Microwave hyperthermia

Hyperthermia - [MICROWAVE TECHNOLGY] (Vol 16) -treatment of [MICROWAVE TECITNOLGY] (Vol 16)... 

Heat inducible gene expression systems can be activated by a variety of technologies, all via the production of hyperthermia. Technologies used in clinical applications of hyperthermia include simple approaches, such as water baths, or more sophisticated methods, such as microwave or radiofrequency radiations and ultrasound (Gemer and Cetas, 1993). The magnitude of heat shock promoter activity induction is dependent on both the time of exposure to hyperthermia and the hyperthermic temperature (Gemer et al., 2000). HSP promoter activity is activated by temperature in a species-specific manner. In flies, HSP promoter activity is activated by temperatures over 30 °C (Lindquist, 1986). In human cells, temperatures of 40 °C and above are required to activate HSP promoters (Gemer et al., 2000). 

Hyperthermia and thermoablation have been accomplished using capacitive or inductive coupling of rf fields (10-100 MHz), microwaves (> 300 MHz), ultrasound, lasers or external heat [171-177]. Macroscopic metal implants of Cu and other high-conductivity metals have been used to induce eddy-current heating. The absorbed power per mass is called the specific absorption rate (SAR), which can be expressed as... 

During hyperthermia, terms representing the heat input to a specific tissue or whole body must be added to the proper system equation(s). For example, during whole-body or local hyperthermia induced by radiofrequency currents, microwaves, or ultrasound, a heat-generation term is added to the section of the body being heated. During hyperthermia with blood perfusion, the afferent blood temperature is set at a desired value, and the efferent blood is circulated to the central blood pool, or to the extracorporeal device used for heating the blood. Suitable numerical... 

It is essential to provide accurate measurements of intratissue temperature distributions during normothermia and hyperthermia. New developments in the noninvasive thermometric techniques using MRI and microwave should alleviate some of these problems. 

Heat is one of the most efficient weapons to destroy tumor cells. But to induce a moderate heat of 41-47°C for a short duration (5-10 min) in the body without affecting normal tissue is quite difficult. Some of the commonly used heating sources to induce localized hyperthermia in the body are radiofrequency (RF), microwaves, ultrasound, magnetic field, and light [24]. 

Local hyperthermia uses very high heat. Radio waves, microwaves, ultrasound waves, and other forms of energy can be used to heat the local area. When ultrasound is used, the technique is called high intensity focused ultrasound, or HIFU. The heat may be applied using different methods ... 

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