Single-grain dose-distribution measurements by optically stimulated luminescence using an integrated EMCCD-based system

We report on the feasibility of assessing single-grain dose-distributions by using an EMCCD-based imaging system with complementary analysis software. Automated image-processing was successfully applied to compensate sample motion and for automated grain identification. Following a dose recovery test, 74 % of the grains were recognized successfully, and 44 % exhibited a suitable OSL dose response behavior to interpolate an equivalent dose value and a central dose recovery ratio of 1.038 was obtained.Comment: 30 pages, 6 figures, 2 table

Response of Photon Dosimeters and Survey Instruments to New Operational Quantities Proposed by ICRU RC26

Operational quantities in radiation protection are defined as conservative estimates of the protection quantities, which are generally not accessible to measurement. Radiation protection dosimeters and monitors are calibrated in the operational quantities. An ICRU Report Committee works on a proposal to replace the operational quantities for external radiation ambient dose equivalent and personal dose equivalent by quantities which are defined in close relation to the protection quantities. In this note, the response of dosimeters and survey instruments for photon radiation to these new operational quantities is evaluated.Comment: 14 page

Comparison of antibody titres between intradermal and intramuscular rabies vaccination using inactivated vaccine in cattle in Bhutan : a thesis presented in the partial fulfilment of the requirements for the degree of Master of Veterinary Science at Massey University, Palmerston North, New Zealand

In developing countries, the cost of vaccination limits the use of prophylactic rabies vaccination, especially in cattle. Intradermal vaccination delivers antigen directly to an area with higher number of antigen-presenting cells. Therefore, it can produce equivalent or higher antibody titres than conventional intramuscular vaccination even when a lower dose is given. This study aimed to compare the antibody response in cattle vaccinated intramuscularly with 1mL of inactivated rabies vaccine (Raksharab, Indian Immunologicals) against intradermally vaccinated cattle with 0.2mL of the same vaccine. The study was conducted in Haa province of Bhutan where rabies is not endemic. One hundred cattle from 27 farms were selected for the study. Virus neutralising antibody (VNA) response was measured using the fluorescent antibody virus neutralisation test on the day of vaccination (day 0) and 14, 30, 60 and 90 days later. Overall, 71% of intradermally vaccinated cattle and 89% of the intramuscularly vaccinated cattle produced a protective response (≥0.5IU/mL). This difference was significant (P<0.02) on days 14 and 30 post vaccination with 36 and 56% in the intradermal group having titres ≥0.5 IU/mL respectively compared to the equivalent figures of 78 and 76% in the intramuscular group. The mean VNA titres were lower for intradermal group than intramuscular group (p<0.001) with the mean difference being greater than 0.6 IU/mL. Although low dose intradermal vaccination did produce a detectable antibody response, it was inferior to intramuscular vaccination. Thus, although, intradermal vaccination has the potential to reduce the cost of vaccination by reducing the dose required, this study showed that a single dose of 0.2mL intradermally was inferior to an intramuscular dose of 1mL. Further research evaluating dose and dose regimen is needed before intradermal vaccination using the Raksharab rabies vaccine can be recommended in cattle

Individual monitoring at accelerator centres

The accurate determination of personal dose equivalent requires the proper use of appropriate radiological quantities and units, knowledge of the dose equivalent response of the personal dosemeters used and detailed information on the fluence as well as dose equivalent spectra at the workplaces. This information can then be used to select the appropriate dosemeters, to set up the optimum calibration conditions and to introduce, in case of need, normalisation factors for application in specific radiation fields. High-energy neutrons contribute significantly to the radiation fields around high-energy particle accelerators. Examples for procedures and methods to determine personal dose equivalent at accelerator centres are give

Neutron Spectrum and Dose with Artificial Neural Networks

Artificial neural networks have been applied to unfold the neutron spectra and to calculate the effective dose, the ambient equivalent dose, and the personal dose equivalent for 252Cf, 239PuBe, and 241AmBe neutron sources. The count rates that these neutron sources produce in a Bonner Sphere Spectrometer with a 6LiI (Eu) were utilized as input in both artificial neural networks. Spectra and the ambient dose equivalent were also obtained with BUNKIUT code and the UTA4 response matrix. With both procedures spectra and ambient dose equivalent agrees in less than 10%. The Artificial neural network technology is an alternative procedure to unfold neutron spectra and to perform neutron dosimetry

Luminescence Dating of Sediments from Ancient Irrigation Features, and Associated with Occupation of the Hinterland around Anuradhapura, Sri Lanka

This study supports a new investigation into the development and decline of irrigation and associated human activity in the Anuradhapura Hinterland, Sri Lanka (section 2). Optically stimulated luminescence (OSL) age determinations have been made for a variety of sediments from bund and tank systems, irrigation channels, palaeosols and ceramic scatter horizons in the Anuradhapura hinterland (section 3). The geomorphological and archaeological significance of the age determinations has been reviewed in the light of the luminescence results and the samples’ depositional contexts, to constrain the deposition/formation dates of the sampled sediments integrate the OSL results with independent archaeological and historical expectations (section 6). A total of 26 age determinations were made (section 5.3). Dose rate determinations were made using thick source beta counting, high-resolution gamma spectrometry, field gamma spectrometry, measured water contents and calculated cosmic dose rates (sections 4.2.1, 5.1). Equivalent dose determinations were made (sections 4.2.2, 5.2) using the OSL signals from sand sized grains of quartz separated from each sample. Dose rates ranged from 1.1 to 5.0 mGy/a, equivalent dose values ranged from 0.29 to 33 Gy. Age estimates for these samples ranged from 0.14 to 13 ka, the average being 2.9 ka ± 3.1 (section 5.3). Uncertainties on the age estimates were commonly 7% at one standard error. The OSL age estimates from the largest bund and some ceramic scatter sites were greater than 2000 BC. This is older than expected on archaeological grounds and further investigation of these sites may be warranted. The OSL results from the other samples in the present study date bund construction during the initial urbanisation of Anuradhapura c. 400BC, coincident with the major Nachchaduwa bund construction c. 300AD, and in the Late Iron Age / Early Mediaeval period c. 600AD. They date abandonment of one irrigation channel to the 8th Century AD and its infill up to the late 10th Century when Anuradhapura was finally sacked. A further 8 age estimates, from silts and colluvium, relate to the collapse of infrastructure in the Anuradhapura hinterland during the 10th century and continued landscape response during the 11th century, followed by the lead-in to restoration of the irrigation system during the colonial era

Calibration and testing of a TLD dosemeter for area monitoring

The response of a TLD-600/TLD-700 area dosemeter has been characterized in neutron fields around the 590 MeV cyclotron ring at the Paul Scherrer Institute (PSI). The dosemeter is based on a cylindrical paraffin moderator with three of each type of TLD chip at the centre, and is intended to use for area monitoring around accelerator facilities. The dosemeter is calibrated in terms of ambient dose equivalent using a non-moderated 252Cf neutron source. The ambient dose equivalent response has been tested in five locations where the neutron fields and dose rates have been well characterized by Bonner sphere spectrometer and active neutron monitor measurements. The different spectrum shapes and dose rates in the five locations permit the comparison of the behavior of the active and passive dosemeters in these neutron field

Evaluation of 2 possible further developments of the UK in-flight radiation warning meter for SSTS

A mass reduction of the moderator and the response to the nucleon flux, responsible for the tissue-star component of the total-dose equivalent rate using a high atomic number material, are discussed. Radiation situations at SST cruising altitudes (approximately 20 km) due to solar proton flares were simulated in the stratosphere and on the ground. Actual stratospheric situations due to galactic cosmic radiation with a limited range of quality factor values (2-4) were encountered during slow ascents by balloons to 36 km. Synthetic situations obtained from high and low energy acclerator radiations were used to obtain radiation distributions having a larger range of quality factor values (11/2-9) than experienced in the stratosphere. The measurements made in these simulations related to the directly ionizing, neutron and tissue-star components of dose-equivalent rate. Due to the restricted range of neutron spectra encountered in the stratosphere, a significant mass reduction of the moderator by 4 kg was made, with the moderator clad with cadmium or some other slow neutron absorber