Zhang Miao, Reyhan Meral, Kim Leonard H
Rutgers Cancer Institute of New Jersey.
J Appl Clin Med Phys. 2015 Jan 8;16(1):5090. doi: 10.1120/jacmp.v16i1.5090.
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.
本研究的目的是评估不透射线水凝胶基准标记物引起的质子深度剂量扰动。计算了能量为0.5 - 250 MeV时水凝胶中的电子质子阻止本领，并对放置在通用质子束中不同水模深度的水凝胶与金标记物进行了蒙特卡罗模拟。在所研究的能量范围内，凝胶/水阻止本领比为1.0146至1.0160。在蒙特卡罗模拟中，水凝胶标记物未引起质子百分深度剂量（PDD）曲线的明显扰动。相比之下，金标记物导致剂量降低多达20%，剂量阴影区域长达6.5 cm。与金标记物不同，不透射线水凝胶标记物引起的质子深度剂量扰动可忽略不计。对于具备合适成像方式的机构进行图像引导质子治疗时，可考虑这一因素。
