RT+HT) the MN counts were not significantly higher than the bi -modality treatments, however there was an immediate tumor shrinkage indicating the contribution of other forms of cell death. Although, MN counts were declined after day five post-treatment, remained significantly higher than the control on day seven-post treatment in hyperthermia alone or its combination with RT and RT+ cDDP groups. Micronucleus assay may be useful for assessing the post-treatment regression response of resistant tumors, while monitoring the response of sensitive tumors the parameters such as apoptosis and necrosis may also contribute considerably to tumor cell loss contributing immediate tumor regression

The aim of preliminary study was determined development process status of T-cell population lymphocytes in Ukrainian children after 22 years from Chernobyl accident for next feasibility study. 150 participants aged 6 to 16 years are included in three groups: Group I (n=65), 30 to 60 km from center accident at zone 3th, Group II (n=65) 60 to 90 km from same location at zone 4th and control group (n=20) from Kiev, 100 km from same location. Peripheral blood leukocytes from buffy coats were analyzed for T-lymphocytes population such as T-lymphocytes (CD3), T-helper (CD4) and T-cytotoxic (CD8) by roseting method using erythrocytes that conjugated with monoclonal antibody against CD3, CD4, and CD8 receptors; then CD4/CD8 ratio were calculated. Percentage of CD3 and CD4 in groups II and I decreased significantly in compared to control group at P<0.001. Percent of CD8 decreased significantly in group I compared to control group at P <0.001. CD4/ CD8 ratio decreased significantly in-group I comparison to control group at P=0.02. Leucocytes count in groups II and I have not changed significantly in comparison to control group (P=0.09,P=0.4) but in group II, it was significantly different in comparison to group I at P <0.008. Our data show that after 2 decade of Chernobyl accident, ionizing radiation may have affected the developmental processes of T-cell population.

The dose rate distribution delivered by a low dose rate 137Cs pellet source, a spherical source used within the source trains of the Selectron gynecological brachytherapy system, was investigated using the MCNP4C Monte Carlo code. The calculations were performed in both water and Plexiglas and the absolute dose rate distribution for a single pellet source and the AAPM TG-43 parameters were computed. A spherical phantom with dimensions large enough (60 cm) was used to provide full scattering conditions. In order to score dose at different distances from the source centre, this sphere was divided into a set of 600 concentric spherical shells of 0.05 cm thickness. The calculations were performed up to a distance of 10 cm from the source centre. To calculate the effect of the applicator and dummy pellets on dose rate constant and radial dose function, a single pellet source was simulated inside the vaginal applicator, and spherical tally cells with radius of 0.05 cm were used in the simulations. The F6 tally was used to score the absolute dose rate at a given point in the phantom. The dose rate constant for a single active pellet was found to be 1.102±0.007 cGyh-1U-1, and the dose rate constant for an active pellet inside the applicator was 1.095±0.009 cGyh-1U-1. The tabulated data and 5th order polynomial fit coefficients for the radial dose function along with the dose rate constant are provided for both cases. The effect of applicator and dummy pellets on anisotropy function of the source was also investigated. The error resulting from ignoring the applicator was reduced using the data of a single pellet. The results indicate that F(r, θ) decreases towards the applicator.

An amount of artificial radionuclide has been released into the environment as fallout, resulting from atmospheric nuclear weapon tests, nuclear accidents such as Chernobyl and together with air currents have polluted the world. 37 surface soil samples of Tehran province were collected in the period between June and September 2008, by implementing methods and standard instruments. The concentration of the artificial radionuclides (137Cs) in the soils of Tehran province were determined by gamma spectroscopy (HPGe), and the data were analyzed both quantitatively and qualitatively. The results have been compared with other radioactivity measurements. The concentration of 137Cs found in top soils (0-5 cm), in the depth of (12.5-17.5 cm) and in the depth of (27.5- 32.5 cm), ranged from 0.29-28.82 Bq.kg-1, 0.3-19.81 Bq.kg-1, 0.8-7.43 Bq.kg-1, respectively. The total average of 137Cs activity, in the above depths was, 11.30, 4.87 and 1.8 Bq.kg-1, respectively. Considering the obtained results from high average values of 137Cs in Europe and its relation to Chernobyl accident, and the higher average concentration of 137Cs in Tehran province, can also be attributed to Chernobyl accident due to the proximity of Iran to the place of the accident''s occurrence.

Activity concentrations of 40K, 226Ra and 228Ra were measured in some sachet drinking water samples produced in Nigeria. The measurement was done by using high-purity germanium (HPGe) detector (Canberra Industries Inc.). The measured activity concentrations for 226Ra (U-series) and 228Ra (Thseries) were used with their ingested dose conversion factors to estimate annual effective doses for the International Commission on Radiological Protection (ICRP) age groups 0 – 1y, 1 – 2y, 2 – 7y, 7 – 12y, 12 – 17y and >17y from consumption of the water samples. Measured activity concentration values varied from 0.57±0.21 to 34.08±5.61 Bq l-1, 2.22±0.97 to 15.50±4.51 Bq l-1 and 0.04±0.01 to 7.04±1.16 Bq l-1 for the radionuclides respectively. Estimated total annual effective doses varied from 4.73 to 49.13, 1.21 to 12.26, 0.86 to 8.54, 1.22 to 11.66, 3.40 to 28.98 and 0.68 to 5.04 mSv y-1 for the age groups respectively. The highest total annual effective dose was found in Tisco sample while the lowest was found in Focar sample. The total annual effective dose in all samples considerably exceeded the average worldwide ingestion exposure dose value of 0.12 mSv y-1 from uranium and thorium series reported by the United Nations Scientific Committee on Effects of Atomic Radiations (UNSCEAR). Therefore the Nigeria populace is advised to consume less of these water samples.

Since 40K is the most important natural radionuclide in the environment, its concentration was measured for all milk and milk powder samples consumed in Tehran-Iran. Milk was chosen, since because it is a reliable indicator of the general population intake of certain radionuclide, and many environmental programs have been applied for its safety. Measurements was done using a CANBERRA gamma spectrometer Model No. S100. Forty one milk and milk powder samples were choosen for the gamma spectroscopy analysis. The average activity concentrations for 40K in the samples were calculated, 31.0 ± 6.1 and 17.1 ± 3.3 Bq.kg-1, in milk and milk powder respectively. These data correspond to the effective dose of 14 μSv.year-1 for adults and in the range of 6.4-15.9 μSv.day-1 for children. Considering the obtained data from liquid milk samples, an almost uniform distribution of 40K can also be obtained. Furthermore, the calculated effective doses were too low to induce important health hazards; however, the data useful for monitoring.

Similar to the thermoluminescence (TL) spectra, the optical parameters variations can also be used in TL crystals for dosimetry purposes. These optical parameters can include absorption, transmission and reflection coefficients. Single crystals of KBr and KCl which have been used in this research were grown from laboratory grade extra pure precursor powders. Crystal growth was performed by using a Czochralski crystal growth apparatus. The grown crystals were irradiated using a 60Co source to doses of 0.5, 1.0 and 1.5 kGy. Reflection spectra were measured by a Shimatzu UVPC 3101 model spectrometer in 5 and 45 incident degree angles. Optical properties of KClxBr1-x mixed crystals surfaces irradiated with gamma radiation were determined. Refraction indices and dielectric coefficients of the crystals in the optical region of 250-750 nm were studied. It was observed that both irradiated and non-irradiated mixed crystals had similar surface behaviour in the order of n ≈ 1.4 and ε ≈ 2.2 in the whole range of 250-750 nm, while colour intensities of irradiated samples were different for various irradiation doses. The reason could have been due to the permanent heat transfer effects with the outer surface layers of the crystal and the rapid relaxation of the excited states in defected surface of the crystal. Reflection spectra along with the crystal surface optical parameters could not be efficient for the dosimetry purposes and additional information such as absorption or transmission data would also be necessary

The increasing evidences show that global depletion of stratospheric ozone layer is caused by pollutant and growing incidence of the skin cancer and cataract is related to the amounts of solar UV radiation reaching the earth ׳s surface. Therefore, the main driving force behind such efforts has been the lack of an appropriate network in scope monitoring of the terrestrial UV radiation. The present work was performed at Khorram Abad province, Lorestan, Iran. Khorram Abad (48°, 21΄ E and 30°, 23΄ N) is approximately 1171m above the mean sea level. UV radiation was measured using a UV-Biometer Model 501, from November 2005 till November 2006. Hourly average UV- index, the effective power and other parameters such as effective UV dose have been "moderate" from April until the end of August 2006 and very low from November till January 2006. However, in some days, the maximum UVI was in the range of "High", especially in May. It was observed that the monthly average hourly UV index values in Khorram Abad were never at the extreme range. Chronic UVB exposure could be the major cause of eye''s and skin disease in months from April to August, during which most people''s activities were performed outdoor in the province of Lorestan.