Method for breath compensation in radiation therapy

• US 6,731,970 B2
• Filed: 07/03/2001
• Issued: 05/04/2004
• Est. Priority Date: 07/07/2000
• Status: Active Grant

• Current Assignee: Brainlab AG
• Original Assignee: Brainlab AG
• Inventors: Schlossbauer, Cornel, Erbel, Stephan, Fröhlich, Stephan
• Primary Examiner(s): MANTIS MERCADER, ELENI M
• Application Number:
  US09/898,891
• Publication Number:
  US 20020091314A1
• Time in Patent Office: 1,036 Days
• Field of Search: 600/407, 600/409, 600/410, 600/411, 600/413, 600/414, 600/415, 600/417, 600/420, 600/421, 600/422, 600/423, 600/424, 600/426, 600/427, 600/428, 600/429, 600/431, 600/439, 600/587, 600/595, 600/1, 600/7, 600/8, 606/130, 128/899
• US Class Current: 600/428
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/7285 for synchronising or triggering a physiological measurement or image acquisition with a physiological event or waveform, e.g. an ECG signal A61B6/5205, A61B6/541, A61B8/5207, A61B8/543 take precedence
• CPC Class Codes: A61B 6/541 involving acquisition triggered by a physiological signal
• CPC Class Codes: A61N 2005/1059 using cameras imaging the patient
• CPC Class Codes: A61N 5/1037 taking into account the movement of the target, e.g. 4D-image based planning
• CPC Class Codes: A61N 5/1049 for verifying the position of the patient with respect to the radiation beam
• CPC Class Codes: A61N 5/1064 for adjusting radiation treatment in response to monitoring
• CPC Class Codes: A61N 5/107 in real time, i.e. during treatment

Abstract

A method for breath compensation in radiation therapy, particularly radiotherapy/radiosurgery, wherein the movement of the target volume inside the patient is detected and tracked in real time during radiation by a movement detector. Adaptation to the movement of the target volume inside the patient is achieved by one or more components of a radiotherapy apparatus to compensate for or take into consideration the movement during treatment.

Claims

1. A method for breath compensation in radiation therapy, said method comprising:

detecting movement of a target volume inside a patient;

tracking said movement in real time using a movement detector during radiation;

detecting an offset based on varying underlying volumes of lung capacity for the patient;

tuning breath compensation to the offset; and

wherein adaptation to the movement of the target volume inside the patient is achieved by means of one or more components of a radiotherapy apparatus, to compensate for said movement during treatment.

2. The method as set forth in claim 1, further comprising:

switching on a treatment beam if the target volume inside the patient is within a predetermined tolerance range of a target point of the radiotherapy apparatus, and wherein the treatment beam is otherwise switched off.

3. The method as set forth in claim 1, further comprising:

moving the target volume inside the patient during radiation in such a way that the target volume is always within a predetermined tolerance range of a target point of the radiotherapy apparatus.

4. The method as set forth in claim 3, wherein moving the target volume inside the patient includes:

adjusting the patient'"'"'s table.

5. The method as set forth in claim 1, wherein the movement detector includes at least one of:

an x-ray apparatus comprising at least one x-ray source and at least one image recorder/detector;

an ultrasonic apparatus with automated three-dimensional image processing and contour recognition means and an ultrasonic head positionally registered in the treatment room; and

a 3D image-generating real time image system integrated into the radiotherapy apparatus.

6. The method as set forth in claim 5, wherein the 3D image-generating real time image system is an open magnetic resonance system.

7. The method as set forth in claim 1, wherein the step of tracking the movement includes:

arranging a marking within the target volume or in the direct vicinity thereof which can be detected and tracked by said movement detector, the movement of such marking allowing the movement of the target volume inside the patient to be deduced.

8. The method as set forth in claim 7, wherein the marking is an implanted coil in combination with external magnetic field coils which are positionally registered in a treatment room.

9. The method as set forth in claim 7, wherein the marking includes implanted markers selected from the group consisting of surgical clips, wires and noble-metal pellets.

10. The method as set forth in claim 1, wherein the steps of detecting and tracking movement of the target volume inside the patient include deducing a current position of the target volume inside the patient from a positional association between parameters easily detected during treatment and the target volume inside the patient.

11. The method as set forth in claim 10, wherein the positional association is obtained by detecting a relationship between the easily detected parameters and breath-dependent movement of the target volume inside the patient prior to the treatment using a movement detector, said easily detected parameters being tracked during the treatment, and the current position of the treatment target being deduced therefrom.

12. The method as set forth in claim 10, wherein detecting and tracking movement of the target volume inside the patient include detecting at least one of:

movement of stick-on markers fixed to the patient said stick-on markers reflecting infrared light;

changes in the patient'"'"'s contours using interference patterns or polarised light;

change in length of wire strain gauges, which change their electrical resistance according to length;

spirometry or breath flux analysis;

electromyography or change of electric potentials in muscles; and

movement of one or more points on a surface of the patient, which is scanned mechanically and detected as co-ordinates.

13. The method as set forth in claim 10, wherein a relationship between the easily detected parameters and breath-dependent movement of the target volume inside the patient is detected prior to treatment by at least one of:

a mobile or stationary x-ray apparatus;

an x-ray apparatus comprising at least one x-ray source and at least one image recorder/detector; and

a breath-controlled body-section image recording CT or MR apparatus, which is triggered by one of the easily detected parameters.

14. The method as set forth in claim 13, wherein the patient'"'"'s breathing activity is detected (I) prior to treatment during a diagnostic, breath-triggered, body-section image recording method, and (ii) during the treatment by tracking the position of the marking fixed to the patient, the trajectories of the marking being detected both prior to and during the treatment between a point of maximum inhalation and a point of maximum exhalation, in order to position the patient by allocating said trajectories.

15. The method as set forth in claim 13, wherein the patient'"'"'s breathing activity is detected (i) prior to the treatment during a diagnostic, breath-triggered, body-section image recording method, and (ii) during the treatment by tracking the position of the marking fixed to the patient, and wherein the patient is positioned by means of a position tracking system.

16. The method as set forth in claim 1, further comprising:

detecting the patient'"'"'s current breath phase; and

tuning the breath compensation and breath phase to one another.

17. The method as set forth in claim 16, wherein detecting the patient'"'"'s current breath phase includes:

affixing at least one marking to the patient'"'"'s body, said at least one marking moving along characteristic trajectories during breathing;

detecting and storing co-ordinates of the extrema corresponding to maximum inhalation and exhalation, which describe a defined difference in each patient;

comparing the stored co-ordinates with currently detected co-ordinates of the markings, wherein the degree of inhalation or breath phase respectively is defined on the basis of the comparing step, if the position of the patient remains unchanged; and

if the position of the patient changes after the co-ordinates have been stored, instructing the patient to fully inhale and exhale, detecting and storing the trajectories of the markings and their extrema, the trajectories before and after the change in the patient'"'"'s position being referenced and the breath phases being qualitatively compared with one another.

18. The method as set forth in claim 16, wherein detecting the patient'"'"'s breath phase includes:

tracking a position of a marking fixed to the patient; and

re-adjusting the breath phase during the treatment if a predetermined breath phase is deviated from.

19. The method as set forth in claim 14 wherein said breath phase is re-adjusted by supplying at least one of (I) acoustic, (ii) visual, and (iii) haptic signals to the patient.