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In the last decade, the study of methodologies for heating biological tissue has been an area of most interest in biology and medicine. As a result, the number of electrode solutions has grown in the past years. In this work, we study the capability of using a tubular electrode for heating biological tissue. To test this possibility, liver samples ex-vivo were used and numerical simulations were made...
3D contrast-enhanced ultrasound (CEUS) is a powerful imaging technique for tumour vascularity assessment, which is critical for radio-frequency ablation (RFA) planning or for the assessment of response to antiangiogenic therapies. In this paper, we propose a novel semi-automated method for the quantification of tumour vascularity in 3D CEUS data. We apply a two-step framework combining an interactive...
Radiofrequency (RF) ablation uses RF current to heat and kill cancer applied via an electrode inserted under image-guidance, and is in clinical use for tumors in liver, lung kidney, and bone. Mathematical models are frequently used to determine tissue temperature during RF ablation, but most prior models do not include accurate implementation of power control algorithms as are used in clinical devices...
We developed a novel radio-frequency (RF) stimulator to mimic heat effects similar to the temperature distributions created by moxibustion in porcine tissue. Moxibustion is a traditional Oriental medicine technique using moxa, which is utilized not only to cure disease, but also to increase immunity. However, it may lead to undesired effects including severe pains, blisters, and burns because of the...
RF ablation (RFA) is used for thermal ablation of tumors in which the RF electrode is placed in the tissue under image-guidance. Because of the good tumor visibility and the lack of ionizing radiation, MR-guided RFA is the method of choice. Additionally, with the help of MR thermometry the RF ablation can be monitored during the intervention. Unfortunately, the imaging of an MR scanner is highly sensitive...
In this paper we outline our main findings about the differences between the use of the Bioheat Equation and the Hyperbolic Bioheat Equation in theoretical models for Radiofrequency (RF) ablation. At the moment, we have been working on the analytical approach to solve both equations, but more recently, we have considered numerical models based on the Finite Element Method (FEM). As a first step to...
In an expanding number of worldwide clinical trials, conventional loop, dipole and square-patch antennas perform as external hyperthermia applicators for the adjunct treatment of cancer cells at superficial depths inside the human body. A smaller patch design in very close proximity with various phantom tissue models produces focused specific absorption rate (SAR) patterns without significant frequency...
We have measured temperature distribution using the infrared optical fibers during radiofrequency ablation (RFA). Infrared radiations generated from the water around inserted single-shaft plain electrode are transferred by the three silver halide optical fibers and are measured by a thermopile sensor array. Also, the output voltages of the thermopile sensor array are compared with those of the thermocouple...
Microwave ablation (MA) is popular as a minimally invasive, painless and effective oncological treatment. The paper presents an approach of characterizing the thermal coagulation during microwave ablation using B-mode ultrasound image textures and pattern recognition technique. During the MA treatment, the series of B-mode ultrasound images were obtained. Textures of different ROIs such as gray level...
Accurate visualization and targeting of specific anatomic locations are key components for successful treatment in catheter based cardiac ablation therapy. In order to augment visualization tools such as bi-plane fluoroscopy and real-time ultrasound, recent work has focussed on registering detailed, patient-specific models into the procedure. Surface based techniques are a popular approach, however,...
There has been a growing need to advance the use of thermal ablation therapy as a minimally invasive technique in cancer management. Consequently, this study was undertaken to investigate the use of radiofrequency (RF) energy by developing and testing an economical and effective radiofrequency thermal probe that will effectively destroy volumes of pathological tumours by means of hyperthermia. The...
Ultrasound (US) elastography in liver imaging applications has recently gained interest in the clinical community. Various techniques explore the use of elasticity information for clinical diagnosis (for fibrosis-cirrhosis staging) and assessment of radiofrequency (RF) or High Intensity Focused Ultrasound (HIFU) ablation. In this paper, we conduct compression-based strain imaging for ex vivo and clinical...
Radio frequency ablation (RFA), which is an important method for treating nonresectable and metastatic liver tumors, has increasingly been used over the past few years. On the positive side, RFA treatment is minimally invasive. On the negative side, the exact dimensions of the coagulated zone are not clearly visible in medical diagnostic images. A practical temperature distribution simulator is needed...
Cryosurgery treatment and Radiofrequency Ablation (RFA) are both effective method of physical therapy for tumor, but both of them have some disadvantages. Some occasional findings in the biological experimental phenomenon show that the alternative use of cryosurgery and RFA may have a better curative effect in the tumor ablation. We developed a joint system, trying to combine the freezing and heating...
We have developed a theoretical model to predict the outcome (i.e. failure/success) of radio-frequency ablation (RFA) therapy via computer calculations of the propagation of action potential in the presence of a ventricular reentry circuit. Our results show that the anatomy (i.e. infarct scar sizes) and the electrical conductivity of the channel between the scars (named isthmus) are critical to inducibility...
Electromagnetic and heat-transfer equations were solved to investigate a radio frequency (RF) rectangular resonant cavity applicator. The possibility of heating a deep-seated tumor was demonstrated. A torso-shaped dielectric phantom was made. It has electrical constants resembling those of human muscle. Several L-type antennas were made and placed at appropriate locations to heat a deep region. Measured...
Esophageal intestinal metaplasia, otherwise known as Barrett's esophagus, is a pre-cancerous condition that afflicts over 1 million Americans annually. Barrett's esophagus is caused by chronic esophageal exposure to stomach acid which can occur in patients afflicted with gastro esophageal reflux disease (GERD). The lining of the esophagus undergoes a metaplastic change, from normal squamous cell epithelium...
An analytical model was developed to predict the specific absorption rate (SAR) pattern of helical antennas in a general medium. Experimental measurements verified the accuracy of the model and revealed the complicated nature of the heating pattern. The calculated and measured results show a distinct standing wave pattern along the length of the antenna, whose wave number depends strongly on the helical...
The development and verification of a mathematical model and finite-element computer simulation that predict the three-dimensional temperature profiles for RF interstitial hyperthermia treatment are reported. An analytical expression for the three-dimensional power-deposition patterns due to finite-length needle electrodes is given. The bioheat transfer equation is then solved numerically using the...
Microwave contraception has been extended from animal experiments to clinical application, and a specialized resonant cavity applicator has been developed. The sperm count can be reduced to the sterility level seven weeks after the volunteer's testes are heated to 40-42 degrees C by microwave exposure for 30 minutes and maintains the low level when testes are treated once a month. The spermatocyte...
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