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HYPERTHERMIA RADIATION APPARATUS AND METHOD FOR TREATMENT OF MALIGNANT TUMORS
BACKGROUND OF THE INVENTION  1. Field of the Invention
 The present invention relates generally to an apparatus for treating and destroying harmful cells within the body. More particularly, the present invention relates to an apparatus for delivering heat and radiation to a tumor within a body to destroy the cells in the tumor.
 2. Background Art
 Hyperthermia, the heating of body cells to above 41° C. for therapeutic purposes, particularly to destroy cancer tumors, has been known and used in the past. It is also known that above 46° C, irreversible destruction of healthy and diseased body cells occurs. The purpose of hyperthermia equipment generally is to deliver heat preferentially to diseased body cells while maintaining adjacent healthy cells at acceptable temperatures, i.e., below the temperature at which irreversible cell destruction occurs.
 There are three main theories which explain why hyperthermia is successful in fighting cancerous growths. Some scientists believe that heat produces a localized fever which causes lymphocytes to congregate (200 lymphocytes are usually needed to destroy one cancerous cell). Other scientists think heat improves the flow of blood in the tumor, and this increased blood flow, in turn, brings more oxygen to the tumor and lowers its Ph, thus starving the tumor cells by reducing nutrients. A third theory contends that the DNA forces that hold tumorous cells together are weaker than those of healthy cells and the heat applied to the tumorous cells breaks them apart and thereby destroys them more easily.
 Hyperthermia or induced high body temperature is beneficial in treating many types of cancer. Some malignant cell masses having poorer heat dissipation characteristics than normal tissue, presumably due to abnormally low blood circulation, are subject to preferential hyperthermia treatment. As a result, such malignant cell masses can often be heated to temperatures substantially higher than that of surrounding healthy cells, to enable hyperthermia treatment, even when both types of cells are heated simultaneously. This characteristic not only enables hyperthermia treatment of some types of malignancies which are no more temperature sensitive than normal cells, but usually permits much shorter hyperthermia treatment times, even of thermally sensitive malignancies, as is important for various medical reasons.
 More specifically, various types of malignant growths are considered by many researchers to have a relatively narrow hyperthermia treatment temperature range. Below a threshold temperature of about 41.5° C. (106.7° E), thermal destruction of these malignancies is not believed to occur. In fact, for hyperthermia temperatures below this threshold, growth of some of these malignancies may tend to be stimulated. In contrast, at temperatures above a range of about 43° C. to 45° C. (109.4° F. to 113° F.) thermal damage evento most normal cells occurs, the exposure duration at any elevated temperature also being a significant factor. Accordingly, if large or critical parts of a human body
are heated into, or above, the 43° C. to 45° C. range for even relatively short durations, serious permanent injury or death is possible.
 Radiation treatment of malignant cells is also known. Radiation treatment is classified into two general categories. Teletherapy is treatment of cells within a body from an area external to the body. Radiation generated outside the body travels through the body to reach the malignant cells when the malignant cells are on the interior of the body. Thus, healthy cells are exposed to harmful, cell killing radiation. One way to minimize exposure of a cell at a specific point is to focus radiation over an area at the source to a point distant from the source, where the cells to be treated are at the focal point. In this way, only the malignant cells are exposed to the full power of the radiation. However, healthy tissue surrounding the malignant cells, and all cells between the malignant cells and the radiation producing device are still exposed to a large amount of radiation.
 Brachytherapy, a second type of radiation treatment, is treatment of cells from a point or source on the interior of the body. Thus, brachytherapy has the advantage of allowing localized radiation treatment. A physician can treat malignant cells by radiating in an area in close proximity to, or within, a group of malignant cells such as a tumor, with only minimal exposure to radiation of healthy cells.
 Recently, it was discovered that hyperthermia and radiation, used in combination, is more effective at killing malignant cells than either hyperthermia or radiation alone. Hyperthermia suppresses the repair mechanism of the cellular DNA which is damaged by ionizing radiation. At normal body temperatures, the time required for a cell to complete repair is about 30-45 minutes. At elevated temperatures, in the range of 42-45° C, the repair mechanism is disabled. Thus, while at elevated temperatures, the cell cannot repair the damage to the tumor caused by the radiation exposure. Therefore, the amount of radiation necessary to break down the tumorous cell is greatly reduced.
 Currently, hyperthermia is used with radiation to treat malignant cells by using the combination of localized hyperthermia treatment to heat the cells, and teletherapeutic treatment to radiate the cells. Despite the advantages of treating malignant cells with both heating and radiation, there is not a brachytherapeutic apparatus capable of delivering both X-ray radiation and interventional heating to a malignant tumor. Therefore, what is needed is an apparatus that is capable of providing brachytherapeutic X-ray radiation and interventional heating to a malignant tumor.
BRIEF SUMMARY OF THE INVENTION
 The present invention relates to a device for simultaneously treating a tumor or cancerous growth with both hyperthermia and X-ray radiation using brachytherapy. The device is comprised of a needle-like introducer serving as a microwave antenna. Microwaves are emitted from the introducer to increase the temperature of cancerous body tissue. As the temperature of the cancerous tissue increases, the tissue's resistance to radiation is lowered or eliminated. The introducer is an inner conductor of a coaxial cable. The coaxial cable allows the introducer to serve as a microwave emitter when an electrical current is passed through the
metal braid portion of the coaxial cable and across a dielectric material. The coaxial cable extends to a microwave generator, which continuously generates microwaves at an adjustable frequency.
 The introducer contains a hollow core which houses an X-ray emitter, which is connected to a high voltage miniature cable extending from the X-ray emitter to a high voltage power source. The X-ray emitter emits ionizing radiation to irradiate cancerous tissue. The X-ray emitter can be moved within the introducer to ensure that a sufficient radiation dose is provided to all of the target tissue. In particular, a mechanism advances and retracts the X-ray emitter within the introducer. Because a large proportion of the delivered power is converted to and emitted as heat by the X-ray emitter, a cooling system is included to control the temperature of the introducer. Flowing liquid coolant serves as a cooling mechanism for the X-ray emitter and the introducer.
 Temperature sensors placed around the periphery of a tumor, monitor the temperature of treated tissue. As temperature begins to exceed a therapeutic temperature range, the temperature reading unit actuates a switch and the microwave generator is turned off or slowed down. If the temperature is below the therapeutic range, the temperature reading unit actuates a switch to activate the microwave generator to either turn on the unit or increase its power. In this way, the heat energy necessary to kill cancer cells in a growth does not exceed a level which might possibly harm healthy cells in the region surrounding the tumor.
 In a second embodiment of a device for simultaneously treating a tumor or cancerous growth with hyperthermia and X-ray radiation, an introducer is comprised of a rigid plastic material, transparent to microwave radiation. The introducer includes a sharp tip for piercing skin and for entering a tumor. The device is designed to allow alternative doses of microwave radiation and X-ray radiation. The introducer is connected to an X-ray leg and a microwave leg. An X-ray emitter is located within a hollow core of introducer, and has a high voltage miniature cable extending through the X-ray leg. The X-ray emitter is attached to the high voltage miniature cable, which is connected to a push-pull device. The push-pull device can retract the X-ray emitter to a point outside of the introducer and into the X-ray leg.
 A microwave antenna is connected to the distal end of a coaxial cable, which extends through the microwave leg, and a push-pull device. The microwave antenna can be advanced into the hollow core of the introducer, and retracted from the hollow core of the introducer into the microwave leg using the push-pull device.
 In use, a controller operates to activate a high voltage source when the Xray emitter is properly positioned within the introducer. The controller also controls the movement of the X-ray emitter by means of the push-pull device. The controller deactivates the high voltage source and activates the push-pull device to retract the X-ray emitter to an idle position in X-ray leg. The controller then activates the push-pull device to advance the microwave antenna from the microwave leg into the introducer. Once the microwave antenna is properly positioned, the controller activates the microwave generator to provide hyperthermia treatment to cancerous cells.
BRIEF DESCRIPTION OF THE
 The foregoing and other features and advantages of the invention will be apparent from the following, more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.
 FIG. 1 is a schematic of a first embodiment of a device for simultaneously treating a tumor or cancerous growth with hyperthermia and X-ray radiation.
 FIG. 2 shows the device of FIG. 1 in use for treating a tumor.
 FIG. 3 is a schematic of a second embodiment of a device for treating a tumor or cancerous growth by alternating hyperthermia emission and X-ray radiation.
 FIG. 4 is a miniature X-ray device for use in the embodiment of FIG. 1 or FIG. 3.
 FIG. 5 is a graph showing curves of functions over a distance from the introducer axis.
DETAILED DESCRIPTION OF THE
 A preferred embodiment of the present invention is now described with reference to the figures where like reference numbers indicate identical or functionally similar elements. Also in the figures, the left most digit of each reference number corresponds to the figure in which the reference number is first used. While specific configurations and arrangements are discussed, it should be understood that this is done for illustrative purposes only. A person skilled in the relevant art will recognize that other configurations and arrangements can be used without departing from the spirit and scope of the invention.
 Biological tissue exhibits high absorption of low energy X-rays, such as X-rays in the 10-50 keV range. High absorption rates result in high gradients of radiation dose in tissue at or near an X-ray emitter, with only limited penetration of radiation into tissue beyond the immediate area of the X-ray emitter. Thus, local X-ray emission in a tumor can be very high, such as 100 Gy (the gray is the SI unit of measurement for absorbed dose of radiation; symbol=Gy), while still causing little damage to healthy cells surrounding the cancerous cells. Such a dose is high enough to kill even the most resistant to radiation (hypoxic) cells with radiation alone, without supplemental heating. As the distance from the X-ray source increases, the dose decreases to 30-45 Gy at the interface of the tumor and the healthy tissue. As the dose is reduced toward the edges of the tumor, it is helpful to increase temperature of the edge to more effectively destroy these cancerous cells. The present invention increases cell killing at the margin of tumors by preferential heating of this area.
 FIG. 1 shows a schematic of a first embodiment of a device 100 for simultaneously treating a tumor or cancerous growth with hyperthermia and X-ray radiation. Device 100 includes an introducer 102 having a distal tip 104. Distal tip 104 may be needle-like, having a sharp point to pierce and penetrate skin, tissue and cancerous clusters, such as tumors. For the most effective treatment, introducer 102 should be implanted approximately across the center of the tumor to be treated. However, some medical situations, such
as advanced colon cancer, may have a plurality of cancerous conglomerates. In this case, introducer 102 is placed in the proximity of the tumors, such that many cancerous conglomerates can be simultaneously treated.
 Introducer 102 is the exposed portion of an inner wire 112 of a coaxial cable 108. Coaxial cable 108 also includes a metal braid portion 110 serving as an outer conductor. Between inner wire 112 and metal braid portion 110 is an insulating dielectric material 114. The configuration of coaxial cable 108 allows introducer 102 to serve as a microwave emitter when an electrical current is passed through metal braid portion 110 and across dielectric material 114.
 Coaxial cable 108 is connected to a connector 116 which serves as a coupling between coaxial cable 108 and a second coaxial cable 118, which extends from connector 116 to a microwave generator 120. Microwave generator 120 continuously generates microwaves at an adjustable frequency, such as 1.5 GHz.
 The frequency of the microwaves generated from microwave generator 120 is usually in the range of 1-5 GHz. The frequency of the microwaves may be selected from a plurality of oscillation frequencies that can be generated from microwave generator 120 depending on the length of introducer 102, also serving as the microwave emitter. An optimal operating frequency can be selected to achieve penetration of the microwave radiation into the surrounding tissue, adequate for heating a particular sized tumor.
 Microwave generator 120 can be of any desired construction. Preferably it is a commercially available product, such as one made by Matsushita Electric Industries, Ltd. of Tokyo, Japan. A generator can be modified so as to produce lower power output levels sufficient for the purposes to which the present invention is to be placed. Typically a microwave generator generates 15-100 watts of power, which is emitted through introducer 102 into surrounding tissue, warming the tissue.
 Introducer 102 contains a hollow core 106 which houses an X-ray emitter 122. In FIG. 1, introducer 102 is shown with a cutout, revealing X-ray emitter 122. X-ray emitter 122 is connected to a high voltage miniature cable 124 which extends from X-ray emitter 122 to a high voltage power source 126. High voltage power source 126 delivers 25-50 kV through high voltage miniature cable 124 to X-ray emitter 122. High voltage miniature cable 124 is a miniature coaxial cable, having a center conductor connected to an anode and an outer conductor connected through an outer surface of emitter 122 to an anode, as described in detail with reference to FIG. 4.
 X-ray emitter 122 emits ionizing radiation in a donut-like irradiation pattern, primarily in radial directions. Thus, as emitter 122 radiates cancerous tissue, it is necessary to move X-ray emitter 122 along a longitudinal axis 146 of introducer 102 so that a radiation dose is provided to all of the target tissue. A push-pull mechanism 128 advances and retracts X-ray emitter 122 within introducer 102. Push-pull mechanism 128 may be attached to connector 116 or may be located elsewhere, provided it is attached to high voltage miniature cable 124. Push-pull mechanism 128 advances X-ray emitter 122 toward distal tip 104 within introducer 102 by applying a compressive force, or pushing, high
voltage miniature cable 124 from a point on high voltage miniature cable 124 located outside of the patient's body. Likewise, push-pull mechanism may retract X-ray emitter 122 away from distal tip 104 within introducer 102 by applying a tensile force, or pulling, high voltage miniature cable 124 from a point on high voltage miniature cable 124 located outside of the patient's body. Because X-ray emitter 122 is fixedly attached to high voltage miniature cable 124, any force applied to advance or retract high voltage miniature cable 124 will likewise advance or retract X-ray emitter 122.
 Push-pull mechanism 128 may be any commonly available apparatus capable of displacing attached components, as would be apparent to one skilled in the relevant art. The embodiment shown in FIG. 1 shows a push-pull mechanism 128 comprising a threaded axle shaft 130 secured within a housing 132. Threaded axle shaft 130 is rotatable about its axis. A threaded nut 134, having the same thread gauge as threaded axle shaft 130, is threaded onto threaded axle shaft 130. Threaded nut 134 is secured in housing 132 such that threaded nut 134 does not rotate around threaded axle shaft 130. Thus, as threaded axle shaft 130 rotates, threaded nut 134 is moved linearly along threaded axle shaft 130.
 A rigid bar 136 is fixedly secured to both threaded nut 134 and high voltage miniature cable 124. As threaded axle shaft is rotated about its axis, threaded nut 134, bar 136 and high voltage miniature cable 124 linearly move to advance or retract X-ray emitter 122. Push-pull mechanism 128 is preferably adapted to provide an automated, computer-controlled, continuous or step-wise motion. Operation of push-pull mechanism could be controlled by a remote control box. Preferably, push-pull mechanism is operated by a control box that includes both high voltage source 126 and control of push-pull mechanism 128, so that control of X-ray emitter 122 is completely controlled by-a single operating device. However, as would be apparent to one skilled in the relevant art, control of high voltage source 126 and pushpull mechanism 128 could be performed separately.
 Due to inefficiencies common in X-ray devices, only a small fraction of the power delivered to X-ray emitter 122 by high voltage source 126 is converted to ionizing radiation. A large proportion of the delivered power is converted to and emitted as heat by X-ray emitter 122. Additionally, introducer 102 can generate heat as it is used as a microwave emitter. As stated above, it is desirable to control the heat output of device 100 so that healthy cells are not damaged. Furthermore, the searing of any cell within a body can be quite painful.
 Device 100 includes a cooling system to control the temperature of introducer 102. Liquid coolant, denoted by arrows 138, serves as a cooling mechanism for X-ray emitter 122 and introducer 102. The cooling system is comprised of an inlet tube 140 and an outlet tube 142. Inlet tube 140 and outlet tube are each fluidly connected to hollow core 106. A liquid pump (not shown) is connected to inlet tube 140 and forces liquid through inlet tube 140 and into hollow core 106, thereby causing the liquid to be circulated through hollow core 106. Likewise, the pressure buildup inside hollow core 106 causes the liquid to exit through outlet tube 142. In a preferred embodiment, fluid exits outlet tube 142 into a reservoir (not shown), from which the pump draws