Comparison between Xe-133 and Tc-99m radio-pharmaceutical for In vivo XRF Analysis of Gold in Kidney Using Monte Carlo Simulation

This study investigate the applicability of X-ray fluorescence to measuring kidney Gold using Tc-99m and Xe-133 radio-pharmaceutical to excite the Gold X-ray with implanting of source in the kidney. Monte Carlo simulation code MCNP4C was used to model phantoms, sources, and collimator. The radioactive implant induced X-ray emission spectra for each implanted sample were measured under the same counting conditions. K-alpha1 and K-alpha2 and minimum detection limit for two types of sources were measured. Skin and kidney dose were calculated for the two sources and then results were compared. According to counts and organs calculated doses, Tc-99m is more efficient than Xe-133. Finally the same simulations were carried out to investigate changes in K XRF response and MDL due to variations in tissue thickness overlying the kidney at the measurement sites. The linearity of the XRF system was also investigated by increasing the gold concentration in the kidney phantom from 0 to 500 μg g kidney tissue.