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Local Radiofrequency Hyperthermia

#2979


Development of Techniques for Local RF Hyperthermia Delivered to Deeply Located Malignant Tumors in Patients with High Body Mass

Tech Area / Field

  • MED-RAD/Radiomedicine/Medicine

Status
3 Approved without Funding

Registration date
21.01.2004

Leading Institute
Medical Radiological Scientific Center, Russia, Kaluga reg., Obninsk

Supporting institutes

  • Kaluga Research Radio Engineering Institute, Russia, Kaluga reg., Zhukov\nFEI (IPPE), Russia, Kaluga reg., Obninsk

Collaborators

  • Tokyo Institute of Technology, Japan, Tokyo\nUniversity Hospital, The Netherlands, Rotterdam

Project summary

In oncology, local hyperthermia means selective heating of malignant tumors up to 41-45 °C, thus it increases the effectiveness of radio- and chemotherapy.

Yet, the systems and techniques currently employed for delivery of RF hyperthermia often fail to provide adequate heating of deep-seated tumors in patients with high body mass.

The problem is that subcutaneous fat is overheated due to its high electric resistance and its low heat conductivity. Pain sensation in the "hot spots" in subcutaneous fat under electrodes-applicators evidences the risk of thermal injury in healthy tissues. So, the appearance of "hot spots" makes it impossible to achieve hyperthermic temperatures in tumors.

This restrains delivery of radio-frequency hyperthermia (RF-hyperthermia) to cancer patients with high body mass. The problem concerned is typical for tumor heating by electric radio-frequency field employed in modern hyperthermia systems: Thermatron RF-8 (8 MHz, Japan); Oncocare (13 MHz, France); Extratherm (40 MHz, Russia).

The frequency of the electric field is of primary importance in heating deep-seated tumors. Extratherm system, which is to be used in the project, generates the frequency which is more advantageous (40 MHz) for heating deep-seated tumors than the similar systems generating the frequencies of 8 MHz and 13 MHz respectively. The electric field of lower frequency increases the possibility of overheating of subcutaneous fat. However, it is not only the selection of the optimal radio frequency in itself that enables to avoid overheating of subcutaneous fat.

The project is aimed at developing therapeutic techniques for delivery of local RF-hyperthermia, which would allow selective heating of malignant tumors to 41-45 °C without damaging subcutaneous fat and surrounding healthy tissues in patients with high body mass.

Three interrelated programs are to be fulfilled to achieve the objectives of the project.

Program 1.

Investigation of the relationship between the electric conductivity of the liquid circulating in the electrodes-applicators and heat distribution over tissues. The focus of the above research effort is on the selection of the liquid with the optimal electric conductivity so that to lower the risks of thermal injury of subcutaneous fat. Basic research into thermal mechanisms of destruction of biologic tissues due to exposure to electric radio frequency field will be carried out with the use of molecular dynamics method.

Program 2.

Investigation of the relationship between thickness and electric conductivity of subcutaneous fat and temperature distribution. Analysis of non-thermal mechanisms for destruction of long molecules exposed to electric radio frequency field will be made by molecular dynamics method.

Artificial reduction of the electrical resistance of subcutaneous fat under electrodes-applicators will be made by electrophoretic administration of ions of medicinal solutions.

Program 3.

Investigation of heat distribution over tumor tissues in the course of hyperthermia by the scanning electric field. Research into thermal and resonance mechanisms of destruction of protein molecules will be carried. out. Supplementary study of factors reducing heat generation in the volume unit of subcutaneous fat by the scanning UHF field will be carried out. Tumor heating by the scanning RF field is provided by the rotationally-oscillatory movement of the electrodes-applicators around the tumor by a trajectory set by a physician.

Three programs on basic and applied research consist thermal physic and model calculations which will be made during three years.

The joint research effort made by the experts-physicians, physicists, engineers, mathematicians will result in development of new techniques and approaches to local RF hyperthermia. It will enable to deliver local RF hyperthermia to a greater number of cancer patients and to increase the effectiveness of radio- and chemotherapy.


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