POSITION LOCATING AND MAINTAINING METHOD AND MEANS

• US 3,861,807 A
• Filed: 08/17/1972
• Issued: 01/21/1975
• Est. Priority Date: 08/17/1972
• Status: Expired due to Term

• Current Assignee: Charles Lescrenier
• Original Assignee: Charles Lescrenier
• Inventors: Lescrenier, Charles
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Buczinski, S. C.
• Application Number:
  US05/281,521
• Time in Patent Office: 887 Days
• Field of Search: 356/152 250/442,446,447
• US Class Current: 356/139.07
• 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: A61N 2005/105 using a laser alignment system
• CPC Class Codes: A61N 5/1049 for verifying the position of the patient with respect to the radiation beam
• CPC Class Codes: G01B 11/26 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G05D 3/14 using an analogue comparing device

Abstract

A locating technique employs a beam of concentrically patterned, varying intensity light to position one object, for example a hospital patient, with respect to a second object, such as a radiation beam emitter. The pattern of light is oriented with respect to the radiation beam and a reflective target is placed on the skin of the patient for providing a reflected light signal to a light sensor. The light sensor is connected to control means for moving a patient-containing bed into the center of the light beam and, hence, into the desired position with respect to the radiation beam.

Claims

1. A device for establishing the location of a first object with respect to a second object comprising:

light source means for generating a diffuse beam of concentrically patterned light bearing a predetermined relationship to said first object and for applying same to said second object, said diffuse beam having a varying intensity from the center to the extremities thereof;

a reflecting target substantially smaller in dimension than the diffuse beam of light mounted on said second object for reflecting a portion of the beam of concentrically patterned light, the intensity of the reflection being indicative of the position of said second object in the diffuse light beam;

a light sensor for receiving the reflection of the target and for providing a signal proportional to its intensity; and

control means responsive to the light intensity signal for indicating the locational relationship between the first and second objects.

2. The device according to claim 1 wherein said light source means is further defined as including a light source and a diffusing means for receiving light from said light source and for diffusing it into a diffuse beam of concentrically patterned light.

3. The device according to claim 2 wherein said diffusing means is further defined as means for receiving the light from said light source and for diverging said light to form said diffuse beam of concentrically patterned light.

4. The device according to claim 1 further defined as a device for establishing and maintaining a locational relationship between the objects wherein a drive means is coupled to one of the objects for moving the object and wherein said control means is interposed between said light sensor and said drive means and is responsive to the light intensity signal for causing said drive means to move the object so as to place the target in the center of said beam of said concentrically patterned light.

5. The device according to claim 4 wherein said drive means is further defined as coupled to the second of said objects.

6. The device according to claim 5 wherein said drive means is further defined as moving the second object in said light beam in a plane normal to the beam.

7. The device according to claim 6 wherein said drive means is further defined as moving the second object along mutually perpendicular axes in a plane normal to the light beam.

8. The device according to claim 7 wherein said drive means is coupled to the second object for moving the object in a direction parallel to the light beam, said movement altering the levels of the light intensity signals in accordance with the location of the second object in said parallel direction, and wherein said control means includes means responsive to the levels of the light intensity signals for causing said drive means to move said second object to a desired location along a path parallel to the light beam.

9. The device according to claim 8 wherein said control means includes means for providing a reference signal proportional to a light intensity signal level corresponding to the desired location of the second object along a path parallel to the light beam and a means for comparing said reference signal and said light intensity signal level and providing an error signal to said drive means to cause said drive means to move the second object to the desired location.

10. The device according to claim 7 wherein said drive means moves said second object along coplanar, mutually perpendicular axes normal to the beam and the control means includes means for causing said drive means to move said second object along said pair of axes so as to place the target in the center of said beam of concentric patterned light.

11. The device according to claim 10 wherein said control means is so constructed as to move said second object Along one of said axes and thereafter move said second object along the other of said axes.

12. The device according to claim 5 wherein said drive means is further defined as having means for angularly moving said object about at least one axis perpendicular to said beam of light.

13. The device according to claim 12 further including:

a pair of light source means generating oppositely directed, parallel, diffuse beams of concentrically patterned light and for applying same to said second object, said diffuse beams having varying intensities from the centers to the extremities thereof;

a pair of reflecting targets substantially smaller in dimension than the diffuse beams of light mounted on opposite sides of said second object for reflecting portions of the beams of concentrically patterned light, the intensities of the reflections being indicative of the position of said second object in the diffuse light beams;

a pair of light sensors for receiving the reflections of the targets and for providing signals proportional to their intensities; and

wherein said control means is further defined as interposed between said light sensors and said drive means for causing said drive means to angularly move said object about an axis perpendicular to said light beams so as to place the targets in center of said beams of concentrically patterned light.

14. The device according to claim 5 including:

a second light source means for generating a second diffuse beam of concentrically patterned light bearing a predetermined orientation with respect to said first light beam and for applying same to said second object, said second diffuse light beam having a varying intensity from the center to the extremities thereof;

said drive means further including means for moving said second object in said second light beam in a plane normal thereto;

a second reflecting target substantially smaller in dimension than said second diffuse beam of light mounted on said second object for reflecting a portion of said second beam of concentrically patterned light, the intensity of the reflection being indicative of the position of said second object in said second light beam;

a second light sensor for receiving the reflection of the second target and for providing a signal proportional to its intensity; and

wherein said control means is further defined as interposed between said second light sensor and said drive means and is responsive to the light intensity signal of said second light sensor for causing said drive means to move said second object so as to place the second target in the center of said second beam of concentrically patterned light.

15. The device according to claim 14 wherein said drive means is further defined as angularly moving said object about at least one axis perpendicular to said pair of light beams.

16. The device according to claim 14 wherein said control means includes means responsive to the magnitude of the light sensor signal of said second light sensor for sensing an extreme light intensity light condition thereof and for providing a pulse output and said control means includes said pulse responsive means for operating said drive means.

17. The device according to claim 1 wherein said control means includes means responsive to the magnitude of the light sensor signal for sensing an extreme light intensity condition thereof.

18. The device according to claim 17 wherein said extreme condition sensing means comprises means for providing a pulse output upon sensing an extreme light intensity condition of said signal and said control means includes pulse responsive means for operating said drive means.

19. The device according to claim 18 wherein said control means further includes a pulse responsive bi-stable logic means coupled to said extreme value sensing means and to said drive means for controlling the direction of movement of said second object in accordance with the pulse output of said extreme Value sensing means.

20. The device according to claim 18 wherein said extreme condition sensing means includes a differential amplifier providing an output signal responsive to a reversal of the relative magnitudes of the signals applied to a pair of amplifier input terminals, one of said input terminals receiving said light sensor signal, the other of said input terminals being biased by a capacitor, a diode connected between said input terminals for charging the capacitor and maintaining one input signal relative magnitude condition when the magnitude of the light sensor signal exceeds the capacitor charge and means for discharging the capacitor during a reversed input signal relative magnitude condition when the capacitor charge exceeds the magnitude of the light signal source.

21. The device according to claim 19 wherein said drive means moves said second object along coplanar, mutually perpendicular axis and said control means is so constructed to cause said drive means to move said second object along one of said axes and thereafter move said second object along the other of said axes.

22. The device according to claim 21 wherein said control means includes timer means coupled to the output of the pulse output means for sensing the rapidity of the output pulses for causing said drive means to move said second object along one of said axes and, upon sensing a predetermined rapidity of the output pulses, to move said second object along the other of said axes.

23. A method of establishing and maintaining the position of one object with respect to a second object comprising the steps of:

placing a reflective target on the second object;

generating a diffuse beam of concentrically patterned light having a varying intensity from the center to the extremities and having a predetermined orientation with respect to the first object;

moving the second object into the beam of concentrically patterned light; and

sensing the magnitude of the light reflected from the target to ascertain the location of the second object.

24. The method according to claim 23 further defined in that the step of sensing the magnitude of the reflected light is further defined as sensing an extreme magnitude of the reflected light.

25. The method according to claim 23 wherein the step of generating a light beam is further defined as generating a second concentrically patterned diffuse light beam having a predetermined orientation with respect to the first light beam, said method being additionally defined as placing a second reflective target on the second object for reflecting the second light beam, moving the second object in the second light beam and sensing the magnitude of the light reflected from the target to ascertain the location of the second object with respect to the second light beam.

26. The method according to claim 23 further including the steps of:

generating a pair of oppositely directed, parallel diffuse, concentrically patterned light beams;

placing a pair of reflective targets on opposite sides of the second object;

placing the second object in the beams of light; and

angularly moving the second object about at least one axis perpendicular to said beams of light to align the pair of targets with the pair of light beams.

27. The method according to claim 23 wherein the first object comprises a radiation beam emitter and said second object comprises a patient.

28. The method according to claim 23 wherein the step of moving the second object is further defined as moving the second object in the light beam along mutually perpendicular axes in a plane normal to the beam.

29. The method according to claim 28 wherein the step of sensing the magnitude of the reflective light is further defined as sensing the levels of the light intensity signals and the step of moving the second object in the light beam is further defined as moving the second object along a path parallel to the light beam in accordance with levels of light intensity signals.

30. The method according to claim 29 wherein the step of moving the second object is further defined as sequentially moving the second object along one axis and thereafter along another axis.

31. A patient positioner for establishing and maintaining a locational relationship between a radiation beam emitter and a patient containing couch comprising:

light source means for generating a diffuse beam of concentrically patterned light bearing a predetermined orientation with respect to said radiation beam and for applying same to said patient containing couch, said diffuse beam having a varying intensity from the center to the extremities thereof;

drive means coupled to the couch for moving the couch in said light beam;

a reflecting target substantially smaller in dimension than the diffuse beam of light mounted on a patient on the couch for reflecting a portion of the beam of concentrically patterned light, the intensity of the reflection being indicative of the position of the patient in the diffuse light beam;

a light sensor for receiving the reflection of the target and for providing a signal proportional to its intensity; and

control means interposed between said light sensor and said drive means and responsive to said signal for causing said drive means to move the couch so as to place the target in the center of said beam of concentrically patterned light, thereby to establish and maintain a locational relationship between the radiation beam and the patient.

32. The patient positioner according to claim 31 wherein said light source means is further defined as including a light source and a diffusing means for receiving light from said light source and for diffusing it into a diffuse beam of concentrically patterned light.

33. The patient positioner according to claim 32 wherein said diffusing means is further defined as means for receiving the light from said light source and for diverging said light to form said diffuse beam of concentrically patterned light.

34. The patient positioner according to claim 31 wherein said drive means is further defined as moving the couch in said light beam along mutually perpendicular axes in a plane normal to the beam.

35. The patient positioner according to claim 34 wherein said drive means is coupled to the couch for moving the couch in a direction parallel to the light beam, said movement altering the levels of the light intensity signals in accordance with the location of the couch in said parallel direction, and wherein said control means includes means responsive to the levels of the light intensity signals for causing said drive means to move the couch to a desired location along a path parallel to the light beam.

36. The patient positioner according to claim 35 wherein said control means includes means for providing a reference signal proportional to a light intensity signal level corresponding to the desired location of the couch along a path parallel to the light beam and a means for comparing said reference signal and said light intensity signal level and providing an error signal to said drive means to cause said drive means to move the couch to the desired location.

37. The patient positioner according to claim 34 wherein said drive means is so constructed as to move the couch along one of said axes and thereafter move the couch along the other of said axes.

38. The patient positioner according to claim 34 including:

a second light source means for generating a second diffuse beam of concentrically patterned light bearing a predetermined orientation with respect to said first light beam, said second diffuse light beam having a varying intensity from the center to the extremities thereof;

said drive means further including means for moving said couch in said second light beam in a plane normal thereto;

a second reflecting target substantially smaller in dimension than said second diffuse beam of light mounted oN the patient for reflecting a portion of said second beam of concentrically patterned light, the intensity of the reflection being indicative of the position of the patient in said second light beam;

a second light sensor for receiving the reflection of the second target and for providing a signal proportional to its intensity; and

wherein said control means is further defined as interposed between said second light sensor and said drive means and is responsive to the light intensity signal of said second light sensor for causing said drive means to move said couch so as to place the second target in the center of said second beam of concentrically patterned light.

39. The device according to claim 38 wherein said drive means is further defined as angularly moving the couch about at least one axis perpendicular to said pair of light beams.

40. The patient positioner according to claim 38 wherein said control means includes means responsive to the magnitude of the light sensor signal of said second light sensor for sensing an extreme light intensity light condition thereof and for providing a pulse output and said control means includes said pulses responsive means for operating said drive means.

41. The patient positioner according to claim 31 wherein said drive means is further defined as having means for angularly moving the couch about at least one axis perpendicular to said beam of light.

42. The patient positioner according to claim 41 further including:

a pair of light source means generating oppositely directed, parallel, diffuse beams of concentrically patterned light, said diffuse beams having varying intensities from the centers to the extremities thereof;

a pair of reflecting targets substantially smaller in dimension than the diffuse beams of light mounted on opposite sides of the patient for reflecting portions of the beams of concentrically patterned light, the intensities of the reflections being indicative of the position of the patient in the diffuse light beams;

a pair of light sensors for receiving the reflections of the targets and for providing signals proportional to their intensities; and

wherein said control means is further defined as interposed between said light sensors and said drive means for causing said drive means to angularly move said object about an axis perpendicular to said light beams so as to place the targets in center of said beams of concentrically patterned light.

43. The patient positioner according to claim 31 wherein said control means includes means responsive to the magnitude of the light sensor signal for sensing an extreme light intensity condition thereof and for providing a pulse output upon sensing an extreme light intensity condition of said signal and said control means includes pulse responsive means for operating said drive means.

44. The device according to claim 43 wherein said extreme condition sensing means includes a differential amplifier providing an output signal responsive to a reversal of the relative magnitudes of the signals applied to a pair of amplifier input terminals, one of said input terminals receiving said light sensor signal, the other of said input terminals being biased by a capacitor, a diode connected between said input terminals for charging the capacitor and maintaining one input signal relative magnitude condition when the magnitude of the light sensor signal exceeds the capacitor charge and means for discharging the capacitor during a reversed input signal relative magnitude condition when the capacitor charge exceeds the magnitude of the light signal source.

45. The patient positioner according to claim 43 wherein said drive means, is so constructed as to move the couch along one of said axes and thereafter move the couch along the other of said axes and wherein said control means includes timer means coupled to the output of the pulse output means for sensing the rapidity of the output pulses for causing said drive means to move sAid second object along one of said axes and, upon sensing a predetermined rapidity of the output pulses, to move said second object along the other of said axes.

46. The patient positioner according to claim 31 wherein said radiation beam emitter includes means for controlling the shape of the radiation beam.

47. The patient positioner according to claim 46 wherein said radiation beam control means includes radiation absorbing blocks replaceably inserted in the path of said radiation beam.

48. The patient positioner according to claim 47 wherein said radiation emitter has a spring loaded shelf extending from a wall thereof for retaining said radiation adsorbing blocks in said radiation beam, said spring loaded shelf being retractable into said wall for removing said radiation absorbing blocks.

49. The patient positioner according to claim 31 wherein said radiation emitter has a means for removably affixing the light source thereto.

50. The patient positioner of claim 49 wherein said radiation emitter has a slot and said affixing means has an expandible flange insertable into said slot to affix said light source.

51. The patient positioner of claim 50 wherein said flange includes a pair of relatively movable members having ramp surfaces for providing the expansion upon relative movement.