Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
  • A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
  • A61B18/18—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves
  • A61B18/1815—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by applying electromagnetic radiation, e.g. microwaves using microwaves
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods
  • A61B2017/00017—Electrical control of surgical instruments
  • A61B2017/00022—Sensing or detecting at the treatment site
  • A61B2017/00084—Temperature
  • A61B2017/00092—Temperature using thermocouples

Definitions

• TECHNICAL FIELD Microwave treatment of cancer is currently in clinical trial.
• the microwaves which are believed by many to be less harmful than X-rays and gamma rays, heat the tissue upon ir ⁇ radiation.
• Malignant tumors often turn out to be more sen ⁇ sitive to heat than normal tissue, so that upon prolonged heating by microwave irradiation, the tumors can be destroyed while the normal tissue is unharmed.
• an intracavitary microwave applicator having improved tissue pen- ' etration due to the use of an optimal lower frequency and longer wavelength so that, as stated before, 5 to 6 cm. of penetration may be obtained.
• This permits the extensive irradiation of large tumors of the bowel and the like, so that the entire tumor area can be irradiated.
• the bowel, esophagus, or surgically-created, temporary bod apertures may be entered by the antenna of this invention , and irradiated.
• microwave antenn .system of this in vention provides an improved cooling system for prevention of burning, which is critical to avoid in unseen, interior portions of the body.
• a microwave anten system being adapted for • intracavitary' insert for inducing hyperthermia by microwave irradiation for can treatment.
• the antenna system comprises an elongated ante adapted to laterally propagate a generally uniform field o microwaves of a wavelength of 85 to 120 cm.
• a preferably flexible dielectric jacket surrounds the antenna, with the jacket having an* enclosed outer end, but open at its inner end.
• a plurality of air flow conduits pass through the in end of the jacket and terminate within the jacket at diffe ent distances from the outer end.
• air entering the flow conduits is released within differen portions of the jacket interior, which may preferably cor- respond to the "hot spots" of the microwave antenna system for optimum cooling. The released air then exits the jack from the inner end.
• electronic temperature mea suring means prefferably be positioned on the jacket, with lead wires extending from the electronic temperature measuring means through the inner end of the jacket to connection wi temperature readout means.
• impedance matching means prefferably be provided in electrical connection with the antenna to permit matching the impedance of surrounding tissue volume when the antenna system is inserted into a body cavity.
• the microwave antenna system of this in ⁇ vention is operated at essentially a 100 cm. wavelength.
• the use of the specified wavelengths of microwaves propagated in accordance with this invention provides not only improved effective penetration of the'microwaves through tissue, so that large areas may be irradiated, but also the size of the antenna capable of effectively propagating such microwaves is substantially reduced from the corresponding sizes of the antennas of the prior art utilized for propa- gating microwaves of lower frequency. This is an obvious significant advantage for an antenna which is intended to be inserted into body cavities.
• the microwave antenna system of this invention prefferably includes a coaxial cable antenna defining an inner conductor and outer cylindrical conductor.
• the outer con ⁇ ductor is folded rearwardly beginning at a point from 10 to 16 centimeters from the end of the antenna and extending from such a point in the direction away from the end of the an ⁇ tenna by a distance essentially, equal to the.spacing of the point from the end of the antenna.
• the antenna is adapted to radiate microwaves of a wave ⁇ length of 85 to 120 centimeters, with the microwave antenna system being enclosed in the jacket as described above.
• Such an antenna structure provides relatively uniform lateral emission of microwaves with the suppression of "hot spots" _ in_. he-pattern of microwave emission.
• the size of the antenna is not excessive, which is an ad ⁇ vantageous feature, coupled with the improved penetrability of microwaves of the wavelength specified above, so that an antenna which is both insertable into a body orifice, coup ⁇ led with an antenna that radiates microwaves having the de ⁇ sirable 5 to 6 centimeters of tissue penetration, is pro ⁇ vided.
• the cooling system of this invention preferably includes the pair of air conduits, one of which extends through the sleeve to the forward end of the anten ⁇ na, and the other of which extends to said point of folding of the outer conductor, which is a point of particularly strong microwave emission.
• a special and selected pattern of air flow is provided to counteract excessive h ing of the antenna in an optimal way.
• the wavelength of the microwaves radiat is from 90 to 110 centimeters and specifically 100 centi ⁇ meters.
• the distance of said point folding to the end of the antenna is essentially 12.5 c timeters, with the length of said folded portion of the o cylindrical conductor being also 12.5 centimeters, a total of 1/4 wavelength.
• a detuning sleeve may also be desirable fo ⁇ a detuning sleeve to be carried by the cylindrical outer conductor, the detuning sleeve being connected to the cylindrical conductor at a position of the outer conductor. Furthermore, it is prefe red for a gap of 2 to 3 centimeters to be present between the folded portion of the outer cylindrical conductor and the detuning sleeve, with the detuning sleeve extending toward the outer end of the antenna from its point of con ⁇ tact with the outer cylindrical conductor.
• the temperature se ing means prefferably have connected lead wires that pass through a inner tubular conduit means.
• This tubular conduit means m in turn reside in a dielectric tube that is carried by the sleeve and communicates with the interior of said sleeve through an aperture thereof.
• the inner tubular conduits containing the lead wire and the temperature sensing means may be re- moved from the dielectric sleeve when desired for maintena and the like, and also may be placed into the dielectric sleeve as desired for use, with the electronic temperature sensing means being positioned generally in the aperture o the sleeve.
• the electronic temperature sensing means a microthermocouple.
• Figure 1 is a longitudinal sectional view of one embodiment of the .microwave antenna system of this invention, shown partly schematically, .and with portions broken away.
• FIG. 2 is another embodiment of the microwave an ⁇ tenna system of this invention, also shown partly schema ⁇ tically..
• Figure 3 is a detailed, enlarged sectional view of the dielectric sleeve and related parts.
• the microwave antenna system of this invention is adapted for insertion into a body cavity such as the colon for inducing hyperthermia by microwave ' irradiation for cancer treatment.
• Coaxial cable 10 termin ⁇ ates in an antenna 11 with its outer tubular conductor 12 being folded back at point 14 to define a folded-back section 16, while central conductor 18 extends outwardly.
• the length ' of the exposed end 19 of central conductor 18 from its end 20 to point of folding 14 is equal to the length of the folded portion 16, for providing optimum irradiation charac ⁇ teristics.
• the distance between end 20 and point 14, as well as the length of folded portion 16, is also preferable for the distance between end 20 and point 14, as well as the length of folded portion 16, to each equal one-eight of the length of the wavelength intended for use. Specifically, when a wavelength of " IOTP " centimeters is used, it is preferable for the above two re ⁇ spective distances to each be 12-1/2 centimeters.
• Coaxial cable 10 and the antenna portion are surrounded by a dielectric jacket 22, which is closed at its forward end 24 and typically open at its rear end 26.
• Apertures 28 may be formed in jacket 22, particularly when the antenna system is intended for shallow penetration into a body aper ⁇ ture, for example in the mouth and upper throat. Typically when the antenna system is intended for deep penetration into the bowel or the like apertures 28 are not used.
• a plurality of air flow conduits 30, 32 are p passing through inner end 26 of the jacket 22, and termina ting within the jacket at different distances from outer e 24. As specifically shown, one air flow conduit 30 terminates adjacent to point 14, while the other conduit 32 ter- minates adjacent to end 20 of the antenna. Alternatively, conduit 32, or a third conduit if desired, may terminate a the rear end 34 of folded portion 16 of outer cylindrical antenna number 12. Accordingly, as air passes through con duits 30, 32, jacket 22 is continuously cooled by the acti of the flowing air, with the air flowing from the respecti conduits 30, 32 into the interior of jacket 22 and then ou rear end 26 of the jacket. The presence of conduit 30 ad ⁇ jacent to point 14 provides added cooling to. the "hot spot which may be generated during microwave Irradiation from t area of the antenna.
• the tissue within which jacket resides during operation remains cooled by the presence of the continuously cooled jacket, so that burning of the tis sues adjacent the jacket may be avoided.
• the electronic temperature measuringme 36 typically microthermocouples, are positioned on jacket Lead wires 38 extend through inner conduits 40 made of a d electric material, so that microthermocouple 36, lead wire 38, and inner conduits 40 comprise a discrete unit.
• Outer conduits 42 which may be made of Teflon or the like, are attached at their ends as shown' to jacket 22 and surroundi an aperture 44 in the jacket.
• the thermocouple 36 ma be threaded into outer conduit 42 and positioned at its de sired place.
• thermocouple, inner conduit, and lead wire may be removed as a unit and/or replaced with another unit.
• outer conduit 42 can be threaded through various apertures 46 in jacket 22 for firm retention there Lead wires 38 may then continue to a conventional temperature readout device for the microthermocouple 36, s that the temperatures of the various microthermocouples ma be continuously monitored.
• the above structure provides a convenient system for temperature monitoring of the device of this invention in which the lead wires are protected by the Teflon outer con ⁇ duits 42, and yet the thermocouples and lead wires may be removed by maintenance or replacement as is required. Also, the latter structure may be preserved for future use, while jacket 22 and the enclosed antenna may be utilized ' only with respect to one patient and then disposed of.
• Impedance matching means is provided in the form of a tuning stub 48, in communication with coaxial cable 10, to permit matching the impedance of surroundin 'tissue volume when the antenna system is inserted into a body cavity.
• FIG. 2 The embodiment of Figure 2 is similar to that of Fig ⁇ ure 1, including coaxial cable 10, jacket 22, and the folded antenna portion of the outer sleeve 16a plus the projecting inner antenna portion of identical design to that of the previous embodiment.
• Air tubes 30a and 32a are also provided to be of equivalent function to the corresponding air tubes of the previous embodiment, along with the related structure which is also of analogous design. The same microwave fre ⁇ quencies may be used.
• jacket 22a is shown to be without perforations and thermocouples, although such'may be used if desired, as previously ⁇
• a detuning sleeve " member 50 is provided, it being connected to outer tubular conductor 12a and extending toward folded portion 16a, being preferably of identical length to folded portion 16a. It is preferred for the space 52 between detuning sleeve 50 and the folded tubular portions 16a to be from 2 to 3 centimeters to avoid causing the detuning sleeve to emit radiation.
• the function of the detuning sleeve 50 is primarily to block rear leakage of radiation, so that the radiation is concentrated in the desired areas.
• a microwave antenna system which yields the combined advantages of increased tissue penetration, coupled with improved means for eliminating burning of adjacent tissues, and further coupled with an a tenna of manageable size so that it can be effectively use for insertion into the body orifice of a patient.
• Antenna of lower wavelength and higher frequency exhibit substan ⁇ tially less penetration of tissue, which is undesirable in many circumstances.
• Antennas of longer wavelength do not exhibit great improvement in tissue penetrability, and at the same time such antennas must generally be larger and t quite difficult to effectively use clinically for the pene tration of body orifices.
• a higher percentage of radiation of the particular frequency utilized in this invention is absorbe by the tumor- tissues, relative to that absorbed in healthy tissues, than at the higher frequencies which have been mo ⁇ commonly used in tumor therapy.

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• Health & Medical Sciences (AREA)
• Surgery (AREA)
• Life Sciences & Earth Sciences (AREA)
• Biomedical Technology (AREA)
• Medical Informatics (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Electromagnetism (AREA)
• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Heart & Thoracic Surgery (AREA)
• Otolaryngology (AREA)
• Molecular Biology (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Radiation-Therapy Devices (AREA)

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• 1981
  • 1981-06-16 WO PCT/US1981/000809 patent/WO1981003616A1/en not_active Ceased
  • 1981-06-16 EP EP19810901955 patent/EP0054064A1/de not_active Withdrawn

Non-Patent Citations (1)

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