Department of Medical Radiation Engineering, Shahid Beheshti University, Tehran, Iran.
Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
J Cancer Res Clin Oncol. 2023 Aug;149(10):7479-7491. doi: 10.1007/s00432-023-04695-1. Epub 2023 Mar 24.
Vertebroplasty is a minimally invasive outpatient procedure to stabilize compression fractures in the spine. This procedure involves injecting bone cement into the vertebrae that have been cracked or broken, typically due to osteoporosis. The cement hardens inside the bones, providing stability to the fractures and supporting the spine. Additionally, radioactive bone cement and brachytherapy sources have been utilized to suppress tumor growth in the vertebral body.
We present a novel brachytherapy technique for treating vertebral body metastases using a liquid form of radioactive sources, Phosphorus-32 and Lutetium-177, separately mixed with bone cement and injected into vertebral body bone prostheses. We also investigated the dose distribution of the radioactive bone cement by theoretically calculating it using GEANT4 Monte Carlo and measuring it using TLD dosimeters for Phosphorus-32 and Lutetium-177 loaded in vertebral bodies.
CT-scanned images of each vertebral body (L2 and L3) were imported into GEANT4 for simulation purposes. Two simulations were performed to evaluate the possibility of using PLA prostheses in ex vivo measurements, using bone and PLA material as a bone substitute for brachytherapy of Lutetium-177 and Phosphorus-32. The simulations calculated the dose distribution, dose rates, and deposited dose to the spinal cord and aorta. Next, 3D-printed bone prostheses were drilled and separately filled with bone cement, including PMMA-P32 and PMMA-Lu177, in liquid form using the Vertebroplasty technique. The dose to regions of interest was measured using Thermoluminescence dosimeters.
When comparing the simulated and measured results of dose rates, it was observed that P32 delivers higher doses to normal organs such as the spinal cord and aorta. At the same time, Lu177 has better sparing in these regions of interest. Therefore, while P32 and Lu177 are suitable for radioactive bone cement treatment, Lu177 delivers relatively lower doses to vital organs such as the spinal cord and aorta. Additionally, Lu177 has characteristics such as a shorter range and lower energies of beta particles in tissue and the presence of gamma rays that make it a better choice for the same treatments. It also provides the possibility of SPECT imaging.
椎体成形术是一种微创的门诊手术，用于稳定脊柱的压缩性骨折。该手术涉及将骨水泥注入破裂或断裂的椎骨中，这些椎骨通常是由于骨质疏松症引起的。水泥在骨骼内部硬化，为骨折提供稳定性并支撑脊柱。此外，放射性骨水泥和近距离放射治疗源已被用于抑制椎体中的肿瘤生长。
我们提出了一种使用液体形式的放射性磷-32 和镥-177 源的新型近距离放射治疗技术，分别将其与骨水泥混合并注入椎体骨假体中。我们还通过理论计算使用 GEANT4 蒙特卡罗方法和使用 TLD 剂量计测量磷-32 和镥-177 负载在椎体内的放射性骨水泥的剂量分布来研究其剂量分布。
将每个椎体（L2 和 L3）的 CT 扫描图像导入 GEANT4 进行模拟。进行了两次模拟，以评估 PLA 假体在离体测量中的使用可能性，使用骨和 PLA 材料作为镥-177 和磷-32 近距离放射治疗的骨替代物。模拟计算了剂量分布、剂量率以及对脊髓和主动脉的沉积剂量。接下来，使用椎体成形术技术，在 3D 打印的骨假体上钻孔，并分别用液态的 PMMA-P32 和 PMMA-Lu177 填充骨水泥。使用热释光剂量计测量感兴趣区域的剂量。
在比较剂量率的模拟和测量结果时，观察到 P32 对脊髓和主动脉等正常器官的剂量更高。同时，Lu177 在这些感兴趣区域的保护更好。因此，虽然 P32 和 Lu177 适用于放射性骨水泥治疗，但 Lu177 对脊髓和主动脉等重要器官的剂量相对较低。此外，Lu177 具有较短的射程和较低的β粒子在组织中的能量以及存在伽马射线等特性，使其成为相同治疗的更好选择。它还提供了 SPECT 成像的可能性。
