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OPTIMIZING THE USE OF LiF:MG,CU,P (GR-200 P) TO MEASURE LOW DOSE IRRADIATION IN NUCLEAR MEDICINE

Azzouzi-Idrissi, M.; Aubert, B.; Chavaudra, J.; Ricard, M.; Tajmouati, J.

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Abstract— We undertook a study in order to determine the optimal conditions under which thermoluminescent powder LiF:Mg,Cu,P (GR-200 P) could be used for applications in nuclear medicine and for dosimetric needs. First, we defined the conditions chiefly related to the readout chain, namely the optimal mass of GR-200 material used for each readout, which is between 15 and 30 mg, and the optimal glow curve readout, which corresponds to heating in two phases: a rise in temperature at the rate of 10°C s−1 up to 150°C followed by a plateau lasting 10 s and then another rise in temperature at the rate of 25°C s−1 up to 260°C followed by a second plateau lasting 6 s. The optimum conditions for using TL material were also studied: using GR-200 P without annealing and performing two successive readouts of the same sample only led to a 0.1% loss in sensitivity per re-use cycle, and the good reproducibility of measurements was preserved with stable and weak residual TL signal. The response of the sample irradiated at three different dose levels with a 60Co gamma photon beam remained constant over 40 d. Sensitivity was preserved to within ±4% between a few tenths of a μGy and 1 Gy. Our observations concur with the results of the literature and show how to optimize the conditions for using the GR-200 thermoluminescent dosimeter to measure low doses with a simple procedure that preserves the sensitivity of material.

** Physics Department, Institut Gustave-Roussy, 39 rue Camille Desmoulins, 94805 Villejuif Cedex, France; Physics Department, Faculty of Science, Meknes, Maroc; Physics Department, Faculty of Sciences, Dhar El Mehraz, Fés, Maroc.

(Manuscript received 21 August 2001;

revised manuscript received 19 August 2002, accepted 20 November 2002)

For correspondence or reprints contact: M. Azzouzi-Idrissi, Service de Physique, Institut Gustave-Roussy, 39 rue Camille Desmoulins, Villejuif Cedex 94805, France, or email at azzouzi@igr.fr.

© 2003 by the Health Physics Society