Dosimetric properties of TL foils based on LiF:Mg,Cu,P (MCP-N) phosphors for clinical applications K. Kisielewicz a, * , J. S ´ wiebocka b , q. Czopyk c , M. K1osowski c , J. Lesiak a , E. Byrski a , D. Kabat a , M. Wawrzak a , A. S ´ ladowska a , A. Dziecichowicz a , P. Olko c , M.P.R. Waligo ´ rski a, c a Centre of Oncology, Maria Sklodowska – Curie Memorial Institute, Krako ´w Branch, ul. Garncarska 11, 31-115 Krako ´w, Poland b Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Krako ´w, Poland c Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342 Krako ´w, Poland article info Article history: Received 15 August 2009 Received in revised form 8 November 2009 Accepted 2 December 2009 Keywords: 2-D TL dosimetry TL foils QA in radiotherapy Stereotactic radiosurgery IMRT abstract Two prototype 2-D thermoluminescence (TL) readers: a laboratory reader equipped with a sensitive 640  480 pixel CCD camera and a heater planchet of 7.2 cm diameter, and a clinical reader with a 14-bit CCD PCO camera of 1024  1024 pixel resolution and a 20  20 cm 2 heater, were developed at the Institute of Nuclear Physics (IFJ PAN) in Krako ´ w, Poland. These readers are able to produce digital images of 2-D dose distributions from exposed TL foils of sizes up to 20  20 cm 2 , composed of ETFE (ethylene tetrafluoroethylene) and LiF:Mg,Cu,P (MCP-N) powder, also developed and manufactured at IFJ PAN in Krakow. The clinical 2-D TL system is being developed specifically for clinical measurements of 2-D dose distributions in external photon or electron radiotherapy beams and around small sources applied in brachytherapy. We report results of our tests of basic dosimetric properties (repeatability, linearity vs. absorbed dose, signal-to-noise ratio and energy dependence) of the 2-D TL foil-reader systems using MCP-N based foils and megavolt X-ray radiotherapy beams, over a range of dose relevant to clinical radiotherapy. We conclude that the clinical 2-D TL system may be useful in clinical dosimetry of external radiotherapy beams and photon-emitting brachytherapy sources. As examples of such applications, we show verifi- cation of computer therapy planning system calculations of fields produced by multileaf collimators or stereotactic radiosurgery systems, performed as part of the quality assurance procedure in radiotherapy. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction A two-dimensional (2-D) thermoluminescence (TL) dosimetry system, consisting of 2-D TL (LiF:Mg,Cu,P- or CaSo4:Dy-based) foils and planar 2-D TL readers: a prototype laboratory reader and a larger clinical reader, able to handle 2-D TL foils of sizes up to 20  20 cm 2 , were developed at the Institute of Nuclear Physics in 2006 (for further details, see Olko et al., 2008). Prior to clinical applications, the system, consisting of ‘‘small’’ (4  4 cm 2 ) or ‘‘large’’ (20  20 cm 2 ) foils and their respective readers with their digital imaging software, were intensively tested in laboratory and clinical conditions, using megavolt X-ray and proton radiotherapy beams (see Olko et al., 2008 and references therein). We report evaluations of some basic, clinically relevant, dosi- metric properties of the clinical 2-D TL system and demonstrate examples of potential application of this system in clinical dosimetry. 2. Materials and methods ETFE (tetrafluoroethylene and ethylene copolymer) TL foils of sizes up to 20  20 cm 2 containing LiF:Mg,Cu,P (MCP-N) powder were developed at the Institute of Nuclear Physics (IFJ PAN) in Krako ´w. The prototype laboratory-type 2-D TL reader equipped with a sensitive 640  480 pixel CCD camera and a heater planchet of 72 mm diameter able to read 4  4 cm 2 ETFE foils, and a ‘‘clinical’’ 2-D TL reader with a heating plate of 20  20 cm 2 and a more sensitive 1024  1024 pixel, 16 bit CCD camera, were also developed at IFJ PAN (Kabat, 2008; Kabat and Nahajowski, 2008; Kisielewicz et al., 2008; Olko et al., 2008). FlatView, a software package, in-house developed at IFJ PAN, is used for CCD reader image processing in the laboratory and clinical 2-D TL readers. This software system enables browsing, operating on, and administration of digital images supplied by the CCD * Corresponding author. Tel.: þ48 502601653. E-mail address: z5kisiel@cyf-kr.edu.pl (K. Kisielewicz). Contents lists available at ScienceDirect Radiation Measurements journal homepage: www.elsevier.com/locate/radmeas 1350-4487/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.radmeas.2009.12.002 Radiation Measurements 45 (2010) 716–718