Balousis Alexandros, Maniotis Nikolaos, Samaras Theodoros
Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
Department of Physics, University of Malta, 2080 Msida, Malta.
Nanomaterials (Basel). 2021 Feb 23;11(2):556. doi: 10.3390/nano11020556.
Attenuation of the unwanted heating of normal tissues due to eddy currents presents a major challenge in magnetic particle hyperthermia for cancer treatment. Eddy currents are a direct consequence of the applied alternating magnetic field, which is used to excite the nanoparticles in the tumor and have been shown to limit treatment efficacy in clinical trials. To overcome these challenges, this paper presents simple, clinically applicable, numerical approaches which reduce the temperature increase due to eddy currents in normal tissue and simultaneously retain magnetic nanoparticles heating efficiency within the tumor. More specifically, two protocols are examined which involve moving the heating source, an electromagnetic coil, relative to a tumor-bearing phantom tissue during the exposure. In the first protocol, the linear motion of the coil on one side with respect to the hypothesized tumor location inside the phantom is simulated. The estimated maximum temperature increase in the healthy tissue and tumor is reduced by 12% and 9%, respectively, compared to a non-moving coil, which is the control protocol. The second technique involves a symmetrical variation of the first one, where the coil is moving left and right of the phantom in a bidirectional fashion. This protocol is considered as the optimum one, since the estimated maximum temperature rise of the healthy tissue and tumor is reduced by 25% and 1%, respectively, compared to the control protocol. Thus, the advantages of a linearly moving coil are assessed through tissue sparing, rendering this technique suitable for magnetic particle hyperthermia treatment.
在用于癌症治疗的磁粒子热疗中,减少因涡流导致的正常组织不必要的发热是一项重大挑战。涡流是所施加交变磁场的直接结果,该交变磁场用于激发肿瘤中的纳米颗粒,并且在临床试验中已显示会限制治疗效果。为了克服这些挑战,本文提出了简单、适用于临床的数值方法,这些方法可减少正常组织中因涡流导致的温度升高,同时保持肿瘤内磁性纳米颗粒的加热效率。更具体地说,研究了两种方案,其中涉及在暴露过程中使加热源(一个电磁线圈)相对于带有肿瘤的模拟组织移动。在第一个方案中,模拟了线圈在一侧相对于模拟体内假设肿瘤位置的线性运动。与作为对照方案的不移动线圈相比,健康组织和肿瘤中估计的最大温度升高分别降低了12%和9%。第二种技术涉及对第一种技术的对称变化,即线圈以双向方式在模拟体的左右两侧移动。该方案被认为是最佳方案,因为与对照方案相比,健康组织和肿瘤中估计的最大温度升高分别降低了25%和1%。因此,通过组织 sparing评估了线性移动线圈的优势,使该技术适用于磁粒子热疗。 (注:原文中“tissue sparing”未明确含义,此处保留英文未翻译)
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