Abstract

Purpose

To develop a head and neck hyperthermia phased array system compatible with a 1.5 T magnetic resonance (MR) scanner for noninvasive thermometry.

Methods

We designed a dielectric-parabolic-reflector antenna (DiPRA) based on a printed reflector backed dipole antenna and studied its predicted and measured performance in a flat configuration (30 mm thick water bolus and muscle equivalent layer). Thereafter, we designed a phased array applicator model (‘MRcollar’) consisting of 12 DiPRA modules placed on a radius of 180 mm. Theoretical heating performance of the MRcollar model was benchmarked against the current clinical applicator (HYPERcollar3D) using specific (3D) head and neck models of 28 treated patients. Lastly, we assessed the influence of the DiPRA modules on MR scanning quality.

Results

The predicted and measured reflection coefficients (S₁₁) of the DiPRA module are below −20 dB. The maximum specific absorption rate (SAR) in the area under the antenna was 47% higher than for the antenna without encasing. Compared to the HYPERcollar3D, the MRcollar design incorporates 31% less demineralized water (−2.5 L), improves the predicted TC25 (target volume enclosed by 25% iso-SAR contour) by 4.1% and TC50 by 8.5%, while the target-to-hotspot quotient (THQ) is minimally affected (−1.6%). MR experiments showed that the DiPRA modules do not affect MR transmit/receive performance.

Conclusion

Our results suggest that head and neck hyperthermia delivery quality with the MRcollar can be maintained, while facilitating simultaneous noninvasive MR thermometry for treatment monitoring and control.

中文翻译：

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MRcollar的仿真指导设计：一种与MR兼容的涂药器，用于头颈部区域的深层加热

摘要

目的

开发与1.5 T磁共振（MR）扫描仪兼容的头颈热疗相控阵系统，用于无创测温。

方法

我们设计了基于印刷后背衬偶极天线的介电抛物面反射天线（DiPRA），并研究了其在平坦配置（30毫米厚的水团和肌肉等效层）中的预测和测量性能。此后，我们设计了一个相控阵施加器模型（'MRcollar'），该模型由放置在180 mm半径上的12个DiPRA模块组成。MRcollar模型的理论加热性能是针对28名接受治疗的患者的特定（3D）头颈模型，相对于当前的临床涂药器（HYPERcollar3D）进行基准测试的。最后，我们评估了DiPRA模块对MR扫描质量的影响。

结果

DiPRA模块的预测和测量反射系数（S ₁₁）低于-20 dB。天线下方区域的最大比吸收率（SAR）比没有封装的天线高47％。与HYPERcollar3D相比，MRcollar设计减少了31％的软化水（-2.5 L），将预测的TC25（目标体积由25％iso-SAR轮廓包围）降低了4.1％，将TC50降低了8.5％。 -hotspot商（THQ）受到的影响最小（-1.6％）。MR实验表明DiPRA模块不会影响MR的发送/接收性能。

结论

我们的结果表明，使用MRcollar可以保持头部和颈部的高温交付质量，同时有利于同时进行非侵入性MR测温，以进行治疗监测和控制。