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    Comparative study by monte carlo simulation of RPL GD-301, TLD-100 and Al2O3:C detectors responses
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    The luminescent dosimeters are widely used in clinical practice, for the monitoring of patient dose in external radiation therapy. Three of the most common dosimeter categories are the thermoluminescence (TLDs), the radiophotoluminescence (RPLs) and the optically stimulated luminescence (OSLs), with similar physical processes on their properties. The aim of the present study is to compare and evaluate the dosimetric properties of three specific luminescent detectors namely: a) RPL glass dosimeter, commercially known as GD-301, b) lithium fluoride TLD-100 (LiF:Mg,Ti) and c) carbon-doped aluminum oxide (Al2O3:C). For this purpose, Monte Carlo simulations were applied, using the MCNP5 code to estimate the responses of these dosimeters in terms of absorbed dose, output factor, the angular and energy dependence. In the present study, we found that the differences between the output factors were less than ± 4.2% for all detector materials RPLGD, TLD and OSLD. The variations in sensitivity for angles up to ± 80 degrees from the central axis of the beam were approximately 0.5%, 0.8% and 1.5% for the TLD-100, GD-301 and Al2O3:C, respectively. The energy dependence of the RPL and OSL dosimeters are stated as less than a 2.2%, and within 5.8% for TLD.
    Optically stimulated luminescence
    Lithium fluoride
    CaF2-based TLD treated at high temperature in air exhibit a high intrinsic thermoluminescence to UV radiations. However, this temperature treatment makes them insensitive to ionising radiations. The increase in thermoluminescence sensitivity is shown to be due to the production of oxide at the TLD material surface, whereas the reduction in gamma ray sensitivity is attributed to a change in the nature of impurity atoms responsible for TL emission.
    Thermoluminescence dosimeter (TLD) CaSO4:Dy was synthesised by coprecipitation. The TLD was observed after radiation exposure to Strontium-90. The thermoluminescence intensity was read using a TLD Reader Harshaw 3500. The thermoluminescent response obtained was 59.29 nC. Then re-annealing was conducted with the temperature varied at 700, 800 and 900 °C. The thermoluminescent intensity obtained at temperatures of 700 °C, 800 °C and 900 °C was 66.12 nC, 169.45 nC, and 552.37 nC respectively. The sensitivity of the TLD increased in response to the re-annealing temperature rise. In addition to observing the thermoluminescence properties, a comparison was made between the TLD obtained from this experiment with an existing TLD in the market. Finally, also the glow-curve characteristics of the TLD were observed.
    TLD-100 (lithium fluoride) thermoluminescence dosimeters are widely employed for the detection of ionizing radiations. This paper shows that these dosimeters may also serve as practical germicidal ultraviolet radiation dosimeters. To measure u.v. radiation, the TLD-100 dosimeters are first exposed to 500,000 R of gamma radiation and then heated to 300°C at a temperature rate of 3°C/sec and annealed at 300°C for 1 min. Subsequent dosage of u.v. radiation may be determined by observation of photostimulated thermoluminescence of the crystal. The presented data indicate that the thermoluminescence response is linear for exposures up to 6000 μJ/cm2 and independent of exposure rate from 0.1 μW/cm2 to above 50 μW/cm2. Optical absorption and sensitivity as a function of temperature of the dosimeters during u.v. exposure are presented.
    Lithium fluoride
    Ultraviolet
    Thermoluminescent Dosimetry