@misc{oai:repo.qst.go.jp:00082805,
 author = {Taku, Nakaji and Nobuyuki, Kanematsu and Taku, Nakaji and Nobuyuki, Kanematsu},
 month = {Apr},
 note = {Purpose: The Gold Anchor is a kind of fiducial marker for radiotherapy. There is a trend toward the greater use of it for IGRT because of its great visibility, instant stability and minimal invasive. It has cut-outs in its structure, which allow itself into a ball or placed as a line during implantation. Towards to use of it for prostate cancer with carbon ion radiotherapy, the physical dose perturbation of carbon ion beam was assessed when a Gold Anchor was located proximal to Bragg peak.
Methods: The Gold Anchor have two size types, one is φ 0.28 mm × 20 mm and another is φ 0.28 mm × 10 mm, respectively. They were made of 99.5% Au and 0.5% iron. Because of its small and complex structure, dose profiles were calculated by Monte Carlo tool Geant4. A 5 × 5 cm2 field with pristine 350 MeV/u carbon ion beam was irradiated into water, and a Gold Anchor was located around 2 cm proximal to Bragg peak. Several shapes of Gold Anchor, such as curled, zigzag and tadpole shapes, were considered.
Results: The differences of depth dose profiles with and without Gold Anchor along beam axis in water were compared. The maximum peak shift was observed with curled 20 mm length Gold Anchor, it was reached around 1 cm.
Conclusion: This study recommends the sparser shapes for reducing the dose perturbation., 第121回日本医学物理学会学術大会},
 title = {A Monte Carlo study of physical dose perturbation of carbon ion beam in water with Gold Anchor},
 year = {2021}
}