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Thermal Therapy Applications of Electromagnetic Energy
Published in Ben Greenebaum, Frank Barnes, Biological and Medical Aspects of Electromagnetic Fields, 2018
P.R. Stauffer, D.B. Rodrigues, D. Haemmerich, C.-K. Chou
EM fields employed for thermal ablation therapy are based primarily on two methods: Radiofrequency Ablation (RFA), which employs EM waves in the lower-frequency range of 450–500 kHz; and Microwave Ablation (MWA), which employs EM in the range of 0.915–2.45 GHz. While RFA is based on resistive heating due to ionic currents, MWA takes advantage of dielectric losses from the rotation of water dipoles present in soft tissues. Both methods require the insertion of a small diameter applicator—either an RF electrode for RFA or microwave antenna for MWA—into or adjacent to the tissue region to be heated. Examples of RFA and MWA applicators are shown in Figure 9.2. Applicator placement is performed manually by the treating physician and is typically guided by real-time medical imaging, such as ultrasound or computed tomography imaging. RFA found its first clinical application for the treatment of cardiac arrhythmia (i.e., irregular heartbeat) in the 1980s by very localized destruction of tissue regions in the heart responsible for the arrhythmias [12]. In the 1990s, RF ablation was increasingly used for cancer therapy by destroying malignant tumor cells with heat [186,187]. Today, thermal ablation is used to treat a wide variety of diseases, such as varicose veins and uterine bleeding [188,189].
An update on locoregional percutaneous treatment technologies in colorectal cancer liver metastatic disease
Published in Expert Review of Medical Devices, 2023
Stavros Spiliopoulos, Ornella Moschovaki-Zeiger, Akshay Sethi, George Festas, Lazaros Reppas, Dimitris Filippiadis, Nikolaos Kelekis
Similar to RFA, microwave ablation eliminates the tumor by causing a direct hyperthermic injury to it using electromagnetic (EM) waves. Microwave ablation produces heat by agitating up the water molecules in the vicinity of the electromagnetic spectrum that ranges in frequencies from 900 to 2450 MHz (in continuous or pulsed delivery modes) to cause frictional heating and so coagulative necrosis. Electromagnetic microwaves that are applied in the target lesion create more heat and less heat sink effect than RFA, due to the lower thermal conductivity and permeability of the tissues in the proximity. As a result, it is capable of producing bigger ablation zones in a shorter period of time. MWA has been widely accepted as an alternative to RFA in the recent years and is the favored ablation choice in many institutes, especially in lesions surrounding big vessels [66–68].
Heat distribution and the condition of hypothermia in the multi-layered human head: A mathematical model
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Ahsan Ul Haq Lone, M.A. Khanday, Saqib Mubarak, Feroze A. Reshi
In this paper, a mathematical model has been formulated to study the temperature distribution in human head under hypothermia conditions, especially hypothermic condition experienced by the people living at high altitudes. The temperature profiles at the interface points of brain, skull and scalp have been estimated with respect to atmospheric temperature, arterial temperature and metabolic heat generation. We modelled the problem and derived comparative analysis of the finite element method with analytical method. It has been observed that there is a considerable agreement between finite element solution and analytical solution of the formulated problem. The spatial difference in heat generated across different tissues has been employed for a number of clinical procedures. Clinical treatments of many diseases, such as cancer are based in part on the transfer of heat across the target tissues. Our model may, therefore, find application in treatment of cancer via microwave ablation (Selmi et al. 2019; Tucci et al. 2021), radiofrequency ablation (Paruch 2019; Tucci et al. 2021) or high frequency focussed ultrasound (Mohammadpour and Firoozabadi 2020). Other potential applications of our model may include cardiac ablation (Iasiello et al. 2020; Pérez et al., 2020), pain therapy (Singh and Melnik 2020) and laser angioplasty (Iasiello et al. 2019).
Analysis of efficiency of different antennas for microwave ablation using simulation and experimental methods
Published in Egyptian Journal of Basic and Applied Sciences, 2018
A.Z. Ibitoye, T. Orotoye, E.O. Nwoye, M.A. Aweda
The potential applications of thermal therapies such as microwave ablation, radiofrequency ablation, high intensity focused ultrasound and cryoablation in tumor treatments have been extensively reviewed in literature [1[2][3]–4] . Microwave ablation is emerging as an attractive modality for thermal therapy of large soft tissue within a short period of time, making it particularly suitable for tumors in different tissues [3,5] . Microwave ablation produces rapid temperature elevation sufficient to cause instant tissue coagulation and necrosis and it is capable of propagating through all types of biological tissues irrespective of tissues’ relative permittivity and effective conductivities. Tissue destruction occurs when tissues are heated to lethal temperatures with a microwave source. Microwave energy radiates into the tissue through an interstitial antenna that functions to couple energy from MW generator to the tissue. As a result of the radiative nature of the antenna, direct heating occurs in a volume of tissue around the antenna.