Sherar M D, Liu F F, Newcombe D J, Cooper B, Levin W, Taylor W B, Hunt J W
Ontario Cancer Institute/Princess Margaret Hospital, Toronto, Canada.
Int J Radiat Oncol Biol Phys. 1993 Apr 2;25(5):849-57. doi: 10.1016/0360-3016(93)90315-m.
Hyperthermia treatments commonly use single element microwave waveguide applicators. The microwave beam patterns produced by these applicators are often non-uniform. As a result, hot spots are formed in the heated tissue and therapeutic temperatures are reached in only small areas of the treatment field. We have constructed new coupling boluses that improve the heating patterns of external microwave applicators.
The microwave beam transmitted through the bolus is modified by microwave absorbing saline/gelatin pads. The pads can be designed to result in a uniform heating pattern over a large area or alternatively, complex heating patterns can be generated for specific clinical applications. An analysis of the effect of bolus design parameters on microwave absorption patterns is presented. The heating patterns of the MA-100 and MA-120 microwave waveguide applicators have been measured in muscle and fat phantom materials with both the manufacturer's boluses and the new boluses.
In the case of the MA-100, the area above the 70% heating level measured in a muscle phantom was increased by a factor of 2.3 by an absorbing pad bolus. Similarly, the heating area of the MA-120 was increased by a factor of 2.6 by an absorbing pad bolus. The boluses were tested in a clinical setting by measuring tissue temperature profiles in patients under different bolus arrangements. The area over which therapeutic temperature was achieved was increased considerably when the absorbing bolus was used. A second bolus was designed for the MA-120 to produce a ring heating pattern for the treatment of a breast cancer patient who had developed recurrences at the periphery of a skin graft. The heating pattern produced in a muscle phantom is compared with tissue temperature profiles measured during the hyperthermia treatment of this patient.
Microwave absorbing filters using saline pads significantly improve the heating patterns of microwave waveguide hyperthermia applicators. This improvement was confirmed in clinical application where much greater areas of homogeneous heating were observed. The technology was extended to produce complex heating patterns for special clinical applications.
热疗通常使用单元素微波波导 applicators。这些 applicators 产生的微波束模式往往不均匀。因此，在加热组织中会形成热点，并且仅在治疗区域的小范围内达到治疗温度。我们构建了新的耦合 boluses，以改善外部微波 applicators 的加热模式。
通过微波吸收盐水/明胶垫来改变穿过 bolus 的微波束。这些垫可以设计成在大面积上产生均匀的加热模式，或者，也可以为特定的临床应用生成复杂的加热模式。本文给出了 bolus 设计参数对微波吸收模式影响的分析。使用制造商的 boluses 和新的 boluses，在肌肉和脂肪模型材料中测量了 MA - 100 和 MA - 120 微波波导 applicators 的加热模式。
在 MA - 100 的情况下，通过吸收垫 bolus，在肌肉模型中测量的 70%加热水平以上的面积增加了 2.3 倍。同样，MA - 120 的加热面积通过吸收垫 bolus 增加了 2.6 倍。通过测量不同 bolus 布置下患者的组织温度分布，在临床环境中对 boluses 进行了测试。当使用吸收 bolus 时，达到治疗温度的面积显著增加。为 MA - 120 设计了第二种 bolus，以产生环形加热模式，用于治疗在皮肤移植周边出现复发的乳腺癌患者。将在肌肉模型中产生的加热模式与该患者热疗期间测量的组织温度分布进行了比较。
使用盐水垫的微波吸收滤波器显著改善了微波波导热疗 applicators 的加热模式。这种改进在临床应用中得到了证实，在临床应用中观察到了更大面积的均匀加热。该技术被扩展用于为特殊临床应用产生复杂的加热模式。
