Determination of the dose enhancement due to Gadolinium using EBT2 and EBT3 gafchromic films irradiated with 192 Ir, 241 Am, and low-energy X-ray sources

M. SANTIBÁÑEZ; Y. GUILLÉN; M. VALENTE; R. FIGUEROA

Santo Domingo

Simposio; ISSSD 2017 - International Symposium of Solid State Dosimetry; 2017

Univ. Aut. Sto Domingo & Univ. Aut. Méx

This work reports on the relative local dose enhancement produced in phantoms containing target volumes doped Gd irradiating with 192Ir (Gamma MedplusiX) barchytherapy, 241Am isotope and suitably configured X-ray beams [1-3]. EBTs and EBT3 Gafchromic films were immersed into 1.7ml target volumes to mimic tumor filling with 100% ultra pure water (blank sample) and ultra pure water infused with 71.86mg/l of Gd solution (Omniscam®) normally used for magnetic resonance imaging. Tumor phantoms were irradiated using 10Ci 192I source during 1 minute, an annular 0.1Ci 241Am source during 24 hours, and different configurations of X-ray tube during 1 minute and testing also the effects of varying accelerating voltage: 60, 75 And 90 kV and incorporating 2.9 mm Cu filtering for 1 min [3]. Thus, dose enhancement due to excitation of Gd K-edge (50.2 keV) was evaluated in terms of optical density variations. Statistical uncertainties were suitably reduced performing 10 equivalent measurements for each irradiation configuration. Tumor phantoms doped with different Gd concentrations (1.0-40 mg/l) were used to obtain the corresponding calibration curve of local dose enhancement within the tolerance range for in-vivo applications [1]. The obtained results confirmed increments in relative dose enhancement according to Gd concentrations. As expected, higher increase were observed when irradiating with energy close o the Gd K-edge suggesting the potentiality of 241Am as well as electronic brachyherapy to attain local dose enhancement by Gd-infusion.