Proton beam digital imaging system

• US 5,825,845 A
• Filed: 10/28/1996
• Issued: 10/20/1998
• Est. Priority Date: 10/28/1996
• Status: Expired due to Term

• Current Assignee: LOMA Linda University Medical Center (Mission Healthcare Services LLC)
• Original Assignee: LOMA Linda University Medical Center (Mission Healthcare Services LLC)
• Inventors: Samantarai, Jagadish P., Yeldell, Berry B., Blair, Mark S., Lin, Pengyue James, Lesyna, David A.
• Primary Examiner(s): WONG, DON KITSUN
• Application Number:
  US08/739,512
• Time in Patent Office: 722 Days
• Field of Search: 378/62, 378/63, 378/64, 378/65, 378/205
• US Class Current: 378/62
• CPC Class Codes: A61N 2005/1061 using an x-ray imaging system having a separate imaging source
• CPC Class Codes: A61N 2005/1062 using virtual X-ray images, e.g. digitally reconstructed radiographs [DRR]
• CPC Class Codes: A61N 2005/1087 Ions; Protons
• CPC Class Codes: A61N 5/1049 for verifying the position of the patient with respect to the radiation beam
• CPC Class Codes: A61N 5/1069 Target adjustment, e.g. moving the patient support

Abstract

A proton beam digital imaging system comprising an X-ray source which is movable into the treatment beam line that can produce an X-ray beam through a region of the patient. An X-ray receiver receives the X-ray beam after it has passed through the patient and the X-ray receiver generates photons that correspond to the X-ray image. The photons are directed to a TEC CCD camera to produce a patient orientation image which displays the orientation of the center of the beam relative to selected monuments in the patient'"'"'s skeletal structure. The system also receives a master prescription image which displays the target isocenter with respect to the same selected monuments of the patient'"'"'s skeletal structure. By comparison of the relative positions of the center of the beam in the patient orientation image and the isocenter in the master prescription image with respect to the selected monuments, the amount and direction of movement of the patient to make the beam center correspond to the target isocenter is determined.

Claims

1. An imaging system for a proton beam therapy system having a proton source, a beam delivery system with a nozzle that is mounted on a gantry so that said proton beam can be delivered to the patient from a plurality of angles, wherein said proton beam therapy system receives a master prescription image of a region of a patient that is to be treated, said imaging system comprising:

an imaging beam source mounted on said beam delivery system wherein said imaging beam source is movable between a first position, wherein said imaging source can project an imaging beam along a treatment beam path towards a first side of said patient, and a second position wherein said imaging source is removed from said beam path to thereby allow said proton beam to travel along said treatment path;

an imaging beam receiver attached to said gantry so that said receiver is centered about said beam path throughout a plurality of angles of orientation of the gantry wherein said receiver receives said imaging beam after it has passed through a region of the patient that is positioned in said beam path;

an image capture device proximate to said receiver, wherein said image capture device directly receives a non-intensified signal from said receiver and produces a patient orientation image of the region of the patient'"'"'s body that is positioned in said beam path; and

a controller which receives both said master prescription image and said patient orientation image, wherein said controller is configured so that one or more rigid structures can be designated on said master prescription image so as to define the relative position of an isocenter to be treated in the patient'"'"'s body with respect to said one or more rigid structures and wherein said controller is also configured so that said one or more rigid structures can be designated on said patient orientation image so that said controller can determine the relative location of the center of said beam line with respect to said one or more rigid structures and wherein said controller using said relative position of said target isocenter and said beam line center with respect to said one or more rigid structures determine the relative movement between the patient and the gantry required so that the position of the center of the beam line with respect to the one or more rigid structures corresponds to the position of the target isocenter with respect to said one or more rigid structures.

2. The system of claim 1, wherein said imaging beam source is comprised of an X-ray source that is mounted so as to be movable in a direction that is transverse to the direction of the proton beam path.

3. The system of claim 2, wherein said imaging beam receiver is comprised of a fluorescing screen that is positioned in said beam path wherein said fluorescing screen produces photons in response to X-rays impinging upon said fluorescing screen.

4. The system of claim 3, wherein said image capture device is comprised of a CCD camera that receives said photons produced by said fluorescing screen and thereby produces said patient orientation image.

5. The system of claim 4, wherein said CCD camera is water cooled so as to remove excess noise from said patient orientation image.

6. The system of claim 5, wherein said receiver and said CCD camera are positioned in an enclosure wherein said receiver is positioned within an aperture of said enclosure that is centered about said beam path and wherein said enclosure defines a path for said photons produced by said receiver which directs said photons to said CCD camera.

7. The system of claim 6, wherein said enclosure includes two mirrors so that said photons emanating from said fluorescing screen travel in a first direction towards one of said mirrors, are reflected in a second direction towards a second mirror and are then reflected in a third direction, which is generally parallel to said first direction, towards said CCD camera.

8. The system of claim 7, wherein said enclosure includes one or more baffles to prevent at least a portion of any photons which are travelling in a direction that has a component transverse to the directions of said path from reaching said CCD camera.

9. The system of claim 8, wherein said X-ray source is comprised of a diagnostic quality X-ray tube that operates in the 30 kV-150 kV energy range, the fluorescing screen is comprised of a square of gadolinium sulphur dioxide and the CCD camera includes a thinned CCD sensor that is 512 by 512 pixels and said CCD camera includes a F.95 lens with a 50 mm focal length.

10. The system of claim 9, wherein said CCD camera receives said photons directly from said fluorescing screen in said path so that said patient orientation image is substantially undistorted by intensification.

11. The system of claim 4, further comprising a pair of cross-wires attached to said receiver so as to be centered in said beam path, wherein said cross-wires interrupt said X-rays from said X-ray source so that fewer photons are produced by said fluorescing screen in the region of said cross-wires which results in an image of said cross-wires appearing on said patient orientation image.

12. The system of claim 1, further comprising:

a first monitor which receives signals from said controller and displays said master prescription image; and

a second monitor which receives signals from said controller and displays said patient orientation image wherein a treating physician can manipulate said controller so as to designate said one or more rigid structures on said patient orientation image.

13. The system of claim 1, wherein said controller performs a least squares approximation to determine the offset between the center of the beam line and the isocenter relative said one or more rigid structures and wherein said one or more rigid structures comprise monuments on said patient'"'"'s skeletal structure.

14. An imaging system for a proton beam therapy system having a proton source, a beam delivery system with a nozzle that is mounted on a gantry so that said proton beam can be delivered to the patient from a plurality of angles, wherein said imaging system receives a master prescription image of a region of the patient that is to be treated, said imaging system comprising:

an X-ray source mounted on said beam delivery system wherein said X-ray source is movable between a first position, wherein said source can project an X-ray beam along a treatment beam path towards a first side of said patient, and a second position wherein said source is removed from said beam path to thereby allow said proton beam to travel along said treatment path;

an X-ray beam receiver attached to said gantry so that said receiver is centered about said beam path throughout the plurality of angles of orientation of the gantry wherein said receiver receives said X-ray beam after it has passed through a region of the patient that is positioned in said beam path and produces a photon image corresponding to the portion of the patient'"'"'s body in the beam line;

an image capture device which receives said photon image directly from said X-ray beam receiver, and produces a patient orientation image of the region of the patient'"'"'s body that is positioned in said beam path so that said patient orientation image is substantially undistorted by intensification; and

a controller which receives both said master prescription image and said patient orientation image, wherein said controller is configured so that one or more monuments can be designated on said master prescription image so as to define the relative position of an isocenter to be treated in the patient'"'"'s body with respect to said one or more monuments and wherein said controller is also configured so that said one or more monuments can be designated on said patient orientation image so that said controller can determine the relative location of the center of said beam line with respect to said one or more monuments and wherein said controller using said relative position of said target isocenter and said beam line center with respect to said one or more monuments determines the movement of the patient required so that the position of the center of the beam line with respect to the one or more monuments corresponds to the position of the target isocenter with respect to said one or more monuments.

15. The system of claim 14, further comprising a pair of cross-wires attached to said receiver so as to be centered in said beam path, wherein said cross-wires interrupt said X-rays from said source so that fewer photons are produced by said X-ray receiver in the region of said cross-wires which results in an image of said cross-wires appearing on said patient orientation image.

16. The system of claim 14, wherein said controller uses the relative position of the target isocenter and the relative position of the center of said beam line with respect to said one or more monuments to perform a least squares approximation to determine the direction and magnitude of movement of the patient with respect to the beam line so that the target isocenter is positioned at the center of the beam line.

17. The system of claim 14, further comprising:

a first monitor which receives signals from said controller and displays said master prescription image; and

a second monitor which receives signals from said controller and displays said patient orientation image wherein a treating physician can manipulate said controller so as to designate said one or more monuments on said patient orientation image.

18. The system of claim 14, wherein said X-ray receiver is comprised of a fluorescing screen that is positioned in said beam path wherein said fluorescing screen produces photons in response to X-rays impinging upon said fluorescing screen.

19. The system of claim 18, wherein said image capture device is comprised of a CCD camera that receives said photons produced by said fluorescing screen and thereby produces said patient orientation image.

20. The system of claim 19, wherein said CCD camera is water cooled so as to remove excess noise from said patient orientation image.

21. The system of claim 20, wherein said receiver and said CCD camera are positioned in an enclosure wherein said receiver is positioned within an aperture of said enclosure that is centered about said beam path and wherein said enclosure defines a path for said photons produced by said receiver which directs said photons to said CCD camera.

22. The system of claim 21, wherein said enclosure includes two mirrors so that said photons emanating from said fluorescing screen travel in a first direction towards one of said mirrors, are reflected in a second direction towards a second mirror and are then reflected in a third direction, which is generally parallel to said first direction, towards said CCD camera.

23. The system of claim 22, wherein said enclosure includes one or more baffles to prevent photons which are travelling in a direction that has a component transverse to the direction of said path from reaching said CCD camera.

24. The system of claim 23, wherein said X-ray source is comprised of a diagnostic quality X-ray tube that operates in the 30 kV-150 kV energy range, the fluorescing screen is comprised of a square of gadolinium sulphur dioxide and the CCD camera includes a thinned CCD sensor that is 512 by 512 pixels and said CCD camera includes a F.95 lens with a 50 mm focal length.

25. A method of aligning a patient in a proton beam therapy system so that the center of a beam line from a nozzle is centered at a target isocenter positioned within the body of the patient, said method comprising the steps of:

obtaining a master prescription image of the patient for a desired orientation of the beam wherein the master prescription image is stored in a computer system;

positioning the patient on a treatment table so that the region of the patient'"'"'s body containing the target isocenter is positioned in front of the nozzle;

transmitting an imaging beam along the treatment beam path so that the imaging beam is transmitted into the region of the patient'"'"'s body positioned in front of the nozzle;

receiving the imaging beam after it has been transmitted into the region of the patient'"'"'s body and directly capturing a non-intensified patient orientation image of the region of the patient'"'"'s body that is positioned in said beam path that is provided to said computer system;

designating said one or more monuments, using said computer system, on said master prescription image;

designating said one or more monuments, using said computer system, on said patient orientation image wherein said one or more monuments designated on both said master prescription image and said patient orientation image correspond to the same point of said patient'"'"'s anatomy;

determining the relative position of the center of said treatment beam with respect to the one or more monuments designated in the patient orientation image;

determining the offset between the target isocenter with respect to the one or more monuments in the master prescription image and the center of the beam with respect to the one or more monuments in the patient orientation image using said computer system; and

determining the distance and direction the patient will have to be moved so that the position of the center of the beam with respect to the one or more monuments coincides with the position of the target isocenter with respect to the one or more monuments.

26. The method of claim 25, wherein the step of transmitting an imaging beam along the treatment beam path comprises the steps of:

positioning an X-ray source in the treatment beam path; and

inducing the X-ray source to emanate X-rays along the treatment beam path.

27. The method of claim 26, wherein the step of receiving the imaging beam comprises receiving X-rays after the X-rays have traveled along the treatment beam path through said patient.

28. The method of claim 27, wherein the step of receiving the imaging beam and capturing a patient orientation image comprises the steps of:

positioning a fluorescing screen in said beam path so that photons are produced in response to the X-rays of said X-ray beam impacting said fluorescing screen;

directing said photons along a compact path to a CCD camera.

29. The method of claim 28, further comprising the step of positioning a pair of cross-wires so as to be centered about the center of the treatment beam path so that a resulting image of the cross-wires appears in said patient orientation image at a point representative of the center treatment beam path.

30. The method of claim 25, wherein the steps of selecting the one or more monuments comprises the steps of:

displaying a digital image of said master prescription image on a display;

manipulating a user input device to a monument on the skeletal structure of said patient displayed on said display;

manipulating said user input device to select said monument;

displaying a digital image of said patient orientation image on a display;

manipulating a user input device to said monument on the skeletal structure of said patient displayed on said display; and

manipulating said user input device to select said monument.

31. The method of claim 30, further comprising the step of:

calculating the relative location between the selected monument in the master prescription image and the target isocenter in said master prescription image; and

calculating the relative location between the selected monument in the patient orientation image and the center of said beam line.

32. The method of claim 25, wherein the step of determining the distance and direction the patient will have to be moved comprises performing a least squares fit between the relative location of the target isocenter with respect to said one or more monuments of the master prescription image and the relative location of the center of the beam path with respect to said one or more monuments.

33. A therapeutic imaging system for a treatment beam therapy system having a treatment beam source, a beam delivery system with a nozzle that is configured to provide the treatment beam from a plurality of different angles, said therapeutic imaging system comprising:

an X-ray beam source mounted on said beam delivery system wherein said X-ray beam source is movable between a first position, wherein said X-ray source can project an X-ray beam along a treatment beam path towards a first side of said patient, and a second position wherein said X-ray is removed from said beam path to thereby allow said treatment beam to travel along said treatment beam path;

a fluorescing screen positioned so as to be centered about said beam path wherein said fluorescing screen receives said X-ray beam after it has passed through a region of the patient that is positioned in said beam path and produces a resulting photon image; and

a digital camera which receives said photon image directly from said fluorescing screen and produces a patient orientation image of the region of the patient'"'"'s body that is positioned in said beam path so that said patient orientation image is substantially undistorted by intensification.

34. The system of claim 33, wherein said therapeutic imaging system is configured to be used with a proton beam therapy system having a proton source, a beam delivery system with a nozzle that is mounted on a gantry so that said proton beam can be delivered to the patient from a plurality of angles and wherein said therapeutic imaging system is capable of producing said patient orientation image over a plurality of orientations of said gantry.

35. The system of claim 34, further comprising a controller which receives a master prescription image of a region of a patient that is to be treated and said patient orientation image wherein said controller is configured so that one or more monuments can be designated on said master prescription image so as to define the relative position of an isocenter to be treated in the patient'"'"'s body with respect to said one or more monuments.

36. The system of claim 35, wherein said controller is also configured so that said one or more monuments can be designated on said patient orientation image so that said controller can determine the relative location of the center of said beam line with respect to said one or more monuments and wherein said controller using said relative positions of said target isocenter and said beam line center with respect to said one or more monuments determines the relative movement between the patient and the nozzle required so that the position of the center of the beam line with respect to the one or more monuments corresponds to the position of the target isocenter with respect to said one or more monuments.