System for monitoring the position of a patient receiving 4pi radiation therapy

Abstract

Disclosed is a method for determining a deviation of the position of an anatomical body part relative to a predetermined position defined by a radiation treatment plan. A monitoring image is taken of the anatomical body part at the instant that a predetermined control point defined in the treatment plan has been reached. The monitoring image is compared to a simulated image simulated from a planning image of the anatomical body from the perspective of a monitoring camera used to generate the monitoring image. The comparison allows for a determination of whether there is a positional deviation.

Claims

1. A method for determining a deviation between a planned and an actual relative position between an anatomical body part of a patient's body and a radiation treatment apparatus, the method comprising executing, on at least one processor, steps of: a) acquiring, at the at least one processor, planned control point data describing predetermined control points each describing a predetermined operational state of the radiation treatment apparatus, the control points having a predetermined temporal order in which they are planned to be assumed by the radiation treatment apparatus and each control point being associated with a predetermined planned relative position between the anatomical body part and a monitoring imaging apparatus, wherein the planned control point data comprises planned position data describing planned relative positions between the anatomical body part and a treatment beam source of the radiation treatment apparatus and, for each at least one planned relative position, the operational state as a reference dose being a predetermined amount of a planned treatment dose associated with the respective at least one planned relative position, wherein each control point is described by at least one of planned relative positions; b) determining, at the at least one processor, current control point data describing whether the radiation treatment apparatus has assumed a predetermined control point, wherein the current control point data comprises monitoring dose data describing the current operational state as a monitoring dose being an amount of the planned treatment dose associated with at least one of a monitoring image or the at least one actual relative position between the anatomical body park and the treatment beam source; c) acquiring, at the at least one processor, monitoring image data describing at least one digital medical monitoring image of the anatomical body part in at least one monitoring relative position between the anatomical body part and the monitoring imaging apparatus, wherein the monitoring imaging apparatus is used to generate the monitoring image; d) acquiring, at the at least one processor, patient image data describing a predetermined medical image of the anatomical body part; e) determining, by the at least one processor and based on the monitoring dose data and the planned control point data, corresponding reference dose data describing a corresponding reference dose being the reference dose corresponding best within a predetermined interval to the monitoring dose; f) determining, by the at least one processor and based on the patient image data and the corresponding reference dose data, comparison image data describing at least one digital medical comparison image of the anatomical body part in the monitoring relative position, wherein the monitoring relative position is the planned relative position between the anatomical body part and the monitoring imaging apparatus; and g) determining, by the at least one processor and based on the comparison image data and the monitoring image data, position deviation data describing a positional deviation between (i) the planned relative position associated with the planned control point assumed by the radiation treatment apparatus and (ii) the monitoring relative position on the other hand, the method further comprising at least one of the following steps h1) and h2): h1) generating the comparison image data if the current control point data describes that the radiation treatment apparatus has assumed a predetermined control point, or h2) generating the monitoring image data if the current control point data describes that the radiation treatment apparatus has assumed a predetermined control point.

2. The method according to claim 1, wherein the monitoring image data is acquired, at the at least one processor, based on the current control point data.

3. The method according to claim 1, wherein the comparison image data is generated substantially at the point in time at which the radiation treatment apparatus assumes the predetermined control point.

4. The method according to claim 1, wherein the monitoring image data is describable in two or three dimensions.

5. The method according to claim 1, wherein the patient image data is tomographic image data and the comparison image is generated from the patient image data and is describable in two dimensions, or three dimensions.

6. The method according to claim 1, wherein the monitoring image data is generated by at least one of x-ray imaging, thermal imaging, structured light imaging, digital still imaging, digital video imaging, or sonography.

7. The method according to claim 1, wherein determining the comparison image data comprises; acquiring, at the at least one processor, positional transformation data describing a positional transformation between a reference system used for defining positional information in the monitoring image data and a reference system used for defining positional information in the patient image data, wherein the positional deviation data is determined, by the at least one processor, based on the positional transformation data.

8. The method according to claim 7, wherein the comparison image data is determined, by the at least one processor, by applying the positional transformation to the planned relative position between the anatomical body part and the monitoring imaging apparatus or to the monitoring relative position.

9. The method according to claim 7, wherein the positional transformation is determined by applying an image fusion algorithm to the monitoring image data and the patient image data.

10. The method according to claim 1, comprising: acquiring, at the at least one processor, planned position data describing a planned relative position between the anatomical body part and the radiation treatment apparatus for each one of the control points; acquiring, at the at least one processor, monitoring imaging apparatus calibration data describing a relative position between the radiation treatment apparatus and the monitoring imaging apparatus, wherein the planned relative position between the anatomical body part and the monitoring imaging apparatus is determined, by the at least one processor, based on the planned position data and the monitoring imaging apparatus calibration data.

11. The method according to claim 1, wherein the corresponding reference dose is the reference dose closest at least within a predetermined interval to the monitoring dose.

12. The method according to claim 1, wherein the planned operational states are respectively defined by at least one of a patient support unit angle, a patient support unit position, a target position, a treatment beam source angle, a collimator geometry, at least one treatment beam source movement speed value, or at least one applied dose rate value.

13. The method according to claim 1, wherein the anatomical body part is not positioned in an isocenter of the radiation treatment apparatus.

14. The method according to claim 1, wherein the radiation treatment apparatus assumes the predetermined control points while the treatment beam source of the radiation treatment apparatus is activated.

15. The method according to claim 1, wherein the at least one planned relative position, and the at least one monitoring relative position are described by vectors and the positional is described by a matrix.

16. The method according to claim 1, comprising: acquiring deviation threshold data describing a threshold for the positional deviation; determining, by the at least one processor and based on the position deviation data and the deviation threshold data, treatment apparatus control data describing a command to be issued, by the at least one processor, to the radiation treatment apparatus.

17. The method according to claim 16, wherein the treatment apparatus control data is determined by comparing the positional deviation to the threshold for the positional deviation, and wherein the command describes at least one of deactivation of the treatment beam source of the radiation treatment apparatus, interruption of a treatment beam emitted by the treatment beam source, or relative movement of the anatomical body part relative to the treatment beam source.

18. A non-transitory computer-readable storage medium having stored thereon computer-executable instructions that, when executed, configure at least one processor to: a) acquire planned control point data describing predetermined control points each describing a predetermined operational state of the radiation treatment apparatus, the control points having a predetermined temporal order in which they are planned to be assumed by a radiation treatment apparatus and each control point being associated with a predetermined planned relative position between an anatomical body part of a patient's body and a monitoring imaging apparatus, wherein the planned control point data comprises planned position data describing planned relative positions between the anatomical body part and a treatment beam source of the radiation treatment apparatus and, for each at least one planned relative position, the operational state as a reference dose being a predetermined amount of a planned treatment dose associated with the respective at least one planned relative position, wherein each control point is described by at least one of planned relative positions; b) determine current control point data describing whether the radiation treatment apparatus has assumed a predetermined control point, wherein the current control point data comprises monitoring dose data describing the current operational state as a monitoring dose being an amount of the planned treatment dose associated with at least one of a monitoring image or the at least one actual relative position between the anatomical body part and the treatment beam source; c) acquire monitoring image data describing at least one digital medical monitoring image of the anatomical body part in at least one monitoring relative position between the anatomical body part and the monitoring imaging apparatus, wherein the monitoring imaging apparatus is used to generate the monitoring image; d) acquire patient image data describing a predetermined medical image of the anatomical body part; e) determine, based on the monitoring dose data and the planned control point data, corresponding reference dose data describing a corresponding reference dose being the reference dose corresponding best within a predetermined interval to the monitoring dose; f) determine, based on the patient image data and the corresponding reference dose data, comparison image data describing at least one digital medical comparison image of the anatomical body part in the monitoring relative position, wherein the monitoring relative position is the planned relative position between the anatomical body part and the monitoring imaging apparatus; and g) determine, based on the comparison image data and the monitoring image data, position deviation data describing a positional deviation between (i) the planned relative position associated with the planned control point assumed by the radiation treatment apparatus and (ii) the monitoring relative position on the other hand, wherein the computer-executable instructions, when executed, further configure the processor to: h1) generate the comparison image data if the current control point data describes that the radiation treatment apparatus has assumed a predetermined control point, or h2) generate the monitoring image data if the current control point data describes that the radiation treatment apparatus has assumed a predetermined control point.

19. A system for determining a deviation between a planned and an actual relative position between an anatomical body part and a treatment beam source, the system comprising: at least one electronic data storage device storing at least planned control point data; a medical imaging device for generating a monitoring image, the medical imaging device being operably coupled to at least one processor for transmitting a signal to the at least one processor corresponding to monitoring image data; and a radiation treatment apparatus comprising a treatment beam source, wherein the at least one processor is operably coupled to the at least one electronic data storage device for acquiring, from the at least one data storage device, at least one of patient image data or the planned control point data, and for issuing a command to the radiation treatment apparatus for controlling the treatment beam source on the basis of position deviation data, wherein the at least one processor is further configured to: a) acquire the planned control point data describing predetermined control points each describing a predetermined operational state of the radiation treatment apparatus, the control points having a predetermined temporal order in which they are planned to be assumed by the radiation treatment apparatus and each control point being associated with a predetermined planned relative position between an anatomical body part of a patient's body and the medical imaging device, wherein the planned control point data comprises planned position data describing planned relative positions between the anatomical body part and the treatment beam source of the radiation treatment apparatus and, for each at least one planned relative position, the operational state as a reference dose being a predetermined amount of a planned treatment dose associated with the respective at least one planned relative position, wherein each control point is described by at least one of planned relative positions; b) determine current control point data describing whether the radiation treatment apparatus has assumed a predetermined control point, wherein the current control point data comprises monitoring dose data describing the current operational state as a monitoring dose being an amount of the planned treatment dose associated with at least one of the monitoring image or the at least one actual relative position between the anatomical body part and the treatment beam source; c) acquire the monitoring image data describing at least one digital medical monitoring image of the anatomical body part in at least one monitoring relative position between the anatomical body part and the medical imaging device; d) acquire the patient image data describing a predetermined medical image of the anatomical body part; e) determine, based on the monitoring dose data and the planned control point data, corresponding reference dose data describing a corresponding reference dose being the reference dose corresponding best within a predetermined interval to the monitoring dose; f) determine, based on the patient image data and the corresponding reference dose data, comparison image data describing at least one digital medical comparison image of the anatomical body part in the monitoring relative position, wherein the monitoring relative position is the planned relative position between the anatomical body part and the medical imaging device; and g) determine, based on the comparison image data and the monitoring image data, the position deviation data describing a positional deviation between (i) the planned relative position associated with the planned control point assumed by the radiation treatment apparatus and (ii) the monitoring relative position on the other hand; wherein the at least one processor is further configured to: h1) generate he comparison image data if the current control point data describes that the radiation treatment apparatus has assumed a predetermined control point, or h2) generate the monitoring image data if the current control point data describes that the radiation treatment apparatus has assumed a predetermined control point.

Description

DESCRIPTION OF THE FIGURES

(1) In the following, the invention is described with reference to the appended figures which give background explanations and represent specific embodiments of the invention. The scope of the invention is however not limited to the specific features disclosed in the context of the figures, wherein.

(2) FIGS. 1 to 3 give an explanation of 4 radiotherapy;

(3) FIGS. 4 to 5 illustrate 4 radiotherapy for an arc representing a trajectory for moving a treatment beam source;

(4) FIG. 6 is a flow diagram representing the basic steps of the disclosed method; and

(5) FIG. 7 is a flow diagram representing an embodiment of the disclosed method.

(6) FIGS. 1 to 3 give an impression of what 4 radiotherapy means, in this case for a conventional treatment plan with static beams. This plan shall improve Dose Conformity (Treated Volume/Planned Target Volume) by moving patient closer to treatment source for every beam, and thereby enabling an improved beam shaping (adapt MLC leafs to target contour). The isocentres (positions of the treatment target) are changed between the beams/between the beam-on intervals.

(7) FIGS. 4 and 5 illustrate what 4 radiotherapy means for arc treatments. FIG. 4 shows a conventional rapid arc treatment. Whenever one of parameters gantry speed, dose rate or shape is changed a new control point is introduced. However, the geometrical alignment between the treatment table and the radiation treatment apparatus is not changed during beam-on. In contras thereto, according to FIG. 5, a new control point is defined whenever the isocentre position (in this case, the relative position between the anatomical body part and the radiation treatment apparatus) changes, and thus the relative position between the treatment table the radiation treatment apparatus changes. The expression control point does not necessarily define a point in space but a milestone (the begin of another segment of a treatment plan) in the process of emitting a treatment beam along an arc-shaped trajectory.

(8) FIG. 5 shows a 4-non-isocentric arc radiotherapy treatment: besides shape of a collimator (multi-leaf collimator), gantry speed and dose rate, the isocentre position changes, and yields new control points. The table angle can additionally be modified at every control point.

(9) FIG. 6 is a flow diagram illustrating the basic steps of the disclosed method in accordance with the first aspect, which in the illustrative example of FIG. 6 starts with a step S11 of acquiring the planned control point data. In subsequent step S12, the current control point data is determined, followed by step S13 which encompasses acquiring the monitoring image data. Then, step S14 acquires the patient image data. Subsequent step S15 is directed to determining the comparison image data. Steps S11 to S15 serve as input steps for the last step shown in FIG. 6 which is step S16 encompassing determination of the position deviation data.

(10) FIG. 7 shows an embodiment of the disclosed method in accordance with the first aspect. The monitoring system (the monitoring imaging apparatus) knows in real-time any change in treatment isocentre (target) position and couch kick (movement increment). Once a new control point/a new milestone in current dose application has been reached, a new changed (corresponding to the above-described comparison image) is created. Thus, the just acquired live data can be compared to that reference image in order to get the positional difference data. The comparison itself would be in terms of the ExacTrac radiation therapy apparatus a 2D/3D fusion using DRRs (digitally rendered radiographs representing the aforementioned comparison image data) created from a CT scan. But the comparison could also be any surface matching/point could registration method, in general any signal registration method that is known in the field.

(11) The comparison image data can be e.g. one of a digitally reconstructed radiograph (DRR), a simulated thermal image, a point cloud generated from a thermal image or a point cloud generated from a structured light image. The data used to create the comparison image is: the camera calibration (corresponding to the aforementioned monitoring imaging apparatus calibration data); and the current isocentre (treatment target) position and couch angle (=currently desired/planned alignment of the patient to the radiation treatment system),

(12) The embodiment of the disclosed method shown in FIG. 7 can be outlined as follows:

(13) (S21) acquiring radiation treatment plan image data describing a digital image of the patient (such as a planning CT);

(14) (S22) acquiring a radiation treatment plan from a radiation treatment planning system, the radiation treatment plan defining at least one reference position (corresponding to the aforementioned planned relative position between the anatomical body part and the radiation treatment apparatus and/or the monitoring imaging apparatus) in the radiation treatment plan image data, the reference position defining the planned alignment of the patient to the radiation treatment system, and the radiation treatment plan defining changes in the reference position depending on the progress of emitting the treatment beam (and/or a predetermined amount of the planned treatment dose);
(S23) acquiring the monitoring image data from a monitoring camera system (representing the monitoring imaging apparatus), the monitoring image data describing a current digital image of the anatomical body part;
(S24) acquiring monitoring image calibration data defining the . geometric camera calibration of the monitoring camera system to the radiation treatment system (the monitoring image calibration data corresponding to the monitoring imaging apparatus calibration data);
(S25) acquiring the reference image data (corresponding to the above-described comparison image data) simulated from the current reference position and the radiation treatment plan image data and the monitoring image calibration data;
(S26) determining positional difference data (corresponding to the position deviation data) based on the reference image data and the monitoring image data;
(S27) determining the treatment apparatus control data.