EP2758131A1

EP2758131A1 - System and method for positioning by means of nuclear imaging

Info

Publication number: EP2758131A1
Application number: EP12775642.7A
Authority: EP
Inventors: Christian Hieronimi; Jörg TRAUB; Thomas Wendler
Original assignee: Humediq GmbH; SURGICEYE GmbH
Current assignee: Humediq GmbH; SURGICEYE GmbH
Priority date: 2011-09-22
Filing date: 2012-09-24
Publication date: 2014-07-30
Also published as: US20140235921A1; WO2013041720A1; DE102011053868A1

Abstract

The invention relates to a system for determining the position of radioactively marked target tissue of a patient in radiation therapy by means of a radiation therapy device. The system comprises at least one detector for the imaging detection of the radiation distribution of a radioactive radiation source that is located in target tissue region, a computing unit that is designed to calculate the pose of the target tissue region from measurement data of the detector and to calculate a correction variable as the difference between the calculated pose and comparison values, and an interface by means of which the data for the calculated pose of the radioactively marked target tissue region and the correction variable can be transmitted by the computing unit to a radiation therapy device or a patient positioning device. The invention further relates to a corresponding method.

Description

description

SYSTEM AND METHOD FOR POSITIONING BY NUCLEAR IMAGING

The invention is in the field of nuclear imaging such as PET or SPECT, and aspects of the invention relate to a system and method for determining the position of a patient's radiolabeled target tissue in radiotherapy with a radiotherapy device and a device for positioning a patient Patient relative to a radiation source for radiation therapy, depending on measurement data of at least one nuclear radiation detector.

[0002] The therapy of tumors with different types of radiation is one of the standard methods in oncology. An important topic in appropriate forms of therapy is the highly selective irradiation of the target tissue, since as little as possible healthy surrounding tissue is to be damaged. Therefore, a precise detection / recognition of the target structure and a subsequent alignment of the radiotherapy device is a goal in the development of appropriate systems.

In the positioning of patients in the irradiation room under a linear accelerator, a proton therapy system or other external irradiation machines usually positioning systems are used. These include e.g. Fixation systems, such as single-limb fixation, thermoplastic fixation masks, laser-assisted positioning systems, robot-based positioning systems, ultrasound-based positioning systems, etc., or X-ray images are used, such as X-ray images. in multiple-2D X-ray positioning systems, gantry-mounted primary beam computed tomography or Megavolt computed tomography, optical positioning systems based on pre-operative CT or MR data and registration.

The positioning is among other things a challenge, since the anatomy between the irradiation fractions may change, for example, by organic changes in the tissue, air, water and food deposits, shrinking of the Tumors, etc., whereby these changes take place on a time scale of days or weeks between the irradiation fractions.

Another problem is that even during treatment the location of the target area may at least change slightly, e.g. minimal posture changes due to patient movement, such as respiration, heartbeat, and coughing.

Several factors therefore play together, which complicate the correct and sustainable positioning of a patient.

Previous approaches are e.g. The above-mentioned X-ray based positioning systems, which can also be used during irradiation. Such systems are often equipped with motion sensors capable of detecting major changes and then trigger the acquisition of new X-ray images. On the basis of these updated X-ray images, the patient can then be repositioned or repositioned. This approach has the disadvantage of involving X-ray exposure in each shot. This means, among other things, that you can not record new images on a real-time basis - and thus not only the additional radiation exposure as a disadvantage is to be expected, but also the slow rate of repositioning the patient.

Another approach is to use the information obtained from the surface of the patient to detect internal deformations or movements. Possible embodiments use markings affixed to the skin (e.g., optical markers) or directly to the surface of the patient himself, such as when using surface detection systems such as time-of-flight cameras, a stereotactic camera system, or laser scanning systems. Such systems have the disadvantage that they can not accurately detect the deformations and movements of deep structures, since their movements are not naturally directly related to movements of the surface.

Alternatively, there are approaches in which sensors are implanted into the target tissue to track internal movements. Examples are systems of the companies Calypso or Navitek. The first is electromagnetic sensors in one Prostate implanted and tracked during the irradiation to actively adjust the radiation. In the case of Navitek, a radiolabel is implanted in the prostate and localized by a collimator system in 3D to then adjust the radiation based on this position. These systems have a problem that they can only track the individual implanted sensors. Technically, no more than 2 or, in favorable cases, 3 such sensors can be tracked with sufficient accuracy. Complex structures and the forms of the tumors can not be detected and thus the irradiation can be adapted only suboptimally. Tumors that can be systemically labeled can not be traced at all by such systems.

For movements of a periodic nature, such as those caused by the heartbeat or respiration, procedures such as gating are used. These are only irradiated when the patient is in a particular phase of respiration, heartbeat, or both, when the position of the target tissue is known. Breathing sensors and heart rate sensors are often used to detect this phase. Non-periodic movements, however, can not track these systems. Furthermore, these systems assume that breathing or heartbeat is indeed periodic, but this is not the case.

Against this background, therefore, a system for determining the position of radiolabeled target tissue of a patient in radiotherapy with a radiotherapy device according to claim 1, and a corresponding method according to claim 11 is proposed. Further preferred aspects of the invention will become apparent from the dependent claims, from the figures and from the description.

According to a first aspect, there is provided a system for determining the position of radiolabeled target tissue of a patient in radiotherapy with a radiotherapy device. The system includes at least one detector for imaging the radiation distribution of a radioactive radiation source located in a target tissue area; an arithmetic unit configured to calculate the pose of the target tissue region from measurement data of the detector and to calculate a correction quantity as the difference between the calculated pose and comparison values; and an interface with which the data for calculated pose of the radiolabelled target tissue region, as well as the correction variable, from the arithmetic unit to a Radiotherapy device or a patient positioning device can be transmitted. Decisive in the invention is the imaging nature of the detector, which can detect the radiation distribution of a radioactive radiation source.

In another aspect, a method for determining the position of radiolabeled tissue of a patient in radiotherapy with a radiotherapy device is provided. The method comprises applying a radioactive radiation source to a target tissue area to be irradiated; imaging detection of an emitted radiation distribution of the radiation source while the patient is in a treatment position; calculating a pose of the target tissue area based on the detected radiation; and calculating a correction amount as a difference between the calculated pose of the target tissue area and a target pose value.

The invention also relates to an apparatus for carrying out the disclosed methods and also includes apparatus parts for carrying out individual process steps. These method steps may be performed by hardware components, by a computer programmed by appropriate software, by a combination of both, or in some other way. The invention is further directed to methods according to which the devices described in each case operate. It includes steps to perform each function of the devices.

In addition, the invention will be explained with reference to embodiments illustrated in figures, from which there are further advantages and modifications.

Figure 1 shows a system for positioning according to embodiments of the invention;

Figure 2 shows a system for positioning according to further embodiments of the invention;

FIG. 3 shows a plan view of a section of a system according to FIG

Embodiments;

FIG. 4 shows a plan view of a detail of a system according to further embodiments; FIG. 5 shows a schematic representation of a method according to embodiments.

In the following, various embodiments of the invention will be described, some of which are also exemplified in the figures. In the following description of the figures, like reference numerals refer to the same or similar components. In general, only differences between various embodiments will be described. Herein, features described as part of one embodiment may also be readily combined with other embodiments to produce still further embodiments.

The structures to be irradiated (target structures, target tissue areas) that are treated here are usually tumors or lymph nodes that interact with a radioactive tracer by nuclear-medical imaging systems (PET, SPECT, gamma cameras, Compton cameras, freehand SPECT , etc.). Alternatively, structures that can not be labeled systemically or with a functional label, such as the sentinel label, can be labeled directly by injection or implantation of radioactivity. Thus, these structures become radioactive and can be represented by nuclear medicine. A typical example is the implantation of a 1-125 marker, which has a titanium sheath, to the site of the tumor.

As used herein, the term "PET detector" refers to any type of coincidence camera system that consists of at least two individual detectors that relate to at least a portion of the relevant anatomy on an imaginary line connecting the two and that are connected to a coincidence device are to prove coincidences (simultaneous detections in one energy range) in both.

The term "free-hand SPECT detector" refers to any type of free-moving tracked detectors (including non-imaging such as gamma probes) that can reconstruct a 3D image from single-photon radiation from measurements from different directions.

In embodiments, prior to radiation treatment, a nuclear medical image of the target structure (eg, a tumor) in the patient in Radiation therapy room generated and used for the initial positioning of the patient. For this purpose, the patient is already lying on the couch of the irradiation device, or sitting, if this is provided for example by the design of the device. The radiation emanating from the marked tissue is detected by a detector system with at least one detector over a certain period of time, which is typically in the range between half a second and a few minutes, for example 3, 10 or 20 seconds. The actual time required for the measurement depends, inter alia, on the nature of the radiation used or detected, the intensity of the radiation source, how deep it sits in the tissue and thus shielded, the sensitivity of the detector and the desired spatial resolution.

The detection system is designed so that information about the size, position and shape of the target tissue in the room can be obtained by means of a downstream computational processing of the detected detector signals. Such a configuration can be achieved with a variety of possible detector variants and combinations, wherein the required location information is obtained in some embodiments by varying the detector position during the measurement, in other embodiments also by the use of collimators in front of the detector (s). The term "pose" also used in the following, known to the person skilled in the art, means that three spatial coordinates and two or three angular coordinates are determined (which indicate the orientation).

In order to calculate the position of the target structure from the detector data, basically known methods of image processing are used. These include, for example, segmentation, classification, and atlas, in order to determine a 3D position, shape and possibly orientation in the space of the target structure. Corresponding methods for obtaining location and shape information from detector data are known to the person skilled in the art and will not be explained in detail here.

By comparing this data with the geometric data of the beam path of the irradiation device can determine how the position of the patient must be changed in order to bring the target tissue, such as the tumor, in the correct position. The determined correction or the correction variable is in the simplest case a three-dimensional vector whose length and direction indicate the required change, so that an irradiation can be started. By means of this correction vector, the patient can at the correct Position for irradiation. The correction quantity can also be a matrix (eg a rigid 4x4 transformation matrix), or in particular a deformation field, as explained in greater detail below.

The correction vector or the correction quantity is displayed to the user of the irradiation machine for the re-positioning of the patient. This may take the form of a graphical representation on a display, e.g. an LCD monitor, or by an audio signal happen. It is also possible to overlay the correction information with a video image of the patient recorded by a camera.

Alternatively or additionally, this correction can be fed into a positioning system, which automatically positions the patient in the correct position relative to the radiation therapy machine. This correction variable can also be stored and used as an initial value for the following irradiation fractions.

In addition, the imaging method described during radiation can continue to generate images, and thus update the mentioned correction vector in real time. This real-time update may be displayed to the user or may trigger / trigger the display of a visual and / or audible warning. Should the required calculated correction be too large (i.e., the position of the tumor should deviate too much from the target position), the irradiation may be automatically stopped, e.g. by switching on / off an interlock. An interlock is a device that stops or stops the movement or irradiation of a radiotherapy device when a patient, an operator or the radiotherapy device itself is in danger of harm.

In addition, the correction quantity can be used to turn on the irradiation if it undershoots a value. In addition, the correction quantity can be fed into a positioning system in order to automatically carry out a correction during the irradiation.

In embodiments, the method described above comprises at least one detector, a computing unit for data evaluation, as well as an interface for the transmission of data between the arithmetic unit and the irradiation device. In exemplary embodiments, the arithmetic unit can also be used as part of the irradiation device be executed, so that one or more detector units are required as the only additional assembly to the irradiation device.

Fig. 1 shows a system according to an embodiment. The patient 50 lies on a treatment couch 60. This is connected to a patient positioning device 70, which can adjust the couch in vertical and horizontal directions in several directions to change the position of the patient to the beam path of the irradiation device 80. Before treatment, the radiation source 90 was applied to the patient at the site of the tissue to be treated. The source may e.g. be an iodine-125 implant. As a detector for detecting the emitted radiation, or as an imaging element, serves in this embodiment, a gamma camera 130 which is connected via a cable 100 to a computing unit 110. The connection may in another embodiment be a wireless connection, e.g. a radio connection.

The camera 130 is freely movable in space and is provided with a tracking marker 190. Its position in space is recorded by a tracking sensor 120, which is also connected to the computing unit 110. The tracking sensor 120 forms, together with the computing unit 110, a tracking system 105. In embodiments, this may be an optical, electromagnetic, acoustic, mechanical or RFID tracking system.

The camera is moved to determine the location of the target 90 freely over the body of the patient 50 and thereby absorbs the radiation emitted by the radiation source 90. Meanwhile, the tracking system 105 continuously picks up the pose of the camera 130. In this case, the orientation of the central axis of the camera is typically also recorded in the room. By temporally associating the measured radiation values with the tracking data, a 3D image can then be generated on the raw data after application of an image processing method (such as in Freehand SPECT) and thus information about the geometric location or the size of the radiation source 90 can be drawn.

The pose data of the gamma camera 130 taken by the tracking sensor 120, in conjunction with the camera's detection data, provide a database to accurately determine the pose of the radiation source 90 with respect to the position of the tracking sensor 120. This is a location of the source 90 with respect to the tracking sensor 120 possible. In order to match whether the absolute position of the radiation source 90, or of the target tissue to be irradiated, is at the desired position in the beam path of the irradiation device 80, a local reference of the tracking sensor 120 to the irradiation device 80 is required. This can be ensured, for example, by knowing and storing the geometric relationships between the irradiation device 80, its beam path and the position of the tracking sensor 120. By depositing this information in a memory of the arithmetic unit 110, for example, during initial startup or calibration, the arithmetic unit on this basis, the calculated pose of the radiation source 90 with the stored geometric data match.

In exemplary embodiments, the tracking sensor 120 not only detects the camera pose but also other components of the irradiation scenario, in particular the irradiation device 80 and the couch 60, which are each provided with their own tracking markers 192, 194. In this way, the arithmetic unit 110 can directly calculate a spatial relationship between the components detector (camera 130), possibly couch 60 and irradiation device 80. The characteristic geometric data of the irradiation device 80, in particular the beam path with respect to the outer dimensions of the device, can be stored in a memory of the arithmetic unit 110. In this case, the arithmetic unit can directly calculate the correction quantity k from the tracking data of all components in connection with the data taken by the camera and processed into an image. With this correction value, the patient positioning device 70 can be controlled directly via an interface.

In embodiments, the calculated pose of the target tissue area can be transmitted via a (radio) interface 73 to a control unit 112 (not shown) of the irradiation device 80. The software for calculating the correction quantity k and for the corresponding control of the patient positioning device 70 is provided in the control unit 112 in this case, in contrast to the previous examples. In exemplary embodiments, the correction variable k can be displayed on an optical display device 180, if it can be represented graphically, optionally as an overlay with a visual camera image of the patient. In this way, a control by an operator is possible. The repositioning of the patient can also be done by manual intervention of the operator. Alternatively or additionally, an acoustic signaling or the triggering of switching on / off provided by the interlock be, for example, when a movement of the patient occurs during the irradiation. This can be done via the arithmetic unit 110 or the irradiation device 80.

The correction quantity k serves as the basis for a correction of the position of the patient 50 and thus also the radiation source 90 or the target tissue. In the simplest case, k is a two-dimensional vector which indicates in which direction and by which distance and direction the patient has to be displaced in an x-y plane (see FIG. 1) in order to position the target tissue in the beam path 82 of the irradiation device. In exemplary embodiments, k is a three-dimensional or multidimensional vector, wherein typically also a displacement component in the direction of the z-coordinate (height position of the patient) is provided.

In embodiments, k may also be a matrix, such as a rigid 4x4 transformation matrix. This may also include, for example, a rotation, e.g. in the event that the position of the structure to be irradiated in the body has changed, which could not be compensated by a purely translatory movement in x, y, z. In other examples, k may be a deformation field. This can e.g. be useful to correct for size changes of the target tissue (e.g., the tumor) over an image taken at a previous radiation session. Deformable registration methods such as nonparametric registration methods, parametric registration methods (eg with B-splines), Curvature Registration, Demons Registration, Diffeomorphic Demons Registration, Symmetic Forces Demons Registration, Level Set Motion Registration, PDE Deformable Registration can be used to calculate this deformation field In general, in the exemplary embodiments described here, it is assumed that the irradiation device or the therapy performed is such that the beam can be adjusted by collimation such that its cross section is at least approximately identical to a cross section of the target tissue to be irradiated. This means at the same time that there is a one-to-one pose of the target tissue or radiation source 90 with respect to the beam path 82 at which the optimal irradiation result is achieved since the beam cross-section covers the entire tumor, while largely sparing adjacent healthy tissue through collimation.

In embodiments, it is also possible that the beam cross-section of the irradiation device 80 is smaller than a cross-sectional area of the radiation to be irradiated Target tissue. In this case, if the target tissue is entirely radioactive not only by an implanted target but by injection of a radioactive tracer substance, the target tissue can be detected by the above-described image recognition system as a three-dimensional spatial structure from the positioning system. The positioning system can be used in this scenario to scan a cross-sectional area of the tumor or target tissue with the beam of the irradiation device, so that successively the entire area of the tumor is irradiated. For this purpose, a limitation or segmentation of the tumor to be irradiated against other, also easily radiating volumes in the body can be made.

In other embodiments, the beam cross-section of the irradiation device 80 is larger than a cross-sectional area of the target tissue to be irradiated. In this case, the form of the target tissue can be used to match the shape of the beam cross-section with that of the target tissue using a multi-leaf collimator.

The real-time capability of the system according to embodiments can be used to perform a continuous monitoring of the pose of the target tissue during a radiation treatment, so that a correction quantity k can be continuously calculated. If this exceeds a certain limit condition, i. In general, the pose of the target tissue deviates too much from a desired pose, i. the target tissue is no longer in the beam path 82, various measures can be provided. A visual display is possible, for example on display 180 or on another operating monitor of the irradiation device 80, as well as an audible warning. If there is no longer a reaction or if the exceeding of the limit value is too great, the arithmetic unit 110 or the processing unit 112 of the irradiation device can also initiate an automatic interruption of the irradiation (for example by means of the switching on / off of an interlock). Alternatively, the arithmetic unit 110, 112 may also initiate an automatic tracking of the patient's position via an activation of the patient positioning device 70 via interface 72.

In embodiments, a tracking element 196 is attached to the patient, and the tracking system is configured to obtain tracking element coordinates that indicate a pose of the tracking element 196. In embodiments, a support surface 86 of the couch is further provided with weight sensors to determine a weight distribution of the person to be imaged 50 when the person rests on the support surface. This can be used, among other things, to additionally determine the movement of the patient. In embodiments, the system further comprises a surface determination system for locating a body surface of the person being imaged; preferably by means of a tracking instrument for scanning the surface, wherein the instrument may be a handheld gamma probe, a handheld gamma camera 130, a time-of-flight camera, a stereoscopic camera, a laser scanner, or any combination of the foregoing.

Fig. 2 shows a further embodiment. In contrast to FIG. 1, there is no hand-held gamma camera 130 as an imaging detector in use, but two stationary detectors 150, 160 which are positioned to the left and right of the patient's body (in the image in front of and behind the imaged person, for reasons of presentation transparent ). By means of the two radiation detectors 150, 160, an imaging, spatially resolved detection of the radiation field of the radiation source 90 in the patient 50 is likewise achieved. The detectors are connected to the arithmetic unit 110 (not shown). Since the detectors are stationary, their spatial relationship to the irradiation device 80 or its beam path 82 is known or can be determined once during a calibration. Thus, in this example, no tracking system is required to set the detected position of the radiation source with respect to the beam path 82 of the irradiation device 80.

FIG. 3 shows a detail of the detector arrangement 150, 160 of the system shown in FIG. 2. The detectors can together form a PET detector or be 2 gamma cameras. Alternatively, the detectors may each be the scatter detector of a Compton camera which may cooperate with an absorption detector (not shown).

Fig. 4 shows a detector arrangement of a system according to another embodiment. In this case, a stationary detector 160 in addition to the patient is combined with a freely movable detector 130, which may be approximately hand-guided, but may also be controlled by a robot arm (not shown) via arithmetic unit 110. Possible detector combinations are, for example, 2 fixed gamma cameras directed to the body part of interest, 1 PET detector consisting of 2 fixed PET plates, a fixed gamma camera and a hand-held tracking non-imaging detector (such as a gamma onde), 2 free moving miniature gamma cameras, etc. It is readily apparent to those skilled in the art that a variety of combinations of different types of detectors can be used to achieve a spatially resolved, imaging detection with the systems described herein. For example, two freely movable detectors of the type of hand-held gamma camera 130 are possible.

5 shows a schematic sequence of a method for determining the position of radioactively marked tissue of a patient during radiotherapy with a radiotherapy device according to exemplary embodiments. In a step (500), a radioactive radiation source is applied to the patient in a target tissue area which is to be irradiated. In step (510), the imaging detection of an emitted radiation distribution of the radiation source takes place, wherein the patient is in a treatment position. In a step (530), the calculation of a pose of the target tissue area or of the radiation source follows from the detected radiation. In a step (540), a correction quantity k is calculated as a difference between the calculated pose of the target tissue area and a target value.

Claims

claims

1. System for determining the position of radiolabeled target tissue of a

A patient (50) in radiotherapy with a radiotherapy device (80), comprising:

- at least one detector (130, 150, 160) for imaging detection of the radiation distribution of a radioactive radiation source (90) located in a target tissue area;

- A computing unit (110, 112) adapted to calculate the pose of the target tissue area from measured data of the detector (130, 150, 160), as well as for calculating a correction quantity as the difference between the calculated pose with comparison values;

- An interface (72, 73), with the data on the calculated pose of the radiolabeled target tissue area, as well as the correction variable, from the computing unit (110) to a radiotherapy device (80) or a patient positioning device (70) can be transmitted.

2. The system of claim 1, wherein the computing unit is further configured to calculate the shape of the marked tissue from the measurement data.

3. System according to claim 1 or 2, wherein the correction quantity is an at least three-dimensional correction vector, a matrix and / or a deformation field.

4. System according to one of the preceding claims, further comprising a tracking system

(105) for detecting the pose of the at least one detector (130, 150, 160) and / or the radiotherapy device (80), preferably an optical, electromagnetic, acoustic, mechanical or RFID tracking system.

A system according to any one of the preceding claims, further comprising an output unit

(180) to graphically and / or acoustically display the at least three-dimensional correction vector, the matrix, or the deformation field.

A system according to any one of the preceding claims, further comprising a device

(70) to change the position of the patient according to the specifications of the correction large.

7. The system of claim 1, wherein the determination of the correction quantity is carried out in real time during a radiation therapy treatment, and wherein, when a limit condition for the correction quantity is exceeded, at least one of the following is carried out:

Signaling the limit condition violation to an operator, and

- automatic interruption of treatment.

A system according to any one of the preceding claims, wherein the at least one radiation detector (130, 150, 160) is a PET detector, a SPECT detector, a freehand SPECT detector, a Compton camera or a gamma camera.

A system according to any one of the preceding claims, comprising at least two radiation detectors (130, 150, 160) having one of the following characteristics:

- both are attached,

- one is attached, the other is freely movable,

- both are free to move.

A system according to any one of the preceding claims, further comprising at least one of the following: (i) a tracking element (196) to be attached to the person to be imaged (50), wherein the tracking system (105) is configured to obtain tracking element coordinates indicative of a pose of the tracking element (196);

(ii) a bearing surface (86) with weight sensors to determine a weight distribution of the person (50) to be imaged when the person is sitting on the person

Bearing surface rests; and

(iii) a surface determination system for locating a

Body surface of the person to be imaged (50); preferably by means of a tracked instrument for scanning the surface, which instrument may be a hand-held gamma camera (130), a time-of-flight camera, a stereoscopic camera, a laser scanner, or any combination of the foregoing.

11. A method for determining the position of radiolabelled tissue of a

Patients in radiotherapy with a radiotherapy device, comprising:

Applying a radioactive radiation source (90) to a target tissue area to be irradiated; imaging detection of an emitted radiation distribution of the radiation source while the patient is in a treatment position;

Calculating a pose of the target tissue area based on the detected radiation; and

Calculating a correction quantity as the difference between the calculated pose of the target tissue area and a target pose value.

12. The method of claim 11, wherein 3D information about the shape and the

Dimensions of the radioactively marked tissue can be determined from the detected radiation measured values.

13. The method of claim 12, wherein the 3D information is obtained by using

Image processing methods are obtained on the determined radiation measurements.

14. The method according to any one of claims 11 to 13, further comprising at least one of the following: a) notification of the calculated correction quantity to an operator of the radiotherapy device, preferably in acoustic and / or optical form, b) activating an interlock to interrupt the irradiation ,

15. The method according to any one of claims 11 to 14, further comprising:

Changing the relative position between the patient (50) and an irradiation source of the therapy device (80) such that the target tissue area is at a defined desired position.

16. The method according to any one of claims 11 to 15, wherein the application of the radiation source comprises at least one of the following:

Implant at least one target containing a radioactive substance

- Injecting a radioactive fluid into the body of the patient.

17. The method according to claim 11, wherein the determination of the correction vector is carried out in real time during a radiation therapy treatment, and wherein, when a limit value of the correction vector is exceeded, at least one of the following is carried out:

Signaling the limit value violation to an operator, and

- automatic interruption of treatment.

18. The method according to any one of claims 11 to 17, wherein the correction quantity is an at least three-dimensional vector, a matrix or a deformation field.

19. The method according to any one of claims 11 to 18, wherein the at least one detector is movable, and whose position is detected by optical, electromagnetic, acoustic or mechanical or radio tracking from the system.