Summary: The purpose was to estimate the dose perturbation introduced by implanted radiopaque fiducial markers in proton beam therapy (PBT) and to compare cylindrical 1.2 x 3.0 mm and 0.6 x 4.0 mm gold markers to 0.28×20 mm Gold Anchor markers. Radiochromic film measurements of a phantom showed that the Gold Anchor marker causes the least dose perturbations in proton beams. It is concluded that the major advantages of the Gold Anchor marker makes it superior and may be used in future PBT.
