Dosimetric properties and stability of thermoluminescent foils made from LiF:Mg,Cu,P or CaSO4:Dy during long-term use

• Dosimetric properties of the detectors foils made from LiF:Mg,Cu,P and CaSO4:Dy are present.
• Sensitivity loss of the detectors during usage is observed.
• 2D detector foils should be cleaned thorough the solvent to increase its use time.

A few dosimetric systems based on thermoluminescence [TL] foils were developed in recent years (Nariyama et al. 2006, Radiat. Prot. Dosim. 120, 213–218; Olko et al. 2006 Radiat. Prot. Dosim. 118, 213–218) (Czopyk et al. 2008, Radiat. Meas., 43, 977–980; Kłosowski et al. 2010, Radiat. Meas., 45, 719–721; Kopeć et al. 2013, Radiat.Meas., 56, 380–383). Major application of these systems is mapping of 2D dose distribution for medical treatment plan verification, similarly to photochromic or radiochromic films. The advantage of TL foils compared to other films is their re-usability. In this work we present dosimetric properties as dose linearity and fadding of the foils made from LiF:Mg,Cu,P or CaSO4:Dy phosphors and high temperature polymers. Both types of the foils have good linearity in the range 1–20 Gy for LiF:Mg,Cu,P and 0.1–2 Gy for CaSO4:Dy. Their long term fading does not exceed 3.7% and 9% respectively. We additionally investigated effects of sensitivity loss and emission spectra for both types of the foils. One shortcoming of TL foils is that every heat process may have negative influence on their properties, causing changes of their sensitivity. Register signal of the foils after 15 readouts may be reduced by 16% of the initial. We consider that the main reason of these changes is oxidation of organic contamination on the surface and degradation of a polymer which is one of the components of the foils. Effect of sensitivity decreasing may be slowed down by proper use and cleaning detectors by solvent.