Principle of RF in Medicine
Radiofrequency is the most widely used, studied, and evaluated energy form in the field of tumor ablation. In addition to tumor destruction nowadays, radiofrequency energy is also used in neurolysis for pain management. Radiofrequency energy is characteri
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Principle of RF in Medicine Dimitrios K. Filippiadis, Argyro Mazioti, Sean Tutton, and Alexis Kelekis
2.1
Introduction
d’ Arsonval in 1891 was the first one reporting increase in local temperature when radiofrequency waves pass through [1]. Years later, radiofrequency energy was introduced for the first time to everyday clinical practice in the form of bovie knife which was using variable radiofrequency current for cauterizing and cutting tissues [1]. In 1992 Rossi and McGahan et al. (for liver tumor ablation) and Rosenthal et al. (for osteoid osteoma ablation) used radiofrequency energy for neoplasm destruction [1, 2]. Ever since, radiofrequency has become the most widely used, studied, and evaluated energy form in the field of tumor ablation. In addition to tumor destruction nowadays, radiofrequency energy is also used in neurolysis for pain management.
D.K. Filippiadis (*) • A. Mazioti • A. Kelekis 2nd Radiology Department, University General Hospital “ATTIKON”, National and Kapodistrian University of Athens, 1 Rimini str, 12462 Haidari/Athens, Greece e-mail: [email protected]; argyromazioti@ yahoo.gr; [email protected] S. Tutton Division of Vascular and Interventional Radiology, Medical College of Wiskonsin, 9200 West Wiskonsin Av, Milwaukee, WI 53226, USA
2.2
Physics and Principles
The electromagnetic spectrum is a continuous wave spectrum including energy forces with common characteristics differing however in terms of frequency. The electromagnetic spectrum includes radio waves, microwaves, infrared radiation, visible spectrum, ultraviolet radiation, x-rays, and γ-rays in increasing frequency (Fig. 2.1). Energy in the electromagnetic field makes ions and polar molecules, which are charged particles, move. This movement is transmitted to the surrounding molecules through friction transforming thus the electromagnetic into kinetic energy at the molecular level resulting in heat production. Heating causes protein coagulation and subsequent necrosis. Radiofrequency energy is characterized by a frequency between 3 Hz and 300 GHz. Wave frequency is the main characteristic defining energy – tissue interaction since it characterizes both penetration length (which affects the power distribution) and absorption rate (which affects the heating velocity). At frequencies below the visible light simply by increasing the frequency, the absorption rate of water increases. Due to this absorption, the intensity of the electromagnetic field steeply decreases during crossing electromagnetic tissues. Penetration length is defined as the distance traveled before the intensity of the field decreases to one third of the initial
© Springer International Publishing Switzerland 2017 S. Marcia, L. Saba (eds.), Radiofrequency Treatments on the Spine, DOI 10.1007/978-3-319-41462-1_2
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Fig. 2.1 The electromagnetic spectrum is a continuous wave spectrum including energy forces with common characteristics differing however in terms of frequency
value. Absorption rate and penetration leng
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