Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Thermal applicators
Reexamination Certificate
1997-07-22
2001-04-10
Dvorak, Linda C. M. (Department: 3739)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Thermal applicators
C607S102000, C607S104000, C607S105000, C607S113000
Reexamination Certificate
active
06216041
ABSTRACT:
The present invention relates generally to an apparatus and method for performing a thermotherapy patient treatment protocol. More particularly, the invention relates to a novel apparatus and method for irradiating and/or heating internal organs, such as the prostate gland, for therapeutic purposes.
Thermotherapy treatment is a relatively new method of treating diseased and/or undesirably enlarged human tissues. Hyperthermia treatment is well known in the art, involving the maintaining of a temperature between about 41.5° through 45° C. Thermotherapy on the other hand usually requires energy application to achieve a temperature above 45° C. for the purposes of coagulating the target tissue. Tissue coagulation beneficially changes the density of the tissue. As the tissue shrinks, forms scars and is reabsorbed, the impingement of the enlarged tissues, such as an abnormal prostate, is substantially lessened.
The higher temperatures required by thermotherapy require delivery of larger amounts of energy to the target tissues. At the same time, it is important to shield nontarget tissues from the high thermotherapy temperatures used in the treatment. Providing safe and effective thermotherapy, therefore, requires devices which have further capabilities compared to those which are suitable for hyperthermia.
Though devices and methods for treating benign prostatic hyperplasia have evolved dramatically in recent years, significant improvements have not occurred and such progress is badly needed. As recently as 1983, medical textbooks recommended surgery for removing impinging prostatic tissues and four different surgical techniques were utilized. Suprapubic prostatectomy was a recommended method of removing the prostate tissue through an abdominal wound. Significant blood loss and the concomitant hazards of any major surgical procedure were possible with this approach.
Perineal prostatectomy was an alternatively recommended surgical procedure which involved gland removal through an incision in the perineum. Infection, incontinence, impotence or rectal injury were more likely with this method than with alternative surgical procedures.
Transurethral resection of the prostate gland has been another recommended method of treating benign prostatic hyperplasia. This method required inserting a rigid tube into the urethra. A loop of wire connected with electrical current was rotated in the tube to remove shavings of the prostate at the bladder orifice. In this way, no incision was needed. However, strictures were more frequent and repeat operations were sometimes necessary.
The other recommended surgical technique for treatment of benign prostatic hyperplasia was retropubic prostatectomy. This required a lower abdominal incision through which the prostate gland was removed. Blood loss was more easily controlled with this method, but inflammation of the pubic bone was more likely.
With the above surgical techniques, the medical textbooks noted the vascularity of the hyperplastic prostate gland and the corresponding dangers of substantial blood loss and shock. Careful medical attention was necessary following these medical procedures.
The problems Previously described led medical researchers to develop alternative methods for treating benign prostatic hyperplasia. Researchers began to incorporate heat sources in Foley catheters after discovering that enlarged mammalian tissues responded favorably to increased temperatures. Examples of devices directed to treatment of prostate tissue include U.S. Pat. No. 4,662,383 (Harada), U.S. Pat. No. 4,967,765 (Turner), U.S. Pat. No. 4,662,383 (Sogawa) and German Patent No. DE 2407559 C3 (Dreyer). Though these references disclosed structures which embody improvements over the surgical techniques, significant problems still remain unsolved.
Recent research has indicated that enlarged prostate glands are most effectively treated with higher temperatures than previously thought. Complete utilization of this discovery has been tempered by difficulties in shielding rectal wall tissues and other nontarget tissues. While shielding has been addressed in some hyperthermia prior art devices, the higher microwave energy field intensities associated with thermotherapy necessitate structures having further capabilities beyond those suitable for hyperthermia. For example, the symmetrical devices disclosed in the above-referenced patents have generally produced relatively uniform cylindrical energy fields. Even at the lower microwave energy field intensities encountered in hyperthermia treatment, unacceptably high rectal wall temperatures have limited treatment periods and effectiveness. Further, while shielding using radioreflective fluid has been disclosed in the prior art (see for example European Patent Application No. 89,403,199) the location of such radioreflective fluid appears to increase microwave energy field intensity at the bladder and rectal wall. This is contrary to one of the objects of the present invention.
Additionally, many prior art references appear to require traditional rubber anchoring balloons for secure placement and retention of a variety of treatment and bladder drainage devices. Further, these devices are typically flexible and have no stiffening capability for straightening the treatment path for more efficient and consistent treatment.
In addition, efficient and selective cooling of the devices is rarely provided. This increases patient discomfort and increases the likelihood of healthy tissue damage. These problems have necessitated complex and expensive temperature monitoring systems along the urethral wall.
Finally, the symmetrical designs of the above-referenced devices do not allow matching of the microwave energy field to the shape of the abnormally enlarged prostate gland. Ideally, the microwave energy field reaching the tissues should be asymmetric and generally should expose the upper and lateral (side) impinging lobes of the prostate gland to the highest energy. In addition, the field is ideally substantially elliptical such that the energy reaching the sphincters is minimized.
It is therefore an object of the invention to provide an improved apparatus and method suitable for thermotherapy or hyperthermia treatment.
It is a further object of the invention to provide an improved apparatus and method for thermotherapy treatment which provides substantially uniform irradiation of target tissues while effectively shielding nontarget tissues from the temperatures of treatment.
It is another object of the invention to provide an improved thermotherapy device which includes a collimated irradiation of a target zone generally and selective cooling of nontarget tissues.
It is yet a further object of the invention to provide an improved thermotherapy device which is capable of carrying radioreflective and/or radiation absorptive fluid in one or more cooling chambers, while utilizing radiotransparent liquid in one or more cooling passages.
It is yet another object of the invention to provide an improved thermotherapy device which is capable of carrying a sound absorptive or reflective substance in one or more chambers, while utilizing a sound transparent substance in at least one other passage.
It is still another object of the invention to provide an improved thermotherapy device which is capable of carrying a light absorptive or reflective substance in one or more chambers, while utilizing a light transparent substance in at least one other passage.
It is yet an additional object of the invention to provide a novel thermotherapy device having at least one chamber lined with a substance which is reflective or absorptive to light, sound or microwaves.
It is still an additional object of the invention to provide a novel thermotherapy device having two or more chambers wherein a chamber located adjacent to the target tissue can be maintained at higher temperatures than the one or more chambers adjacent nontarget tissues.
It is a still further object of the invention to provide an improved method and apparatus for thermotherapy treatment which
diMonda Richard
Tierney Mark
Dvorak Linda C. M.
Kearney R.
Lyon & Lyon LLP
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