Mastella E, Molinelli S, Magro G, Mirandola A, Russo S, Vai A, Mairani A, Choi K, Fiore M R, Fossati P, Cuzzocrea F, Gasbarrini A, Benazzo F, Boriani S, Valvo F, Orecchia R, Ciocca M
CNAO Foundation - National Centre for Oncological Hadron Therapy, I-27100 Pavia, Italy.
CNAO Foundation - National Centre for Oncological Hadron Therapy, I-27100 Pavia, Italy.
Phys Med. 2017 Dec;44:18-25. doi: 10.1016/j.ejmp.2017.11.008. Epub 2017 Nov 14.
The aim of this study was to evaluate the dosimetric impact caused by recently introduced carbon fiber reinforced polyetheretherketone (CF/PEEK) stabilization devices, in comparison with conventional titanium (Ti) implants, for post-operative particle therapy (PT).
As a first step, protons and carbon ions Spread-Out Bragg Peaks (SOBPs) were delivered to CF/PEEK and Ti screws. Transversal dose profiles were acquired with EBT3 films to evaluate beam perturbation. Effects on image quality and reconstruction artifacts were then investigated. CT scans of CF/PEEK and Ti implants were acquired according to our clinical protocol and Hounsfield Unit (HU) mean values were evaluated in three regions of interest. Implants and artifacts were then contoured in the sample CT scans, together with a target volume to simulate a spine tumor. Dose calculation accuracy was assessed by comparing optimized dose distributions with Monte Carlo simulations. In the end, the treatment plans of nine real patients (seven with CF/PEEK and two with Ti stabilization devices) were retrospectively analyzed to evaluate the dosimetric impact potentially occurring if improper management of the spine implant was carried out.
As expected, CF/PEEK screw caused a very slight beam perturbation in comparison with Ti ones, leading to a lower degree of dose degradation in case of contouring and/or set-up uncertainties. Furthermore, CF/PEEK devices did not determine appreciable HU artifacts on CT images thus improving image quality and, as a final result, dose calculation accuracy.
CF/PEEK spinal fixation devices resulted dosimetrically more suitable than commonly-used Ti implants for post-operative PT.
本研究的目的是评估与传统钛（Ti）植入物相比，最近引入的碳纤维增强聚醚醚酮（CF/PEEK）稳定装置对术后粒子治疗（PT）的剂量学影响。
第一步，将质子和碳离子扩展布拉格峰（SOBP）照射到CF/PEEK和Ti螺钉上。使用EBT3薄膜获取横向剂量分布，以评估束流扰动。然后研究对图像质量和重建伪影的影响。根据我们的临床方案获取CF/PEEK和Ti植入物的CT扫描图像，并在三个感兴趣区域评估亨氏单位（HU）平均值。然后在样本CT扫描中勾勒出植入物和伪影，以及一个模拟脊柱肿瘤的靶体积。通过将优化后的剂量分布与蒙特卡罗模拟进行比较，评估剂量计算的准确性。最后，回顾性分析9例真实患者（7例使用CF/PEEK，2例使用Ti稳定装置）的治疗计划，以评估如果脊柱植入物管理不当可能产生的剂量学影响。
正如预期的那样，与Ti螺钉相比，CF/PEEK螺钉引起的束流扰动非常轻微，在轮廓勾画和/或摆位不确定的情况下，剂量降解程度较低。此外，CF/PEEK装置在CT图像上不会产生明显的HU伪影，从而提高了图像质量，最终提高了剂量计算的准确性。
在剂量学方面，CF/PEEK脊柱固定装置比常用的Ti植入物更适合术后PT。
