Radiographic/fluoroscopic imaging system with reduced patient dose and faster transitions between radiographic and fluoroscopic modes

• US 5,917,882 A
• Filed: 11/29/1996
• Issued: 06/29/1999
• Est. Priority Date: 11/29/1996
• Status: Expired due to Fees

• Current Assignee: Hologic Incorporated
• Original Assignee: Continental X-Ray Corp. (Thermo Fisher Scientific Incorporated)
• Inventors: Taylor, James, Khutoryansky, Oscar, Rosevear, Thomas, Simak, Thomas, Maltsev, Yevgeniy, Tomsic, Cyril
• Primary Examiner(s): Church, Craig E.
• Application Number:
  US08/753,772
• Time in Patent Office: 942 Days
• Field of Search: 378/116, 378/108, 378/98.7, 378/97
• US Class Current: 378/116
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 6/0487 Motor-assisted positioning
• CPC Class Codes: A61B 6/08 Auxiliary means for directing the radiation beam to a particular spot, e.g. using light beams
• CPC Class Codes: A61B 6/4225 using image intensifiers
• CPC Class Codes: A61B 6/4233 using matrix detectors
• CPC Class Codes: A61B 6/4464 the source unit or the detector unit being mounted to ceiling
• CPC Class Codes: A61B 6/4488 Means for cooling A61B6/045 takes precedence
• CPC Class Codes: A61B 6/481 involving the use of contrast agents
• CPC Class Codes: A61B 6/504 for diagnosis of blood vessels, e.g. by angiography
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: A61B 6/542 involving control of exposure
• CPC Class Codes: H05G 1/46 Combined control of different quantities, e.g. exposure time as well as voltage or current
• CPC Class Codes: H05G 1/58 Switching arrangements for changing-over from one mode of operation to another, e.g. from radioscopy to radiography, from radioscopy to irradiation or from one tube voltage to another
• CPC Class Codes: H05G 1/60 Circuit arrangements for obtaining a series of X-ray photographs or for X-ray cinematography

Abstract

A radiographic/fluoroscopic imaging system provides rapid transition from fluoroscopic to radiographic imaging mode by maintaining the X-ray tube high voltage, increasing the filament current, allowing X-ray tube current to increase toward the desired radiographic current, and terminating exposure when the desired X-ray dose has been achieved. Rapid transition from radiographic to fluoroscopic imaging mode is provided by reducing x-ray tube high voltage to produce an equivalent fluoroscopic-level x-ray output at high initial current, dropping filament current, and enabling ABS control of the high-voltage. As x-ray tube current drops, ABS correspondingly increase high voltage to maintain the desired output. The imaging system obtains movement-related information by analyzing a video signal (such as from fluoroscopic image or an image from an optical camera trained on the patient), or from operator movement requests. The imaging system uses movement-related information to responsively control fluoroscopic pulse rate or other imaging parameters. The imaging system can also use such information to initiate a radiographic exposure, or advance to the next step of an operator programmed examination consisting of interspersed fluoroscopic and radiographic exposures. This results in a lower dose to both the patient and the examiner, consistent with high image quality.

Claims

1. A diagnostic medical imaging system adapted for radiographic and fluoroscopic examinations, said system being capable of operating in a fluoroscopic examination mode and in a radiographic examination mode, comprising:

X-ray tube means;

means for receiving x-rays;

said X-ray tube means delivering an x-ray output which is responsive at least in part to filament current provided to said X-ray tube and high-voltage power supply provided to said x-ray tube;

said output of said X-ray tube being responsive to a change in said filament current by gradually approaching an output level corresponding to said change over a time interval;

said output of said X-ray tube being essentially immediately responsive to a change in said high-voltage power supply;

fluoroscopic examination mode x-ray output set point means;

means, operable during a fluoroscopic examination and including automatic brightness control means, for establishing fluoroscopic-mode preferred values for said filament current and said high-voltage power supply;

means operable during a radiographic examination for operating said x-ray tube means at predetermined values of said filament current and said high-voltage power supply;

means responsive to said predetermined value of said filament current and said fluoroscopic examination mode x-ray output set point means for determining a fluoroscopic mode initial value for said high-voltage power supply which is required to cause said x-ray tube to produce an x-ray output approximating said set point during an initial period after a change occurs in said filament current from said radiographic mode predetermined value to said fluoroscopic-mode preferred value;

means responsive to an instruction to transition from said radiographic examination mode to said fluoroscopic examination mode for rapidly causing said x-ray tube means to operate according to said fluoroscopic mode initial value of said high-voltage power supply and said fluoroscopic-mode preferred value for said filament current;

means responsive to the output of said x-ray tube means for adjusting the high-voltage power supply as needed to maintain said x-ray output at said desired fluoroscopic mode x-ray output.

2. A diagnostic medical imaging system adapted for radiographic and fluoroscopic examinations, said system being capable of operating in a fluoroscopic examination mode and in a radiographic examination mode, comprising:

means for producing x-rays directed toward an examination region of interest;

means for receiving x-rays;

said means for producing x-rays delivering an x-ray output which is responsive at least in part to first and second controllable electrical parameters;

said output of said means for producing x-rays being responsive to a change in said first controllable electrical parameter by approaching an output level corresponding to said change over a time interval;

said output of said means for producing x-rays being essentially immediately responsive to a change in said second electrical parameter;

means for establishing a desired fluoroscopic mode x-ray output to be delivered while in said fluoroscopic examination mode;

means operable during a fluoroscopic examination for establishing a fluoroscopic-mode preferred value for said first electrical parameter;

means operable during a radiographic examination for operating said means for producing x-rays at a predetermined value of said first parameter;

means responsive to said predetermined value of said first electrical parameter and said desired fluoroscopic mode x-ray output for determining a fluoroscopic mode initial value for said second electrical parameter which is required to cause said means for producing x-rays to produce an x-ray output approximating said desired fluoroscopic mode x-ray output during an initial period after a change occurs in said first electrical parameter from said radiographic mode predetermined value;

means responsive to an instruction to transition from said radiographic examination mode to said fluoroscopic examination mode for rapidly causing said means for producing x-rays to operate according to said fluoroscopic mode initial value of said second electrical parameter and said fluoroscopic-mode preferred value for said first electrical parameter.

3. A diagnostic medical imaging system adapted for radiographic and fluoroscopic examinations, said system being capable of operating in a fluoroscopic examination mode and in a radiographic examination mode, comprising:

means for producing x-rays directed toward an examination region of interest;

means for receiving x-rays;

said means for producing x-rays delivering an x-ray output which is responsive at least in part to first and second controllable electrical parameters;

said output of said means for producing x-rays being responsive to a change in said first controllable electrical parameter by approaching an output level corresponding to said change over a time interval;

said output of said means for producing x-rays being essentially immediately responsive to a change in said second electrical parameter;

means for establishing a desired fluoroscopic mode x-ray output to be delivered while in said fluoroscopic examination mode;

means operable during a fluoroscopic examination for establishing a fluoroscopic-mode preferred value for said first electrical parameter;

means operable during a radiographic examination for operating said means for producing x-rays at a predetermined value of said first parameter;

means responsive to an instruction to transition from said radiographic examination mode to said fluoroscopic examination mode for rapidly causing said means for producing x-rays to operate according to said fluoroscopic-mode preferred value for said first electrical parameter;

means responsive to the output of said means for producing x-rays for adjusting said second electrical parameter as needed to maintain said x-ray output at said desired fluoroscopic mode x-ray output.

4. For use with a radiographic/fluoroscopic diagnostic imaging system having a radiographic exposure mode, a fluoroscopic exposure mode, x-ray emitting means, said x-ray emitting means having an x-ray output level responsive substantially instantaneously to a first electrical power supply parameter;

said x-ray emitting means having an x-ray output level responsive to a second electrical power supply parameter;

the method of rapidly transitioning from said radiographic to fluoroscopic imaging mode comprising the steps of;

(a) establishing a desired value of said x-ray output level during said fluoroscopic exposure mode;

(b) determining a value of said second parameter which was used during said radiographic exposure mode;

(c) determining an initial value for said first parameter which will result in said x-ray emitting means producing said desired value of said x-ray output level when said x-ray emitting means operates at said determined value of said second parameter;

(d) initiating a change in said second parameter to a value appropriate for said fluoroscopic imaging mode;

(e) changing said first parameter to said determined initial value for said first parameter; and

(f) measuring said x-ray output level and responsively adjusting said first parameter to cause said x-ray output level to approximate said desired value thereof.

5. For use with a radiographic/fluoroscopic diagnostic imaging system having a radiographic exposure mode, a fluoroscopic exposure mode, and x-ray emitting means, said x-ray emitting means having an x-ray output level responsive substantially instantaneously to a first electrical power supply parameter;

said x-ray emitting means having an x-ray output level substantially non-instantaneously responsive to a second electrical power supply parameter;

a method of rapidly transitioning from said fluoroscopic to radiographic imaging mode of the type including the steps of;

(a) establishing a desired x-ray dose;

(b) maintaining said first parameter at a level used during said fluoroscopic exposure mode;

(c) changing said second parameter to a value appropriate for said radiographic exposure mode;

(d) measuring an accumulated x-ray dose delivered by said x-ray emitting means;

(e) and terminating said radiographic exposure mode when said measured accumulated x-ray dose equals or exceeds said desired x-ray dose;

wherein the improvement comprises measuring said accumulated x-ray dose as an integrated measurement of an electrical parameter of the energy supplied to said x-ray emitting means.

6. A diagnostic medical imaging system adapted for radiographic and fluoroscopic examinations, said system being capable of operating in a fluoroscopic examination mode and in a radiographic examination mode, comprising:

means for producing x-rays directed toward an examination region of interest;

means for receiving x-rays;

said means for producing x-rays delivering an x-ray output which is responsive at least in part to first and second controllable electrical parameters;

said output of said means for producing x-rays being responsive to a change in said first controllable electrical parameter by gradually approaching an output level corresponding to said change over a time interval;

said output of said means for producing x-rays being essentially immediately responsive to a change in said second electrical parameter;

means operable during a fluoroscopic examination for establishing fluoroscopic-mode preferred values for said first and second electrical parameters;

means for establishing a desired radiographic mode x-ray output and a desired radiographic mode x-ray dose to be delivered while in said radiographic examination mode;

means responsive to said fluoroscopic-mode preferred values and said desired radiographic mode x-ray output for determining radiographic mode preferred values for said first and second electrical parameters;

means responsive to an instruction to transition from said fluoroscopic examination mode to a radiographic examination mode for rapidly causing said means for producing x-rays to operate according to said radiographic mode preferred values for said first and second electrical parameters; and

radiographic exposure termination means responsive to the output of said means for producing x-rays for restoring operation thereof according to previous values of said first and second electrical parameters when said desired radiographic mode x-ray dose has been delivered.

7. The imaging system of claim 6 wherein said means for producing X-rays is an X-ray tube.

8. The imaging system of claim 7 wherein said first controllable electrical parameter is filament current provided to said X-ray tube.

9. The imaging system of claim 7 wherein said second controllable electrical parameter is the high-voltage power supply provided to said X-ray tube.

10. The imaging system of claim 6 wherein said means operable during a fluoroscopic examination for establishing fluoroscopic-mode preferred values for said first and second electrical parameters includes an automatic brightness system.

11. The system of claim 6 wherein said radiographic exposure termination means comprises an automatic exposure control system.

12. A diagnostic medical imaging system adapted for radiographic and fluoroscopic examinations of a patient, said system being capable of operating in a fluoroscopic examination mode and in a radiographic examination mode, said system being of the type including:

means for producing x-rays directed toward an examination region of interest;

means for receiving x-rays and producing therefrom image information relating to said examination region of interest;

means for deriving movement related information producing an indication when movement of said patient with respect to said imaging system, requests for movement of said patient with respect to said imaging system, or change in a visible feature of said image information occur;

means responsive to said means for deriving movement related information for operating said imaging system in said fluoroscopic examination mode while said indication is absent; and

means responsive to said means for deriving movement related information for performing a radiographic exposure when said indication is received;

wherein the improvement comprises;

first image change detection means responsive to image change in a first selected image region for producing a first signal indicating said change;

second image change detection means responsive to image change in a second selected image region for producing a second signal indicating said change;

means for initially causing said imaging system to operate according to a first set of fluoroscopic and imaging operating parameters;

means responsive to said first signal for causing said imaging system to operate according to a second set of fluoroscopic and imaging operating parameters non-identical with said first set; and

means responsive to said second signal for initiating a radiographic exposure.

13. A method for use with a diagnostic medical imaging system adapted for radiographic and fluoroscopic examinations of a patient, said system being capable of operating in a fluoroscopic examination mode and in a radiographic examination mode, said system having means for collecting image information from said patient to form a representation of an image;

the method including the steps of;

a) establishing fluoroscopic and imaging operating parameters;

(b) defining at least one region of said representation of an image;

(c) performing the fluoroscopic examination;

(d) detecting image change in at least one of said defined regions of said representation of an image; and

(e) causing said imaging system to initiate a radiographic exposure;

wherein the improvement comprises;

step (a) further comprising the step of (a1) defining initial fluoroscopic and imaging examination parameters;

step (b) further comprising the step of (b1) defining at least first and second regions of said representation of an image;

step (c) further comprising the steps of;

(c1) initiating the fluoroscopic examination according to the initial fluoroscopic and imaging examination parameters; and

(c2) detecting image change in said first defined region of said representation of an image, and responsive thereto, causing said imaging system to operate according to adjusted fluoroscopic and imaging examination parameters;

step (d) further comprising in the step of (d1) detecting image change in said second defined region of said representation of an image; and

step (e) further comprising in the step of (e1) responsive thereto, causing said imaging system to initiate said radiographic exposure.

14. A diagnostic medical imaging system adapted for radiographic and fluoroscopic examinations, said system being capable of operating in a fluoroscopic examination mode and in a radiographic examination mode, comprising:

means for producing x-rays directed toward an examination region of interest;

means for receiving x-rays;

said means for producing x-rays delivering an x-ray output which is responsive at least in part to first and second controllable electrical parameters;

said output of said means for producing x-rays being responsive to a change in said first controllable electrical parameter by gradually approaching an output level corresponding to said change over a time interval;

said output of said means for producing x-rays being essentially immediately responsive to a change in said second electrical parameter;

means for establishing a desired fluoroscopic mode x-ray output to be delivered while in said fluoroscopic examination mode;

means operable during a fluoroscopic examination for establishing fluoroscopic-mode preferred values for said first and second electrical parameters;

means operable during a radiographic examination for operating said means for producing x-rays at predetermined values of said first and second electrical parameters;

means responsive to said predetermined value of said first electrical parameter and said desired fluoroscopic mode x-ray output for determining a fluoroscopic mode initial value for said second electrical parameter which is required to cause said means for producing x-rays to produce an x-ray output approximating said desired fluoroscopic mode x-ray output during an initial period after a change occurs in said first electrical parameter from said radiographic mode predetermined value to said fluoroscopic-mode preferred value;

means responsive to an instruction to transition from said radiographic examination mode to said fluoroscopic examination mode for rapidly causing said means for producing x-rays to operate according to said fluoroscopic mode initial value of said second electrical parameter and said fluoroscopic-mode preferred value for said first electrical parameter;

means responsive to the output of said means for producing x-rays for adjusting said second electrical parameter as needed to maintain said x-ray output at said desired fluoroscopic mode x-ray output.

15. The imaging system of claim 14 wherein said means operable during a fluoroscopic examination for establishing fluoroscopic-mode preferred values for said first and second electrical parameters comprises an automatic brightness system.

16. The imaging system of claim 14 wherein said means responsive to the output of said means for producing x-rays for adjusting said second electrical parameter to cause said x-ray output as needed to maintain said desired fluoroscopic mode x-ray output comprises an automatic brightness system.

17. The imaging system of claim 14 wherein said means for producing X-rays is an X-ray tube.

18. The imaging system of claim 17 wherein said first controllable electrical parameter is filament current provided to said X-ray tube.

19. The imaging system of claim 17 wherein said second controllable electrical parameter is the high-voltage power supply provided to said X-ray tube.