Patent Application
20100130880
This invention relates to monitoring blood flow in the prostate gland. Embodiments of the invention provide methods and systems for treating tumors or other tissues within the prostate gland.
Prostate cancer, benign prostatic hyperplasia and other conditions can cause the prostate to become enlarged. These conditions can result in urinary blockage and other adverse effects on health. These conditions are sometimes treated by selectively heating tissues of the prostate gland. Some systems for heating the prostate gland and tissues use a temperature sensor inserted in the subject's rectum to measure the amount of heat being delivered to the prostate gland. Since the rectum passes close to the prostate gland, the temperature measured in the rectum can be useful in controlling the application of heat to raise the temperature of the prostate gland.
There is a need for improved methods and apparatus for heating the prostate gland which provide better control over the temperatures achieved in the prostate gland.
Near Infrared Spectroscopy (“NIRS”) is a technique which involves emitting near infrared (“NIR”) light and receiving the NIR light after it has passed through a tissue or other medium of interest. NIRS can be applied to study and monitor biochemical compounds in the body. Emitted NIR light penetrates skin and other tissues and some of it is absorbed by biochemical compounds which have an absorption spectrum in the NIR region. NIR light which is not absorbed is scattered. Each biochemical compound has a different absorption spectrum. It is possible to estimate the concentration of biochemical compounds in the tissues by measuring characteristics of NIR light that has been detected after it has passed through the tissues. The use of NIRS to measure changes in concentrations of various compounds in living tissues by monitoring appropriate wavelengths is understood by those of skill in the art.
This invention provides a range of methods and apparatus that can be used together in various combinations, can be used individually or can be used in combination with other methods and apparatus.
Various non-limiting example aspects of the invention and features of example embodiments of the invention are described below.
The accompanying drawings illustrate non-limiting embodiments of the invention.
Throughout the following description specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense.
Apparatus 10 comprises a heater 12 that directs energy 14 toward the subject's prostate gland P. Heater 12 may heat the tissues of the prostate using any suitable modality. For example, heater 12 may comprise one or more of:
The output of heater 12 is controlled by a heater controller 16. Heater controller 16 takes as an input a tissue temperature signal 17 from a tissue temperature sensor 18. In the illustrated embodiment, tissue temperature sensor 18 comprises a probe 20 that is inserted into the rectum R of the subject. Probe 20 senses the temperature at a point 20A which is adjacent to the subject's prostate when probe 20 is inserted into the subject's rectum R. Temperature sensor 18 and its associated probe 20 are desirable but optional.
Heater controller 16 may provide closed-loop control of energy 14 based on feedback from temperature sensor 18 and/or other sensors to achieve a desired temperature within the tissues of prostate P.
Apparatus 10 also includes a near infrared spectrometer system (NIRS system) 22 that monitors blood flow in the subject's prostate. Near infrared spectrometry is a known technique that can be used to monitor for changes in the concentrations of various bio-compounds in living tissues. For example, NIRS can be used to monitor the concentrations of one or more of:
NIRS involves directing near infrared light from a light source into tissues of interest and detecting the infrared light after it has passed through the tissues of interest. In the illustrated embodiment, a NIRS light source 25 and light detector 26 are provided on a catheter 30 that can be inserted through the subject's urethra U. An anchoring structure is provided to retain catheter 30 in the subject's urethra. In the illustrated embodiment, the anchoring structure comprises a balloon 32 on the distal end of catheter 30. Balloon 32 can be inflated after the distal end of catheter 30 has passed into the subject's bladder B. Balloon 32 may, for example, be inflated by pumping a fluid into balloon 32 through catheter 30. Balloon 32 retains catheter 30 in the subject's urethra.
Catheters for insertion into the urethra are known. The details of construction and operation of catheter 30 are not described herein since such details can readily be developed by those skilled in the art, for example by reference to commercially-available catheters.
Light source 25 and light detector 26 are spaced apart from balloon 32 by a distance which is suitable to locate source 25 and light detector 26 in the portion of the subject's urethra U that passes through the subject's prostate. Light emitted by light source 25 is back-scattered by tissues in the subject's prostate P and picked up at light detector 26. An amount of one or more bio compounds related to blood flow for example, oxygenated hemoglobin (HbO2); non-oxygenated hemoglobin (Hb); and/or total hemoglobin (HbTot) may be determined by processing the signal from light detector 26. The result is that NIRS spectrometer 22 generates a signal 23 indicative of blood flow in the subject's prostate.
Blood flow in the subject's prostate is important because flowing blood can carry away heat from the subject's prostate. Heater controller 16 may be programmed to increase the output of heater 12 as blood flow increases (e.g. in response to a measure of blood flow determined by NIRS system 22), so as to suitably increase the amount of heat deposited in tissues of the subject's prostate P to compensate at least partially for heat that is carried away by flowing blood, and thereby raise those tissues to a desired temperature.
In some embodiments, heater 12 delivers energy 14 to the subject's prostate P by way of catheter 30. For example, energy 14 could be microwave energy that is delivered from a microwave antenna 34 supported in or on catheter 30. In other embodiments, energy 14 is delivered from outside of the subject. Any suitable mechanism for heating the tissues of the prostate may be used.
There are a wide range of ways in which each of NIRS light source 25 and light detector 26 may be provided in a catheter 30. These can be applied in any combination. Some such combinations are disclosed in the illustrated embodiments.
As an alternative to carrying light along catheter 30 in an optical fibre 42, NIRS light sources such as suitable light-emitting diodes (LEDs) could be provided in catheter 30 and supplied with electrical power by way of wires or other electrical conductors extending along catheter 30.
Light detectors 26 comprise photo transistors, photo-diodes, or other detectors sensitive to light at the wavelengths emitted by light source 25. In the illustrated embodiment, there is a plurality of light sensors 26 that sense light incident from different directions and which also include light sensors 26 that are spaced apart from light source 25 by different distances. The depth within the tissues at which the concentration(s) of the monitored bio-compound(s) is measured depends in part on the separation between light source 25 and a light detector 26. By providing light detectors 26 that are separated from light source 25 by different distances one can determine the blood flow at different depths in the prostate. In
A light barricade 46 is disposed between light source 25 and light detectors 26 to prevent light from passing directly from light source 25 to light detectors 26. In the illustrated embodiment, light barricade 46 has a labyrinth construction to permit the flow of a fluid to inflate balloon 32.
As can be appreciated, the construction of the NIRS light source and receiver may be varied in many ways. In some embodiments, one fixed light source and one fixed light receiver may be provided. The light source may emit light that is directed in a particular direction or may emit light so that it radiates in all directions from catheter 30. In some embodiments, the separation between the light source and detector can be varied. In some embodiments there are a number of pairs of light sources and detectors (for example, one light source and a plurality of different light detectors) in such embodiments the light detectors may be spaced apart by different distances from the light sources so as to sample the concentrations of the bio-compounds being monitored at various depths in the tissue of the prostate gland.
In embodiments where there are a plurality of different light receivers 26, the light receivers 26 may receive light incident on catheter 30 from different directions, thereby making it possible to sense the concentrations of monitored bio-compounds in tissues located on different sides of catheter 30.
In some embodiments, heater controller 16 switches heater 12 on and off (or modulates the output of energy 14) in response to the detection of blood flow by NIRS system 22. Treatment efficacy can be improved by applying heat to tissues of the prostate during periods in which blood flow is below a threshold value and not applying heat during periods wherein the blood flow exceeds the threshold value.
In some embodiments, apparatus 10 includes a mechanism 19 (see
In some embodiments, a NIRS light source and receiver are provided on a rectal probe. In such embodiments, the NIRS light source and receiver on the rectal probe may provide an output indicative of blood flow in a portion of the rectal wall close to a subject's prostate. Changes in the blood flow in the rectal wall can signal the onset of damage to tissues of the rectal wall. Such damage could be caused, for example, by overly-long and/or overly-intense treatment by a heater 12 as described above.
In some embodiments, a controller for a heater receives a rectal-wall-blood-flow signal indicative of blood flow in the rectal wall and causes the heater to be reduced in intensity and/or shut down when the rectal-wall-blood-flow signal satisfies a criterion. The criterion may be selected to cause the heating to be reduced or stopped prior to the rectal wall undergoing significant damage.
In the illustrated embodiment, a rectal wall blood flow monitor 63 receives signals from rectal-wall blood-flow sensor 64 and outputs a rectal wall blood flow signal. In cases where rectal-wall blood-flow sensor 64 generates a signal indicative of blood flow in the rectal wall that can be used directly by heater controller 16 the rectal wall blood flow monitor may not be present or may provide signal conditioning.
Rectal-wall blood-flow sensor 64 may comprise any of a variety of blood-flow sensors. For example, Rectal-wall blood-flow sensor 64 may comprise:
A NIRS system 68 supplies driving signals to NIRS light source 67A and receives signals from NIRS light detector 67B. NIRS system 68 processes signals received from NIRS light source 67A to derive an output signal indicative of blood flow in the rectal wall. The output signal is supplied to heater controller 16.
In some embodiments, the NIRS system 68 generates outputs which represent concentrations in the rectal wall of one or more of:
A heat treatment is initiated at time 72. As the heat begins to act on the subject's prostate and to heat surrounding tissues, blood flow in the subject's rectal wall initially increases. As the rectal wall begins to suffer damage, the blood flow peaks at 73. When the rectal wall has become seriously damaged, the blood flow in the damaged portion of the rectal wall declines precipitously. Curve 70 is schematic only and is not based on any specific clinical data.
Controller 16 may reduce the output of, or shut off, heater 12 by determining that the rectal-wall-blood-flow signal matches a criterion. The criterion may include, for example:
Apparatus 60 preferably operates to prevent heater 12 from operating in a way that causes lasting damage to the subject's rectal wall while allowing heater 12 to operate in a way that will provide sufficient heating to the subject's prostate P to achieve a desired treatment outcome.
In alternative embodiments, probe 60 may comprise a plurality of NIRS light sources 67A and/or a plurality of NIRS light detectors 67B. In such embodiments, the light sources and light detectors may be arranged in various ways. For example:
In embodiments that provide a plurality of pairs of NIRS light sources and detectors, signals from the different pairs of NIRS light sources and detectors may be applied in different ways. In some embodiments, a rectal-wall-blood-flow signal is derived from each of a plurality of NIRS output signals and the rectal-wall-blood-flow signals are each treated separately. In such embodiments, if any one of the rectal-wall-blood-flow signals indicates impending tissue damage to the rectal wall then heater controller 16 may be configured to shut off or reduce the output from heater 12. In some embodiments, a rectal-wall-blood-flow signal is obtained from a plurality of NIRS output signals. For example: NIRS output signals from differently-spaced pairs of NIRS light sources and receivers may be processed and combined to provide a rectal-wall-blood-flow signal characteristic of blood flow at both shallower and deeper parts of the rectal wall; and/or NIRS output signals from pairs of NIRS light sources and receivers facing in different directions may be combined to provide a rectal-wall-blood-flow signal representative of blood flow over a larger area of the rectal wall than is covered by one pair of NIRS light source and light detector.
In some embodiments, heater controller 16 provides a display, or other readout that displays a graph or other indicia indicating one or more blood-flow-signals for the rectal wall and/or prostate. Heater controller 16 may also display indicia indicating when a criterion for shutting off or reducing the output of heater 12 is almost satisfied or has been satisfied.
The curve shown in
Where the prostate-blood-flow signal is compared to a threshold, the threshold may be based on one or more of:
For example, unless a rectal-wall-blood-flow signal satisfies a criterion that causes heater controller 16 to discontinue a treatment, heater controller 16 may be configured to continue treatment (by operating heater 12 continuously or intermittently) until one or more of the following is satisfied:
In some embodiments, heater controller 16 comprises a data processor that executes software instructions that cause it to control heater 12 as described herein. The software instructions may be stored in a memory accessible to the data processor. Aspects of the invention may be provided in the form of program products. The program products may comprise any medium which carries a set of computer-readable instructions which, when executed by a data processor, cause the data processor to execute a method of the invention. Program products according to the invention may be in any of a wide variety of forms. The program product may comprise, for example, physical media such as magnetic data storage media including floppy diskettes, hard disk drives, optical data storage media including CD ROMs, DVDs, electronic data storage media including ROMs, flash RAM, or the like. The computer-readable instructions on the program product may optionally be compressed or encrypted.
In such embodiments, thresholds or other parameters that regulate the operation of heater controller 16 and/or functions that represent criteria for determining whether heater 12 should be shut down or have its output reduced may be stored in a memory accessible to the processor.
While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. For example:
It is therefore intended that the following claims and any claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.
This application claims priority from U.S. patent application No. 61/028,870 filed 14 Feb. 2008 and U.S. patent application No. 60/912,125 filed 16 Apr. 2007. For purposes of the United States of America, this application claims the benefit under 35 U.S.C. §119 of U.S. patent application No. 61/028,870 filed 14 Feb. 2008 and U.S. patent application No. 60/912,125 filed 16 Apr. 2007, both of which are hereby incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CA2008/000698 | 4/16/2008 | WO | 00 | 10/9/2009 |
| Number | Date | Country | |
|---|---|---|---|
| 60912125 | Apr 2007 | US | |
| 61028870 | Feb 2008 | US |
