**4. Microwave applicators**

Our research work is oriented toward studies and developments of local external applicators working at 27, 70, 434, and 2450 MHz (see **Figure 2**). These applicators were used to treat deep-seated and/or superficial tumors (treatment depth from 2 up to 8 cm).

Now, following new trends in this field, we continue our research in the important directions of regional applicators (see **Figure 3**). Moreover, we are trying to implement new microwave technologies in the design of new hyperthermia applicators, e.g., applicators based on metamaterial technology. Our BioEM team with Prof. Paul Stauffer from Thomas Jefferson University Hospital in Philadelphia has developed such applicators. Research of MW thermotherapy systems and MW medical diagnostics is in Prague done in cooperation with Dept. of EM Field (Faculty of Electrical Engineering) and Dept. of Biomedical Technique (Faculty of Biomedical Engineering), both are part of the Czech Technical University in Prague. The most important technical activities in this field can be specified as:


#### **Figure 5.**

*Calculation of the temperature distribution at 3.5 cm depth under the 3 2 MTM elements array. The yellow color denotes the threshold of the treated area.*

In **Figure 5**, there is an example of the calculated distribution temperature obtained by a matrix of a 3x2 MTM elements array. The highest temperature level is displayed here in red color, and the yellow color denotes the threshold therapeutic temperature of 41°C.

In actual clinics, we need the treatment planning to create so-called phantoms of the patient body or at least phantoms of the area to be treated, see **Figure 6a** and **b**. In **Figure 6a**, there is an example of a homogeneous phantom; in **Figure 6b** then, there is an example of the anatomical phantom. The first one is suitable for verifying the fundamental behavior of the applicator; the second one then is needed for the 3D SAR and 3D temperature distribution during the treatment of the actual patient.

In **Figure 7**, an example of SAR distribution is calculated for the case of the anatomical phantom. A very strong focus of MW power on a big tumor can be observed here.
