title: Depth dose perturbation by a hydrogel fiducial marker in a proton beam.
abstract: The purpose of this study was to evaluate proton depth dose perturbation caused by a radio-opaque hydrogel fiducial marker. Electronic proton stopping powers in the hydrogel were calculated for energies 0.5-250 MeV, and Monte Carlo simulations were generated of hydrogel vs. gold markers placed at various water phantom depths in a generic proton beam. Across the studied energy range, the gel/water stopping power ratio was 1.0146 to 1.0160. In the Monte Carlo simulation, the hydrogel marker caused no discernible perturbation of the proton percent depth-dose (PDD) curve. In contrast, the gold marker caused dose reductions of as much as 20% and dose shadowing regions as long as 6.5 cm. In contrast to gold markers, the radio-opaque hydrogel marker causes negligible proton depth dose perturbation. This factor may be taken into consideration for image-guided proton therapy at facilities with suitable imaging modalities.
authors: Rutgers Cancer Institute of New Jersey. 123@123.com.
authors: Miao
authors: M
authors: Zhang
authors: Meral
authors: M
authors: Reyhan
authors: Leonard H
authors: LH
authors: Kim
mesh_terms: D003198:Computer Simulation; D057918:Fiducial Markers; D006046:Gold / Q000737:chemistry; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D009010:Monte Carlo Method; D009369:Neoplasms / Q000532:radiotherapy*; D019047:Phantoms, Imaging; D011522:Protons; D011879:Radiotherapy Dosage; D061089:Radiotherapy, Image-Guided; D014867:Water / Q000737:chemistry
chemical_list: D011522:Protons; D014867:Water; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D006046:Gold