Device for determining the characteristics of blood flow through coronary bypass grafts

• US 5,105,452 A
• Filed: 03/26/1991
• Issued: 04/14/1992
• Est. Priority Date: 03/26/1991
• Status: Expired due to Fees

• Current Assignee: Joseph J. Mcinerney
• Original Assignee: Joseph J. Mcinerney
• Inventors: McInerney, Joseph J.
• Primary Examiner(s): Howell, Janice A.
• Assistant Examiner(s): WONG, DON KITSUN
• Application Number:
  US07/674,913
• Time in Patent Office: 385 Days
• Field of Search: 378/44, 378/49, 378/87, 378/62, 378/99, 378/42, 378/19, 378/21, 378/24, 378/25, 378/6, 378/5, 378/46, 378/90, 358/111
• US Class Current: 378/44
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/4291 the detector being combined with a grid or grating
• CPC Class Codes: A61B 6/483 involving scattered radiation
• CPC Class Codes: A61B 6/507 for determination of haemodynamic parameters, e.g. perfusion CT

Abstract

A narrow x-ray beam is scanned through the chest cavity of a subject to create a scattered radiation signal. The scattered radiation signal is used to construct a tomographic image of the contents of the subject'"'"'s chest cavity on a display screen. A crosshair on the display screen is used to mark the location of a bypass graft in the image. A computer senses the position of the crosshair and subsequently positions a fluorescence detector over the subject to interrogate the location of the bypass graft within the chest cavity. A tracer material injected into the subject fluoresces as it passes through the irradiated bypass graft. The resulting fluorescence transient is recorded and provides a measure of graft patency and flow characteristics.

Claims

1. An apparatus for monitoring flow through a coronary bypass graft in a subject comprising:

(a) x-ray source means for generating a shaped x-ray beam for directing into the chest cavity of the subject to scatter from and fluoresce the contents of said chest cavity;

(b) means for sweeping the said shaped x-ray beam so that a plurality of locations comprising a cross-section of the chest of said subject will emit scattered and fluorescence radiation;

(c) a means for creating a sweep-start signal at the start of each sweep of the sweeping x-ray beam;

(d) scattered- and fluorescence-radiation detector means for detection, at a plurality of locations, the scatter and fluorescence radiation emitted from the chest cavity of said subject, said detection assembly means including;

(d.1) a scattered-radiation detector, said scattered-radiation detector having a directional radiation receptance port and a radiation-intensity signal output and being adapted to produce a radiation intensity signal at said output which is a measure of the intensity of radiation incident upon the scattered-radiation detector radiation receptance port and propagating in a direction admitted by the scattered-radiation detector radiation receptance port having a limited field of view;

(d.2) a fluorescence-radiation detector, said fluorescence-radiation detector having a directional radiation receptance port and a radiation-intensity signal output and being adapted to produce a radiation-intensity signal at said output which is a measure of the intensity of radiation incident upon the fluorescence-radiation detector radiation receptance port and propagating in a direction admitted by the fluorescence-radiation detector radiation receptance port having a limited field of view;

(d.3) a means for positioning of the scattered-radiation detector at a plurality of locations;

(d.4) a means for positioning of the fluorescence-radiation detector at a plurality of locations;

(e) position control signal input means to control the positions of the said scattered- and fluorescence-radiation detectors;

(f) an x-ray energy spectrum analysis means for isolating a selected energy level of fluorescence radiation;

(g) a means for displaying and recording the intensity of said selected fluorescence-radiation as it changes with time;

(h) a computer assembly comprising;

(h.1) an image display interface means for creating a cross-sectional image of the chest of the subject from the scattered-radiation signal output from the scattered-radiation detector;

(h.2) an input/output means;

(i) an image display means for displaying said cross sectional image of the chest of the subject.

2. Apparatus as recited in claim 1 wherein the said computer assembly input/output means includes an input which senses the said sweep-start signal.

3. Apparatus as cited in claim 1 wherein the said input-output means includes an interface with the said position control signal input means.

4. Apparatus as cited in claim 1 wherein the said input/output means includes a spectrum analysis control interface with said x-ray energy spectrum analysis means to control the processing of signals input to the energy spectrum analysis means.

5. Apparatus as recited in claim 1 wherein the said image display interface means includes a means for encoding the said cross sectional image in computer memory in such a manner as to relate each image pixel to an ordered memory location.

6. Apparatus as recited in claim 5 wherein the said means for encoding the cross-sectional image encodes:

(a) the position of the scattered-radiation detector at the time each image pixel was acquired;

(b) the configuration of the means for sweeping the shaped x-ray beam at the time each image pixel was acquired.

7. Apparatus as recited in claim 1 wherein the image display interface means for displaying the cross-sectional image includes a means selecting an individual pixel on the said image.

8. Apparatus as recited in claim 7 wherein means for selecting an individual image pixel includes:

(a) a means to relate the position of the said individual image pixel to the position of the scattered-radiation detector at the time the data for that image pixel was acquired;

(b) a means to relate the position of the said individual image pixel to the configuration of the means for sweeping the shaped x-ray beam at the time the data for the said image pixel was acquired.

9. Apparatus as recited in claim 1 wherein the said computer assembly can direct the position control signal input means to position the fluorescence-radiation detector such that the fluorescence-radiation detector is approximately centered at the position held by the scattered-radiation detector when the scattered-radiation detector acquired data for a selected image pixel.

10. Apparatus as recited in claim 4 wherein the said spectrum analysis control interface means restricts spectrum analysis means data collection to the approximate time interval during which the sweeping x-ray beam is passing through the chest of the subject at the location corresponding to a selected image pixel.

11. Apparatus as recited in claim 1 wherein the energy spectrum analysis means includes a means for storing the data it acquires.

12. Apparatus as recited in claim 11 wherein the said energy spectrum analysis means includes a means for transmitting stored data to a computer.