CN102908159B - Radiotherapy with superposition-free 3D computerized tomography imaging - Google Patents

Abstract

The invention relates to a radiation therapy device comprising: a therapeutic radiation source; a recording device for a computed tomography 3D image data set, comprising the radiation source and an opposite device for recording raw image data for non-overlapping computed tomography 3D A radiation detector for the image data set; a reconstruction device for reconstructing a non-overlapping computed tomography 3D image data set from the raw image data; and a control device for coordinated control of: irradiation with a therapeutic radiation source, and use of The recording device and the reconstruction device record and reconstruct the non-overlapping computed tomography 3D image datasets. Furthermore, the invention relates to a method for recording image data in radiotherapy, comprising the steps of recording raw image data for a non-overlapping computed tomography 3D image data set after the start of an irradiation, and extracting from the raw image data before the end of the irradiation A non-overlapping computed tomography 3D image data set is reconstructed from the data.

Description

Radiation Therapy with Overlap-Free 3D-CT Imaging

technical field

The invention relates to a radiotherapy system with a computed tomography imaging device and to a method for recording image data during radiotherapy.

Background technique

Radiation therapy is a mainstream method in which ionizing radiation is used for the treatment of pathological tissue, such as tumor tissue. The goal of radiation therapy is to deliver a sufficient therapeutic dose to the tissue to be treated without damaging healthy surrounding tissue. Furthermore, the therapeutic effect is dependent on the fact that ionizing radiation acts differently on healthy and pathological tissue.

When irradiating a patient with radiation therapy equipment, the site to be irradiated moves due to intentional and unintentional patient movements (eg breathing, gastrointestinal motility). As a result, the irradiation deviates from the previously determined radiation plan.

US6778850 describes the implementation of radiotherapy in which multiple diagnostic x-ray images are recorded in order to reconstruct a low-resolution tomosynthesis image (Tomosynthese-Abbildung) from them, which is then used to focus the radiation onto on the target volume.

US Pat. No. 7,684,647 describes the practice of radiation therapy in which 2D radiographs recorded during radiation are correlated with 3D image data sets recorded prior to irradiation.

Contents of the invention

The technical problem to be solved by the present invention is to provide a radiation therapy device and a method for recording image data during radiation therapy, which allow precise monitoring of the irradiation and in which a comparison with previously recorded image data can be easily compared .

The radiotherapy device according to the invention comprises:

- therapeutic radioactive sources,

- Acquisition device for a computed tomography 3D image dataset, comprising a diagnostic radiation source and an opposite radiation detector, by means of which raw image data can be recorded for the non-overlapping computed tomography 3D image dataset ,

- a reconstruction device, by means of which a non-overlapping computed tomography 3D image dataset can be reconstructed from the raw image data, and

- a control device for coordinated control of the irradiation with the therapeutic radiation source and the recording and reconstruction of the non-overlapping computed tomography 3D image data sets using the recording device and the reconstruction device.

Accordingly, a recording device for a three-dimensional CT image data record (CT stands for Computed Tomography) can be installed or integrated in the radiotherapy system. With the aid of the recording device, three-dimensional non-overlapping computed tomography image data sets can be recorded. The three-dimensional non-overlapping image data set can be reconstructed from the recorded raw image data by means of a common CT reconstruction algorithm. An image of the site to be irradiated depicting the site to be irradiated with high contrast resolution can thus be obtained.

Compared with two-dimensional radiography, three-dimensional CT image data can more precisely describe and localize the site to be irradiated (in particular the soft tissue to be irradiated) with significantly higher contrast resolution. Using only multiple two-dimensional radiography from different directions can only delineate the area to be irradiated with limited three-dimensional information. If a correlation should now be made between these radiographs and the planning CT data set, this is not technically easy to do because of the different image types.

Although tomosynthesis alone images the object to be examined on a section through the object, it does not describe the section through the object completely without overlapping. The tomosynthesis has a certain ambiguity, since the structures located in front of and behind the section in the object are also imaged (if also clearly blurred) and are thus displayed in the image superimposed with the actual sectional image information. Correspondingly, the tomosynthesis recordings are not overlap-free. As a result, not only the contrast resolution is limited, but also the three-dimensional information.

Even if a link to the planning CT data set should now be established, this is also technically not easy to do, since the different image types are compared with one another.

On the other hand, the three-dimensional CT image datasets recorded by current radiotherapy installations are three-dimensional datasets which image object structures completely without overlapping. For example, a cross-sectional image can be generated from the three-dimensional CT data record, which only visualizes the object in this cross-section without “diluting” the image information by superimposing other regions of the target object. The three-dimensional image dataset has the good low-contrast detectability typical of CT images.

Due to the similarity between the three-dimensional computed tomography image data set and the planning CT image data set, a comparison and/or correlation of the two data sets can be carried out easily and with relatively little technical effort.

The radiation detector can comprise an array with one or more detector rows arranged in the longitudinal direction of the patient for detecting x-rays. The detector row may be arranged so that it is perpendicular to the axis about which the therapeutic radiation source rotates. Each detector row of a CT detector can contain several hundred detector elements. The array may comprise a plane having a lengthwise extension that is at least 2 times, or even 3 or 5 times, the longitudinal extension as the transverse extension.

The detector can thus be such that the measuring field covers at least 50 cm at the center of symmetry of the radiotherapy system in the direction of the patient cross-section, while the measuring field covers at most 20 cm at the center of symmetry in the longitudinal direction. The detector thus differs significantly from so-called flat-panel detectors, which are used, for example, in cone-beam CT (Cone-Beam-CT) or for generating radiography, X-ray Optical examination or tomosynthesis and thus often have a distinct square shape. The recording device can thus be a single-line computed tomography or a multi-line computed tomography.

The imaging device can be rotatably supported. In this case, the recording device can be rotated by at least the sum of 180° and the sector angle of the radiation detector in order to record the raw image data. For example, the imaging device and the therapeutic radiation source can be fastened to the rotary device of the radiotherapy system in such a way that the therapeutic radiation source and the imaging device rotate together about a central axis. This enables a compact construction. In this way, the complete raw image data required for the reconstruction of the CT image data set can also be recorded during the irradiation and before the end of the irradiation.

In an embodiment, the control device can be configured in such a way that the irradiation is started. The recording of the raw image data for the non-overlapping computed tomography 3D image data records is controlled in such a way that the recording starts after the start of the irradiation. The raw image data can be recorded partially (or even completely) while the treatment beam is being applied, that is to say when the treatment beam is directed from the treatment radiation source to the patient. The possibly necessary rotation of the imaging device for this purpose can likewise take place (at least partially) during application of the treatment beam.

In one embodiment, the control device has an input via which an external signal characterizing the movement of the object to be imaged is transmitted to the control device. The external signal can be recorded, for example, by an external motion sensor, for example by an optical recording device which monitors the patient's surface or by a compression belt which monitors the chest pressure during respiration.

The control device can be configured to control the recording of the raw image data in such a way that the raw image data are only recorded during defined time intervals during which the object to be imaged is in a defined state of motion. The recording of raw image data can be triggered by an external signal. For example, raw image data can only be recorded in certain breathing phases. Motion blur is thereby reduced in the reconstructed computed tomography image data.

The reconstruction device can be configured in such a way that the recorded raw image data are temporally linked to an external signal characterizing the motion of the object to be imaged. This connection can also be used to reconstruct the computed tomography image data set in such a way that motion-induced blurring is reduced or even minimized.

The reconstruction device can be configured in such a way that from the recorded raw image data linked to the external signal a plurality of non-overlapping computed tomography 3D image data sets are determined, which 3D image data sets are to be imaged at different times object imaging. For example, raw image data can be recorded continuously. A reconstruction can then take place using external signals associated with the raw image data, and the raw image data can be temporally classified. In this way, a temporal sequence of three-dimensional computed tomography image data records can be generated, each individual image data record representing object structures three-dimensionally and without overlapping.

Furthermore, the control device can be configured to compare the non-overlapping computed tomography 3D image data set recorded and reconstructed during the irradiation with a previously recorded 3D image data set (for example with the planning CT image data set) and The irradiation process is controlled on the basis of this comparison.

How the object to be irradiated is moved and/or deformed can be determined via this connection. This link can be produced, for example, by a strict or non-strict registration of the relevant object parts, from which information about object movements, rotations and/or deformations is obtained and used to control the irradiation.

It is also possible here to link the CT image data set recorded during the irradiation with the time-resolved CT image data set of the examination object recorded before the irradiation, wherein the CT images were taken at different times before the examination (for example at different breathing phase) shows the area to be irradiated.

Irradiation can be controlled based on the comparison. For example, the irradiation can be interrupted; the irradiation can be performed only at a predetermined position of the irradiation subject, which is determined by comparison; or the irradiation can be controlled such that the irradiation follows the movement of the subject.

The method according to the invention for recording image data in radiotherapy comprises the following steps:

- after starting the irradiation, recording raw image data for the non-overlapping computed tomography 3D image data set, and,

- Before the end of the irradiation, a non-overlapping computed tomography 3D image data set is reconstructed from the raw image data.

The raw image data can be recorded by means of a computed tomography imaging system with radiation detectors comprising an array with one or more detector rows arranged in the longitudinal direction of the patient. The raw image data can be recorded in that the radiation detector is rotated around the patient by at least 180° plus the sector angle of the radiation detector.

The raw image data can be recorded and/or the non-overlapping computed tomography image can be reconstructed using external signals which characterize the motion of the object to be imaged. For example, the raw image data can only be recorded during certain time intervals during which the object to be imaged is in a certain state of motion. However, raw image data can also be recorded continuously or independently of the movement of the object.

The raw image data recorded for the reconstruction can be linked to the external signal, wherein in particular a plurality of non-overlapping computed tomography 3D image data sets are reconstructed, which visualize the object to be imaged at different times.

The non-overlapping computed tomography 3D image data set can be compared with the 3D image data set recorded before the irradiation, in order to control the irradiation process in particular on the basis of the comparison.

The above and below descriptions of the individual features, advantages and effects relate not only to the scope of the device but also to the scope of the method, without being explained in detail in each case individually; the individual features disclosed here can also be further developed according to the invention the right combination.

Description of drawings

Embodiments of the invention are explained in greater detail with the aid of the following illustrations, but are not restricted thereto. in,

Figure 1 shows a strong schematic structure of a radiotherapy facility, with an o-shaped gantry in which a CT imaging device is integrated,

FIG. 2 shows an embodiment of the method according to the invention for recording image data during irradiation,

FIG. 3 shows a further embodiment of the method according to the invention for recording image data during irradiation.

Detailed ways

FIG. 1 shows a radiotherapy installation 11 with an o-gantry 13 .

The gantry 13 has a central opening 13 in which a patient 17 on a patient couch 19 is positioned for irradiation.

Located on the gantry ring is a rotating device 21 , by means of which a therapeutic radiation source 23 can be rotated around the patient 17 . The radiation of the therapeutic radiation source is collimated by means of a multi-leaf collimator, whereby the radiation field is limited to two dimensions. Accordingly, the multi-leaf collimator is different from the one-dimensional binary collimator ( Kollimator), the binary collimator only allows the illumination field to vary in one dimension.

Likewise connected to the rotary device 21 and integrated in the radiotherapy system 11 are a CT-X radiation source 25 and a CT detector 27 , by means of which raw image data can be recorded for three-dimensional computed tomography without overlapping.

The CT detector 27 comprises an array with one or more detector rows, which are arranged in the longitudinal direction of the patient 17 . In order to record raw image data, the imaging component can be rotated together with the rotating device by the sum of 180° and the sector angle of the radiation detector.

The radiotherapy system 11 has a control device 29 by means of which the individual components of the radiotherapy system 11 are controlled in a coordinated manner.

Furthermore, the control device 29 has an input 31 , via which a signal can be supplied to the control device 29 , which signal is recorded by an external sensor 33 or a motion monitor and characterizes the movement of the patient 17 (for example breathing movement).

Furthermore, the radiotherapy system 11 has a reconstruction device 35 , by means of which a non-overlapping three-dimensional computed tomography image dataset can be generated from the raw image data.

The control means 29 and the reconstruction means 35 can be realized, for example, by a computer unit.

FIG. 2 shows a flow chart describing an embodiment of the method according to the invention.

First, irradiation is started (step 51).

The respiratory motion of the patient is monitored and recorded by an external motion monitor. Signals characterizing the motion are recorded and transmitted to the radiotherapy device (step 53).

Raw image data are recorded during the irradiation and in particular when the irradiation radiation is applied (step 55 ). The recordings are only made during defined time intervals, ie when the patient is in a defined breathing phase. Whether it is in the appropriate breathing phase is determined according to the external signal.

After sufficient raw image data has been recorded, a three-dimensional non-overlapping computed tomography image data set is generated from the raw image data before the end of the irradiation (step 57 ).

The non-overlapping three-dimensional computed tomography image data set is compared with the planning CT image data set (Planungs-CT-Bilddatesatz) (step 59 ).

Irradiation is controlled in dependence on the comparison, for example by repositioning the patient or by controlling a gated or tracked irradiation method (step 61 ).

FIG. 3 shows another embodiment of the method according to the invention. In contrast to the exemplary embodiment shown in FIG. 2 , the raw image data are here continuously recorded (step 55 ′).

During the reconstruction, however, the raw image data are linked to external signals characterizing the movement. The reconstruction is performed in a time-resolved manner, that is to say the raw data are classified according to the external signal and a temporal sequence of non-overlapping three-dimensional CT image data records is generated (step 57 ′).

The temporal sequence of the CT image data records recorded during the irradiation is linked to the time-resolved CT image data records of the examination object recorded before the irradiation in order to control the irradiation (step 59 ′).

list of reference signs

11 Radiation therapy equipment

13 racks

15 central opening

17 patients

19 patient couch

21 rotating device

23 Radioactive Sources for Therapy

25 Diagnostic radioactive sources

27 Radiation detectors

29 control device

31 input terminal

33 external sensor

35 reconstruction device

51 steps 51

53 steps 53

55, 55' step 55, step 55'

57, 57' step 57, step 57'

59, 59' step 59, step 59'

61 steps 61

Claims (9)

1. A radiotherapy apparatus (11) comprising: - healing radioactive sources (23), - Acquisition device for computed tomography 3D image datasets, comprising a diagnostic radiation source (25) and an opposite radiation detector (27), by means of which raw image data can be recorded for a computer without overlapping tomographic 3D image dataset, - a reconstruction device (35), by means of which the non-overlapping computed tomography 3D image data set can be reconstructed from the raw image data, and - a control device (29) for coordinated control of the irradiation with the therapeutic radiation source (23) and the processing of the non-overlapping computed tomography 3D image data sets using the recording device and the reconstruction device (35) record and reconstruct, Therein, the control device (29) is configured to compare the non-overlapping computed tomography 3D image data set recorded and reconstructed during the irradiation with a previously recorded 3D image data set and to control the irradiation process. 2. The radiotherapy apparatus (11) according to claim 1, wherein the radiation detector (27) comprises an array having one or more detectors for detecting X-rays arranged in succession in the longitudinal direction of the patient. detector line. 3. Radiotherapy apparatus (11) according to claim 2, wherein the array comprises a plane having a lengthwise extension which is at least twice as long in the longitudinal direction as in the transverse direction. 4. The radiotherapy system (11) according to claim 1, wherein the imaging device is mounted rotatably and is capable of at least 180° plus the sector angle of the radiation detector for recording the raw image data The sum is rotated. 5. The radiotherapy apparatus (11) according to claim 1, wherein the control device (29) is configured to start irradiation and to control the recording of the raw image data for the non-overlapping computed tomography 3D The image data set is such that the recording starts after the start of the irradiation. 6. The radiotherapy apparatus (11) according to claim 1, wherein the control device (29) has an input terminal (31) via which the control device (29) can be inputted with a characterizing The external signal of the motion of the object (17). 7. The radiotherapy apparatus (11) according to claim 1, wherein the control device (29) is configured to control the recording of the raw image data such that the raw image data is only at certain time intervals The time interval during which the object (17) to be irradiated is in a defined state of motion is recorded. 8. The radiotherapy apparatus (11) according to claim 6, wherein the reconstruction device (35) is configured for combining the recorded raw image data with an external The signals are related to each other in time. 9. The radiotherapy apparatus (11) according to claim 8, wherein the reconstruction means (35) are configured to determine from the recorded raw image data associated with the external signal a plurality of In each case non-overlapping computed tomography 3D image data sets which image the object to be imaged at different times.