This analysis shows that VEDO facilitates a quantitative treatment strategy allowing standardised application of HT by technicians of different HT centres, which will potentially lead to improved treatment quality and the possibility of tracking the effectiveness of different treatment strategies.

Accumulating evidence shows that hyperthermia improves head-and-neck cancer treatment. Over the last decade, we introduced a radiofrequency applicator, named HYPERcollar, which enables local heating also of deep locations in this region. Based on clinical experience, we redesigned the HYPERcollar for improved comfort, reproducibility and operator handling. In the current study, we analyze the redesign from an electromagnetic point of view. We show that a higher number of antennas and their repositioning allow for a substantially improved treatment quality. Combined with the much better reproducibility of the water bolus, this will substantially minimize the risk of underexposure. All improvements combined enable a reduction of hot-spot prominence (hot-spot to target SAR quotient) by 32% at an average of 981 W, which drastically reduces the probability for system power to become a treatment limiting source. Moreover, the power deposited in the target selectively can be increased by more than twofold. Hence, we expect that the HYPERcollar redesign currently under construction allows us to double the clinically applied power to the target while reducing the hot-spots, resulting in higher temperatures and, consequently, better clinical outcome.

The HYPERcollar redesign improves water bolus shape, stability and skin contact. The renewed positioning strategy allows for positioning of the patient within the required precision of ±5 mm. By clinically introducing the new design, we aim at improving not only treatment quality and reproducibility, but also patient comfort and operator handling, which are all important for a better hyperthermia treatment quality.

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The techniques presented here may be used to simplify calibration experiments that use an interstitial heating device, or any heating method that provides rapid and spatially localised heat distributions. Overall, the experimental verification of the data registration and PRFS thermal coefficient calibration technique provides a useful benchmarking method to maximise MRT accuracy in any similar context.

The developed amplifier system prototype is capable of accurate power and phase delivery, over the entire frequency band of the system. The output power of the present system allows for an experimental verification of a recently developed TR-method on phantoms or animals. The system is suitable for further development for head and neck tumours, breast or extremity applications.

In this article, we evaluated a planar microwave applicator for in vivo superficial hyperthermia treatments on small tumors in the mouse mimicking treatments for human neoplasms. The design of the applicator, was challenged by the small dimensions of the tumors and unwanted diffusion of heating in the tumor-bearing animals. The required solution was to limit the penetration of microwaves in the depth of the tissue maintaining the full efficacy of hyperthermia. The study was firstly performed by computer simulations of SAR distribution inside a flat homogeneous phantom, considering various thicknesses of the integrated water bolus. Simulations, validated by the measurements, were also used to evaluate the impedance matching. Further tests were performed on homogeneous agar phantom to simulate the temperature distribution in the biological tissue and to preliminary assess the possible modality and schedule of microwave hyperthermia delivery. The in vivo experiments showed the evidence of direct microwave-induced heating and damage of the melanoma tissue in a range of penetration coherent both with computer simulations and phantom studies. The described approach appears perspective for designing limited-microwave-delivery applicators tailored for treatments of human superficial tumors and pre-tumoral lesions.

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