Dosimetric evaluation and beam characterization of pair production enhanced radiotherapy (PPER) with the use of organometallics.

Dosimetric evaluation and beam characterization of pair production enhanced radiotherapy (PPER) with the use of organometallics.
Phys Med Biol. 2019 Mar 15;:
Authors: Tsiamas P, Brown SL, Chetty IJ, Kim JH, Isrow D
Abstract
The current study evaluates dosimetric and spectral effects when platinum (Pt)-based chemotherapeutics and less toxic tungstophosphoric-acid (TPA) organometallics are present during x-ray radiotherapy. We hypothesize that the use of high energy photon beams (i.e. 18 MV) will increase absorbed dose due to increased pair production from high Z elements and thus result in additional tumor cell kill. EGSnrc code was used to examine the contribution of pair production to dose in the presence of the high Z material (TPA, Pt mixtures and tungsten, W) as a function of beam energy. Variables included different concentrations (100μmolar, 1mmolar), depths (5mm, 10cm), thicknesses (5mm, 5cm) and energies (6, 18MV). Overall, for the deeper depth, the 511keV photon fluence increase was up 31% (18MV-1mmolar) while at 6MV it was between 10-11% depending on the concentration. For the shallower depth, 18MV fluence increase was up 14.6% (1mmolar) and 18.6% (1mmolar) for the 6MV. The dose enhancement effect due to pair production was up 25-30% and a total 33-58% depending on the depth. The benefit related to pair production was more for 18MV and under conditions that simulated a realistic clinical setup. While part of the effect cou...

Source: Physics in Medicine and Biology - March 14, 2019 Category: Physics Authors: Tsiamas P, Brown SL, Chetty IJ, Kim JH, Isrow D Tags: Phys Med Biol Source Type: research