Impact of variations in physical parameters on glow curves for planchet heating of TL dosimeters

Abstract

This study consists of a theoretical analysis of the directional planchet heating of Thermoluminescent Dosimeters (TLD) with an emphasis on influence of radiation field type, TL material properties, and heating scheme parameters on the resulting glow curve. Computer software is developed to simulate the thermal conduction and TL production processes in a planchet-heated TLD chip. The results of the simulation are benchmarked to previous experimental findings for a LiF TLD and excellent agreement is obtained. The system thermophysical parameters and initial depth-dose distribution in the TLD are varied and the position of the main glow peak and integral glow are examined. A demonstration is given of how a set of thermophysical parameters may provide information about the depth-dose distribution in the TLD and how variation in the values of these parameters may limit the reconstruction of this depth-dose information .

Kinetic parameters of some tissue equivalent thermoluminescence materials

“…During TL readout in readers using contact heating, there is a TLA between the heating element and the thermoluminescent sample. The non-ideal thermal contact between the heater and the sample, as well as the thermal gradient (TG) across the sample itself, plays a critical role in trapping parameter evaluation, as it has been well established [10][11][12][13][14][15]. A simple method, recently proposed [16], allows a correction for the TLA and it is based on TL measurements only.…”

The optically stimulated luminescence (OSL) properties of LiF:Mg,TI, Li2B4O7:CU, CaSO4:Tm, and CaF2:MN thermoluminescent (TL) materials

“…In the case of Li 2 B 4 O 7 :Cu and CaSO 4 :Tm, in spite of their use in commercially-available dosemeters, and the presence of substantial published TL data (Takenaga et al, 1983;Driscoll et al, 1983;Samei et al, 1994;Sunta et al, 1994;Kearfott et al, 1995Kearfott et al, , 2000Simpkins and Kearfott, 1997;Lee et al, 2008;Nambi et al, 1974;Lewandowski et al, 1996;Lakshmanan et al, 2005;Yamashita et al, 1971;Harvey et al, 2010Harvey et al, , 2011Harvey and Kearfott, 2011a, 2011b, 2012, little published research exists documenting their OSL properties. However, CaSO 4 :Tm has been shown to produce a signal using photo-transferred thermoluminescence techniques (PTTL) techniques (Lakshmanan et al, 2005).…”

“…OSL has become an accepted personnel dosimetry method during the past two decades, primarily because of the success of a commercially-available dosemeter based upon anion-defective, carbondoped aluminum oxide, or α-Al 2 O 3 :C (Luxel s , Landauer, Inc., 2 Science Road, Glenwood, Illinois, 60425-1586, USA, custserv@-landauer.com, þ1 800 323 8830, www.landauer.com). Thermoluminescent dosemeters (TLDs) long dominated personnel dosimetry, and they are well characterized (Samei et al, 1994;Kearfott et al, 1995Kearfott et al, , 2000Kearfott et al, , 2015Simpkins and Kearfott, 1997;Harvey et al, 2011) and have tissue-equivalent forms essential for meaningful application to medical applications (Kearfott and Grupen-Shemansky, 1990;Kearfott et al, 1990). Unfortunately, TLDs are subject to signal fading post-irradiation (Harvey et al, 2010(Harvey et al, , 2011, which is particularly significant at high ambient temperatures (Harvey and Kearfott, 2012).…”

Reproducibility of glow peak fading characteristics of thermoluminescent dosimeters

“…TLD-to-TLD calibration factor variability may be quite large, resulting in large errors in the performance of mixed field dosimetry algorithms (Kearfott et al, 1990(Kearfott et al, , 1995. Substantial variability in glow curve parameters may also arise as a result of variability in heating processes, as demonstrated for a detailed analysis of planchet heating (Samei et al, 1994). The goal of this study was to determine if fading properties of individual TLD elements need to be characterized individually, or if empirical fading functions can be used for a larger group.…”