U.S. patent application number 11/752451 was filed with the patent office on 2007-09-27 for injection systems capable of using feedback for adjustment of injection parameters.
This patent application is currently assigned to MEDRAD, INC.. Invention is credited to Rosemary Almon-Martin, Alan D. Hirschman, Arthur E. III Uber, Thomas R. Welch.
Application Number | 20070225601 11/752451 |
Document ID | / |
Family ID | 23199802 |
Filed Date | 2007-09-27 |
United States Patent
Application |
20070225601 |
Kind Code |
A1 |
Uber; Arthur E. III ; et
al. |
September 27, 2007 |
INJECTION SYSTEMS CAPABLE OF USING FEEDBACK FOR ADJUSTMENT OF
INJECTION PARAMETERS
Abstract
This invention relates generally to the field of medical devices
for delivering contrast media during medical diagnostic and
therapeutic imaging procedures and more particularly, this
invention relates to improved contrast media delivery systems and
methods of use which allow adjustment of contrast media
concentration and injection parameters either before or during an
injection procedure to provide patient specific dosing of contrast
media, thus decreasing the waste and cost of these procedures while
increasing their efficiency.
Inventors: |
Uber; Arthur E. III;
(Pittsburgh, PA) ; Hirschman; Alan D.; (Glenshaw,
PA) ; Welch; Thomas R.; (Gibsonia, PA) ;
Almon-Martin; Rosemary; (Saxonburg, PA) |
Correspondence
Address: |
GREGORY L BRADLEY;MEDRAD INC
ONE MEDRAD DRIVE
INDIANOLA
PA
15051
US
|
Assignee: |
MEDRAD, INC.
Indianola
PA
|
Family ID: |
23199802 |
Appl. No.: |
11/752451 |
Filed: |
May 23, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10775235 |
Feb 11, 2004 |
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11752451 |
May 23, 2007 |
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09749894 |
Dec 29, 2000 |
6889074 |
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11752451 |
May 23, 2007 |
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09197773 |
Nov 23, 1998 |
6385483 |
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11752451 |
May 23, 2007 |
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08309820 |
Sep 21, 1994 |
5840026 |
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11752451 |
May 23, 2007 |
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Current U.S.
Class: |
600/431 ;
604/30 |
Current CPC
Class: |
A61B 8/481 20130101;
A61M 5/1723 20130101; A61M 2205/581 20130101; G16H 20/17 20180101;
Y10S 128/13 20130101; G16H 40/63 20180101; G16H 50/20 20180101;
A61M 2205/80 20130101; A61B 8/06 20130101; G16H 30/20 20180101;
A61M 5/007 20130101; Y10S 128/12 20130101 |
Class at
Publication: |
600/431 ;
604/030 |
International
Class: |
A61B 6/00 20060101
A61B006/00 |
Claims
1-21. (canceled)
22. A system for injecting fluid media into a patient, the system
comprising: (a) a pressurizing unit for pressurizing at least one
of a contrast medium and a diluent for injection into the patient
during an injection procedure; (b) an electronic control means
operatively associated with the pressurizing unit for calculating
an initial set of injection parameters based on data characteristic
of the patient; and (c) an electronic interface for enabling the
electronic control means to receive from an imaging system feedback
in the form of one or more images of a desired region of the
patient through which the at least one of the contrast medium and
the diluent flows; wherein the electronic control means is adapted
for using the feedback to automatically adjust the injection
parameters during the injection procedure in order to enable
improvement in quality of the images obtained in connection with an
imaging procedure.
23. The system of claim 22 wherein the injection parameters include
at least one of flow rate, concentration, volume, pressure and time
delay for administration of the fluid medium(s).
24. The system of claim 22 wherein the data characteristic of the
patient includes at least one of size, weight, hydration, cardiac
status, vessel type, vessel status, circulation transit time, and
kidney function.
25. The system of claim 22 wherein the electronic control means
includes a microprocessor, memory and associated software for
permitting input of the data characteristic of the patient, for
calculating the initial injection parameters based thereon, and for
adjusting the injection parameters based on the feedback from the
imaging system.
26. The system of claim 25 wherein the electronic control means
calculates the injection parameters based not only on the data
characteristic of the patient but also on initial parameters
particular to the imaging procedure to be performed.
27. The system of claim 22 wherein the electronic interface also
enables the electronic control means to receive the data
characteristic of the patient from a separate information
system.
28. The system of claim 27 wherein the separate information system
is a hospital information system.
29. The system of claim 22 wherein the adjusted injection
parameters are stored for use in subsequent or other injection
procedures.
30. A system for injecting fluid media into a patient, the system
comprising: (a) a pressurizing unit for pressurizing at least one
fluid medium for injection into the patient during an injection
procedure; (b) an electronic control means operatively associated
with the pressurizing unit for calculating an initial set of
injection parameters based on data characteristic of the patient;
(c) a sensor for providing feedback on operation of the system; and
(d) an electronic interface for enabling the electronic control
means to receive from the sensor the feedback pertaining to the
operation of the system; wherein the electronic control means is
adapted for using the feedback to automatically adjust the
injection parameters during the injection procedure in order to
enable improvement in quality of images obtained during an imaging
procedure.
31. The system of claim 30 wherein the sensor is an imaging system
from which the feedback is one or more of the images obtained
during the imaging procedure.
32. The system of claim 31 wherein the at least one fluid medium
includes a contrast medium, and the feedback provided in the form
of the one or more images reveals concentration of the contrast
medium in a desired region of the patient during the injection
procedure.
33. The system of claim 30 wherein the sensor is for monitoring
concentration of the at least one fluid medium in the patient
during the injection procedure.
34. The system of claim 30 wherein, for when the imaging procedure
is one that employs x-rays, the sensor includes a source of x-rays
and a receiver for determining an amount of x-ray radiation that
passes through a desired region of the patient.
35. The system of claim 30 wherein the sensor employs
electromagnetic radiation to determine concentration of the at
least one fluid medium in the patient during the injection
procedure.
36. The system of claim 35 wherein the electromagnetic radiation
takes the form of at least one of visible light and infrared
light.
37. The system of claim 30 wherein the sensor is capable of
measuring pressure within a vessel of the patient.
38. The system of claim 30 wherein the sensor provides the feedback
in the form of a voltage proportional to concentration of the at
least one fluid medium in the patient.
39. The system of claim 30 wherein the injection parameters include
at least one of flow rate, concentration, volume, pressure, and
time delay for administration of the at least one fluid medium.
40. The system of claim 30 wherein the data characteristic of the
patient includes at least one of size, weight, hydration, cardiac
status, vessel type, vessel status, circulation transit time, and
kidney function.
41. The system of claim 30 wherein the electronic control means
includes a microprocessor, memory and associated software for
permitting input of the data characteristic of the patient, for
calculating the initial injection parameters based thereon, and for
adjusting the injection parameters based on the feedback from the
sensor.
42. The system of claim 41 wherein the electronic control means
calculates the injection parameters based not only on the data
characteristic of the patient but also on initial parameters
particular to the imaging procedure to be performed.
43. The system of claim 30 wherein the electronic interface also
enables the electronic control means to receive the data
characteristic of the patient from a separate information
system.
44. The system of claim 43 wherein the separate information system
is a hospital information system.
45. The system of claim 30 wherein the adjusted injection
parameters are stored for use in subsequent or other injection
procedures.
46. A system for injecting a contrast medium into a patient, the
system comprising: (a) a pressurizing unit for pressurizing the
contrast medium for injection into the patient during an injection
procedure; (b) an electronic control means operatively associated
with the pressurizing unit for calculating initial injection
parameters based on data characteristic of the patient; (c) at
least one sensor for providing feedback on operation of the system;
and (d) an electronic interface for enabling the electronic control
means to receive from the at least one sensor the feedback
pertaining to the operation of the system; wherein the electronic
control means is adapted for using the feedback to automatically
adjust the injection parameters for the injection procedure.
47. The system of claim 46 wherein the at least one sensor includes
an imaging system from which the feedback includes one or more of
images obtained during an imaging procedure.
48. The system of claim 47 wherein the feedback provided in the
form of the one or more images reveals concentration of the
contrast medium in a desired region of the patient.
49. The system of claim 46 wherein the at least one sensor is for
monitoring concentration of the contrast medium in the patient
during the injection procedure.
50. The system of claim 46 wherein the at least one sensor provides
the feedback in the form of a voltage proportional to concentration
of the contrast medium in the patient.
51. The system of claim 46 wherein the injection parameters include
at least one of flow rate, concentration, volume, pressure, and
time delay for administration of the contrast medium.
52. The system of claim 46 wherein the data characteristic of the
patient includes at least one of size, weight, hydration, cardiac
status, vessel type, vessel status, circulation transit time, and
kidney function.
53. The system of claim 46 wherein the electronic control means
includes a microprocessor, memory and associated software for
permitting input of the data characteristic of the patient, for
calculating the initial injection parameters based thereon, and for
subsequently adjusting the injection parameters based on the
feedback from the at least one sensor.
54. The system of claim 53 wherein the electronic control means
calculates the injection parameters based not only on the data
characteristic of the patient but also on initial parameters
particular to an imaging procedure to be performed.
55. The system of claim 46 wherein the electronic interface also
enables the electronic control means to receive the data
characteristic of the patient from a separate information
system.
56. The system of claim 46 wherein the electronic control means
adjusts the injection parameters for the injection procedure to
enable an imaging system to produce images of a quality better than
those produced in connection with the initial parameters.
57. The system of claim 46 wherein the adjusted injection
parameters are stored for use in subsequent or other injection
procedures.
58. A system for injecting fluid media into a patient, the system
comprising: (a) a first pressurizing device, adapted for operative
use with a source of a first fluid medium, for pressurizing the
first fluid medium for injection into the patient during an
injection procedure; (b) a second pressurizing device, adapted for
operative use with a source of a second fluid medium, for
pressurizing the second fluid medium for injection into the patient
during an injection procedure; (c) an electronic control means for
controlling the first and second pressurizing devices and for
calculating an initial set of injection parameters based on data
characteristic of the patient; (d) at least one sensor for
providing feedback on operation of the system; and (e) an
electronic interface for enabling the electronic control means to
receive from the at least one sensor the feedback pertaining to the
operation of the system; wherein the electronic control means is
adapted for using the feedback to automatically adjust the
injection parameters for the injection procedure.
59. The system of claim 58 wherein the at least one sensor includes
an imaging system from which the feedback includes one or more of
the images obtained during the imaging procedure.
60. The system of claim 59 wherein the feedback provided in the
form of the one or more images reveals concentration of at least
one of the fluid mediums in the patient.
61. The system of claim 58 wherein the injection parameters include
at least one of flow rate, concentration, volume, pressure, and
time delay for administration of at least one of the first and
second fluid mediums.
62. The system of claim 58 wherein the data characteristic of the
patient includes at least one of size, weight, hydration, cardiac
status, vessel type, vessel status, circulation transit time, and
kidney function.
63. The system of claim 58 wherein the electronic control means
includes a microprocessor, memory and associated software for
permitting input of the data characteristic of the patient, for
calculating the initial injection parameters based thereon, and for
adjusting the injection parameters based on the feedback from the
at least one sensor.
64. The system of claim 63 wherein the electronic control means
calculates the injection parameters based not only on the data
characteristic of the patient but also on initial parameters
particular to an imaging procedure to be performed.
65. The system of claim 58 wherein the electronic interface also
enables the electronic control means to receive the data
characteristic of the patient from a separate information
system.
66. The system of claim 58 wherein the electronic control means
adjusts the injection parameters for the injection procedure to
enable an imaging system to produce images of a quality better than
those produced in connection with the initial parameters.
67. The system of claim 58 wherein the adjusted injection
parameters are stored for use in subsequent or other injection
procedures.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Divisional Application of co-pending
U.S. patent application Ser. No. 09/749,894, filed Dec. 29, 2000,
which is a divisional of U.S. patent application Ser. No.
09/197,773, filed Nov. 23, 1998, now U.S. Pat. No. 6,385,483, which
is a divisional of U.S. patent application Ser. No. 08/309,820,
filed Sep. 21, 1994, now U.S. Pat. No. 5,840,026, the contents of
all of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates generally to the field of medical
devices for delivering contrast media during medical diagnostic and
therapeutic imaging procedures and more particularly, this
invention relates to improved contrast media delivery systems and
methods of use which allow adjustment of contrast media
concentration and injection parameters either before or during an
injection procedure to provide patient specific dosing of contrast
media, thus decreasing the waste and cost of these procedures while
increasing their efficiency.
DESCRIPTION OF THE RELATED ART
[0003] It is well recognized that the appropriate dose for many
medications is related to the size and weight of the patient being
treated. This is readily apparent in the difference between the
recommended doses which most medications have for adults and
children. The appropriate dose of contrast media for a given
medical imaging procedure is equally dependent upon the size and
weight of the patient being examined as well as other additional
factors.
[0004] Although differences in dosing requirements for medical
imaging procedures have been recognized, conventional medical
imaging procedures continue to use pre-set doses or standard
delivery protocols for injecting contrast media during medical
imaging procedures. Using fixed protocols for delivery simplifies
the procedure, however, providing the same amount of contrast media
to patients weighing between 100 and 200 pounds, for example,
produces very different results in image contrast and quality. If
the amount of contrast media used is adequate to obtain
satisfactory imaging for the 200 pound person, then it is likely
that the 100 pound person will receive more contrast media than
necessary for the procedure to produce a diagnostic image. With
high contrast costs, this is a waste of money as well as increased
patient risk.
[0005] Standard protocols are used primarily to minimize the
potential for errors by hospital personnel and decrease the
likelihood of having to repeat the procedure, an occurrence which
requires that the patient be exposed to additional radiation and
contrast media. Furthermore, in prior art contrast delivery
systems, once a bottle of contrast media was opened for use on a
patient it could not be used on another patient due to
contamination considerations. Existing contrast delivery systems do
not prevent the source of contrast media used for an injection from
being contaminated with body fluids of the patient. The containers
which supplied the contrast media were generally therefore all
single use containers and, consequently, the entire container of
contrast media was given to the patient being studied.
[0006] Present protocols include delivery rate in volume per unit
time. Usually the injection is at a constant flow rate or with one
change between two fixed flow rates. However, physically, pressure
drives fluid flow. Thus, present fluid delivery systems employ some
type of servo to develop the pressure needed to deliver the
programmed flow rate, up to some pressure limit. The pressure
needed depends upon the viscosity of the fluid, the resistance of
the fluid path, and the flow rate desired. This is considerably
better than the older injector systems which controlled pressure at
a set value, and let the flow rate vary.
[0007] There are significant drawbacks to fluid delivery systems
which are unable to adjust the concentration of contrast media and
other injection parameters during an injection procedure. Many
patients may receive more contrast media than is necessary to
produce an image of diagnostic quality, while others may receive an
amount of contrast media insufficient for producing a satisfactory
image. Existing procedures also frequently result in waste of
contrast media as well as the need for repeating the procedure
because an image of diagnostic quality could not be produced.
[0008] Some of the shortcomings of existing procedures have been
addressed and resolved as described in application Ser. No.
08/144,162, titled "Total System for Contrast Delivery," filed Oct.
28, 1993, now abandoned, and incorporated herein by reference. This
application discloses a contrast media delivery system which
provides a source of contrast media that is sufficiently isolated
from a patient undergoing an imaging procedure that the source of
contrast media may be used on additional patients without concern
for contamination. Additionally, this system is capable of
adjusting contrast media concentration and other injection
parameters during an injection procedure.
[0009] The system incorporates a source of contrast media and, if
desired, a diluent. Each is sufficiently isolated from the patient
to prevent contamination. The contrast media preferably has a
concentration which is the highest that would be used in an
injection procedure so that the operator may combine the contrast
media with a diluent and select virtually any concentration of
contrast media desired for any given procedure. The concentration
of the contrast media injected into a patient may be varied during
the injection procedure by varying the ratio of diluent to contrast
media. Each patient therefore receives only the amount of contrast
media necessary to provide a proper diagnostic image.
[0010] It is recognized that this system will be much more
versatile and useful if the operator is able to select and adjust
contrast media concentration and other injection parameters based
on patient information or feedback received during the injection
imaging procedures. Additionally, this system would be more
efficient if it were capable of automatically choosing the
appropriate concentration and injection rate for a given patient.
Even more utility and efficiency would be realized from a system
that is capable of automatically adjusting concentration and other
injection parameters during an injection procedure based on
feedback related to the resultant image quality.
[0011] Accordingly, it is an object of this invention to provide an
improved contrast media delivery system which is capable of
automatically varying the injection rate and concentration of
contrast media given to a patient during an imaging procedure,
based on information received either before or during the injection
procedure.
[0012] It is another object of the present invention to provide an
improved contrast media delivery system which obtains and utilizes
feedback information during the imaging procedure to automatically
adjust the flow rate, volume and/or concentration of the contrast
media into the patient if needed.
[0013] It is a further object of this invention to provide a system
which is capable of selecting the appropriate injection flow rate
and concentration for a given patient based on patient information
entered into the system.
[0014] Numerous other objects and advantages of the present
invention will become apparent from the following summary,
drawings, and detailed description of the invention and its
preferred embodiment.
SUMMARY OF THE INVENTION
[0015] The invention includes apparatus and methods for medical
contrast imaging and comprises embodiments which provide patient
specific dosing of contrast media in a variety of medical imaging
procedures, as opposed to fixed protocols. In this invention, the
protocol variables are determined by the system and are dependent
upon patient specific information supplied by the operator, and/or
information measured by the contrast delivery system either prior
to, or during the injection procedure. These apparatus and
procedures disclosed herein apply to all of the systems disclosed
and described in the application titled "Total System for Contrast
Delivery", Ser. No. 08/144,462, now abandoned. Further systems are
described in which the system receives input from an operator to
provide the appropriate adjustment of system parameters.
[0016] In a principal embodiment, information specific to any given
patient is entered into the system and the appropriate
concentration and injection parameters are computed before
initiating the imaging fluid injection procedure. The system is
then ready for injection of a patient. It is important to note that
the system is not limited to choosing a particular concentration of
contrast media or injection rate for the entire procedure, or even
a moderate number of phases with constant velocity as present
injectors can now do, but rather is capable of selecting an
injection profile which may include a continuously varying
injection rate and/or concentration of contrast media. The
particular injection profile selected by the system is designed to
provide the best image quality for the particular patient based on
a variety of factors such as patient weight and circulation system
variables.
[0017] In a refined version of the system, feedback from at least
one sensor is employed by the control system to modify the
concentration of the contrast media, injection rate, and/or total
volume during the injection procedure. Various types of sensors are
disclosed for use with this system, in particular, various
electromagnetic sensors or video monitoring devices provide
feedback for the system or operator to use. In angiography, where
the contrast is injected into the region of interest, the sensor
needs to make a measurement in that region of interest. In CT and
MR it is sufficient for the sensor to measure a remote area of the
body, although measuring within the region of interest (ROI) could
be advantageous in some applications. The sensor provides an
indication of the actual amount of contrast media in the patient.
This is used to calculate the appropriate injection rate or
concentration of contrast media to provide a diagnostic image with
minimum risk and cost.
[0018] In critical locations such as coronary arteries, it will
take a while for doctors to have confidence in automatically
controlled fluid delivery system, thus, rather than automatically
altering injection parameters based on feedback signals received
from automatic sensors, the concentration, or other injection
parameters may be manually adjusted based on images seen by the
doctor or operator.
[0019] A final version of the invention is disclosed which works to
further improve doctors confidence by providing tactile feedback to
a doctor or operator in addition to visual or other sensed feedback
on the amount of contrast media in a patient. This provides the
operator with additional information to use in determining
injection rate, concentration and pressure for the injection
procedure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a flow diagram illustrating the prior art
procedure for implementing a standard protocol.
[0021] FIG. 2 is a flow diagram for a system of the present
invention in which injection parameters are calculated based on
patient specific information.
[0022] FIG. 3a illustrates an embodiment of the present invention
which employs the improved procedure for calculating injection
parameters of the present invention.
[0023] FIG. 3b illustrates an embodiment of the present invention
which employs the improved procedure for calculating the filling of
a syringe used with an injector.
[0024] FIG. 4 is a flow diagram outlining an injection procedure
which incorporates a sensor for sensing contrast concentration in a
patient during a test injection.
[0025] FIG. 5 is a flow diagram outlining an injection procedure
which incorporates a sensor for sensing contrast concentration in a
patient for modifying the injection parameters throughout the
injection.
[0026] FIG. 6 illustrates an example of a sensor for use with the
present invention.
[0027] FIG. 7 illustrates the present invention wherein the system
is able to automatically adjust fluid flow rate based on the
resulting image.
[0028] FIG. 8 illustrates an embodiment of a tactile feedback
pressure measurement device which allows the system operator to
adjust injection parameters based on tactile feedback.
[0029] FIG. 9 illustrates an embodiment of the present invention
which incorporates a Tactile Feedback Control (TFC) unit which
allows the system operator to adjust injection parameters based on
this sensor as well as the resulting image. The TFC is in fluid
communication with the fluid being injected.
[0030] FIG. 10a illustrates an embodiment of the present invention
which incorporates a Tactile Feedback Control (TFC) unit which
allows the system operator to adjust injection parameters based on
this sensor as well as the resulting image. The TFC is not in fluid
communication with the fluid being injected.
[0031] FIG. 10b illustrates an embodiment of the TFC in greater
detail.
[0032] FIGS. 11a-d illustrate various relationships between TFC
inputs and contrast delivery system actions which an operator could
select with the system.
[0033] FIG. 12 illustrates disposable manifolds operated by
electronic solenoids or motors which are designed for use with the
present invention during cardiology.
[0034] FIG. 13 illustrates a manifold for use with the present
invention during cardiology procedures.
[0035] FIG. 14 illustrates a system by which the manifold
illustrated in FIG. 13 is voice-activated.
DETAILED DESCRIPTION OF THE INVENTION AND ITS PREFERRED
EMBODIMENT
[0036] FIG. 1 is a flow diagram showing a conventional medical
imaging procedure for implementation of a standard protocol. This
diagram is indicated generally by the numeral 10. The imaging
procedure standard protocol is selected at first operative step 11,
and a decision is made at step 12 as to whether the patient's
weight is within a broad range considered to be appropriate for the
particular concentration of contrast media and set of injection
parameters for the selected protocol. If the patient's weight is
within the broad range of weights acceptable for the particular
contrast media and set of injection parameters, the standard
protocol is determined to be appropriate at step 14. The patient is
injected and the image is acquired at step 18. Alternatively, if
the weight of the patient is not within the given range, an
alternate contrast media concentration and set of injection
parameters are chosen at step 16. Once the alternate concentration
or set of injection parameters are chosen at step 16, the patient
is then injected and the image is acquired at step 18. The operator
then reviews the image at step 20. If the image is satisfactory,
the procedure is successfully completed and the system is prepared
for the next imaging procedure with this patient or another patient
at step 22.
[0037] If the image is not satisfactory, the procedure must be
repeated as noted at step 24. A decision is then made as to whether
there is a specific problem with the system or selected protocol at
step 26. If there is a problem with the protocol, the selected
protocol is revised at step 28. Alternatively, if the initially
selected protocol is appropriate, step 14 is repeated and the
patient is injected at step 18. As noted, this type of system and
its lack of versatility has significant disadvantages compared with
the system of the present invention.
[0038] The present invention takes advantage of the increased
versatility of the advances set forth in the co-pending application
previously noted and further advances the art by adding automatic
functions and increased versatility.
[0039] A flow-diagram illustrating an improved contrast media
delivery of the present invention is shown generally by the numeral
30 in FIG. 2. In this system the operator initially inputs
information relating to the patient such as size and weight in
addition to other factors related to the particular imaging
procedure being performed at first operative step 32. This
information could be stored in a hospital computer and simply
downloaded to the imaging system. The Electronic Control System
(ECS) of the contrast media delivery system then determines the
appropriate concentration of the contrast media and other injection
parameters such as flow rates, volume, time delay, etc. at step 34.
The computed concentration of contrast media and injection
parameters are then displayed at step 36.
[0040] In this and other embodiments, the step of displaying
parameters for user review is optional. As this capability is first
introduced, operators will want to retain control. As they become
familiar with the equipment and gain confidence with it, it will be
possible to manufacture and market systems which no longer display
injection parameters for operator review. In the preferred
embodiment, however, the system operator then reviews the
calculated parameters at step 38 and decides whether to manually
modify the parameters at step 40 or proceed with the injection of
the patient at step 42. The injection begins in step 42, the image
is acquired, and the system operator or physician reviews the
resulting image at step 44. If the image is satisfactory for
diagnosis, the image is stored and the procedure is complete. The
system may be prepared for the next imaging procedure at step 46.
Prior to preparing the system for the next imaging procedure, the
operator may choose to perform optional step 47 in which the
operator may input information to modify the algorithm which
determines the injection parameters so that before the system
stores the parameters they are set to levels which would have
provided an image which is more personally satisfactory. The system
software keeps track of the various injection parameters a doctor
or operator selects for patients of a particular size and for a
given procedure. These factors are analyzed for preferred
tendencies of the doctor or operator so that the system is able to
select injection parameters based on the operators personal
preferences. By performing this optional step, the system will be
able to automatically select operating parameters which provide a
more satisfactory image for an individual. If the operator chooses
to perform optional step 47, the system is prepared for the next
imaging procedure upon completion of this step.
[0041] Alternatively, if the image is not satisfactory, the image
parameters are extracted at step 48 and the ECS is updated at step
49. The ECS then recalculates new parameters and repeats step 34.
The remainder of the procedure is also repeated. It is anticipated
that this will happen very seldom once the algorithm is adapted to
the doctor's preference.
[0042] FIG. 3a illustrates an embodiment of the improved contrast
media delivery system of the present invention generally at 50. The
user interface of the ECS is indicated at 52 with direct connection
to the ECS 54. There is an additional electronic interface 56. The
electronic interface 56 may be connected to other systems which are
not shown, such as imaging equipment and the hospital information
system. If this interface is connected to the hospital information
system, it could rely on this system to receive patient specific
information necessary for performing the procedure such as size,
weight, etc. An operator would therefore only be required to input
a patient number and the appropriate information would be
downloaded from the hospital information system.
[0043] The electronic interface 56 is also connected to the imaging
equipment 57. The ECS is capable of sending and receiving
information so that, for example, the operator only needs to
program the CT scanner with the number of slices and section of the
body being imaged. This would be transmitted to the contrast
delivery system to be used in determining flow rates and delays,
etc. Additionally, information relating to image quality or sensed
concentration of contrast media is received to allow for automatic
adjustment of the system.
[0044] An information scanner 58 is also shown with direct
connection to the ECS 54. The information scanner 58 scans
information encoded and attached to fluid storage tanks for the
contrast container 60 and diluent container 62. The information
encoded and read by the scanner 58 includes information such as
tank volume, type and concentration of fluid etc. This information
is then employed by the ECS in controlling and calculating the
implementation of the imaging procedure. Alternatively, this
information is downloaded from memory located on a fluid delivery
module as noted in the application titled Closed Loop Information
Path for Medical Fluid Delivery Systems, application Ser. No.
08/273,665, filed Jul. 12, 1994, now abandoned.
[0045] Contrast and diluent tank volume, type and concentration of
fluid is stored in the system memory and is updated after using the
system. The system is therefore able to automatically warn the
operator when the system is running low on contrast or diluent.
Additionally, the system is able to warn the operator if the wrong
contrast media was connected for a particular procedure.
[0046] The ECS 54 is also connected to respective contrast and
diluent heaters 64, 65. The ECS 54 controls the heaters 64, 65
through this connection and receives feedback so that the system
may make appropriate adjustment of the heaters to provide the
desired temperature of contrast media. Metering pumps 68, 69 are
connected to the ECS 54 which also controls fluid flow of contrast
and diluent through the pumps.
[0047] The output of each of the metering pumps 68, 69 is connected
to the helical vane static mixer 71 which ensures that the desired
concentration of contrast media is produced by the system. A
backflow valve 73 in the fluid flow path to the patient prevents
the contrast media from returning to the sources of contrast and
diluent 60, 62 and causing contamination. A fluid assurance sensor
75 is also directly connected to the ECS 54. The final element in
the fluid path which is connected to the ECS 54 is the pressurizing
pump 76. The pressurizing pump 76 provides the desired injection
rate of contrast media for the particular procedure. A per patient
connector 77 is followed by a sterile filter 78 which is also
connected in line to prevent contamination of the sources of
contrast media and diluent by preventing body fluids of the patient
from flowing back into the sources of contrast and diluent. The
fluid path then flows through connector tube 80 and a medical
stopcock 82.
[0048] A hand held syringe 84 is also connected to a port of the
stopcock 82 to allow the doctor to perform what are considered test
or scout injections. For example, the doctor may get a small amount
of fluid at a concentration, and then do hand powered injections
during his manipulations to get a catheter into the proper vessel.
In a preferred embodiment, a contrast media sensor (not shown) is
added to the system to provide additional feedback during an
injection procedure in order to provide for better monitoring of
concentration as it is adjusted by the system.
[0049] FIG. 3b illustrates a second embodiment of the improved
contrast media delivery system of the present invention generally
at 50. Most of the system components and their function are
identical to those of FIG. 3a, but instead of the per patient
connector 77, sterile filter 78, tubing 80, connector 82 and hand
syringe 84, 3b has a syringe 79 which is filled with fluid. This
syringe is then placed in an injector for delivery of the fluid to
the patient. Prevention of contamination is accomplished by having
the syringe allowed to be filled only once. The label printer
prints the patient specific injection information, and this label
is then read by the ECS of the injector. The injector ECS 35 can
utilize any of the improved patient specific processes of this
invention, such as sensors or tactile feedback controllers, neither
of which are shown.
[0050] Alternatively, the injector ECS 35 could communicate with
the filling station ECS 54 so that the injector is programmed by
the filling station. A third alternative involves having the
filling station user interface 52 display the injector parameters
and then the operator enters these parameters into injector ECS 35
via the injector user interface. An advantage of this most manual
system is that it can work with present injector equipment,
enabling the customer to achieve patient specific dosing while
utilizing equipment which he has already purchased.
[0051] One embodiment, not shown, that uses even less hardware and
sophistication consists of only a user interface and an electronic
control system. The operator enters the patient specific data, and
the volume, concentration and injection parameters are displayed
for the operator. Then the operator manually fills the syringe
using a manual method, such as that supplied by NAMIC, of Glens
Falls, N.Y., preserving any unused contrast for the next patient.
The injector is then automatically or manually programmed according
to the patient specific parameters computed, and is ready to
inject.
[0052] It will be appreciated that various devices could be
employed to function as the ECS 54. ECS 54 at the very least must
incorporate a microprocessor and memory along with control outputs
for the various devices. It is understood that software controls
the system. The software relies on a variety of factors for
calculating the appropriate contrast media concentration and
injection parameters for a particular patient.
[0053] The appropriate weight given to each of the factors in the
software for calculating these parameters cannot now be disclosed
because of the varied relationship between these factors and the
numerous imaging systems and sensors which may use this invention.
It is contemplated that experimentation with various weight factors
applied to the variables will provide the best results with any
given system. This is why embodiments are described with varying
degrees of operator control, operator verification and automatic
operation.
[0054] The following table provides an outline of the factors which
the system may consider in evaluating the appropriate concentration
of contrast media and injection rate for a particular patient as
well as the general effect an increase in these factors would have
on calculation of the injection parameters. Some factors such as
weight have a continuous effect. A slightly heavier patient gets a
little more contrast. Others, such as hydration or kidney function
have no effect until some threshold is crossed. TABLE-US-00001
TABLE I FOR INTRA VENOUS INPUT PARAMETER EFFECTED PARAMETER EFFECT
Patient Weight Total volume Increases (mg of Iodine) Flow rate to
get Increases mgl/kg/sec Concentration (optional) Increases Patient
Hydration Concentration Increases Kidney Function Use minimum total
mgl if poor or questionable Cardiac Status With poor status, use
minimum total fluid volume to minimize fluid loading Circulation
Transit Use longer delay time Time until start of scanner if
circulation time is poor Change from single phase to multi-phase or
continuously varying Length of Scanning Flow rate Decreases to
lengthen image contrast time Connector tube Provides limit to
prevent diameter or catheter over pressure size Patient vein status
If weak, use lower concentration, lower FOR INTRA ARTERIAL INPUT
PARAMETER EFFECTED PARAMETER EFFECT Vessel Diameter Flow rate
Increases Volume of Injection Increases Concentration Increases
Catheter Diameter Concentration Increases Procedure/body Duration
of injection Varies location Patient Weight Limit on total iodine
Increases dose
[0055] Given the variety of factors to be considered, fuzzy logic
or neural networks may be appropriate for implementation of the
program, however, a conventional computer program also provides
satisfactory results.
[0056] FIG. 4 illustrates a flow-chart of the injection procedure
of the present invention with sensor measurement. In this
procedure, a test injection is made and a contrast media sensor is
used to provide feedback on the actual concentration of contrast
media within the patient. Initially, the operator enters the type
of imaging procedure to be performed and patient information at
first operative step 90. It is important to note the system will
already be aware of the type and concentration of the fluid
available in the system tanks because the information scanner would
have input this information when the tanks were installed. In the
next step 92, the ECS computes the appropriate concentration of
contrast media and the injection parameters such as flow rates,
volume, and time delay etc. The resultant concentration and
injection parameters are then displayed at step 94. The operator
then reviews the parameters and decides whether to manually modify
the procedure at step 96.
[0057] If the operator is satisfied with the injection parameters,
a test injection of the patient is performed in step 98.
Alternatively, the operator may modify the procedure in step 100
and then perform a test injection of the patient at step 98. A
sensor measurement of the concentration of contrast media within
the patient's body is then performed at step 102 and a decision is
made at step 104 as to whether the results of the sample injection
are sufficiently close to the desired value. If the results of the
test injection are not satisfactory, the system returns to step 100
to modify the injection parameters, either manually or
automatically and then repeats the test injection at step 98.
[0058] When the results of the test injection are satisfactory, the
final injection parameters are selected at step 106 which may
involve having the operator fine tune the procedure by making minor
adjustments and updating specific parameters to provide more
desirable results. If more significant changes are needed, the test
injection should be repeated as noted. The imaging injection
procedure begins at step 108. Upon completion of the injection
procedure step 108, the operator reviews the image at step 110 and
determines whether the procedure produced a satisfactory diagnostic
image. If the image is satisfactory, the procedure is complete and
the system may be prepared for the next imaging procedure at step
112. Step 113 is an optional step which may be performed before
preparing the system for the next imaging procedure if the operator
wishes to update the algorithm which determines the injection
parameters that are used to customize injection procedure to a
doctor's preference.
[0059] Alternatively, if the image is unsatisfactory, the image
parameters are extracted at step 114 and the ECS injection
parameters are updated at step 115. The procedure is repeated
beginning with recalculation of the injection parameters step 92.
It is anticipated that this will happen very seldom once the
algorithm has been adapted to the imaging equipment and the
doctor's preferences as previously noted.
[0060] FIG. 5 illustrates an alternate procedure for performing an
imaging procedure with the improved contrast delivery system of the
present invention. In this procedure, a sensor measurement is used
throughout the injection procedure to provide an indication of the
actual concentration of contrast media within the patient.
Initially, information relating to the particular imaging procedure
to be performed and patient are input to the system at step first
operative step 116. The ECS computes concentration, and other
injection parameters such as flow rates, volume, time delay, etc.
at step 117. The calculated concentration of contrast media and
other injection parameters are then displayed at step 119 and the
operator reviews the calculated results and determines whether they
are satisfactory at step 120. If the results appear to be within
the desired range, injection of the contrast media begins in step
122.
[0061] Alternatively, the operator may modify the injection
parameters at step 123 before initiating the injection at step 122.
A sensor measurement is made at step 125 and a decision is made as
to whether the results are satisfactory at step 126. If they are
not satisfactory, the injection parameters are modified at step 127
and the sensor measurement is continued at step 125. The sensor
measurement is made and the injection parameters are adjusted
throughout the injection process based on the sensor measurements.
The adjustments continue until the procedure is complete as
indicated at step 128. If the sensor measurement indicates a
serious problem, the system may automatically stop the injection
procedure depending on the severity of the problem. Upon
completion, the operator then reviews the image at step 130 and
decides whether the results are satisfactory.
[0062] If satisfactory results are achieved, the system is prepared
for the next imaging procedure as indicated at step 132. Step 133
is an optional step which may be performed before preparing the
system for the next imaging procedure if the operator wishes to
update the algorithm which determines the injection parameters to
customize the injection procedure to a doctor's preference.
[0063] Alternatively, if the results are not satisfactory, the
image parameters are extracted at step 134 and the ECS injection
parameters are updated at step 136. The ECS then recalculates the
concentration of contrast media and injection parameters at step
117 and the operator repeats remaining steps in the procedure.
Again, this will be a seldom occurrence once the doctor's
preferences have been included. In this embodiment and all others,
the repeat procedure may need to be postponed if the patient is
near the maximum daily contrast dose.
[0064] Having the sensor provide to the ECS, a measure of contrast
in the body during an injection and having the ECS be able to
continuously adjust fluid concentration, flow rate, and/or timing
of the signals to start the imaging equipment provides an ability
to optimally adapt the dosing to patient specific parameters which
may be unknown or inaccurately estimated before the start of the
injection. For example, in a CT injection, contrast may arrive at a
site more quickly in some patients than others.
[0065] Systems are available which allow the operator to adjust the
timing of the beginning of CT scans, however, these systems, unlike
the systems of the present invention, are unable to adjust the flow
rate, concentration, and/or stop the injection sooner than
originally planned, thus limiting the amount of contrast injected
into the patient, saving money and reducing patient risk.
[0066] FIG. 6 illustrates an example of a sensor which can be used
with the improved contrast media injection system of the present
invention. The sensor is shown generally at 140. It is contemplated
that a variety of sensors may be used for evaluating the
concentration of contrast media within a patient at particular
time. These sensors use various wavelengths of electromagnetic
radiation to determine the presence of contrast media. The
particular sensor disclosed in FIG. 6 is designed for sensing
contrast media used during procedures which use x-rays to create
the desired image. Therefore this sensor employs a source of x-rays
and a receiver for determining the amount of x-ray radiation which
passes through the tissue of a patient. It is understood that use
of other sensors for x-ray or different types of contrast media
could be used in a similar manner.
[0067] The sensor includes a silicon diode radiation detector 142
and source of radioactive material 144. A movable shield 146 is
capable of alternately shielding and exposing the radioactive
material 144 to the radiation detector 142. Electronic actuator 148
moves the shield 146 upon command from the ECS. The sensor includes
control and power cables 150 connected to the ECS not shown. It has
been found that a small radioactive source works best. One example
of a commercially available product which can be used to generate
an output which varies depending upon the level of x-rays passing
through body tissue is the Lixi scope manufactured by Lixi, Inc. of
Downers Grove, Ill. 60515. This product uses a similar design for
portable imaging of small body parts such as the hand or ankle.
Although this product is designed for producing images, it is also
capable of being adapted to provide signals which are proportional
to the level of contrast media in a patient. When used with the
system of the present invention, the source and detector are placed
on opposite sides of a thin tissue region such as the ear lobe,
finger tip, or fleshy part of the hand between the thumb and index
finger. It is known that the attenuation of the tissue will change
as the concentration of x-ray contrast builds up in the blood and
then surrounding tissue. It should be noted that the radioactive
source should be shielded when not in use.
[0068] Another type of sensor which could be used with the system
is one which employs visible or infrared (IR) light, preferably of
two different wavelengths. This is similar to the technique
currently employed in pulse oximeters. It is known that iodinated
contrast interferes with the signals used to make oxygen
measurements with pulse oximeters and that these systems are
capable of measuring the level of iodinated contrast. Most x-ray
contrasts contain a benzene ring with three iodine atoms attached
at positions 1, 3 and 5. Various organic molecules are attached at
positions 2, 4 and 6. The infrared spectrum for iodine atoms bonded
to a benzene ring is unlike those for naturally occurring
compounds. Dual or multiple wavelengths help to minimize
interference or prevent positioning differences from giving
incorrect readings. Sensors with other visible, IR or different
electromagnetic wavelengths would be used for MRI or ultrasound
contrast materials.
[0069] Another sensor which could be used with the improved
injection system of the present invention is a pressure sensor
inserted into a vessel. A tiny pressure sensor on an IC, such as
those made by SenSim, Inc., Sunnyvale, Calif., are capable of
providing this type of feedback. A dual lumen catheter and a
conventional blood pressure monitor could be also used. During the
injection procedure, the flow rate of the injector would be
adjusted based upon the sensed intra-luminal pressure. For
intravenous injections, the pressure within the vein could be used
to limit or appropriately adjust flow rate or concentration to
prevent vessel damage or extravasation. For intra-arterial
injections, appropriate adjustment would minimize backflow by
timing variations in flow rate to match internal variations due to
pressure waves created by the heart. When backflow occurs, some of
the injected contrast moves upstream in the vessel and may go to
unintended side vessels. This is not usually dangerous, but does
represent a waste of contrast. Measuring the pressure at one or
more places in the artery or vein during injection provides the
information which is necessary to safely inject the optimum amount
of contrast.
[0070] Regardless of the type of sensor used by the system, it is
contemplated that the sensor will send a feedback signal to the ECS
such as a voltage proportional to the concentration of contrast
media present in a patient. The system could then either provide
this information to the system operator for manual adjustment of
the injection parameters, or alternatively, the system could use
these signals to automatically adjust the concentration of the
contrast media or the flow rate to provide a more desirable image.
For intra-arterial, the delay between change in injection parameter
and effect is small enough so that the operator may be part of the
feedback loop. For intravenous injections, the delay is longer and
variable, so having the ECS measure and automatically account for
the delay is preferable.
[0071] FIG. 7 illustrates another embodiment of the present
invention. In this embodiment, the system is capable of
automatically adjusting the injection parameters to alter the image
produced by the system based upon feedback from the actual image.
This embodiment includes an image processor 160 which analyzes a
bitmap of the video image produced by the contrast delivery system
in conjunction with the imaging equipment 57. The operator 162
selects one area of interest on the image via the monitor 163, for
example, by moving a box or pointer over the area via a user
interface such as a mouse and then selecting the position by
clicking the mouse. The user selects a desired area of interest
such as a blood vessel being examined. The image processor 160 then
calculates the average intensity of the pixels in the designated
area. It is understood that pixel intensity would be proportional
to the amount of contrast media in the patient's body due to the
effect on the electromagnetic wave or ultrasonic energy wave being
used for the imaging procedure. Depending upon the resultant
average pixel intensity, the system then makes appropriate
adjustments in contrast concentration and injection rate.
[0072] The use of a video image for providing feedback to make
adjustments to the injection parameters requires real time or
approximately real time display of the ROI. All x-ray fluoroscopic
systems provide real-time video. One such system that is capable of
providing such images in CT is a system called Smart Prep
manufactured by General Electric of Milwaukee, Wis. Once the
injection is started with this system, a scan is repeated
periodically after a small delay. A delay of approximately eight
seconds is of short enough duration to provide satisfactory
results. The concentration of the contrast in the ROI's is measured
on each scan and plotted for the operator. In the General Electric
system, this plot is used to help the operator decide when to begin
scanning the organ. In the invention described herein, a mechanism
similar to GE's may also be used as the sensor input to the ECS to
automatically control the flow rate or concentrations.
[0073] Another way in which the system of the present invention can
use the resulting image for adjusting the injection parameters is
for the operator to select two areas of interest on the image. The
system produces a relative pixel intensity measurement by
calculating the difference in pixel intensity between the two
different areas. The operator selects one area located in the
background and second area located within part of the patient being
examined such as a blood vessel of interest. The image processor
calculates the appropriate concentration of contrast media based
upon the resulting measurement.
[0074] A further embodiment of the present invention is disclosed
in FIG. 8. The injection system is shown generally at 170. The ECS
54 is connected to the contrast delivery system 172 and an
embodiment of a Tactile Feedback Control (TFC) unit 173. An
additional connection is made between the ECS and the user display
176. The TFC 173 comprises a disposable syringe 174 which is
located within a durable/reusable cradle 178. The cradle 178 is
electrically connected to the ECS 54 and is physically connected to
a sliding potentiometer 180 which is driven by plunger 181.
[0075] The doctor holds the cradle and syringe during the injection
procedure and as the doctor depresses the sliding
potentiometer/syringe piston assembly, the plunger is moved
forward, displacing fluid toward the patient and creating a
pressure in the syringe. The sliding potentiometer 180 tracks the
position of the syringe plunger. Alternatively, optical encoders
could be used to prevent contact skipping thus increasing the
system reliability.
[0076] The ECS controls the Contrast Delivery System (CDS) to
inject an amount of fluid into the patient based on the change in
position of the plunger. The disposable syringe 174 is in fluid
communication with a multi-port stopcock 182. As the fluid is
injected, the pressure the doctor feels in his hand is proportional
to the actual pressure produced by the contrast delivery system.
The force required to move the piston provides the operator with
tactile feedback on the pressure in the system. The doctor is able
to use this feedback to ensure the safety of the injection
procedure. Separate from this mechanism, the ECS may employ other
pressure measurement mechanisms such as the contrast delivery
system motor drive current.
[0077] The primary benefit over a totally manual injection is that
the doctor is not required to develop the pressure and flow rate.
He only develops the pressure and pushes some of the fluid. The
required manual power output (pressure*flow rate) is decreased.
[0078] The ECS also incorporates preprogrammed flow rate and
pressure limits which prevent the pressure of the injection from
exceeding safe limits. Additionally, the user display 176
incorporates warning lights which indicate when certain pressure
levels have been exceeded as well as an indication of the actual
pressure.
[0079] The ECS of the preferred embodiment of the present invention
also stores the injection parameters or flow rate profiles used by
individual doctors or other system operators so that the system is
able to customize injection procedures to match the particular
injection profile preferred by the individual. It has been
recognized that doctors have varying preferences in the images used
for diagnosing patients during medical imaging procedures. Varying
degrees of contrast media concentration and injection rates alter
the contrast in the resultant image. The system would be able to
use information on a doctor's preference to customize procedures
primarily based on the type of procedure and the weight of the
patient. These and other injection statistics would be stored and
after a sufficient sample size was available in system memory for
the particular doctor or system operator, the system would make
minor adjustments to the weight given to variables in the injection
parameter calculation algorithm used by the ECS. This would enable
the system to operate in the more automatic modes illustrated in
FIGS. 2, 4, or 5.
[0080] FIG. 9 illustrates the embodiment of the present invention
disclosed in FIG. 8, wherein the operator 162 is able to adjust
flow rate via the Tactile Feedback Control unit (TFC) 174. The
operator is able to feel the actual pressure used during the
injection procedure and is able to adjust flow rate based on the
resultant image displayed on the video monitor 163. The system
incorporates pressure limitations to prevent patient injury. This
system is similar to that shown in FIG. 7, except that the operator
views the region of interest, and pushes on the TFC in proportion
to the amount of contrast media desired to be injected based on the
resulting image. In addition to the feedback via the video image,
the doctor receives pressure feedback via the hand held unit.
Doctor are familiar with this type of feedback because it is
similar to the situation encountered when a powered fluid delivery
system is not used. This increases their confidence when using the
system in critical areas such as coronary vessels. As the operators
gain confidence in the safety and reliability of the system, it
will be possible for the system operation to be more automatic as
shown in FIGS. 2, 4, 5, or 7.
[0081] FIG. 10a illustrates use of another embodiment of the
present invention wherein the ECS uses signals generated in the TFC
190 to determine a proportionate amount of fluid to be injected
into the patient. In this embodiment, displacement is proportional
to the actual amount of fluid delivered and the TFC is not in fluid
communication with the fluid being delivered.
[0082] FIG. 10b shows more details of the TFC unit disclosed in
FIG. 10a which would eliminate the fluid path connection between
the TFC and the actual fluid being injected. It consists of a
plunger 200 with a threaded section 201. The base consists of an
outside case 205, a pressure sensor 207 attached to the case, and a
motor 209, the base of which is attached through the pressure
sensor 207 to the base of the case 205. The shaft of the motor is
connected to a threaded rod 210. The plunger 200 freely slides back
and forth with respect to the base. The plunger 200 cannot rotate
with respect to the base. On the end of the plunger nearest the
base is a threaded section 201. As the threaded rod 210 rotates,
the plunger 200 is moved in or out, depending upon the direction of
rotation. If desired, a linear potentiometer may be connected to
the plunger to provide a resistance proportional to the position of
the plunger in the base for measurement by the ECS.
[0083] To the doctor, the TFC functions as a syringe. When the
doctor pushes on the plunger 200, he generates a force which is
sensed by the force sensor 207. The output of this sensor is
proportional to the force applied by the doctor. Various types of
force sensors may be used such as, for example, a piezoelectric
film or a stiff spring with a linear displacement potentiometer.
The ECS receives the pressure signal, and generates a proportional
pressure in the contrast delivery system (CDS). As the fluid is
delivered by the CDS, the ECS energizes the motor 209 which rotates
the threaded cylinder 210. Thus the plunger moves toward the base
as the fluid is being delivered to the patient, and the doctor is
sensing a resistance force which is proportional to the pressure
required to deliver the fluid.
[0084] The TFC of FIG. 10b provides several benefits. It is
completely reusable, because it may be either sterilized or simply
covered by a bag. The fluid path is simplified, and therefore less
expensive, easier to install, fill and assure the removal of air.
The TFC can be much farther from the patient thereby also allowing
the doctor or operator to be farther from the radiation field and
receive less X-ray radiation. Both the ratios between the applied
force and pressure in the CDS and between flow rate and
displacement rate can be varied electronically, whereas in the
previously described TFC, the force was set by the diameter of the
disposable syringe.
[0085] In either of the TFC embodiments shown in FIGS. 8 and 10b,
it is possible to operate in several modes. In the preferred mode,
the displacement of the TFC is proportional to the volume of fluid
being injected, and the rate of fluid injection is proportional to
the rate at which the plunger of the TFC is displaced. A second
mode is described with a control system which is similar to that
found in a variable speed drill. In this system, the flow rate of
the injection is proportional to the displacement of the TFC. This
mode is not the primary one but may be preferred by some
operators.
[0086] The simplest algorithm assumes a linear relationship between
the TFC displacement and the volume injected or the flow rate being
injected. Other relationships are possible. Some examples are given
in FIGS. 11a-11d. In the TFC of FIG. 8, the syringe is actually
connected to the fluid line therefore the pressure in the TFC is
the same as that at the injection, and the force felt by the
operator is controlled by the diameter of the syringe. In the
electronically actuated TFC the relationship between input at the
TFC and output from the CDS can follow any of the relationships of
FIG. 11 or many others as well. The relationship may be different
for different operators. A strong man is likely to prefer a
different relationship than a smaller woman. In a preferred
embodiment, the system would be configured according to individual
preferences and the operator could simply enter their name and
password to set the desired preferences.
[0087] The example in FIG. 11d describes a relationship that might
be used to inflate a balloon for angioplasty. The pressure in the
CDS would be increased in steps as the pressure in the TFC is
increased.
[0088] Another capability of this embodiment is to synchronize the
CDS with an electrocardiogram signal. Present injectors can be
programmed to inject a specific volume at specific flow rate and
position relative to a marker on an electrocardiogram such as, for
example, the R wave. These systems are preferred by some, but do
not have the confidence of others. It is not possible for an
operator to manually synchronize with the electrocardiogram signal,
so they inject by hand at a constant rate. This practice results in
a waste of contrast media because the fluid flows into vessels
which are not being studied. A benefit of the TFC is that the
operator now has the instantaneous control of the injection with
feedback on pressure and flow rate. The CDS is able to synchronize
with the electrocardiogram thus minimizing the use of contrast
media thus saving cost and dose to the patient.
[0089] The selected exemplary embodiments of the TFC units set
forth above describe two design choices for the TFC. It is
contemplated that various substitutions and modifications could be
made to accomplish the results of the selected designs. The claims
are in no way limited to these preferred embodiments.
[0090] FIG. 12 illustrates an enhanced version of the system which
is designed for cardiology. In CT, MR and many angiographic
procedures, the contrast injector does not share the fluid path to
the patient with any other devices. In cardiology, the situation is
different. Presently, cardiologists use a manually activated
manifold with several three-way or four-way valves. These valves
are used so a single fluid line can measure pressure, perform scout
injections, and provide various fluids during manipulation of the
catheter to get it into the proper vessel. In this embodiment of
the invention, the disposable manifolds 215 are operated by
electronic solenoids or motors controlled by the ECS. Thus the
whole sequence of the procedure is automated to a great extent.
[0091] FIG. 13 provides additional detail. A sterile disposable
manifold 215 is shown and is similar to those manufactured by North
American Instrument Corporation of Glen Falls, N.Y. The only
difference is that manifold 215 includes valve adaptor plugs 217,
218, 219 which mate with slots in quarter-turn solenoid heads 221,
222, 223. Although numerous mating geometries are possible, there
is a safety advantage if mating may be accomplished in a single
orientation. In the preferred embodiment described in FIG. 13, a
single orientation is assured by having slots located in the
solenoid heads which are more narrow on one end than the other.
Mounting pins 225 and 226 located on the solenoid mounting case 227
mate with mounting holes 228, 229 on the disposable manifold 215 to
secure the manifold to the solenoid mounting case.
[0092] The ECS controls the position of the quarter-turn solenoids
231, 232, 233 via control lines 235, 236, 237. The quarter-turn
solenoids are simple electromechanical devices which rotate
ninety-degrees each time they are energized. In the described
system, the solenoids need only rotate in a single direction
because three successive energizations is the same as moving one
quarter-turn in the opposite direction. It is also important that
the system is capable of determining the position of the manifolds
to ensure that this information is available when power is first
turned on and also to verify that the valves move as commanded.
Simple position sensors are utilized for this purpose and send
signals to the ECS via sense lines 240, 241, and 242. In a
preferred embodiment the sensors are optical encoders for
simplicity and reliability.
[0093] A doctor may activate the manifold via any type of remote
control such as hand switches, foot switches or verbally with the
aid of voice recognition equipment. This last possibility is
illustrated by FIG. 14. There is a significant benefit in the
ability of the doctor to activate a control for example by simply
stating, "measure pressure," and have all the valves move to the
proper position. Alternatively, the doctor could say, "scout
injection," and the ECS operating in conjunction with the voice
recognition equipment 244 would set the valves to the proper
position for that function. This would eliminate many of the
separate actions which a doctor currently is required to perform in
using currently available systems. An additional advantage is that
a doctor using the system is able to operate the equipment while
being physically further from the patient thus being able to avoid
the damaging effects of the x-ray radiation.
[0094] In those embodiments where the operator is in the feedback
loop, additional feedback relating to system operation may be
provided to enhance system performance. For example, the operator
may receive audio feedback related to operational characteristics
such as speed, volume injected or pressure. Tone of an audible
signal could be used such that a higher pitch would indicate a
higher speed, greater volume, or greater pressure. Alternatively,
an audible click could be used to indicate injection of each
milliliter of fluid or the click repetition rate could be
proportional to the pressure. Audible feedback allows the operator
to receive this information while the operator continues to monitor
the patient or the image on the display 163. In a preferred
embodiment, the audio feedback is transmitted to the operator via
an ear phone which is either hard wired or battery powered to
eliminate an additional distraction in a busy room and to avoid the
possibility of the patient becoming alarmed as a result of the
audio signal.
[0095] Alternatively, the additional feedback could be displayed on
the video monitor 163 along with the patient image. Providing the
additional feedback visually avoids the possible distraction of
others and is particularly useful if it can be displayed without
distracting the operator from viewing the patient image. One method
of simultaneous display is the use of numbers on the monitor which
indicate flow rate. A bar graph or a syringe outline which empties
as the fluid is injected are other options.
[0096] Although the present invention has been described in terms
of preferred embodiments, the present description is given by way
of example and is not intended to be limiting to the scope of the
invention described and claimed herein.
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