Polymer gel dosimetry for measuring the dose near thin high-Z materials irradiated with high energy photon beams.

Purpose: To investigate the feasibility of three-dimensional (3D) dose measurements near thin high-Z materials placed in a water-like medium by using a polymer gel dosimeter (PGD) when the medium was irradiated with high energy photon beams.

Methods: PGD is potentially a useful tool for this application because it can record the dose around a small object made of a high-Z material in a continuous 3D medium. In this study, the authors manufactured a methacrylic acid-based normoxic PGD, nMAG.

The local enhancement of radiation dose from photons of MeV energies obtained by introducing materials of high atomic number into the treatment region.

With the advent of therapeutic radiation treatment machines with photon end point energies of several MeV, a new channel is available to transfer the photon energy to biological material, namely, pair production. This process has a photon threshold energy of 1.02 MeV.