Добірка наукової літератури з теми "TLD BADGE READER"

The clinical efficacy of using ionizing radiation in diagnosis and treatment of diseases has been revolu­tionized, benefitting humankind and, at the same time, imposing deleterious health effects, if not han­dled carefully. Personnel dosimetry has emerged as an essential tool to monitor occupational radiation exposure. The present study intends to reveal and describe the scenario of occupationally exposed staff by assessing an individual’s dose in radiological facilities at different hospitals in Nepal. Thermo luminescent Dosimetry (TLD) has been used for assessing individual doses. Altogether eight hospitals were chosen from different locations of Nepal. TLD badges were worn by the radiation workers on their chest level while working with the radiological equipment for about three to ten months during their routine work. Later the badges were read out in the TLD badge reader system available at Nepal Academy of Science and Technology (NAST) to obtain the exposed doses. CaSO4: Dy was used as TL phosphor. Exposed doses for health personnel during their routine work were founding the range of (2.21 to 16.17) 0.01 mSv per year, which was low compared to the permissible dose limit of 20 mSv per year set up by International Commission on Radiological Protection(ICRP). Although the exposed dose rates in the monitored hospitals are below the recommended dose limits, it should be made as low as possible based on the ALARA principle.

Abstract The objective of this paper is to study the effect of consecutive heating of TL elements of a thermoluminescence dosemeter (TLD) card in hot N2 gas-based TLD badge reader. The effect is studied by theoretical simulations of clamped heating profiles of the discs and resulting TL glow curves. The simulated temperature profile accounts for heat transfer to disc from hot gas as well as radiative and convective heat exchanges between the disc and the surrounding. The glow curves are simulated using 10 component glow peak model for CaSO4:Dy using the simulated temperature profile. The shape of the simulated glow curves and trend in total TL signal of the three discs were observed to match closely with the experimental observations when elevated surrounding temperature was considered for simulation. It is concluded that the readout (heating) of adjacent TLD disc affects the surrounding temperature leading to the changes in temperature profile of the next disc.

In this work, entrance skin dose was used to evaluate patient absorption dose of conventional X-rays using a direct method in some hospitals in Port-Harcourt, Rivers State. The method was based on the guidelines established by the NBIRR protocols. Questionnaires were distributed to two (2) X-ray facilities in Port Harcourt, Rivers State with code names GHC and UPTH in order to obtain information about X-ray machines such as type, model, waveform, filtration, etc., and radiological parameters used during two common diagnostic procedures such as Kilo Peak Voltage (kVp) and Milli Ampere Times Seconds (mAs). The two types of X-ray exams considered were chest (PA) and abdomen (AP). The weight and height of each patient totaling one hundred (100) were measured and two TLD badges were used on each patient to record the patient’s dose while a TLD reader (Harshaw 6600) was used to read the chips and an oven (annealing machine) was also used to anneal the chips. Mean ESD (mGy) was estimated and compared with International Established Reference Values. It was found that the mean ESD (mGy) for chest (PA) was 1.40, which is higher than the standard values of 0.17, 0.40, and 0.30 for USA, IAEA, and NRP, respectively. While the mean ESD (mGy) for the abdomen (AP) was found to be 1.62, which was higher than the standard values of 0.56, 1.02, and 102 for the USA, IAEA, and NRP, respectively. Generally, it was observed that there was a wide variation in patient dose for the two different types of x-ray examinations, which could be attributed to several factors, such as the type of x-ray machine used, radiographic techniques.

The Semi-Automatic TLD Badge Reader TL1010S is a personnel monitoring system, developed & manufactured by Nucleonix Systems is primarily designed to read the TLD card (TL dosimeters) worn by radiation workers. Several Personnel radiation monitoring systems such as photographic films, pocket ionization chambers and thermoluminescent dosimeters (TLD) have been used for the routine evaluation of radiation exposures to personnel. Recently there has been a rapid increase in the use of TLD for personnel monitoring of radiation workers. This Semi-Automatic TLD Badge Reader is primarily designed to read Bhabha Atomic Research Centre (BARC) developed CaSo4 (D4) PTFE disc dosimeter based TLD cards. These cards utilize three dosimeters. The TLD personnel monitoring system essentially consists of two major parts: TLD badge and TLD badge reader. The TLD Badge comprises of a plastic cassette containing a TLD Card made of aluminum with three Teflon TLD discs (13.3mm and 0.8mm thick) that are mechanically clipped on to circular holes (12.0mm) punched on it (52 x 30 x 1mm). Each TLD Card also comprises of a unique punched hole ID which is readout during the acquisition cycle for identifying the wearer of the TLD. The TLD Badge Reader is designed to measure X, Gamma and Beta radiation dose. The metal filter combination (1mm Al + 0.9mm Cu) is provided to reduce the photon energy dependence of the TL discs. The TL badge reader is calibrated such that the TL output of the disc under the metallic filter reads directly the gamma radiation dose. The radiation workers wear the dosimeter & the radiation exposure is estimated on the basis of TL dosimetric reading. Thermoluminescent dosimeters make use of the property of certain materials, which absorb energy when exposed to X, Gamma or Beta radiation. On heating, the absorbed energy is released in the form of visible light. A plot of light intensity emitted against temperature is known as a glow curve.