Some Heat Transfer Problems Associated With Heating by Ultrasound, Microwaves, or Radio Frequency*

Hahn, George M.; Kernahan, Peter J.; Martínez, Álvaro; Pounds, Douglas; Prionas, Stavros D.; Anderson, Thomas L.; Justice, Greg

doi:10.1111/j.1749-6632.1980.tb50757.x

Cited by 72 publications

(26 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To ascertain this, we compared the Debye and Cole-Cole models in the case of blood. As shown in Figure 5, the two parameterizations describe equally well data from References [20,21,22,23,24,25,26] in the frequency range 1 MHz-100 GHz, important for nanopulse research. It can be concluded that replacing the Cole-Cole model with the Debye model does not compromise the level of description of physical properties of the material.…”

Section: Dielectric Properties Of Exposed Samplementioning

confidence: 76%

FDTD simulation of exposure of biological material to electromagnetic nanopulses

Šimičević

Haynie

2005

Phys. Med. Biol.

View full text Add to dashboard Cite

Abstract.Ultra-wideband (UWB) electromagnetic pulses of nanosecond duration, or nanopulses, are of considerable interest to the communications industry and are being explored for various applications in biotechnology and medicine. The propagation of a nanopulse through biological matter has been computed in the time domain using the finite difference-time domain method (FDTD). The approach required existing Cole-Cole model-based descriptions of dielectric properties of biological matter to be re-parametrized using the Debye model, but without loss of accuracy. The approach has been applied to several tissue types. Results show that the electromagnetic field inside a biological tissue depends on incident pulse rise time and width. Rise time dominates pulse behavior inside a tissue as conductivity increases. It has also been found that the amount of energy deposited by 20 kV /m nanopulses is insufficient to change the temperature of the exposed material for the pulse repetition rates of 1 M Hz or less.

show abstract

Section: Dielectric Properties Of Exposed Samplementioning

confidence: 76%

FDTD simulation of exposure of biological material to electromagnetic nanopulses

Šimičević

Haynie

2005

Phys. Med. Biol.

View full text Add to dashboard Cite

show abstract

“…15) Applying a surface cooling system using water pads covering the electrodes solves these problems. 12) In the present study, we also used water pads to avoid excess heating of skin covering the tumor.…”

Section: Discussionmentioning

confidence: 99%

Effect of Functional Magnetic Particles on Radiofrequency Capacitive Heating: An in vivo Study

Shinkai

Ueda

Ohtsu

et al. 2002

Japanese Journal of Cancer Research

View full text Add to dashboard Cite

Specific heating of magnetic particles in radiofrequency (RF) capacitive hyperthermia and its hyperthermic effect were investigated in an in vivo study. Magnetite cationic liposomes (MCLs) were injected into a rat tumor on the femur and 8 MHz-RF capacitive heating was applied to the rat under 'mild heating' conditions. Although the input power of RF capacitive heating was low under the same power conditions, the MCLs-injected tumor was heated over 43°C, whereas it was only heated to 41°C in the case of the rats not injected with MCLs. A necrotic area in the tumor was observed in the heated rats. From the results of histological observation of the removed tissue, the necrotic area in the MCLs-injected tumor was wider than that in MCLs-free tumor. Complete tumor suppression was observed in 71% (5/7) of MCLs-injected rats, and the hyperthermic effect was greatly improved by the MCLs.Key words: RF capacitive heating -Magnetic particle -Regional hyperthermia Hyperthermia is a promising approach in cancer therapy and various methods are employed to achieve it.1, 2) However, the inevitable technical problem with hyperthermia is the difficulty of uniform heating of only the tumor region to the required temperature without damaging normal tissue. Therefore, some researchers have proposed inductive heating methods using submicron magnetic particles for hyperthermia. [3][4][5] We have also developed 'magnetite cationic liposomes' (MCLs) for intracellular hyperthermia. [6][7][8] MCLs were developed to improve adsorption and accumulation into the tumor cells and showed ten-fold higher affinity for the tumor cells than neutrally charged magnetoliposomes.6) This is enabled by the electrostatic interaction with the negatively charged cell membrane.9, 10) The hyperthermic effect of the MCLs was examined in vivo. 8)MCLs were directly injected into solid tumors formed subcutaneously in F344 rats and the rats were irradiated three times for 30 min with an alternating magnetic field. An alternating magnetic field with relative low frequency of the order of 100 kHz heated only the tumor containing the MCLs. As a result, complete tumor regression was observed in many rats after the irradiation.Inductive heating using submicron magnetic particles is a superior method as stated above, but it cannot yet be practiced in Japan since magnetic field generators are still in an experimental stage. In Japan, capacitive heating of tumors using a radiofrequency (RF) electric field is a popular heating method and has been clinically used. 11,12) Capacitive heating is, however, not suitable for site-specific hyperthermia, because it is unable to heat tumors specifically. The specific adsorption rate (SAR) of electric field energy depends on the electrical properties of each tissue, such as permittivity and electric resistance. Since the difference in the electrical properties of tumors and normal tissues is not high, it is difficult to heat only the tumor specifically. In order to prevent excessive heating of normal tissue, 'mild' heating condition...

show abstract

“…However, there appear to be no direct measurements made on exposed human lung. HAHN et al (1980) quote measurements made on pig lung at a frequency of 1 MHz of 14.3 f~m inflated and 6.6 f~m deflated. Lower resistivity values are expected in neonates from what is known about their lung composition.…”

Section: Medical and Biological Engineering And Computing 2002 Vol 40mentioning

confidence: 99%

Neonatal lungs-can absolute lung resistivity be determined non-invasively?

Brown

Primhak

Smallwood

et al. 2002

Med. Biol. Eng. Comput.

View full text Add to dashboard Cite

The electrical resistivity of lung tissue can be related to the structure and composition of the tissue and also to the air content. Conditions such as pulmonary oedema and emphysema have been shown to change lung resistivity. However, direct access to the lungs to enable resistivity to be measured is very difficult. We have developed a new method of using electrical impedance tomographic (EIT) measurements on a group of 142 normal neonates to determine the absolute resistivity of lung tissue. The methodology involves comparing the measured EIT data with that from a finite difference model of the thorax in which lung tissue resistivity can be changed. A mean value of 5.7 +/- 1.7 omega(m) was found over the frequency range 4 kHz to 813 kHz. This value is lower than that usually given for adult lung tissue but consistent with the literature on the composition of the neonatal lung and with structural modelling.

show abstract

Some Heat Transfer Problems Associated With Heating by Ultrasound, Microwaves, or Radio Frequency*

Cited by 72 publications

References 7 publications

FDTD simulation of exposure of biological material to electromagnetic nanopulses

FDTD simulation of exposure of biological material to electromagnetic nanopulses

Effect of Functional Magnetic Particles on Radiofrequency Capacitive Heating: An in vivo Study

Neonatal lungs-can absolute lung resistivity be determined non-invasively?

Contact Info

Product

Resources

About