Mansi Ahmed, Rezaii Elhaum G, Wang Shuo, Zhang Chi, Katzir Miki
Departments of1Neurological Surgery and.
2Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska.
J Neurosurg Spine. 2025 Feb 7;42(5):615-623. doi: 10.3171/2024.10.SPINE24584. Print 2025 May 1.
Carbon fiber instrumentation has gained popularity in spine oncology for its radiographic advantage of reduced artifact on imaging. With its increased use in patients who undergo radiation therapy, the dosimetric accuracy of postoperative radiation with carbon fiber constructs compared to classic titanium instrumentation becomes an important question. The purpose of this study was to compare the dosimetric accuracy of postoperative radiation in carbon fiber-instrumented versus titanium-instrumented cadaveric cervical spines after corpectomy.
Two cadaveric specimens underwent two-level corpectomy using either titanium or carbon fiber instrumentation. Dosimeter chips were placed circumferentially around the constructs to calculate the dose of radiation to surrounding areas. The cadavers underwent one round of radiation with their respective constructs, and the dose of radiation was calculated and compared to the measured dose in each chip. After the first round of radiation, the instrumentation was switched between cadavers and the radiation therapy was repeated. The difference between the calculated and measured dose in carbon fiber versus that in titanium instrumentation in each cadaveric model was subsequently compared.
There was a significant difference in the dosimetry calculated at the area of the spinal cord dorsal to the corpectomy cage, with 68% less variability between the calculated and measured dose in the carbon fiber construct compared to that of the titanium construct. The mean variation of the measured dose at the spinal cord was 7.73% in titanium versus 4.6% in carbon fiber (p = 0.024, 1-tail; p = 0.048, 2-tail). There was also 30% less variability between the measured and calculated dose in the carbon fiber construct at the dosimeter chips lateral to the spinal cord, with a mean variation in the carbon fiber-instrumented cadaver of 4.94% compared to 6.45% with titanium (p = 0.01, 1-tail; p = 0.02, 2-tail). When all the dosimeters were combined without the control group, there was a statistically significant 14.5% difference in the mean variation of the calculated versus measured doses between the carbon fiber-instrumented cadavers versus titanium-instrumented cadavers (4.8% vs 5.5%, respectively; p = 0.015, 1-tail; p = 0.03, 2-tail).
There is less variation in the calculated versus measured doses of radiation therapy in carbon fiber instrumentation compared to titanium instrumentation. This suggests improved radiation therapy delivering accuracy and complication avoidance in carbon fiber-instrumented spines.
碳纤维内固定因其在影像学上减少伪影的优势，在脊柱肿瘤学中越来越受欢迎。随着其在接受放射治疗患者中的使用增加，与传统钛合金内固定相比，碳纤维内固定术后放疗的剂量测定准确性成为一个重要问题。本研究的目的是比较椎体次全切除术后碳纤维内固定与钛合金内固定的尸体颈椎放疗的剂量测定准确性。
两个尸体标本接受了两级椎体次全切除术，分别使用钛合金或碳纤维内固定。剂量计芯片围绕内固定物圆周放置，以计算周围区域的辐射剂量。尸体使用各自的内固定物接受一轮放疗，并计算辐射剂量，并与每个芯片中的测量剂量进行比较。第一轮放疗后，在尸体之间交换内固定物并重复放疗。随后比较每个尸体模型中碳纤维与钛合金内固定物计算剂量与测量剂量之间的差异。
在椎体次全切除椎间融合器后方脊髓区域计算的剂量测定存在显著差异，与钛合金内固定物相比，碳纤维内固定物计算剂量与测量剂量之间的变异性降低了68%。脊髓处测量剂量的平均变异在钛合金中为7.73%，在碳纤维中为4.6%（单尾p = 0.024；双尾p = 0.048）。在脊髓外侧的剂量计芯片处，碳纤维内固定物测量剂量与计算剂量之间的变异性也降低了30%，碳纤维内固定尸体的平均变异为4.94%，而钛合金为6.45%（单尾p = 0.01；双尾p = 0.02）。当所有剂量计组合且无对照组时，碳纤维内固定尸体与钛合金内固定尸体计算剂量与测量剂量的平均变异之间存在统计学上显著的14.5%差异（分别为4.8%和5.5%；单尾p = 0.015；双尾p = 0.03）。
与钛合金内固定相比，碳纤维内固定放疗计算剂量与测量剂量的变异性更小。这表明碳纤维内固定脊柱的放疗给药准确性提高且并发症减少。
