Radiation protection dosimetry最新文献

Natural radioactivity measurement, radiation monitoring of the region, dose assessment and interpretation of radiological-related parameters are crucial aspects from the public awareness and environmental safety point of view. The ionising radiations (gamma-rays) emitted from radionuclides such as 226Ra, 232Th and 40K present in environmental materials contributes significantly to the external radiation dose received by the public. High-efficiency gamma spectrometry based on a 4″ × 4″ NaI (Tl) detector was employed for estimating activity concentrations of the gamma-emitting radioelements. The spectra from the detector were recorded using a PC-based 1k multichannel analyser system (WinTMCA 32). Each sample spectrum was acquired for a counting period of 60 000 s (16.67 hr). Assuming the daughter products of 226Ra and 232Th in equilibrium, the activity concentration of these radionuclides were estimated by using the prominent gamma photo peaks of daughter products. Using the same technique, dose-related radiological parameters were calculated for all the samples. The activity concentrations of the radionuclides and the dose-related parameters for the samples were found to be comparable with the global literature values. The data generated from our study will contribute to the baseline radiological data of the region.

Medicinal plants of the Moraceae family, such as Ficus racemosa linn, have been traditionally used in the North Karnataka region for treating various ailments. This study aims to analyze the elemental composition and nano-micro structural morphology of selected species of Moraceae family medicinal plants, focusing on their potential therapeutic applications. Samples were collected from the Dharwad and Gadag districts in North Karnataka. The surface morphology at nano and micro levels was examined using a field emission scanning electron microscope, while the elemental composition was analyzed through energy-dispersive X-ray spectroscopy. The study emphasizes the detailed examination of the specific weight percent of elemental concentration and the morphological features observed. The analysis revealed fine, irregularly shaped particles with an average diameter of 20 to 50 μm on the plant surface. Elemental composition analysis showed the presence of Mg, Al, Si, Cl, K, Ca, Mn, Fe, Cu, and Zn within WHO-recommended limits.

Prof. P. Venkataramaiah (P.V.), born on July 08, 1937, has been active in research for the past five decades in several areas of Nuclear Physics and Environmental Sciences. He has visited several Universities and research institutes in various countries such as Japan, Hong Kong, Singapore, France, the UK, Canada and the USA. Apart from research work he has also held many administrative positions and made revolutionary improvements in the education sector of India. Even after retirement, Prof. P.V. has actively involved himself inspiring and encouraging the younger generation at secondary level. As an honour for his untiring dedication even in his eighties, his colleagues and students have written articles about his contributions to research and education. This include contributions from Prof. P.V. himself along with Prof. K.S. Mallesh, Prof. N. Nagaiah, Prof. S.A. Bari, Prof. M. Venkateshwaralu, Shri. M. Vasudev, Dr K. Nagaraja, Mrs. Sreemathi Hariprasad and Dr N. Bhagyalakshmi.

Finger photo pulse plethysmography is a simple, inexpensive and non-invasive method for measurement of arterial stiffness. The objective is to assess the correlation of arterial stiffness in low back pain subjects with lumbar disc degeneration. Thirty-four back pain patients of both sexes in age group of 30-65 were included. Anthropometric measures like height, body weight, body mass index (BMI) were included. Stiffness index (SI) and reflection index (RI) were measured from the digital volume pulse waveform. There was a negative correlation between SI/RI and no correlation between SI and RI with BMI in both sexes. A significant correlation found between weight and BMI in both sexes. Arterial stiffness may not have any influence on disc degeneration. BMI showed some influence on disc degeneration and back pain.

There has been an increase in the use of high energy photon beam for container scanners in many countries for multi purposes such as detecting high atomic number materials which might be nuclear materials, drugs, high explosive materials and other contrabands etc. High energy photon beams generally 6 and 9 MV can be used for scanning such materials. However, it is important to ensure that radiation level beyond the container scanner installation is within the permissible dose limit specified by the national competent authority for the protection of public and radiation workers. In this paper, challenges in the biological shielding during the installation of high energy X-ray system for scanning vehicles containing suspected materials are discussed. The purpose of the present study is to develop a methodology for shielding design and evaluation for container scanner installations. The basic concept pertaining to shielding evaluation of radiotherapy installations provided in National Council on Radiation Protection and Measurements (NCRP)/International Atomic Energy Agency (IAEA) reports are referred, and appropriately used to calculate optimized shielding thicknesses requirements for container scanner installation. Workload is estimated based on number of containers scanned, machine ON time and dose rate at 1 m. The shielding evaluation includes use of beam stopper in the primary beam, scattering by heterogeneous metallic scrap materials or any other suspected materials contained in the vehicle and their impact on the thickness of shielding walls. A model lay out plan to be used for installation of container scanner is developed. A methodology for shielding evaluation for various protective walls and ceiling of this model is also discussed. The study provides basic requirement for designing a structural room for installing 9MV container scanner from radiological safety view point.

The present study is carried out in 42 sampling sites for the measurement of background gamma dose rate in six tehsils of the Bageshwar district that comes under the Kumaun Himalaya, Uttarakhand. The annual effective dose in the pre-monsoon and post-monsoon seasons was estimated from the measured values of the Gamma dose rate. It is found that the minimum and maximum values ranged between 0.01-0.39 mSv per y (Arithmetic Mean = 0.19 mSv per y) in the pre-monsoon and 0.11-0.42 mSv per y (Arithmetic Mean = 0.20 mSv per y) in the post-monsoon season of the year. The finding of the present study shows that the annual effective dose equivalent is higher than the worldwide average value recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation.

Groundwater is in direct contact with the soil and rocks that dissolve many compounds and minerals including uranium and its daughter products. 210Po is one of the decay products of 238U series that cause internal radiation dose in humans when consumed in the form of water and food, including sea food. Therefore, activities of 210Po have been studied in ground and surface water, and in food samples that are commonly used in Chamarajanagar region of Karnataka, India. The average 210Po concentration in bore well water samples and surface water samples are 3.21 and 1.85 mBq L-1, respectively. In raw rice and wheat, the average values of 210Po are 96 and 41 mBq kg-1, respectively. In millets and pulses, the average activity of 210Po is 157 and 79 mBq kg-1, respectively. Among food items, the highest activity of 1.3 kBq kg-1 is observed in marine crabs and the lowest activity of 2.6 mBq kg-1 is found in milk samples. The average ingestion dose due to 210Po in ground and surface water are 2.8 and 1.62 μSv y-1, respectively. The ingestion dose due to various food samples to the population is also calculated. Total ingestion dose due to 210Po to pure vegetarian population and general population are 38.09 and 590.80 μSv y-1, respectively. The concentration of 210Po in water samples and food samples of this region are in a comparable range with the world and Indian average values and lies well below the recommended guideline level.

The noble radioactive gas radon and its isotope thoron dominate terrestrial radiation in the indoor environment. These gases eventually disintegrate generating radioactive ions that readily adhere to aerosol particles. This study was conducted in a tectonically active location with significant radon concentrations. The obtained average values of radon mass exhalation and thoron surface exhalation rate from this study are higher than the global average values of 56 mBq kg-1 h-1 and 1000 mBq m-2 s-1, respectively. As the exhalation rates are higher, naturally the average radon and thoron concentrations are also greater than the worldwide average values of 40 and 10 Bq m-3, respectively. No significant correlation was observed between 222Rn and 220Rn exhalation rate and indoor 222Rn/220Rn concentration. The exposure dose due to 222Rn, 220Rn and their progenies shows no significant health risk.

The 60Co gamma radiation effects on the DC electrical characteristics of silicon NPN transistor were studied in the dose range of 100 krad to 6 Mrad at room temperature (300 K) and cryogenic temperature (77 K). The measurements were carried out at both 300 and 77 K temperature. The electrical characteristics such as Gummel characteristics, excess base current (ΔIB), current gain (hFE), transconductance (gm) and output characteristics were studied in situ as a function of total dose. The results show that there is a considerable degradation in the electrical parameters of the device irradiated both at 300 and 77 K as a consequence of increase in excess base current (ΔIB) because of the formation of generation and recombination centers in the emitter-base spacer oxide (SiO2). At cryogenic temperature irradiation, the degradation in electrical characteristics is less because of the physical phenomena such as carrier freezeout effect, decreased recombination rate, reduced charge yield, decreased electron mobility, etc.

In the present work, the efficacy of waste glass as fillers in concrete for gamma-ray shielding has been studied. Glass fillers of 0, 15, 30, 45, and 60% concentrations have been incorporated into the concrete mixture. The attenuation measurements were performed using gamma spectrometer with NaI(Tl) detector at 511, 662, 1173, and 1332 keV gamma energies. Gamma-ray shielding parameters, such as the mass attenuation coefficient (μ/ρ), are determined for all filler concentrations. The mass attenuation coefficient of the prepared samples was found to be varied from 0.081 to 0.088, 0.071 to 0.088, 0.05 to 0.058, and 0.05 to 0.055 (cm2 per g) for 511, 662, 1173, and 1332 keV gamma energies, respectively. It was observed that experimentally determined (μ/ρ) values were in very good agreement with theoretical values calculated from EDAX data. Furthermore, it was observed that (μ/ρ) showed an increasing trend with an increase in filler concentration, which is attributed to the increase in the shielding property of the material. Therefore, the glass-concrete composite can be accustomed to reduce the intensity of gamma radiation.