Katsifis Georgio Andrew, McKenzie David R, Suchowerska Natalka
VectorLAB-School of Physics, University of Sydney, Sydney, Australia.
Phys Imaging Radiat Oncol. 2022 May 21;22:123-130. doi: 10.1016/j.phro.2022.04.011. eCollection 2022 Apr.
Cancer patients often require a titanium orthopaedic implant to support or replace lost bone. In radiation treatment, the dose distribution is perturbed causing regions of high and low dose at material interfaces. Since the survival of integrating bone tissue is critical to implant success, the aim of this study was to determine the dose distribution in and around the scaffold, when constructed from titanium or Poly-ether-ether-ketone (PEEK).
The dose distributions in the pores and along boundaries for three implant scaffold designs were calculated using Monte-Carlo methods in Geant4/GATE, with the material taken as titanium or PEEK. The 3D dose distributions were analysed in MATLAB and segmented using image masks, yielding the dose distributions in key regions of interest. To evaluate the effect of the predicted dose perturbations, the cell survival was calculated using the linear-quadratic model for SAOS-2 cells (bone) using experimentally determined radiation response data.
High dose gradients were found along the boundaries of the titanium implants, but not for the corresponding PEEK implants. The dose to the internal cavities of the titanium implants was enhanced by 10-15% near the proximal interface whereas for PEEK, there was no significant dose perturbation. The predicted perturbation caused by the titanium implant was shown to decrease the survival for SAOS-2 cells by 7% which was not found for the PEEK implants.
PEEK was shown to be a more favourable orthopaedic implant material over titanium for cancer patients considering radiation therapy.
癌症患者常需钛制骨科植入物来支撑或替代缺失的骨骼。在放射治疗中，剂量分布会受到干扰，在材料界面处形成高剂量区和低剂量区。由于整合骨组织的存活对植入成功至关重要，本研究的目的是确定由钛或聚醚醚酮（PEEK）构建的支架内部及周围的剂量分布。
使用Geant4/GATE中的蒙特卡罗方法计算三种植入支架设计在孔隙和边界处的剂量分布，材料选用钛或PEEK。在MATLAB中分析三维剂量分布，并使用图像掩码进行分割，得出关键感兴趣区域的剂量分布。为评估预测的剂量扰动的影响，使用线性二次模型，根据实验确定的辐射响应数据计算SAOS-2细胞（骨细胞）的存活情况。
在钛植入物的边界处发现了高剂量梯度，而相应的PEEK植入物则没有。钛植入物近端界面附近的内部腔体剂量增加了10%-15%，而PEEK则没有明显的剂量扰动。结果表明，钛植入物引起的预测扰动使SAOS-2细胞的存活率降低了7%，而PEEK植入物则未出现这种情况。
对于考虑接受放射治疗的癌症患者，PEEK被证明是比钛更有利的骨科植入材料。
