**2. Prospective applications of microwaves in medicine**

In the following text we would like to outline scope and new trends in medical applications of microwaves. We can divide these results and new trends into two major groups:


#### **2.1 Clinical results and trends**

Applications of microwaves in medicine is a quite a new field of a high interest in the world (since early 80's). It is necessary to mention one of the most important trends in the research of medical applications of microwaves, i.e. the thermal effects of EM field (since early 80's a microwave thermotherapy is used for cancer treatment, Benign Prostate Hyperplasia (BPH) treatment and for some other areas of medicine; it can be used in combination with other complementary treatment methods also.

To give a basic overview, we can divide medical applications of microwaves in following three basic groups according to purpose, how are microwaves used:


Prospective Applications of Microwaves in Medicine 509

a) b) c) d)

distribution (coverage) of Specific Absorption Rate (SAR).

development (covered also by our activities) can be specified as:


Fig. 1. Typical example of 4 phases of the patient treatment: a) Patient before the treatment. b) At the end of the treatment. c) Two months after treatment. d) One year after treatment.

Our work is focused on the design, optimization and tests of the microwave applicators for medical applications, above all for hyperthermia cancer and BPH treatment. This means to



Our applicators (working at 434 MHz and at 2450 MHz) were used for the treatment of more than 500 patients with superficial or subcutaneous tumour. Now, following new trends in this field, we continue our research in the important directions of deep local and regional applicators. Most important technical fields of microwave thermotherapy




Simulations of SAR distribution obtained by array of microwave applicators radiating at frequency 434 MHz will be described here. We will compare here the SAR distribution in a homogeneous agar phantom (which has similar dielectric characteristics to muscle tissue) and in an anatomical based biological model, which has been developed from a Computer



**2.2 Technical results and trends** 

microwave generator,

treatment

measurements.

Tomography (CT) scan.

design a microwave structure capable to:

intracavitary and regional treatment,

**3. Applicators for microwave thermotherapy** 


As is given above, until now medical applications of microwaves are above all represented by the treatment methods based on thermal effect – i.e. we can speak about the Microwave thermotherapy, which can be further divided into three different modalities distinguished according to the goal temperature level or interval:



First three of the following list of thermotherapeutical applications are just largely used in many countries around the world, last three instead are in this moment in the phase of very promising projects:


E.g. in cancer treatment is thermotherapy usually used in the combination with some of other modalities used in the clinical oncology (e.g. radiotherapy, chemotherapy, immunotherapy or chirurgical treatment). It is used in USA, Japan and in many countries in European Union (EU), including the Czech Republic, from early 80s. Up to now local microwave hyperthermia for cancer treatment and thermotherapy of BPH are the most important applications of microwaves in medicine. In the Czech Republic we have treated more than 500 patients. Results of our treatments are given the following table:


Table 1. Clinical results of cancer treatment by radiothermotherapy

Successful treatment thus has been indicated in the case of 84 % of patients. This corresponds very well to the results published in EU and USA. Actual scientific information about microwave thermotherapy and its new developments is possible to get from "International Journal of Hyperthermia" issued by European Society for Hyperthermia Oncology (ESHO) together with North American Hyperthermia Society (NAHS) and Asian Society of Hyperthermia Oncology (ASHO). On the following series of photographs (Fig. 1) there is example of the typical 4 phases of the treatment of one of our patients obtained by radio-thermo-therapy (i.e. combination of microwave hyperthermia with significantly reduced doses of radiotherapy).

Very interesting results for the near future can give us the research of microwave medical applications based on so called non-thermal effects. In the literature it is possible just now to identify research projects on:



As is given above, until now medical applications of microwaves are above all represented by the treatment methods based on thermal effect – i.e. we can speak about the Microwave thermotherapy, which can be further divided into three different modalities distinguished

First three of the following list of thermotherapeutical applications are just largely used in many countries around the world, last three instead are in this moment in the phase of very

E.g. in cancer treatment is thermotherapy usually used in the combination with some of other modalities used in the clinical oncology (e.g. radiotherapy, chemotherapy, immunotherapy or chirurgical treatment). It is used in USA, Japan and in many countries in European Union (EU), including the Czech Republic, from early 80s. Up to now local microwave hyperthermia for cancer treatment and thermotherapy of BPH are the most important applications of microwaves in medicine. In the Czech Republic we have treated

> Complete response of the tumor 52.4 % Partial response of the tumor 31.7 % Without response 15.9 %

Successful treatment thus has been indicated in the case of 84 % of patients. This corresponds very well to the results published in EU and USA. Actual scientific information about microwave thermotherapy and its new developments is possible to get from "International Journal of Hyperthermia" issued by European Society for Hyperthermia Oncology (ESHO) together with North American Hyperthermia Society (NAHS) and Asian Society of Hyperthermia Oncology (ASHO). On the following series of photographs (Fig. 1) there is example of the typical 4 phases of the treatment of one of our patients obtained by radio-thermo-therapy (i.e. combination of microwave hyperthermia with significantly

Very interesting results for the near future can give us the research of microwave medical applications based on so called non-thermal effects. In the literature it is possible just now to

more than 500 patients. Results of our treatments are given the following table:

Table 1. Clinical results of cancer treatment by radiothermotherapy


future can be a microwave tomography).

according to the goal temperature level or interval:



reduced doses of radiotherapy).

identify research projects on:


(e.g.linear accelerator).

promising projects:


Fig. 1. Typical example of 4 phases of the patient treatment: a) Patient before the treatment. b) At the end of the treatment. c) Two months after treatment. d) One year after treatment.

### **2.2 Technical results and trends**

Our work is focused on the design, optimization and tests of the microwave applicators for medical applications, above all for hyperthermia cancer and BPH treatment. This means to design a microwave structure capable to:


Our applicators (working at 434 MHz and at 2450 MHz) were used for the treatment of more than 500 patients with superficial or subcutaneous tumour. Now, following new trends in this field, we continue our research in the important directions of deep local and regional applicators. Most important technical fields of microwave thermotherapy development (covered also by our activities) can be specified as:

