International Journal of Particle Therapy
Purpose: To quantitatively investigate the dose perturbations difference between gold and platinum VISICOILTM fiducial markers in proton beam therapy Method: Gold and platinum VISICOILTM fiducial markers with two different dimensions were tested, including 0.35 & 0.5mm in diameter and 5mm in length. Total four kinds of markers. Gafchromic EBT2 was used to measure dose perturbations along the beam path in a ‘‘sandwich’’ setup (Figure 1). Dose perturbation was reported in each depth (0.3mm, 1.65mm, 3.00mm, 5.40mm, 7.80mm, 10.20mm, 12.60mm, 18.15mm). Relative proton stopping power relative to water were calculated through National Institute of Standards and Technology database and SRIM (version -2013) in the therapeutic energy range (70- 220MeV). Result: There is no statistical difference between gold and platinum VISICOILTM fiducial markers in all the depth with diameter 0.35mm (p¼0.125), and 0.5mm (p¼0.130). The maximum point dose perturbation between Au and Pt marker with the same dimension are similar (0.35mm diameter at 7.8mm WET: 2.85%62.31% Au vs. 2.70%62.60% Pt; 0.5mm diameter at 5.4mm WET: 8.81%62.60% Au vs. 8.81%62.57% Pt.) (Figure 2). Bilateral treatment field arrangement could further reduce the dose perturbation by half. The relative stopping power ratio to water was calculated based on gold and platinum materials. The result showed there are about 3.5% difference between the two materials. Conclusion: The study indicated that the Au and Pt VISICOILTM fiducial markers have very similar physics properties and could interchangeable in the proton beam therapy as long as the clinical users correct the RSP during the planning process.
Ding X, Liu G, Zheng W, Vada J, Li X, Zhao L, et al. A Quantitative dose pertubation comparison study between gold an platinum VISICOIL fiducial markers in proton beam therapy. Int J Part Ther. 2022 Spring;8(4):98.