MEASUREMENT OF THE DIRECTIONAL EQUIVALENT DOSE RADIATION IN THE SKIN AND LENS OF THE EYES

The results of calibration of individual dosimeters in Hp(0.07) and Hp(3) units using a 90Sr+90Y radionuclide source are presented. A method for measuring the characteristics of the 90Sr+90Y source is presented, which allows measuring Hp(0.07) and Hp(3) with an error of less than 10%.Measurements were made of the directional dose equivalents rate H '(0.07), H'(3), the ambient dose equivalent rate at the working places of the personnel of Balakovo NPP. Based on the results, an assessment is made of the need for instrumental monitoring of lens exposure in the event of a possible reduction in the dose limit.

Monte Carlo simulation study on the 241Am-Be radionuclide source reference neutron radiation

In order to study the feasibility of using lightweight 241Am-Be radionuclide reference neutron radiation field for the calibration of neutron measurement instruments, this paper reported the Monte Carlo simulation work on free field reference neutron radiation, standard reference neutron radiation regulated by ISO-8529 series standards and minitype reference neutron radiation we designed. The distributions of dose equivalent rates and neutron energy spectrum in different conditions, such as different room types, different room sizes and different shield materials were the main simulation contents for analyzing the characteristics of the three types of reference neutron radiation. According to the simulation results, theoretical supports were provided for the discussion on the minitype reference neutron radiation for calibration purpose.

3D RECONSTRUCTION OF INNER STRUCTURE OF RADIOACTIVE SAMPLES UTILIZING GAMMA TOMOGRAPHY

Unique 3D tomography apparatus was built and successfully tested in Research Centre Rez. The apparatus allows three-dimensional view into the interior of low-dimension radioactive samples with a diameter up to several tens of millimeters with a betterresolution then 1 mm3 and is designed to detect domains with different levels of radioactivity. Structural inhomogeneities such as cavities, cracks or regions with different chemical composition can be detected using this equipment. The SPECT scanner has been successfully tested on several samples composed of a 3-mm radionuclide source located eccentrically within homogeneous steel bushings. To detect fine cracks inside a small sample, an ultrafine scan of the sample was carried out in the course of 24 hours with a 0.5-mm longitudinal and transverse step and 18° angular step. The exact location and orientation of a fine crack artificially formed inside a sample has been detected.

Quality Assurance with Dosimetric Consistency of a Co-60 Teletherapy Unit

<p class="Default">It is essential to know the standard dose rate, output of Co-60 source in the radiation treatment periodically. It is because the over dosage may cause radiation hazards where as under dosage may lead to unsatisfactory treatment of cancer. Present study focused on the radiation standards and dosimetry for the assurance of the quality and verify that the output of the ionizing radiation emitting medical instruments such as Teletherapy Unit (TTU) which should be within ±2% of the stated one. Present study was done as a part of the regularity of quality assurance (QA) of telecobalt radiotherapy unit that includes the dosimetric measurements of Co-60 TTU at Bhaktapur Cancer Hospital (BCH), Bhaktapur per each month from 29 March 2012 to 29 December 2014. The radionuclide source is Co-60 which has been incorporated in TTU, BCH for the purpose of therapeutic treatment of cancer. The Co-60 source decays continuously to Ni-60 (half-life of 5.27 years) with the decrease in its activity and hence the output dose rate. The calculations of actual dose rate of Co-60 TTU were done by the source to surface distance (SSD) technique. It has been concluded that there is a quality assurance management in Co-60 TTU, BCH with the consistency in the average output dose rate obtained by the actual dosimetry values and the expected output values obtained by decay method. The values obtained by actual dosimetry are within ±2% of the expected values so that the deviation of the actual output dose rate from the expected output data lies within the permissible limit as prescribed by International Atomic Energy Agency (IAEA) and International Commission on Radiation Units and Measurement (ICRUM). In conclusion, our study shows a trend towards uniform and better dose delivery from Co-60 TTU, BCH, Nepal</p><p><strong>Journal of Nepal Physical Society</strong><em><br /></em>Volume 4, Issue 1, February 2017, Page: 88-92</p>