School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth, UK.
Departement of Oncology and Metabolism and Insigneo Institute for in Silico Medicine, University of Sheffield, Sheffield, UK.
J Mech Behav Biomed Mater. 2023 Feb;138:105636. doi: 10.1016/j.jmbbm.2022.105636. Epub 2022 Dec 20.
Exposure to X-ray radiation for an extended amount of time can cause damage to the bone tissue and therefore affect its mechanical properties. Specifically, high-resolution X-ray Computed Tomography (XCT), in both synchrotron and lab-based systems, has been employed extensively for evaluating bone micro-to-nano architecture. However, to date, it is still unclear how long exposures to X-ray radiation affect the mechanical properties of trabecular bone, particularly in relation to lab-XCT systems. Indentation has been widely used to identify local mechanical properties such as hardness and elastic modulus of bone and other biological tissues. The purpose of this study is therefore, to use indentation and XCT-based investigative tools such as digital volume correlation (DVC) to assess the microdamage induced by long exposure of trabecular bone tissue to X-ray radiation and how this affects its local mechanical properties. Trabecular bone specimens were indented before and after X-ray exposures of 33 and 66 h, where variation of elastic modulus was evaluated at every stage. The resulting elastic modulus was decreased, and micro-cracks appeared in the specimens after the first long X-ray exposure and crack formation increased after the second exposure. High strain concentration around the damaged tissue exceeding 1% was also observed from DVC analysis. The outcomes of this study show the importance of designing appropriate XCT-based experiments in lab systems to avoid degradation of the bone tissue mechanical properties due to radiation and these results will help to inform future studies that require long X-ray exposure for in situ experiments or generation of reliable subject-specific computational models.
长时间暴露于 X 射线辐射会对骨组织造成损伤，从而影响其机械性能。具体来说，高分辨率 X 射线计算机断层扫描（XCT），无论是在同步加速器还是实验室系统中，都被广泛用于评估骨的微观到纳米结构。然而，迄今为止，X 射线辐射对小梁骨机械性能的影响，特别是与实验室 XCT 系统相关的影响，仍不清楚。压痕已广泛用于识别骨和其他生物组织的局部力学性能，如硬度和弹性模量。因此，本研究的目的是使用压痕和基于 XCT 的研究工具，如数字体相关（DVC），评估小梁骨组织长时间暴露于 X 射线辐射引起的微损伤及其对局部力学性能的影响。在对小梁骨样本进行 33 小时和 66 小时的 X 射线照射之前和之后进行了压痕实验，在每个阶段都评估了弹性模量的变化。第一次长时间 X 射线照射后，弹性模量降低，且标本中出现微裂纹，第二次照射后裂纹形成增加。从 DVC 分析还观察到损伤组织周围应变集中超过 1%。本研究的结果表明，在实验室系统中设计适当的基于 XCT 的实验非常重要，以避免由于辐射导致的骨组织机械性能下降，这些结果将有助于为未来需要长时间 X 射线暴露进行原位实验或生成可靠的特定于个体的计算模型的研究提供信息。
