Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Magnetic Insight, Inc, Alameda, CA, USA.
Int J Hyperthermia. 2023;40(1):2272067. doi: 10.1080/02656736.2023.2272067. Epub 2023 Oct 24.
Magnetic particle hyperthermia is an approved cancer treatment that harnesses thermal energy generated by magnetic nanoparticles when they are exposed to an alternating magnetic field (AMF). Thermal stress is either directly cytotoxic or increases the susceptibility of cancer cells to standard therapies, such as radiation. As with other thermal therapies, the challenge with nanoparticle hyperthermia is controlling energy delivery. Here, we describe the design and implementation of a prototype pre-clinical device, called HYPER, that achieves spatially confined nanoparticle heating within a user-selected volume and location.
Spatial control of nanoparticle heating was achieved by placing an AMF generating coil (340 kHz, 0-15 mT), between two opposing permanent magnets. The relative positions between the magnets determined the magnetic field gradient (0.7 T/m-2.3 T/m), which in turn governed the volume of the field free region (FFR) between them (0.8-35 cm). Both the gradient value and position of the FFR within the AMF ([-14, 14], [-18, 18], [-30, 30]) mm are values selected by the user the graphical user interface (GUI). The software then controls linear actuators that move the static magnets to adjust the position of the FFR in 3D space based on user input. Within the FFR, the nanoparticles generate hysteresis heating; however, outside the FFR where the static field is non-negligible, the nanoparticles are unable to generate hysteresis loss power.
We verified the performance of the HYPER to design specifications by independently heating two nanoparticle-rich areas of a phantom placed within the volume occupied by the AMF heating coil.
磁粒子热疗是一种已被批准的癌症治疗方法，它利用磁性纳米粒子在交变磁场（AMF）中暴露时产生的热能。热应激要么直接细胞毒性，要么增加癌细胞对标准治疗（如辐射）的敏感性。与其他热疗一样，纳米粒子热疗的挑战在于控制能量传递。在这里，我们描述了一种名为 HYPER 的临床前原型设备的设计和实现，该设备能够在用户选择的体积和位置内实现空间受限的纳米粒子加热。
通过在两个相对的永磁体之间放置一个 AMF 产生线圈（340 kHz，0-15 mT），实现了纳米粒子加热的空间控制。磁铁之间的相对位置决定了磁场梯度（0.7 T/m-2.3 T/m），进而控制了它们之间的无场区域（FFR）的体积（0.8-35 cm）。梯度值和 FFR 在 AMF 中的位置（[-14, 14]、[-18, 18]、[-30, 30]）mm 都是用户通过图形用户界面（GUI）选择的值。然后，软件控制线性执行器移动静态磁铁，根据用户输入在 3D 空间中调整 FFR 的位置。在 FFR 内，纳米粒子会产生磁滞加热；然而，在 FFR 之外，静态场不可忽略，纳米粒子无法产生磁滞损耗功率。
我们通过独立加热放置在 AMF 加热线圈占据的体积内的一个体模中的两个富含纳米粒子的区域，验证了 HYPER 按照设计规格执行的性能。
