Patent Application
20080004478
a is a side view of an integrated embodiment of the invention comprising an x-ray source, imaging, targeting, flush and suction functionality, steer-ability, and illumination in one device.
b is a cross-sectional view through the shaft of the embodiment of
c is a partially sectioned side view of the tip of the embodiment of
d is a distal end view of the tip of the embodiment of
Within the endoscope 101 is a radiation source catheter 501, having a miniature x-ray tube 502 at its distal tip and a hub 503 at its proximal end. The power supply 400 provides power to drive the x-ray tube 502 through a power connection cable 401. The radiation source 502 has a distally directed radiation beam 105, such that radiation beam can be directed onto tumor 201 by manipulating the distal tip of endoscope 101 within the operating field. Alternatively, the beam can be directed elsewhere. At the proximal end of the catheter 501 is the catheter hub 503. The hub comprises a connection to the power cable 401 coming from the power supply 400 to drive the x-ray tube, a connection to the on/off switch 504, and an optional suction, flush or vent system 505 connection communicating with the distal tip of the catheter 501, as described above.
The endoscope 100 generally has a flexible section which can be steered as desired by the therapist. The endoscope has a hub 103 at its proximal end, the controls of which can be used to manipulate the direction in which the distal tip is directed, and hence the catheter tip and/or visualization apparatus. Such controls are well understood by those of skill in the art, and are therefore not detailed here. By hand manipulation of the endoscope, the lesion can be illuminated and targeted, and by advancing or withdrawing the catheter 501, the distance from the radiation source 502 to the lesion 201 can be optimized for therapeutic effect. Because visualization methods such as those described often lack the means to provide depth perception, the catheter may be advanced to touch a visualized surface within the operative field, then withdrawn a calculated distance for free beam targeting at optimal range. Graduated marks 106 can be provided on the catheter shaft at or about the endoscope hub 103 to facilitate this procedure.
The input device (keyboard, tablet or voice-actuated device) 302 is used to input prescription dose parameters for the x-ray source 502 into the processor 303. The processor 303 computes input voltage and current (and if required, laser light) parameters corresponding to the prescription, and commands the power source 400 as necessary to produce the prescribed dose. During therapy, a manual switch 504 emanating from the catheter hub 503 is used to control whether the source 502 is powered and active. Preferably, the switch 504 is normally open (switching radiation off when untended) such that radiation is only emitted while the therapist manually closes the switch. If desired, the source catheter 501 or endoscope 101 may include a lumen or lumina connected to a circuit 505 connected to a suitable receptacle (not shown) to vent, flush or suction the operative field.
If a greater degree of automation is desired, the apparatus and system may further comprise optical recognition methodology as described in co-pending patent application Ser. No. 60/742,118 filed Dec. 2, 2005, the specification of which is included by reference herein in its entirety. The processor system may then optionally comprise a timer and audible signaling device, for example a buzzer, to indicate to the therapist when the prescribed dose has been delivered. This is accomplished by cumulatively tracking delivered dose intensity over time. By comparing the real-time cumulative dose with a prescribed treatment plan and prescription dose information entered into the processor, verification of treatment to prescription can be accomplished and radiation emission may then be terminated. This system eliminates treatment beyond defined lesion boundaries as determined by the therapist, and can further modulate dose intensity within the treatment area.
a through 3d depict a single device with all functionalities described above combined into one device embodiment. Other functionality could be included or substituted. Device 600 shown in
Targeting is accomplished by edge fibers 613 positioned at the circumferential extremes of lumina 611. (See
Adjacent to the source 605 at the distal tip of shaft 601 are two chip cameras 604 in diametrically opposed positions. With this arrangement, stereoscopic visualization is provided through a visualization cone 607 (phantom line cone in
Although the above describes a source-bearing catheter positioned in a lumen of an endoscope or device, the construction can be otherwise and more integral. With the x-ray source 605 at the distal end of the device, the shaft 601 can be constructed in various ways, so long as the source 605 is supported by adequate dielectric and standoff spacing for high-voltage conductors leading through the shaft. The dielectric material can be formed solidly and fixedly in the center of the endoscope 600. The entire shaft 601 or endoscope 600 could be of dielectric material, with conductors adequately spaced and not necessarily in the central space described as a lumen with catheter 615 in
The miniature electronic x-ray source 502, 605 described in connection with an endoscope has great advantages over treatment with isotope radiation.
Radiation from radioisotopes is emitted in a known manner with a decaying intensity measured by the isotope's half-life—the time at which half the original intensity remains. Within practical time constraints, these parameters for a given radioisotope are fixed and they cannot be altered thus offering no possibilities for control. Furthermore, radioisotopes emit radiation at a few distinct energy bands, radiation from each band having its own ability to penetrate tissue and deliver dose. For example, the high-energy band of radiation emitted from 192Ir, the most common high dose-rate brachytherapy isotope, penetrates through large thicknesses of shielding materials. In addition, isotopes are always “on”, so controlling the output with on/off switching is not possible. Other common medically relevant radioisotopes also have emission spectra containing high energy components that make selective shielding within a body cavity impractical due to space considerations. The radiation from these isotopes will penetrate any practical thickness of shielding material. This high-energy radiation easily penetrates well beyond the target site requiring therapy, thus delivering radiation to healthy parts of the body and risks injury.
In contrast, with electronically controlled radiation sources, the shape of the anode and its structure, and any minimal shielding utilized, determines the directionality of the x-rays emitted. The emitted x-rays may be emitted isotropically, they may be directed radially, axially, or a combination thereof. Anode shaping is well known by those skilled in the art of x-ray generation apparatus. Anode shape, target thickness and target configuration can be used to change the radiation profile emitted from the miniature x-ray source. For low energy miniature x-ray sources, thin radiation shields can easily produce directional radiation. For electronically produced x-rays, the acceleration voltage determines the energy spectrum of the resulting x-rays. The penetration of the x-rays in tissue is directly related to the energy of the x-rays. The cumulative radiation dose directed at a point of the lesion may be controlled by x-ray source beam current or “on” time within the body of the patient.
In using the system of the preferred embodiment, the therapist enters the desired prescription dose into the processor system 300. The processor computes power parameters and transmits those to the power supply 400. The therapist then positions the endoscope 100 within the anatomical cavity in which the treatment is to take place, and if necessary, performs flushing and/or suctioning to prepare the treatment field. This can be done under direct visualization. Next, and if needed, the therapist can verify calibration of the radiation source using an ion chamber or similar device. Then, the radiation catheter 501 is introduced and positioned to treat the lesion, both by use of the endoscope controls and by advancing the catheter 501 to achieve the proper treatment range between the tip of the source and the lesion. When ready to proceed with the treatment, the therapist closes the switch 504, continually or intermittently as desired, until the processor alarm sounds (or total time is determined by other means) at which point the switch 504 is opened (released), concluding the treatment. As previously described, some of these steps may be wholly or partially automated.
Although this embodiment is discussed with particular reference to endoscopic practice, similar methods can be utilized with either laparoscopic or catheter methods without departing from the scope of the invention. References to endoscope or endoscopic in the claims is to be taken as referring to any of those instruments and methods.
The above-described preferred embodiments are intended to illustrate the invention, but not to limit its scope. Other embodiments and variations to these preferred embodiments will be apparent to those of skill in the art and may be made without departing from the spirit and scope of the invention.
