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[en] The RisoeScan software is used for dose measurements with radiochromic films that color visibly. This report consists of two documents for use with the RisoeScan software. The User Manual tells how to use the program and the Toolset for Retrospective Validation describes how to perform a retrospective validation of the software. (au)
[en] It is now recognized that beta radiation can be a significant radiation problem for exposure of the skin. There is thus a need for a portable and rugged active beta dosemeter-spectrometer to carry out immediate measurements of doses and energies of beta particles even in the presence of photon radiation. The main objective of this report is to describe the development of such an instrument. A beta-spectrometer has been developed consisting of three silicon surface barrier detectors with the thickness: 50μm/150μm/7000μm covered by a 2 μm thick titanium window. The spectrometer is capable of measuring electron energies from 50 keV to 3.5 MeV. The spectrometer is characterized by a compact low weight design, achieved by digital signal processing beginning at an early stage in the signal chain. 255 channels are available for each of the three detectors. The spectrometer is controlled by a laptop computer, which also handles all subsequent data analysis. By use of coincidence/anti-coincidence considerations of the absorbed energy in the three detector elements, counts caused by electrons are separated from those originating from photons. The electron energy distribution is multiplied by a set of conversion coefficients to obtain the dose at 0.07 mm tissue. Monte Carlo calculations has been used to derive the conversion coefficients and to investigate the influence of noise and the design of detector assembly on the performance of the spectrometer. This report describes the development of the spectrometer and its mode of operation, followed by a description of the Monte Carlo calculations carried out to obtain the conversion coefficients. Finally is the capability of the telescope spectrometer to measure beta and photon spectra as well as beta dose rates in pure beta and mixed beta/photon radiation fields described. (au)
[en] The features of a newly developed portable beta telescope spectrometer are described. The detector probe uses three silicon detectors with the thickness: 50 μm/150 μm/7000 μm covered by a 2 μm thick titanium window. Rejection of photon contributions from mixed beta/photon exposures is achieved by coincidence requirements between the detector signals. The silicon detectors, together with cooling aggregate, bias supplies, preamplifiers and charge generation for calibration are contained in a handy detector probe. Through a 3- or 10-m cable the detector unit is connected to a compact, portable processing unit including a laptop computer executing control, monitor, histogram and display tasks. The use of digital signal processing at an early stage of the signal chain has facilitated the achievement of a compact, low-weight device. 256 channels are available for each of the three detectors. The LabVIEWTM software distributed by National Instruments was used for all program developments for the spectrometer, comprising also the capability of evaluating the absorbed dose rates from the measured beta spectra. The report describes the capability of the telescope spectrometer to measure beta and photon spectra as well as beta dose rates in mixed beta/photon radiation fields. It also describes the main features of the digital signal-processing electronics
[en] Lecture describes application of the developed at the High Dose Reference Laboratory, Risoe National Laboratory, B3 film dosimeter. Emphasis on calibration, depth dose curves and surface dose profiles is put
[en] Complete text of publication follows. Low energy electron irradiation (80-300 keV) is used increasingly for sterilization or decontamination in connection with isolators for aseptic filling lines in the pharmaceutical industry. It is not defined how validation for this process shall be carried out. A method can be derived from the medical device standard for radiation sterilization, ISO 11137, because the principles described in this standard can be applied to almost any industrial irradiation process. The validations elements are: Process definition, concerning specification of the dose required for the process and the maximum acceptable dose for the product. Installation qualification, concerning acceptance the irradiation facility. Operational qualification, concerning characterization of the facility. Performance qualification, concerning setting up the process. Process control, concerning routine monitoring. The limited penetration of the low energy electrons leads to problems with respect to executing these validation steps. This paper discusses these problems, and shows with examples how they can be solved.
[en] Complete text of publication follows. Riso B3 dosimeters were laminated by standard office lamination technique in order to protect them against environmental humidity influence. The properties of this modified dosimeter were determined and compared with the properties of the un-modified thin-film dosimeter. Irradiations were carried out at a 10 MeV electron accelerator and at a cobalt-60 gamma cell. Optimum post irradiation heating conditions were determined. It was possible to irradiate the dosimeter immersed in water, but the lamination did not provide an effective humidity barrier, and some influence of different humidities during irradiation on the response of the laminated dosimeter was found. The response of the laminated dosimeter was found to be as stable in time after irradiation as the un-modified dosimeter
[en] Published data on the effect of irradiation temperature on the response of alanine dosimeters does not extend to the temperatures that may be experienced in high-dose industrial irradiations, particularly in the case of electron beams. We describe here results of the irradiation of alanine dosimeters at temperatures up to 80 deg. C and doses up to 70 kGy. Data have been obtained for both 60Co and electron beam irradiations and the effect of temperature on the stability of the radiation-induced signal has also been investigated. At temperatures above 50 deg. C the irradiation temperature coefficient begins to deviate significantly from linearity and shows marked dose dependence. The effect of this behaviour under conditions typically experienced in industrial processing is evaluated and recommendations made concerning the use of alanine dosimeters at high doses and temperatures.
[en] Bioresorbable polymers increasingly are the materials of choice for implantable orthopaedic fixation devices. Controlled degradation of these polymers is vital for preservation of mechanical properties during tissue repair and controlled release of incorporated agents such as osteoconductive or anti-microbial additives. The work outlined in this paper investigates the use of low energy electron beam irradiation to surface modify polyhydroxyacid samples incorporating beta tricalcium phosphate (β-TCP). This work uniquely demonstrates that surface modification of bioresorbable polymers through electron beam irradiation allows for the early release of incorporated agents such as bioactive additives. Samples were e-beam irradiated at an energy of 125 keV and doses of either 150 kGy or 500 kGy. Irradiated and non-irradiated samples were degraded in phosphate buffered saline (PBS), to simulate bioresorption, followed by characterisation. The results show that low energy e-beam irradiation enhances surface hydrolytic degradation in comparison to bulk and furthermore allows for earlier release of incorporated calcium via dissolution into the surrounding medium. - Highlights: • Electron beam irradiation of bioresorbable polymer. • Controlled surface degradation. • Controlled release of incorporated agent