U.S. patent number RE38,030 [Application Number 09/512,190] was granted by the patent office on 2003-03-11 for use of a-mode echography for monitoring the position of a patient during ultrasound therapy.
This patent grant is currently assigned to Technomed Medical Systems, S.A.. Invention is credited to Emmanuel Blanc, Jean-Yves Chapelon.
United States Patent |
RE38,030 |
Chapelon , et al. |
March 11, 2003 |
Use of a-mode echography for monitoring the position of a patient
during ultrasound therapy
Abstract
An A-mode ultrasound echography method is employed for
monitoring the position of a patient during hyperthermia treatment.
A therapy apparatus includes a therapy device having at least one
ultrasound therapy transducer and at least one monitoring
ultrasound transducer, where the ultrasound monitoring transducer
is linked to an electronic circuit for processing A-mode signals
and is part of an A-mode echography device. The therapy apparatus
further includes a device for causing the ultrasound transducer
operating in A-mode to transmit a brief signal and to receive the
echo of the brief signal. A comparing device compares the echo
received with a reference echo, and transmits the result of the
comparison to a control device.
Inventors: |
Chapelon; Jean-Yves
(Villeurbanne, FR), Blanc; Emmanuel (St. Genis Laval,
FR) |
Assignee: |
Technomed Medical Systems, S.A.
(FR)
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Family
ID: |
9463636 |
Appl.
No.: |
09/512,190 |
Filed: |
February 22, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
451914 |
May 26, 1995 |
05720286 |
Feb 24, 1998 |
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Foreign Application Priority Data
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May 30, 1994 [FR] |
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94 06539 |
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Current U.S.
Class: |
600/439 |
Current CPC
Class: |
A61B
8/12 (20130101); A61N 7/022 (20130101); A61B
8/4272 (20130101); A61B 2017/00119 (20130101); A61B
2017/00274 (20130101); A61B 2018/00547 (20130101); A61B
2090/3784 (20160201) |
Current International
Class: |
A61B
8/12 (20060101); A61N 7/02 (20060101); A61N
7/00 (20060101); A61B 19/00 (20060101); A61B
17/00 (20060101); A61B 008/00 () |
Field of
Search: |
;601/2-4
;600/439,462 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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WO9317646 |
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Sep 1993 |
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DE |
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WO9115154 |
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Oct 1991 |
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FR |
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WO9312742 |
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Jul 1993 |
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FR |
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Other References
IEEE Transactions on Sonics and Ultrasonics, Ultrasonic
Hyperthermia for Ophthalmic Therapy, vol. 31, No. 5, Sep. 1984, pp.
473-481. Rapport De Recherche Preliminaire (Completion date Jan.
23, 1995). .
International Search Report (Completion date Apr. 14, 1993). .
International Search Report (Completion date Jul. 23, 1991). .
International Search Report (Completion date Sep. 3,
1993)..
|
Primary Examiner: Casler; Brian L.
Attorney, Agent or Firm: Welsh & Katz, Ltd.
Claims
What is claimed is:
1. A method of monitoring a position of a patient during a therapy
session, the method comprising the steps of: providing an A-mode
echography device having an A-mode echography transducer;
activating the A-mode echography transducer to determine a distance
between the A-mode transducer and a target structure of the patient
to be monitored, the target structure having a predetermined
relationship to an organ of the patient to be treated; providing a
therapy transducer, the therapy transducer operatively coupled to
the A-mode echography transducer; and determining whether the
therapy transducer is within a predetermined distance relative to
the organ of the patient by monitoring the distance between the
A-mode transducer and the target structure.
2. The method according to claim 1, wherein the distance between
the therapy transducer and the organ of the patient is modified as
a function of movements detected between the A-mode echography
transducer and the organ of the patient.
3. The method according to claim 1, wherein said A-mode echography
device interrupts operation of the therapy transducer if it is
detected that movements of the patient relative to the A-mode
echography transducer are greater than a predefined amount.
4. The method according to claim 1, wherein said A-mode echography
device carries out real time control of the position of the therapy
transducer, with respect to a predetermined reflecting contour.
5. A method for monitoring and treating an organ of a patient
during a therapy session, the treatment of the organ provided by a
therapy device having a therapy transducer, the method comprising
the steps of: a) providing an ultrasound monitoring transducer
operating in A-mode, the monitoring transducer acoustically coupled
to a target structure, the target structure having a predetermined
relationship to the organ to be monitored; b) exciting the
ultrasound monitoring transducer with a signal in the form of a
pulse, the pulse applied during a time interval between the
application of therapy by the therapy transducer; c) receiving
echoes of the signal produced by the monitoring transducer; d)
transforming the received echoes into an electrical signal; e)
locating, in the electrical signal corresponding to the received
echoes, the position of the target structure to determine a
measured distance from the monitoring transducer to the target
structure, the target structure defining a highly echogenic
interface relative to the organ to be monitored and treated; f)
comparing the distance measured between the monitoring transducer
and the target structure with a reference distance, the reference
distance corresponding to the distance between the highly echogenic
interface in contact with a wall of a balloon means corresponding
to the ultrasound therapy transducer; and g) transmitting a control
signal to a control device operative to selectively control the
position of the therapy transducer in response to the change in
distance between the monitoring transducer and the target structure
relative to the reference distance.
6. The method according to claim 5, wherein the control device
triggers an alarm when information is transmitted to the control
device indicating that a change in the measured distance is greater
than a predetermined amount.
7. The method according to claim 5, wherein said control device
performs real time closed-loop control of the position of said
therapy device as a function of the movements of said patient with
respect to a reflecting contour of said patient, said reflecting
contours having a known relationship to the organ of the
patient.
8. The method according to claim 5 wherein said ultrasound
monitoring transducer operating in A-mode is mechanically linked to
said therapy transducer.
9. The method according to claim 5 wherein said therapy device
comprises at least one ultrasound therapy transducer providing
therapy using focused ultrasound.
10. The method according to claim 5 wherein said ultrasound therapy
transducer is arranged inside balloon means filled with an acoustic
coupling fluid.
11. The method according to claim 5 wherein if said measured
distance is smaller than said reference distance, the control
device controls said therapy transducer to increase a distance
between the therapy transducer and the target structure to be
treated while if said measured distance is greater than said
reference distance, the control device controls said therapy
transducer to decrease a distance between the therapy transducer
and the target structure to be treated.
12. The method according to claim 5 wherein said ultrasound therapy
transducer is a focused ultrasound therapy transducer integrated
into an endocavital probe for providing treatment of the prostate
or the thyroid.
13. The method for monitoring and treating an organ of a patient
during a therapy session, the treatment of the organ provided by a
therapy device having a therapy transducer, the method comprising
the steps of: a) providing an ultrasound monitoring transducer
operating in A-mode, the monitoring transducer acoustically coupled
to a target structure, the target structure having a predetermined
relationship to the organ to be monitored; b) exciting the
ultrasound monitoring transducer with a signal in the form of a
pulse, the pulse applied during a time interval between application
of therapy by the therapy transducer; c) receiving echos of the
signal produced by the monitoring transducer; d) transforming the
receive echoes into an electrical signal; e) locating, in the
electrical signal corresponding to the receive echoes, the position
of the target structure to determine a measured distance from the
monitoring transducer to the target structure, the target structure
defining a highly echogenic interface relative to the organ to be
monitored; f) comparing the distance measured between the
monitoring transducer and the target structure, with a reference
distance; and g) transmitting a control signal to a control device
operative to selectively control the position of the therapy
transducer in response to change in distance between the monitoring
transducer and the target structure relative to the reference
distance.
14. The method according to claim 13 wherein the control device
triggers an alarm when information is transmitted to the control
device indicating a change in the measured distance cannot be
determined.
15. The method according to claim 13 wherein the control device
triggers an alarm when information is transmitted to the control
device indicating a change in the measured distance is greater than
a predetermined amount.
16. The method according to claim 13 wherein the monitoring
transducer received the echos reflected from the target structure,
the target structure being at least one of a rectal wall during
prostate treatment and a trachea during thyroid treatment.
17. The method according to claim 16 wherein the target structure
is a reflecting contour having a predetermined relationship
relative to the organ of the patient to be treated.
18. The method according to claim 13 wherein said ultrasound
monitoring transducer operating in A-mode is mechanically linked to
said therapy transducer.
19. The method according to claim 13 wherein said therapy device
comprises at least one ultrasound therapy transducer providing
therapy using focused ultrasound.
20. The method according to claim 13 wherein said ultrasound
therapy transducer is arranged inside balloon means filled with an
acoustic coupling fluid.
21. The method according to claim 13 wherein if the measured
distance between the monitoring transducer and the target structure
is smaller than the reference distance, the control device
increases a distance between the therapy transducer and the organ
to be treated, while if the measured distance between the
monitoring transducer and the target structure is greater than the
referenced distance, the control device controls decreases the
distance between the therapy transducer and the organ to be
treated.
22. The method according to claim 13 wherein the ultrasound therapy
transducer is a focused ultrasound therapy transducer integrated
into an endocavital probe for providing treatment of the prostate
or the thyroid.
23. A therapy apparatus for treating an organ of a patient, the
apparatus comprising: at least one ultrasound therapy transducer
and at least one ultrasound monitoring transducer, the monitoring
transducer operating in A-mode; the ultrasound monitoring
transducer operatively coupled to an electronic circuit for
processing A-mode signals produced by the ultrasound monitoring
transducer; means for coupling the ultrasound monitoring transducer
to transmit a pulse signal, the pulse signal causing an echo to be
received by the ultrasound monitoring transducer, the echo caused
by a reflection of the pulse signal from a target structure, the
target structure defining an echogenic interface having a
predetermined relationship relative to the organ to be monitored;
means for comparing the echo received with a reference echo and
transmitting the result of the comparison to a control device; and
the control device coupled to the means for comparing and coupled
to the ultrasound therapy transducer, the control device receiving
the result of the comparison and controlling the ultrasound therapy
transducer in response thereto.
24. The apparatus according to claim 23, wherein said control
device triggers an alarm in response to the result of the
comparison.
25. The apparatus according to claim 23, wherein said control
device performs real time closed-loop control of the position of
said therapy transducer as a function of the movements of the
patient, the control device controlling the position of the therapy
transducer in real time with respect to a predetermined reflecting
contour of said patient, said reflecting contour having a known
relationship to the organ of the patient to be treated.
26. The apparatus according to claim 23 wherein said ultrasound
therapy transducer is of the focused type.
27. The apparatus according to claim 26, wherein said focused-type
therapy transducer is linked to means for supplying an electronic
signal providing variable focusing.
28. The apparatus according to claim 27, wherein said control
device provides closed-loop control of the focal length of said
therapy transducer as a function of the movements of said patient,
during the course of therapy.
29. The apparatus according to claim 23, wherein both said
ultrasound therapy transducer and said A-mode monitoring transducer
are integrated into an endocavital probe.
30. The apparatus according to claim 23, wherein said therapy
apparatus includes means for continuously recording the echoes
created by said monitoring transducer operating in A-mode.
31. The apparatus according to claims 23, wherein said ultrasound
monitoring transducer is mechanically linked to said therapy
device.
32. The apparatus according to claim 23, wherein said therapy
device comprises at least one ultrasound therapy transducer
providing therapy using focused ultrasound, said ultrasound therapy
transducer enclosed within a balloon means filled with an acoustic
coupling fluid.
33. The apparatus according to claim 23, wherein said apparatus is
operative to treat the prostate or the thyroid.
34. A method for monitoring and treating an organ of a patient
during a therapy session, the treatment of the organ provided by a
therapy device having a therapy transducer, the method comprising
the steps of: a) providing an ultrasound monitoring transducer
operating in A-mode, the monitoring transducer acoustically coupled
to a target structure, the target structure having a predetermined
relationship to the organ to be monitored; b) exciting the
ultrasound monitoring transducer with a signal in the form of a
pulse, the pulse applied during a time interval between the
application of therapy by the therapy transducer; c) receiving
echoes of the signal produced by the monitoring transducer; d)
transforming the received echoes into an electrical signal; e)
locating, in the electrical signal corresponding to the received
echoes, the position of the target structure to determine a
measured distance from the monitoring transducer to the target
structure, the target structure defining a highly echogenic
interface relative to the organ to be monitored and treated; and f)
comparing the distance measured between the monitoring transducer
and the target structure with a reference distance, the reference
distance corresponding to the distance between the highly echogenic
interface in contact with a wall of a balloon means corresponding
to the ultrasound therapy transducer. .Iadd.
35. A method of treating an organ of a patient during a therapy
session, the method comprising the steps of: positioning a therapy
transducer in operative relation to the organ to be treated so that
the organ is located at a first position with respect to said
therapy transducer; acoustically coupling a monitoring transducer
to a target structure which has a predetermined relationship to the
organ to be treated, wherein said monitoring transducer operates in
A-mode; exciting said therapy transducer to provide ultrasound
therapy to said first position thereby treating the organ of the
patient with ultrasound therapy; utilizing said monitoring
transducer to determine whether the patient has moved during a
therapy session thereby causing the organ of the patient to be
located at a second position with respect to said therapy
transducer that is different from said first position; and if the
patient has moved during a therapy session, controlling said
therapy transducer so that ultrasound therapy is provided to said
second position thereby continuing the ultrasound therapy of the
organ to be treated during the therapy session..Iaddend..Iadd.
36. The method of claim 35 wherein said organ is a thyroid
gland..Iaddend..Iadd.
37. The method of claim 35 wherein said therapy transducer provides
high intensity focused ultrasound..Iaddend..Iadd.
38. The method of claim 35 wherein said therapy transducer is
controlled by means of changing a focal length of said therapy
transducer..Iaddend..Iadd.
39. The method of claim 35 wherein said step of utilizing said
monitoring transducer comprises the steps of: exciting said
monitoring transducer with a signal in the form of at least one
pulse, said at least one pulse being applied during a time interval
between the application of therapy by said therapy transducer;
receiving echoes of said signal produced by said monitoring
transducer; transforming said received echoes into an electrical
signal; locating, in said electrical signal corresponding to said
received echoes, the position of said target structure to determine
a measured distance from said monitoring transducer to said target
structure, said target structure defining a highly echogenic
interface relative to the organ to be monitored and treated;
comparing the distance measured between said monitoring transducer
and said target structure with a reference distance, said reference
distance corresponding to the distance between the highly echogenic
surface in contact with the wall of a balloon corresponding to said
therapy transducer; and transmitting a control signal to a control
device operative to selectively control the position of the therapy
transducer in response to the change in distance between the
monitoring transducer and the target structure relative to the
reference distance..Iaddend..Iadd.
40. The method of claim 35 wherein an alarm is triggered when the
distance between the first and second locations is greater than a
predetermined amount..Iaddend..Iadd.
41. The method of claim 35 wherein said therapy transducer is
arranged inside a balloon filled with an acoustic coupling
fluid..Iaddend..Iadd.
42. The method of claim 35 wherein said therapy transducer is a
focused ultrasound therapy transducer integrated into an
endocavital probe for providing treatment of as thyroid
gland..Iaddend..Iadd.
43. A method of treating the thyroid of a patient during a therapy
session, the method comprising the steps of: providing a therapy
transducer that is capable of generating high intensity focused
ultrasound; positioning said therapy device is operative relation
to the thyroid so that the thyroid is located at a first position
with respect to said therapy transducer; exciting said therapy
transducer to provide high intensity focused ultrasound to said
first position thereby treating the thyroid with high intensity
focused ultrasound therapy; acoustically coupling a monitoring
transducer to a target structure which has a predetermined
relationship to the thyroid, wherein said monitoring transducer
operates in A-mode; utilizing said monitoring transducer to
determine whether the patient has moved during a therapy session
thereby causing the thyroid to be located at a second position with
respect to said therapy transducer that is different from said
first position; and if the patient has moved during a therapy
session, controlling said therapy transducer so that ultrasound
therapy is provided to said second position thereby continuing the
ultrasound therapy of the thyroid..Iaddend..Iadd.
44. The method of claim 43 wherein said therapy transducer is
controlled by means of changing a focal length of said ultrasound
therapy transducer..Iaddend..Iadd.
45. The method of claim 43 wherein said step of utilizing said
monitoring transducer comprises the steps of: exciting said
monitoring transducer with a signal in the form of at least one
pulse, said at least pulse being applied during a time interval
between the application of therapy by said therapy transducer;
receiving echoes of said at least one signal produced by said
monitoring transducer; transforming said received echoes into an
electrical signal; locating, in said electrical signal
corresponding to said received echoes, the position of said target
structure to determine a measured distance from said monitoring
transducer to said target structure, said target structure defining
a highly echogenic surface relative to thyroid; comparing the
distance measured between said monitoring transducer and said
target structure with a reference distance, the reference distance
corresponding to the distance between the highly echogenic
interface in contact with the wall of a balloon corresponding to
said therapy transducer; and transmitting a control signal to a
control device operative to selectively control the position of
said therapy transducer in response to the change in distance
between said monitoring transducer and said target structure
relative to the reference distance..Iaddend..Iadd.
46. The method of claim 45 wherein an alarm is triggered when the
distance between the first and second locations is greater than a
predetermined amount..Iaddend..Iadd.
47. The method of claim 45 wherein said therapy transducer is
arranged inside a balloon filled with an acoustic coupling
fluid..Iaddend..Iadd.
48. The method of claim 45 wherein said therapy transducer is a
focused ultrasound therapy transducer integrated into an
endocavital probe..Iaddend..Iadd.
49. A method of treating a thyroid gland of a patient during a
therapy session, the method comprising the steps of: positioning a
therapy transducer in operative relation to the thyroid gland so
that the thyroid gland is located at a first position with respect
to said therapy transducer, said therapy transducer being capable
of providing high intensity focused ultrasound; acoustically
coupling a monitoring transducer to a target structure which has a
predetermined relationship to the thyroid gland, wherein said
monitoring transducer operates in A-mode; exciting said therapy
transducer to provide high intensity focused ultrasound therapy to
said first position thereby treating the thyroid gland with high
intensity focused ultrasound therapy; utilizing said monitoring
transducer to determine whether the patient has moved during a
therapy session thereby causing the thyroid gland to be located at
a second position with respect to said therapy transducer that is
different from said first position; and if the patient has moved
during a therapy session, controlling said therapy transducer so
that high intensity focused ultrasound therapy is provided to said
second position thereby continuing the high intensity focused
ultrasound therapy of the thyroid during the therapy
session..Iaddend..Iadd.
50. The method of claim 49 wherein said therapy transducer is
controlled by means of changing a focal length of said therapy
transducer..Iaddend.
Description
BACKGROUND OF THE INVENTION
This invention essentially relates to the use of an ultrasound
echography device operating in A-mode for monitoring the position
of a patient during a therapy session, and to a method and
apparatus applying it.
It is known that focused ultrasound can be used for treating
tumors. Generally, this is done in several stages, and more
specifically consists in first locating the volume to be treated,
then calculating the firing positions and after this directing
successive shots to the calculated positions.
In accordance with known methods, the shot is either done "blind"
or sometimes advantage is taken of the vacant period between shots
for providing an ultrasound image for monitoring purposes.
Treatment that is done "blind" can be dangerous as the sessions are
frequently long and the patient--even if anesthetized--may well
move. In this case, there is a danger of damaging healthy or even
vital parts.
Thus, by providing an image, the actual position of the therapeutic
transducer with respect to organs close to the target can be
monitored. However, this method does not offer absolute safety as
one cannot be sure that the medical personnel will pay sustained
attention to the screen displaying the ultrasound image throughout
the whole duration of the treatment. Image analysis techniques have
been proposed in order to overcome this disadvantage but these
require specific and highly complex electronic systems and software
which increases the cost of equipment and can be the source of
additional problems.
Another disadvantage of this solution resides in the actual
ultrasound scan itself. The system used may be conventional in the
sense that it includes an ultrasound scanning head as described in
International application WO 92/15253. This document discloses the
incorporation of an ultrasound scanning head into a therapy
transducer, but this means that the head masks a portion of the
therapy transducer thus reducing the effectiveness of the
apparatus, as is pointed out in said application where it is
indicated that one always attempts to maximize the transmission
surface area of the therapy transducer.
It is also possible to obtain an ultrasound image of the target and
the area surrounding it without reducing the transmission surface
area of the therapy transducer. This is achieved by using a
transducer element connected to B-type scan apparatus as described
in IEEE 1992 Ultrasonics Symposium Proceedings, in an article by N.
T. Sanghyi, R. S. Foster, F. J. Fry, R. Birhle, C. Hennige and L.
V. Hennige entitled "Ultrasound intracavitary system for imaging,
therapy and planning, and treatment of focal diseases", pages 1,249
to 1,253. For each position of the therapy transducer head, one
line of the image will be obtained. In order to obtain the complete
image, it is thus necessary to move the therapy head sequentially.
This is a slow process as the image rate is limited by the
mechanical scanning of the therapy head.
Moreover, before it was known how to produce an image with B-mode
scanning equipment, A-mode echography was employed either for
measuring distance, for example in echography of the eye, or for
measuring the degree of opening of mitral valves, or, yet again,
for measuring and locating the mid-axis of the brain, or, still
further, for bone positional location with a view to treatment as
described in an earlier document in the name of the assignee,
FR-A-2,660,186 equivalent to U.S. Pat. No. 5,235,981.
However, A-mode echography has never been employed at the actual
time of therapy and even less for monitoring the position of a
patient during therapy.
Additionally, to check the position of a patient during therapy,
the use of luminous markers has been proposed; see FR-A-2,663,529
in the name of the present assignee; U.S. Pat. No. 4,132,900 (W. E.
Smith); DE-A-2,361,155 (C. Lescrenier) and EP-A-0,260,550 (Siemens
A. G.). However, luminous markers can obviously not be employed in
certain cases, as is for example the case in endocavital
treatment.
SUMMARY OF THE INVENTION
The present invention thus sets out to resolve the technical
problem of supplying a way of reliably and accurately monitoring
the position of a patient during therapy. It would be advantageous
if this solution could be particularly simple.
A further aim of the invention is to provide a way of supplying an
image allowing the position of a patient to be automatically
monitored during therapy in a reliable, accurate and particularly
simple fashion.
A further aim of the invention is to provide a way of not only
monitoring the position of a patient during therapy, but also of
performing correction and closed-loop control of the position
either of the patient or of the therapy apparatus during therapy,
so that said therapy may be correctly performed throughout the
whole duration thereof. Preferably, this solution should also
enable real time control of a therapy transducer to be obtained
with respect to a predetermined reflecting contour this being done
independently of all other traditional imaging systems.
Yet a further aim of the invention is to resolve the above
technical problems while at the same time providing a way of
alerting the practitioner and/or medical staff during therapy
should the patient's position inadvertently change.
This invention makes it possible to simultaneously resolve all the
technical problems stated above in a safe and reliable manner that
can be applied on an industrial and medical scale.
Thus, according to a first aspect, the invention provides for the
use of an A-mode echography device for monitoring the position of a
patient, during a therapy session.
When A-mode echography is used in this way, it is advantageous to
modify the aim of the therapy apparatus as a function of movements
detected by the A-mode echography device.
It can also be arranged for the A-mode echography device to
interrupt therapy if it is detected that movements of the patient
are above a predefined limit which may be a function of a safety
margin.
According to one preferred feature, the A-mode echography device
carries out real time control of the position of therapy apparatus
comprising, for example, a therapy probe with respect to a
predetermined reflecting contour, preferably independently of any
other conventional imaging system, this being particularly
simple.
For example, to take the example of treatment of the prostate, it
is possible to control the therapy device which for example
includes at least one therapy transducer, using the A-type echo
from the rectal wall. This is performed independently of the
imaging system. This makes it possible to create lesions situated
at a precise distance, typically some 3 mm, from the rectum, for
correct treatment. Similarly, in the case of thyroid treatment,
provision can also be made to control the therapy device in real
time on the basis of the echo from the trachea.
For the actual therapy, therapy apparatus using focused ultrasound
is preferably employed.
According to a second aspect, this invention also provides a method
for monitoring the position of a patient, in particular the
position of an organ of the patient to be treated, during a therapy
session including: a) providing an ultrasound monitoring transducer
operating in A-mode in acoustic contact with the patient to be
monitored, in particular with an organ to be treated, the
transducer being in a known position, for example fixed to a
structure which, in particular, is the supporting means for said
patient; b) exiting the ultrasound monitoring transducer operating
in A-mode with a brief signal in the form of a pulse, for example
between shots of an apparatus providing said therapy; c) receiving
the echoes of the signal at the transducer; d) transforming said
received echoes into an electrical signal; e) locating, in the
signal corresponding to the echoes, the position or shape of a
structure that is characteristic of the echo from a tissue to be
monitored of the patient; f) comparing the position or shape of the
structure characteristic of the echo from a tissue to be monitored
in the patient with the position or shape of a reference echo
signal from tissue to be monitored of said patient; and g) when the
result of the comparison indicates a change of the position or
shape of the received echo signal with respect to the reference
echo signal position or shape, transmitting this information to an
appropriate control device.
According to an advantageous feature, the control device triggers
an alarm when information is transmitted thereto indicating a
change in the position or shape of the echo signal received with
respect to a reference echo signal, or even the absence of
reception of said echo signal.
Advantageously, the control device performs real time closed-loop
control of the position of the therapy device as a function of the
movements of the patient, in particular of said organ to be
treated, preferably with respect to a predetermined reflecting
contour of said patient such, as the rectal wall during prostate
treatment, or the trachea during thyroid treatment.
According to a further advantageous feature, the ultrasound
monitoring transducer operating in A-mode is mechanical linked to
the therapy device.
The therapy device preferably includes at least one ultrasound
therapy transducer providing therapy using focused ultrasound.
The ultrasound therapy transducer is advantageously arranged inside
balloon means filled with an acoustic coupling fluid.
Preferably, the reference echo signal corresponds to the desired
distance between a highly echogenic interface, such as the
interface in contact with the wall of the balloon means and the
ultrasound therapy transducer, the comparison consisting of
comparing the actual distance measured for the echo corresponding
to said interface and the reference distance for the interface
relative to said therapy transducer.
According to a preferred feature, when the measured distance is
smaller than the reference distance, the therapy transducer is
controlled whereby its distance with respect to the patient, in
particular with respect to an organ to be treated increases, while
if the measured distance is greater than said reference distance,
the therapy transducer is controlled whereby its distance with
respect to the patient, and in particular with respect to the organ
to be treated, is decreased.
The ultrasound therapy transducer is preferably a focused
ultrasound therapy transducer integrated into an endocavital probe,
preferably a rectal probe, for providing treatment of benign or
malignant tumors, in for providing treatment of the prostate or the
thyroid, notably cancers.
Other advantageous embodiments will also become evident from the
detailed description provided below that relates to the therapy
apparatus and from the examples and the drawings which constitute
an integral part of this disclosure.
According to a third aspect, the invention provides a therapy
apparatus including a therapy device including at least one
ultrasound therapy transducer and at least one monitoring
ultrasound transducer, wherein said ultrasound monitoring
transducer is linked to an electronic circuit for processing A-mode
signals and constituting part of an A-mode echography device, the
therapy apparatus further including means for causing the
ultrasound transducer operating in A-mode to transmit a brief
signal and receive the echo of the brief signal at the A-mode
transducer, means for comparing the echo received with a reference
echo, and means for transmitting the result of the comparison to a
control device.
According to one advantageous feature, the control device triggers
alarm means.
The control device advantageously performs real time closed-loop
control of the position of the therapy transducer relative to the
patient and in particular, relative to the organ to be treated.
Advantageously, the ultrasound therapy transducer is of the focused
type.
According to one preferred feature, both the ultrasound therapy
transducer and the A-mode monitoring transducer are integrated into
an endocavital probe, in particular a rectal endocavital probe.
In an advantageous embodiment, the focused-type therapy transducer
is linked to means for supplying an electronic signal providing
variable focusing. The control device preferably provides
closed-loop control of the focal length of said therapy transducer
as a function of the movements of the patient during the course of
therapy.
The therapy apparatus preferably includes means for continuously
recording the echoes created by the monitoring transducer operating
in A-mode. The A-mode electronic circuit may include an echography
device operating in A-mode.
Other advantageous embodiments will also become evident from the
description that follows that relates to the therapy apparatus and
from the examples and drawings which constitute an integral part of
this disclosure.
It will be seen that the invention makes it possible to monitor the
position of a patient during therapy in a simple, accurate and
reliable fashion, thus resolving the technical problems discussed
above, as well as providing other technical advantages which will
be evident to those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatical view of a first embodiment of the
therapy apparatus according to the invention, showing the actual
therapy device which here takes the form of a rectal endocavital
transducer with an A mode monitoring transducer, in longitudinal
cross-section, together with essential control and detection
means.
FIG. 2 is an alternative embodiment of the device shown in FIG.
1.
FIG. 3 shows the movement detection circuit in greater detail.
FIG. 4 shows a second embodiment of a therapy apparatus according
to this invention which here takes the form of a therapy device
with a rectal endocavital transducer for treating the prostate, in
the working position, inside a bag or balloon filled with an
acoustic coupling fluid, the surface of the bag or balloon being in
contact with the organ to be treated.
FIG. 5 shows the therapy device coupled to the A-mode ultrasound
monitoring transducer of FIG. 4, on a larger scale, with the echo
signal received by the A-mode transducer following transmission of
a short pulse signal making it possible to observe the shape and
structure of the echo pulse corresponding to an interface being
monitored, which here is the rectal wall.
FIG. 6 shows a third embodiment of therapy apparatus according to
the invention, the therapy device taking the form of an
extracorporeal probe in the form of a cup-shaped focusing
dish--here for treating the thyroid--showing a horizontal section
passing through the thyroid.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
With reference to FIGS. 1 to 4, the therapy apparatus according to
the present is generally identified by the reference numeral 10.
The therapy apparatus includes an actual therapy device generally
indicated by reference numeral 12, including a therapy transducer
14 which here takes the form of a naturally focusing cup-shaped
dish, together with at least one ultrasound monitoring transducer
16 linked to an electronic circuit for A-mode echography. Those
skilled in the art will readily recognize that the transducer 16
can constitute part of an A-mode echography device.
In one preferred embodiment, the active part of ultrasound
monitoring transducer 16 is an integral part of therapy transducer
14 and thus does not constitute a transducer separate from the
latter, although such an alternative embodiment would also be
possible.
The monitoring element can be situated at the center of the
transducer, on its axis of symmetry.
The monitoring transducer can be obtained by partitioning the metal
film deposited on the piezo-electric material forming the therapy
transducer and designed to stimulate it electrically. This method
is an easy way of obtaining two piezo-acoustic elements able to be
controlled separately. The partitioning of the metallization layer
can be arranged so that the monitoring element has minimal surface
area so that there is only a very slight reduction of useful
surface of the element used for therapy.
In an advantageous embodiment, therapy device 12 may take the form
of an endocavital probe 18 of the type described in WO 92/15253
which is incorporated herein by reference.
In particular, and also in accordance with this earlier document,
the rear part of endocavital probe 18 may include a motor system 20
enabling endocavital probe 18 to be driven in translation and/or
rotation so that the endocavital probe can be accurately positioned
facing a target T requiring treatment, such as a tumor inside an
organ O, for example, the prostate PR, defined by a surface forming
an interface I of patient P. The same references are employing in
the embodiments of FIGS. 4 to 6.
The therapy apparatus also includes a control unit 22 which is not
only responsible for controlling the motor means 20 providing
translatory and/or rotational movement for endocavital probe 18,
but also for controlling an electronic signal generator 24 which in
turn controls the operation of therapy transducer 14 and/or
monitoring transducer 16 via an electronic movement detector 28,
the structure of which is described in more detail with reference
to FIG. 3. A switching circuit 26 as shown in FIG. 2 (in
conjunction with electronic movement detector 28) can be provided.
FIG. 3 shows the internal structure of the movement detector 28.
Monitoring transducer 16 can be linked, via a transmit/receive
switchover device 30, either to a pulse generator subassembly 32 or
to a signal processing subassembly including an amplifier 34 and a
detector 36. Both subassemblies are synchronized by a
synchronization device 38 triggered by a signal from control unit
22. The processing subassembly 34, 36 analyzes the echo received by
monitoring transducer 16 and generates a control signal for an
output unit 40 which can take the form of alarm generating means or
means for driving the translatory and/rotational displacement means
20 for endocavital probe 18, optionally via control unit 22.
The operation of the treatment apparatus of this invention will
become more clear from the two examples of treatment illustrated in
FIGS. 4 to 6.
Referring now to FIGS. 4 to 6, it will first be observed that
therapy transducer 14 is delivering a beam focused to focal region
F which here has been shown diagrammatically as having an
approximately triangular shape which, for good therapy, should be
situated at or within the target zone to be treated, such as a
tumor T inside an organ O which may for example be the prostate, as
will be described with reference to FIG. 4, or the thyroid, as will
be described with reference to FIG. 6.
In the embodiment shown in FIGS. 1 to 6, the monitoring transducer
16 operating in A-mode is integrated into therapy transducer 14
and, for example, occupies the central portion thereof as can be
clearly seen in FIGS. 2 and 4 to 6.
In an advantageous embodiment, therapy transducer 14 integrating
the monitoring transducer 16 can be manufactured from a composite
material as described in an earlier French patent application in
the name of Technomed International FR-A-2,679,125 which is
incorporated herein by reference.
It is also possible as shown in FIG. 2, to employ the central
element of the transducer for both monitoring and therapy purposes-
In this case, a switching circuit 26FIG. 2 is used to successively
link the central element to an electronic power signal generator 24
or to movement detector 28.
The same central transducer can also be employed for tissue
characterization purposes prior to, during and after treatment. In
this mode, the return echoes are analyzed in order to determine the
structure of the treated tissue or the effect of treatment
itself.
Monitoring transducer 16 transmits an A-mode signal the beam shape
of which is shown on each of FIGS. 1, 2, 4, 5 and 6. In the
framework of this invention, it is preferable for the beam from
A-mode monitoring transducer 16 to cover the focal region F so that
this region can also be monitored during treatment. However, with
respect to monitoring the position of the patient, in particular
organ O, it is not absolutely essential for the beam from
monitoring transducer 16 operating in A-mode to pass through the
focal region, as the essential purpose of the monitoring transducer
is to monitor the position of a highly echogenic surface which will
generally consist of the interface I of the trachea of patient P,
as will be described with reference to FIG. 6, or the wall of the
organ O to be treated, for example the prostate PR as shown in
FIGS. 1, 2, 4 and 5, these interfaces being highly echogenic.
It will also be observed here that the therapy device is preferably
enclosed inside a membrane 50 (FIGS. 5-6) filled with an acoustic
coupling fluid 52 which for example is water, enabling acoustic
waves to be transmitted to the target, for example tumor T inside
organ O, which here, in FIGS. 4 and 5, is the prostate PR.
In the framework of FIGS. 4 and 5, which more particularly concern
treatment of the prostate, the interface I that is being monitored
is the rectal wall R as, when focused ultrasound is used with the
focal point F of focused therapy transducer 14 located very close
to the rectal wall W. This presents a risk to the patient P as
incorrect positioning of therapy device 12 could lead to
destruction of the rectal wall W with obvious serious consequences.
It is thus extremely important to permanently monitor the position
of the rectal wall with respect to the therapy transducer 14.
Monitoring is done in the following manner. Monitoring transducer
16, which here constitutes the central portion of therapy
transducer 14, issues a brief pulse, for example, having a 1 is
width at a frequency of 2.25 MHz, supplied by pulse generator 32
(FIG. 3), the echo being received by the movement detecting device
28 where it is processed by amplifier 34 and detector 36, the
latter analyzing the echo and comparing it with a reference
echo.
The manner in which this comparison is achieved can be understood
with reference to FIG. 5 where the shape of the echo signal as a
function of time T is shown on the x-axis, the y-axis showing the
signal amplitude A. The echo signal E following transmission of a
pulse at instant O from monitoring transducer 16 first indicates
passage through a feebly echogenic region E.sub.e due to the
coupling water, such as water e, and then corresponds to an
encounter with the interface I constituted by the rectal wall and,
specifically, the wall of the prostate PR, the latter being the
organ O to be treated. This interface I constituted by rectal wall
W is highly echogenic and gives rise to a reference echo E.sub.I,
which is the echo that will be monitored in the framework of this
invention. It will be noted that this echo is encountered at a time
t.sub.I from the moment the signal was generated, corresponding to
travel over a distance D.sub.I between monitoring transducer 16 and
rectal wall W, in the monitoring zone of monitoring transducer
16.
It will be understood that when the patient moves, this will also
lead to the organ O of FIGS. 4 and 5, which is here the prostate
PR, moving with a corresponding change in the distance D.sub.I
between the monitoring transducer 16 and the rectal wall W.
In a first embodiment of the invention, one can simply compare the
instant t.sub.I at which the echo E.sub.I arrives at with a
reference echo, which can be the echo received just prior to, or at
the beginning of, treatment. Alternately, one can compare the
distance travelled by the return echo with the distance measured by
distance measuring means prior to the commencement of treatment.
When the time t.sub.I deviates from the reference echo time, this
signifies that the distance D.sub.I has changed with respect to the
initially measured distance between the monitoring transducer 16
and the rectal wall, meaning that the patient has moved. In this
case, the detection and analysis device 36 may issue a command to
output unit 40 to supply an alarm signal and/or to issue a command
to the translatory and/or rotational movement control means for
therapy device 12 incorporating monitoring device 16, whereby the
echo from interface I may once again be brought to appear at a time
t.sub.I identical or close to the time of appearance of the
reference echo.
It can thus be noted that provision can be made to either trigger
an alarm signal 42 or issue commands to move the therapy transducer
16 only in the case where the time t.sub.I at which the echo from
interface E.sub.I occurs is below or above a predetermined value
for the reference echo time.
It can thus be noted that with the invention, monitoring of the
patient's movement can be automated as can correction of the
position of therapy device 12 during treatment.
Provision can also be made not only to calculate the time t.sub.I
of the echo from interface E.sub.I, but also the distance D.sub.I
corresponding to the substantially constant known speed of sound in
the acoustic coupling fluid and in tissue, this distance D.sub.I
together with the time t.sub.I being able to be displayed on a
screen permits the practitioner to follow the progress of treatment
with an enhanced degree of safety.
FIG. 6 shows a further embodiment of the invention concerning here
the treatment of nodules N of the thyroid gland. The same reference
numerals and symbols as those used in FIGS. 4 and 5 have been used
to indicate identical elements.
Here, the interface that it is particularly important to monitor
occurs at the trachea, this interface being identified by symbol
I.sub.2 on FIG. 6. The interface at the trachea also generates a
pronounced echo E.sub.I2 which can be clearly seen as a strong echo
signal on FIG. 6. Before this interface at the trachea I.sub.2,
there is obviously a first interface I.sub.1 constituted by the
skin S of the patient P but here, this interface which furthermore
generates a first strong echo E.sub.11 is of little significance
compared to the interface at the trachea I.sub.2.
When treating the thyroid, it is the interface I.sub.2 that will be
used for measuring the time t.sub.I2 for the echo to appear, this
time corresponding to the distance D.sub.I2 between the monitoring
transducer and the interface I.sub.2 at the trachea.
Monitoring is done in the same way as in FIGS. 4 and 5. Changes in
the time t.sub.I2 at which the echo E.sub.I2 appears, when compared
to the reference expected time of appearance, makes it possible to
set off an alarm signal 42 via the output unit 40 (FIG. 3) and/or
to command a change of position of therapy device 12 via the
control unit 22 and the translatory and/or rotational displacement
20.
The invention thus makes it possible to resolve all the problems
discussed above, and to obtain all the technical advantages derived
therefrom, as will be readily appreciated by those skilled in the
art.
Obviously, the invention includes all means that constitute
technical equivalents to those described, as well as the various
combination thereof.
For example, monitoring transducer 16 operating in A-mode can also
be set to transmit a continuous signal, the echoes being recorded
continuously thus making it possible to provide visual monitoring
of movements made by the patient p.
Additionally, this invention covers all features that appear to be
novel vis-a-vis any state of the art, given in the description
incorporating FIGS. 1 to 6 which constitute an integral part
thereof, and in the claims.
* * * * *