Apparatus and method for compensation of movements of a target volume during ion beam irradiation

• US 7,482,606 B2
• Filed: 06/09/2005
• Issued: 01/27/2009
• Est. Priority Date: 06/09/2004
• Status: Active Grant

• Current Assignee: Gessellschaft Fur Schwerionenforschung MbH
• Original Assignee: Gessellschaft Fur Schwerionenforschung MbH
• Inventors: Ott, Wolfgang, Groezinger, Sven Oliver, Poppensieker, Klaus, Haberer, Thomas
• Primary Examiner(s): Vanore; David A.
• Assistant Examiner(s): Sahu; Meenakshi S
• Application Number:
  US11/148,808
• Publication Number:
  US 20060033042A1
• Time in Patent Office: 1,328 Days
• Field of Search: 250/492.3, 250/492.1, 250/505.1, 378/65, 378/162, 378/163, 378/98.5, 600/439
• US Class Current: 250/492.3
• CPC Class Codes: A61N 2005/1061 using an x-ray imaging system having a separate imaging source
• CPC Class Codes: A61N 2005/1074 Details of the control system, e.g. user interfaces
• CPC Class Codes: A61N 2005/1087 Ions; Protons
• CPC Class Codes: A61N 2005/1095 Elements inserted into the radiation path within the system, e.g. filters or wedges
• CPC Class Codes: A61N 5/1043 Scanning the radiation beam, e.g. spot scanning or raster scanning
• CPC Class Codes: A61N 5/1049 for verifying the position of the patient with respect to the radiation beam
• CPC Class Codes: A61N 5/1067 in real time, i.e. during treatment

Abstract

The invention relates to an apparatus and method for compensation of three-dimensional movements of a target volume (1) during ion beam irradiation. For the purpose, the apparatus comprises a position location and tracking system (4) for detecting the movements and a depth modulator (6) for modifying the depth of penetration of the ion beam. For the purpose of compensation, the movements are divided vectorially into a transverse component and a longitudinal component. The transverse component is compensated from irradiation point to irradiation point using the raster scanning apparatus (3) and the longitudinal component is compensated from irradiation point to irradiation point using the depth modulator (6) by means of the fact that, in addition to the change in the location of the target volume, the change in the structure of healthy tissue covering the target volume is, in the preliminaries to irradiation, detected and modelled and stored in the form of a look-up table in a memory of a movement measurement, control and read-out module SAMB and compared with the actual values during irradiation.

Claims

1. Apparatus for compensation of three-dimensional movements of a target volume (1) on a patient support apparatus (2) during ion beam irradiation using a raster scanning apparatus (3),

wherein a compensation apparatus comprises:

a position location and tracking system (4) which detects the three-dimensional movements of the target volume (1), and

a depth modulator (6) which re-adjusts the depth of penetration w of the ion beam (5),

the raster scanning apparatus (3), which deflects the ion beam (5) transversely and which is in operative connection with a location measurement, control and read-out module (SAMO) and a module for changing the beam excursion (SAMS), wherein

the position location and tracking system (4) is in operative connection with a movement measurement, control and read-out module SAMB;

and the depth modulator (6) is in operative connection with the movement measurement, control and read-out module SAMB,

and the movement measurement, control and read-out module (SAM B) comprising a microprocessor having a memory,

and the memory comprising data of a model of a structure of healthy tissue that covers the target volume (1) in the upstream direction of the beam, and the microprocessor comprising computational components which break down the detected movements of the target volume (1) vectorially into longitudinal and transverse components relative to the ion beam (5) and which compare the longitudinal components with the stored model for correction of the depth of penetration w of the ion beam (5).

2. Apparatus according to claim 1, wherein the raster scanning apparatus (3) comprises two raster scanning magnets (7, 8), which deflect an ion beam (5) orthogonally in relation to a coupling-in direction into the raster scanning magnets (7, 8), in two directions preferably arranged orthogonally relative to one another, which are in turn arranged perpendicular to one another, for scanning the area of the target volume (1) slice-wise.

3. Apparatus according to claim 2, wherein the raster scanning magnets (7, 8) are controlled by fast-reacting power supply units.

4. Apparatus according to claim 1, wherein the apparatus comprises ion acceleration elements by means of which the energy of the ion beam (5) can be adjusted so that the target volume (1) can be irradiated slice-wise, staggered in terms of depth of penetration w.

5. Apparatus according to claim 1, wherein the depth modulator (6) comprises two ion-braking plates (9, 10) of wedge-shaped cross-section which cover the entire irradiation zone of the scanned ion beam (5).

6. Apparatus according to claim 5, wherein the ion-braking plates (9, 10) are mounted on linear motors (11, 12).

7. Apparatus according to claim 5, wherein the ion-braking plates (9, 10) are arranged on electromagnetically actuatable carriages.

8. Apparatus according to claim 5, wherein the ion-braking plates (9, 10) are displaceable relative to one another with their wedge-shaped crosssections overlapping in the region of the ion beam (5).

9. Apparatus according to claim 1, wherein the position location and tracking system (4) has at least one precision video camera (13) and/or X-ray detection means and/or ultrasound detection means, which are in operative connection with an image evaluation unit in the movement measurement, control and read-out module SAMB.

10. Apparatus according to claim 1, wherein an ionisation chamber (14, 15) having a fast read-out for monitoring the intensity of the ion beam stream is arranged as a transmission counter in the beam path of the ion beam (5).

11. Apparatus according to claim 1, wherein the ionisation chamber (14, 15) is arranged between the raster scanning apparatus (3) and the depth modulator (6).

12. Apparatus according to claim 11, wherein a multiwire proportional chamber (16, 17) is arranged as a location-sensitive detector in the beam direction upstream of the depth modulator (6).

13. Apparatus for modifying the depth of penetration of an ion beam in dependence upon movement of a patient on a patient support apparatus of a therapy facility, comprising

a position location and tracking system (4) for monitoring movements of the patient,

a depth modulator for adjusting the depth of penetration of the ion beam into the patient, and

a movement measurement and control unit which is connected to the position location and tracking system (4) and to the depth modulator and which receives information relating to the movement of the patient from the position location and tracking system (4) and controls the depth modulator for modifying the depth of penetration,

wherein the movement measurement and control unit comprises a microprocessor having a memory, and the memory comprising data of a model of a structure of healthy tissue that covers the target volume in the upstream direction of the beam, and the microprocessor, with the aid of the model and the information relating to the movement of the patient, so controlling the depth modulator that the depth of penetration of the ion beam is adjusted to a target volume element in the patient irrespective of the movement of the patient, especially irrespective of the movement of the healthy tissue relative to the target volume.

14. Apparatus according to claim 13, wherein the energy absorption of the tissue that the beam passes through and, as a result, the change in the range of the ion beam in dependence upon the tissue that the beam passes through can be calculated from the model.

15. Apparatus according to claim 13, wherein the tissue through which the beam is to pass can be determined from the information relating to the movement of the patient and the model.

16. Apparatus according to claim 13, wherein the model correlates changes in the electron density distribution in the healthy tissue (for example, obtained by means of multidimensional projection radiographs or from time-resolved CT data sets) with movement states of the body.

17. Apparatus according to claim 13, wherein the depth modulator for modifying the depth of penetration includes an apparatus for modifying the kinetic energy of the ions.

18. Apparatus according to claim 13, wherein the apparatus additionally comprises means of obtaining location information relating to the location of the ion beam relative to the patient, the movement measurement and control unit so controlling a raster scanning apparatus on the basis of the location information together with the aid of the model and the information relating to the movement of the patient that the ion beam follows a movement of the target volume in a transverse direction to the ion beam.

19. Apparatus according to claim 13, wherein the raster scanning apparatus (3) comprises two raster scanning magnets (7, 8), which deflect an ion beam (5) orthogonally in relation to a coupling-in direction into the raster scanning magnets (7, 8), in two directions preferably arranged orthogonally relative to one another, which are in turn arranged perpendicular to one another, for scanning the area of the target volume (1) slice-wise.

20. Apparatus according to claim 19, wherein the raster scanning magnets (7, 8) are controlled by fast-reacting power supply units.

21. Apparatus according to claim 13, wherein the apparatus comprises ion acceleration elements by means of which the energy of the ion beam (5) can be adjusted so that the target volume (1) can be irradiated slice-wise, staggered in terms of depth of penetration w.

22. Apparatus according to claim 13, wherein the depth modulator (6) comprises two ion-braking plates (9, 10) of wedge-shaped cross-section which cover the entire irradiation zone of the scanned ion beam (5).

23. Apparatus according to claim 22, wherein the ion-braking plates (9, 10) are mounted on linear motors (11, 12).

24. Apparatus according to claim 22, characterised in that the ion-braking plates (9, 10) are arranged on electromagnetically actuatable carriages.

25. Apparatus according to claim 22, wherein the ion-braking plates (9, 10) are displaceable relative to one another with their wedge-shaped cross-sections overlapping in the region of the ion beam (5).

26. Apparatus according to claim 13, wherein the position location and tracking system (4) has at least one precision video camera (13) and/or Xray detection means and/or ultrasound detection means, which are in operative connection with an image evaluation unit in the movement measurement, control and read-out module SAMB.

27. Apparatus according to claim 13, wherein a multiwire proportional chamber (16, 17) is arranged as a location-sensitive detector in the beam direction upstream of the depth modulator (6).

28. Apparatus according to claim 13, wherein the apparatus for detecting the structure of the healthy tissue covering the target volume in the upstream direction of the beam comprises X-ray and/or ultrasound detection in the preliminaries to and during ion beam irradiation.

29. Apparatus according to claim 13, wherein the raster scanning magnets (7, 8) comprise scanner magnet current power supply units for horizontal and vertical correction by means of control and read-out modules (SAMS) for the raster scanning magnets (7, 8).

30. Apparatus according to claim 13, wherein, for location measurement, a multiwire proportional chamber (16, 17) is provided by way of a location measurement, control and read-out module (SAMO), it being possible, for the purpose of transverse compensation, to compare information stored in the location measurement, control and read-out module (SAMO) of a supervisory control system relating to the desired position of an irradiation plan with the measured actual position of the beam position from the location-sensitive detector in real time taking into account the detected transverse movement component of the target volume (1).

31. Apparatus according to claim 13, wherein, for location correction in the transverse X and Y directions, the scanner magnets comprise power supply units of the raster scanning apparatus (3) comprise and longitudinal depth correction of the depth modulator (6) from beam position to beam position is provided.

32. Apparatus according to claim 13, wherein fast shut-down of the beam by the location measurement, control and read-out module (SAMO) of the location-sensitive detector in real time and/or by the movement measurement, control and read-out module (SAMB) of the depth modulator (6) is possible, if the difference between a measured value and a desired value of the transverse beam position and/or of the longitudinal depth of penetration w exceeds a threshold that can be set in the realtime software of the control and read-out modules SAMO and/or SAMB.

33. Method for compensation of three-dimensional movements of a target volume (1) on a patient couch (2) during ion beam irradiation using a raster scanning apparatus (3), the method comprising the following method steps:

detecting a structure of healthy tissue covering the target volume (1) in the upstream direction of the beam;

producing a digital model of the detected structure of the covering healthy tissue;

storage of the model in a memory of the movement measurement, control and readout module (SAMB);

positioning of the target volume (1) on a patient couch (2) in a treatment room (18);

detecting three-dimensional movements of the target volume (1) in real time during the irradiation procedure by means of a position location and tracking system (4);

vectorially dividing the movements into longitudinal and transverse components;

compensating the transverse components of the movements by corrective control of raster scanning magnets (7, 8) of the raster scanning apparatus (3);

compensating the longitudinal components of the movements by comparison with data of the stored model and comparison-based modification of the settings of a depth modulator (6).

34. Method according to claim 33, wherein detecting the structure of the healthy tissue covering the target volume in the upstream direction of the beam is carried out by means of X-ray and/or ultrasound detection in the preliminaries to and during ion beam irradiation.

35. Method according to claim 33, wherein the raster scanning magnets (7, 8) are controlled by way of scanner magnet current power supply units for horizontal and vertical correction by control and read-out modules (SAMS) for the raster scanning magnets (7, 8).

36. Method according to claim 33, wherein location measurement is registered and evaluated using a multiwire proportional chamber (16, 17) by way of a location measurement, control and read-out module (SAMO), information stored in the location measurement, control and read-out module (SAMO) of a supervisory control system relating to the desired position of an irradiation plan being compared, for the purpose of transverse compensation, with the measured actual position of the beam position from the location-sensitive detector in real time taking into account the detected transverse movement component of the target volume (1).

37. Method according to claim 33, wherein, by means of the scanner magnet power supply units of the raster scanning apparatus (3), location correction transversely in the X and Y direction and, by means of the depth modulator (6), longitudinal depth correction are carried out from beam position to beam position.

38. Method according to claim 33, wherein fast shut-down of the beam is initiated by the location measurement, control and read-out module (SAMO) of the location-sensitive detector in real time and/or by the movement measurement, control and read-out module (SAMB) of the depth modulator (6), if the difference between a measured value and a desired value of the transverse beam position and/or of the longitudinal depth of penetration w exceeds a threshold that can be set in the realtime software of the control and read-out modules SAMO and/or SAMB.