Estimation and correction of produced light from prompt gamma photons on luminescence imaging of water for proton therapy dosimetry.

Estimation and correction of produced light from prompt gamma photons on luminescence imaging of water for proton therapy dosimetry. Phys Med Biol. 2018 Jan 19;: Authors: Yabe T, Komori M, Toshito T, Yamaguchi M, Kawachi N, Yamamoto S Abstract Although the luminescence images of water during proton-beam irradiation using a cooled charge-coupled device (CCD) camera showed almost the same ranges of proton beams as those measured by an ionization chamber, the depth profiles showed lower Bragg peak intensities than those measured by an ionization chamber. In addition, a broad optical baseline signal was observed in depths that exceed the depth of Bragg peak. We hypothesize that this broad baseline signal originates from interaction of proton-induced prompt gamma photons with water. These prompt gamma photons interact with water to form high-energy Compton electrons, which may cause luminescence or Cherenkov emission from depths exceeding the location of Bragg peak. To clarify this idea, we measured the luminescence images of water during the irradiations of protons in water with minimized parallax errors, and also simulated the produced light by the interactions of prompt gamma photons with water. We corrected the measured depth profiles of the luminescence images by subtracting the simulated distributions of the produced light by the interactions of prompt gamma photons in water. Corrections were also conducted using the estimated depth...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research