Calibration of TLD-100 powder for energies of 60 Co, 137 Cs, 192 Ir and RX of 250, 50 kVp in absorbed dose in water with dosimetric quality control purposes for brachytherapy of high dose rate

To help solve the traceability and quality control dosimetric problems for the users of 192 Ir sources in the Mexican Republic, the Secondary Standard Dosimetric Laboratory at ININ to calibrated a batch of powder TLD- 100 (LiF: Mg,Ti) in terms of absorbed dose to water Dw for the following radiation sources: 60 Co, 137Cs and RX 250 and 50 k Vp. Later on, the calibration is interpolated to obtain the 192 Ir. The calibration radiation field is carried out with the following protocols: For the 60 Co, IAEA TRS 398 protocol employing a secondary standard Farmer chamber PTW N30013, calibrated on Dw at the NRC (Canada). For 137 Cs the AAPM TG 43 protocol is used, in terms of air kerma strength Sk determined by the air kerma Ka, measured with a secondary standard chamber type thimble NE2611 traceable to the NIST (USA). For Rays X 250 and 50 k Vp, the protocol AAPM TG 61 using a tertiary standard Farmer chamber PTW 30001, with traceability to the LCIE (France) on air kerma Ka. The calibration curves are built for the TLD response RTLD vs Dw, they are fitted by means of a least squares fit technique with a second degree polynomial that corrects the supra linearity response. The curves are validated by the lack of fit test, and the Anderson Darling normality test. Later on, the sensibility factors are interpolated for the sources of 192 Ir: Micro Selectron and Vari Source. Two capsules are sent to two hospitals to verify a nominal Dw = 2 Gy, in the first one an underestimate of the Dw is obtained, and in other one an overestimation is presented. Finally, the expanded uncertainty associated to Dw and the Fs are calculated. (Author)