Method for breath compensation in radiation therapy

• US 20020091314A1
• Filed: 07/03/2001
• Published: 07/11/2002
• Est. Priority Date: 07/07/2000
• Status: Active Grant

• Current Assignee: Brainlab AG
• Original Assignee: Brainlab AG
• Inventors: Erbel, Stephan, Schlossbauer, Cornel, Frohlich, Stephan
• Granted Patent: US 6,731,970 B2
• Time in Patent Office: Days
• US Class Current: 600/407
• 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

The invention relates to 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 detection means, 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 or take into consideration said movement during treatment.

Claims

1. 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 by a movement detection means during radiation, 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 and take into account said movement during treatment, respectively.

2. The method as set forth in claim 1, wherein the treatment beam is switched on if the target volume inside the patient is within a predetermined tolerance range of the target point of the radiotherapy apparatus, and wherein it is otherwise switched off.

3. The method as set forth in claim 1, wherein the target volume inside the patient is moved during radiation in such a way that it is always within a predetermined tolerance range of the target point of the radiotherapy apparatus, in particular by moving the patient, and preferably by adjusting the patient'"'"'s table.

4. The method as set forth in any one of claims 1 to 3, wherein the movement detection means employs one or more of the following means:

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

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

a 3D image-generating real time image system, particularly an open magnetic resonance system, integrated into the radiotherapy apparatus.

5. The method as set forth in any one of claims 1 to 4, wherein a marking is arranged within the target volume or in the direct vicinity thereof which can be detected and tracked by said movement detection means, the movement of such marking allowing the movement of the target volume inside the patient to be deduced.

6. The method as set forth in claim 5, wherein the marking is an implanted coil in combination with external magnetic field coils which are positionally registered in the treatment room.

7. The method as set forth in claim 5, wherein the marking consists of implanted markers which can be detected and tracked by said movement detection means, particularly implants such as surgical clips, wires or noble-metal pellets.

8. The method as set forth in any one of claims 1 to 4, wherein the movement of the target volume inside the patient is detected and tracked in real-time, by deducing the 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.

9. The method as set forth in claim 8, wherein the association is obtained by detecting a relationship between the easily detected parameters and the breath-dependent movement of the target volume inside the patient prior to the treatment using a movement detection means, said easily detected parameters being tracked during the treatment, and the current position of the treatment target being deduced therefrom.

10. The method as set forth in either claim 8 or 9, wherein one or more of the following movement-characterising parameters is/are used for the easily detected parameters:

the movement of markers fixed to the patient, particularly stick-on reflection markers, preferably reflecting infrared light;

changes in the patient'"'"'s contours, especially monitored by a video camera using interference patterns or polarised light;

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

spirometry or breath flux analysis;

electromyography or the change of electric potentials in muscles;

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

11. The method as set forth in any one of claims 8 to 10, wherein the relationship between the easily detected parameters and the breath-dependent movement of the target volume inside the patient is detected prior to treatment by one or more of the following means:

a standard x-ray apparatus, either mobile or stationary, preferably a C-arc x-ray apparatus;

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

a breath-controlled body-section image recording method (e.g. CT or MR), triggered by one of the easily detected movement-characterising parameters.

12. The method for breath compensation in radiation therapy, in particular as set forth in any one of claims 1 to 11, wherein the patient'"'"'s current breath phase is detected, and the breath compensation and breath phase tuned to one another.

13. The method as set forth in claim 12, wherein the current breath phase is detected as follows:

one or more markings moving along characteristic trajectories during breathing are fixed to the patient'"'"'s body, preferably in the region of the thorax;

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

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

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

14. The method as set forth in claims 12 and 13, wherein the patient'"'"'s breath phase is monitored by tracking the position of a marking fixed to the patient, and re-adjusted during the treatment if a predetermined breath phase is deviated from.

15. The method as set forth in claim 14, wherein said breath phase is re-adjusted by signals supplied to the patient, preferably automatically, in particular by acoustic, visual or haptic signals.

16. The method as set forth in claim 11, wherein the patient'"'"'s breathing activity is detected prior to treatment, and in particular during a diagnostic, preferably breath-triggered body-section image recording method, as well as 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.

17. The method as set forth in claim 11, wherein the patient'"'"'s breathing activity is detected prior to the treatment, and in particular during a diagnostic, preferably breath-triggered body-section image recording method, as well as 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.