Computed tomography system

Abstract

The present invention relates to a computed tomography (CT) system having the following features: a) at least one X-ray beam source; b) at least one patient couch for a patient to lie on; c) at least one collimator in a beam path of an X-ray beam passing from the X-ray beam source through the patient, whereby a directional X-ray beam is emitted towards the patient from the entire X-ray radiation of the X-ray beam source; d) at least one X-ray detector permanently or at least temporarily arranged in the beam path of the directional X-ray beam passing from the collimator through the patient; e) at least one automatically actuable drive mechanism, whereby the collimator is adjustable with respect to the direction of emission of the directional X-ray beam transmitted by the collimator relative to the patient and / or the X-ray detector; and f) at least one electronic control mechanism adapted for automatic actuation of the drive mechanism.

Description

Technical Field

[0001] The present invention relates to a computed tomography system (hereinafter also referred to as a CT system) for examining and treating a patient by computed tomography.

Background Art

[0002] CT systems are known, for example, from DE1020132019676A1. For a specific CT examination, the X-ray beam emitted from the X-ray tube of the CT system can be collimated, for example, by a diaphragm.

Summary of the Invention

[0003] The underlying problem of the present invention is to further improve such a CT system with respect to functionality. This problem is solved by a CT system having the following features, namely a) at least one X-ray beam source, b) at least one patient table for the patient to lie on, c) at least one collimator in the beam path of the X-ray beam penetrating the patient from the X-ray beam source, whereby a directional X-ray beam is emitted from the entire X-ray radiation of the X-ray beam source towards the patient, d) at least one X-ray detector permanently or at least temporarily arranged in the beam path of the directional X-ray beam penetrating the patient from the collimator, e) at least one automatically operable drive mechanism, whereby the collimator is adjustable with respect to the radiation direction of the directional X-ray beam transmitted by the collimator towards the patient and / or the X-ray detector, f) at least one electronic control mechanism adapted for the automatic operation of the drive mechanism

[0004] ​The CT system according to the present invention can thus be improved by an active collimator. Such an active collimator enables the assistance of diagnosis and treatment using a CT system by an automatic auxiliary function, for example, the automatic alignment of a directional X-ray beam by adjusting the collimator to a desired position. In addition to this, further auxiliary functions are made possible, for example, the automatic tracking of instruments during an intervention on a patient for dose reduction or the imaging of a volume of interest, in which, by the automatic alignment of a directional X-ray beam by adjusting the collimator, a specific body range of the patient to be captured, for example a specific organ, is accurately fluoroscoped during and after the rotation of the gantry.

[0005] As is clear from the above explanation, the collimator is a device that narrows down a directional X-ray beam (also referred to as a utilization beam) having a specific solid angle from the entire X-ray radiation emitted by an X-ray beam source and passes it to a patient. The collimator may be formed, for example, as an adjustable aperture, for example, in the form of mutually displaceable plates having openings.

[0006] The X-ray detector may be formed, for example, as a multi-row detector. The multi-row detector has the advantages of imaging by high dynamics (contrast resolution) and a very accurate determination of the Hounsfield value, and a very short integration time. In addition or instead, the X-ray detector may be formed as a flat panel detector, which has the advantages of very high spatial resolution and a large imaging range. A plurality of such X-ray detectors may be attached to the CT system, and in that case, one or the other X-ray detector may be used as required.

[0007] An important application field of the present invention is X-ray image-guided intervention on a patient, for example, needle placement for biopsy, instrument placement for tumor treatment, surgery, and catheter-based intervention for the treatment of blood vessels. In this regard, by the CT system according to the present invention, the narrowing of the X-ray beam source to a transmitted directional X-ray beam and the active automated layer andImage section tracking may be combined.

[0008] The electronic control mechanism may have, for example, a computer that executes specific control steps and / or adjustment steps by means of a computer program. This computer may be formed as a commercially available computer, for example, as a PC, laptop, notebook computer, tablet, or smartphone, or as a microprocessor, microcontroller, or FPGA, or as a combination of such elements.

[0009] According to an advantageous form of the invention, it is contemplated that the automatically operable drive mechanism is adapted to adjust the collimator in at least two spatial directions with respect to the radiation direction of the directional X-ray beam transmitted by the collimator towards the patient and / or the X-ray detector. The drive mechanism may be formed, for example, by a mechanism similar to an industrial two-axis positioning system for two-dimensional adjustment of the collimator, for example, in the X and Z directions.

[0010] According to an advantageous form of the invention, the control mechanism is adapted to use the drive mechanism to adjust the collimator depending on the determined position in order to determine the position of an object within the area of the patient's bed and such that the recognized object is within the area of the directional X-ray beam transmitted by the collimator, in particular at the center of the directional X-ray beam. This object may be, for example, part of a medical device, such as for tumor treatment, catheter-based intervention, or biopsy needles. In particular, it may be the distal end of such a device. In this way, the automatic function of the control mechanism ensures that the object or device is always within the imaging range of the CT system.

[0011] According to an advantageous form of the invention, when the position of the object changes, the control mechanism is used to automatically track the recognized object and, using the drive mechanism, to move the collimator to the changing position with respect to the radiation direction of the directional X-ray beam TrackingIt is intended to be adapted for doing so. This enables, together with an object, for example a medical device, to automatically Tracking perform this. In this way, the user is considerably liberated from manual work. This automatic function of the control mechanism ensures that the object or device remains within the capture range of CT imaging even if its position changes.

[0012] According to an advantageous form of the invention, it is intended that the control mechanism is adapted to determine the position of the object by image processing based on the projections obtained by the X-ray detector and the reconstructed 3D data set. This has the advantage that no additional sensor elements are required for position capture and possibly tracking of the object. The projections and the reconstructed 3D data set captured by CT image capture can be used as they are. Depending on the type of X-ray detector used, for example, a 3D approach or a 2D approach can be taken, as will be further explained below based on examples. In particular, multi-row detectors enable a 3D approach when recognizing and tracking an object in a CT image, that is, the three-dimensional coordinates of the object can be automatically determined from the CT image.

[0013] An algorithm for recognizing the position and orientation from the projection image or the reconstructed image of the device can be used to determine the position of the object using image processing. According to an advantageous form of the invention, it is intended that the control mechanism is adapted to determine the position of the object based on the data of an external measuring device for capturing the position of the object. Thus, the position capture of the object can be carried out either only by an external measuring device or additionally by an external measuring device as a supplement to CT imaging.

[0014] According to an advantageous form of the invention, the control mechanism has access to a dataset presenting the desired directional trajectory of the directed X-ray beam, where the control mechanism is adapted to use the dataset to adjust the collimator using the drive mechanism such that the directed X-ray beam has a directional trajectory corresponding to the directional trajectory of the dataset. This directional trajectory is the changing beam direction of the directed X-ray beam over time. In this way, a specific preset path along which the directed X-ray beam should move can be preset by automatic control. In this regard, not only the directional trajectory but also, depending on the embodiment, the speed of adjustment and generally the time response of the change in the direction of the directed X-ray beam can be preset. For example, it can be preset that the directed X-ray beam does not move for some time in a specific direction until it is adjusted to another direction.

[0015] According to an advantageous form of the invention, the CT system has a further drive mechanism for automatically adjusting the position of the patient relative to the gantry of the CT system, and it is contemplated that an electronic control mechanism is adapted for the automatic operation of the further drive mechanism. Generally, the adjustment range of the collimator using an automatically operable drive mechanism is defined by the maximum projected area on the detector. Depending on the type of examination or intervention on the patient, it may be necessary to perform CT imaging over a larger range made possible by the adjustable collimator. For this purpose, it is advantageous if the position of the patient can be automatically adjusted via a further drive mechanism, whereby the desired position of the patient within the image capture range of the CT system can be determined. For example, the further drive mechanism may be adapted to adjust the patient table or at least the lying area of the patient table relative to the gantry.

[0016] According to an advantageous form of the invention, it is contemplated that the drive mechanism and / or further drive mechanisms are formed as electromechanical, hydraulic or pneumatic drive mechanisms or as a combination of such drive mechanisms. This enables a simple and inexpensive implementation of a reliable drive mechanism. The drive mechanism can have, for example, an electric motor for the movement of the collimator or a regulating cylinder incorporated hydraulically or pneumatically or a combination from a plurality of such elements. The same applies to further drive mechanisms.

[0017] According to an advantageous form of the invention, it is contemplated that the control mechanism is additionally adapted for the control of the X-ray beam source and the evaluation of the signals of the X-ray detector. In this way, all the necessary data are available within the control mechanism both with respect to the signals of the X-ray detector and with respect to the respective position of the directional X-ray beam from the collimator. Thereby, additional information can be combined with each other, which results in a simplification of CT imaging and an improvement of the imaging quality.

[0018] According to an advantageous form of the invention, it is contemplated that the CT system has at least one display unit for displaying a CT image obtained from the signals of the X-ray detector. Thus, a CT image generated by the image reconstruction of computed tomography can be displayed on the display unit, for example, on a screen.

[0019] Hereinafter, the present invention will be explained in more detail based on exemplary embodiments with reference to the drawings.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

DETAILED DESCRIPTION OF THE INVENTION

[0021] The CT system shown in the figures has an X-ray beam source 1, for example an X-ray tube, a collimator 3, an X-ray detector 7, an automatically operable drive mechanism 11 for adjusting the collimator 3, a further automatically operable drive mechanism 12, electronic control mechanisms 8, 9 which may have a computer, and a display unit 10.

[0022] As can be recognized in FIG. 1, the patient 16 is on a patient table (not shown in the figures) of the CT system. The X-ray beam source 1 emits an X-ray beam into the beam path 2 towards the collimator 3. The collimator 3 blocks a part of the X-ray radiation so that only the directional X-ray beam 4 passes through the collimator 3 to the patient 16. On the side of the patient 3 opposite to the X-ray beam source 1 or the collimator 3, there is an X-ray detector 7, for example the conventional multi-row detector shown in FIGS. 1 and 2. The collimator 3 can be adjusted by an automatically operable drive mechanism 9 (not shown in FIG. 1) so that the radiation direction of the directional X-ray beam 4 changes with respect to the patient 16 or the X-ray detector 7.

[0023] FIG. 1 shows the first region 14 of the X-ray detector 7, in this case relatively on the left side, which is irradiated by the directional X-ray beam 4. The remaining region 15 of the X-ray detector 7 is not irradiated by the directional X-ray beam 4. Then, when the collimator 3 is adjusted as shown in FIG. 2, the direction of the directional X-ray beam 4 changes, for example, so that the irradiated region 14 of the X-ray detector 7 is then further to the right. The irradiated region 14 can be actively Tracking activated.

[0024] In the examples of FIGS. 1 and 2 respectively, it is assumed that, with the automatic assistance of the CT system, an object 5, such as a medical device, should be image-guided and moved from some starting point where the object 5 is present in FIG. 1 to a target point 13. This means that, by means of an automatically operable drive mechanism 9 and automatic control of the collimator 3 using electronic control mechanisms 8, 9, the directional X-ray beam 4 should always be adjusted to follow the position of the object 5, for example the distal end of the object 5. Due to this automatic tracking function, the object 5 is accurately tracked towards the target point 13 reached in FIG. 2 by means of permanent imaging of the distal end of the object 5.

[0025] FIGS. 3 and 4 show diagrams equivalent to FIGS. 1 and 2 and the same process of tracking the object 5 from the starting point to the target point 13. Different from FIGS. 1 and 2, here another X-ray detector 7, such as a flat detector, is utilized. Different from FIGS. 1 and 2 where a multi-row detector approach can be implemented, in FIGS. 3 and 4, a 2D approach for instrument guidance can be implemented.

[0026] Multi-row detector approach: The goal is to continuously Image section inside to arrange in the frame of (minimally invasive) image-guided intervention, the instrument necessary for treatment or the organ to be observed. At this time, the instrument is guided by the therapist either freehand or using, for example, a robot. Patient centering has been done so far by manually pushing the patient table. The present invention addresses, for example, the problem of needle imaging in a fluoroscopic 3D image, by means of the Active layer tracking collimator 3 on the tube side. This approach offers the advantage that the intervention can be carried out without interruption and manual alignment of the patient table is not required. In particular, by means of automatic alignment of the directional X-ray beam using adjustment of the collimator, during and after the rotation of the gantry, automatic region-of-interest imaging is possible in which a specific body region of the patient to be captured, for example a specific organ, is accurately fluoroscoped.

[0027] For fluoroscopic 3D imaging, the severalonly layer is used only because otherwise section simultaneous display as an image is impossible. However, regarding this, it is not important which detector row contributes to interventional fluoroscopic imaging. The detector rows can be individually controlled. a few layers By collimating the utilization beam bundle of the width of a few layers , this bundle can, due to the change of the coordinates of the tube collimator, be all over the depth shift done. In the latest systems, this can be a maximum of 512 detector rows, which is approximately 256 mm in the case of an exemplary pixel size of 0.5 mm. This means that for needle guidance perpendicular to the collimated layer the needle can capture up to 256 mm without displacing the patient table.

[0028] To enable image reconstruction, it is advantageous to know the needle path in advance or capture it during imaging. Instead, the entire projection data set required for image reconstruction can be completely captured by one rotation with an invariant collimator layer This enables updates depending on the gantry rotation speed, which is 0.5 Hz to 5 Hz in a commonly available commercial CT system. At that time, the Tracking of the collimator can be performed on the coordinates from an image processing method or an external tracking method (for example, optical, electromagnetic). be tracked when the layer is the maximum of the detector dimension to exceed in the case of step by step automatic positioning of the patient table Tracking or the gantry system of is advantageous. Therefore Layer tracking can be formed as the cooperation between the active collimator and the positioning of the gantry and / or the patient table.

[0029] 2D approach: Different from the 3D approach, in the case of the 2D approach, individual patients ofRather than layer display, a wider field-of-volume X-ray projection is performed. This method of imaging is applicable, among other things, in the case of vascular interventions and tumor treatments. The advantage over the 3D approach is the wide-area observation and understanding. The disadvantage is that depth information is not provided. In the context of 2D projection, an active collimator system should be utilized to reduce the fluoroscopy area where the instrument (e.g., catheter) is located, thereby reducing the dose to the patient.

[0030] Figure 5 schematically shows the entire CT system. Here again, the X-ray beam source 1 can be recognized together with the beam path 2 of the X-ray beam, and the beam path 2 is narrowed by the collimator 3 into a directed X-ray beam 4. The directed X-ray beam 4 penetrates the patient 16 and reaches the X-ray detector 7. At this time layer 6 is taken as a projection image and, in some cases, subsequently reconstructed into a 3D data set. The X-ray detector 7 transmits the captured signal to the processing computer 8, which is adapted, for example, for data recording, reconstruction, and image processing. The processing computer 8 forms part of an electronic control mechanism. The processing computer 8 is connected to a control unit 9 that is adapted to control an automatically operable drive mechanism 11.

[0031] The control unit 9 obtains a control signal from the processing computer 8. In response to this control signal, the control unit 9 controls the drive mechanism 11, whereby the collimator 3 is adjusted as desired. In addition to this, the control unit 9 can activate a further automatically operable drive mechanism 12, for example, to adjust the position of the patient relative to the CT gantry. For example, the patient table can be adjusted by the drive mechanism 12.

[0032] In addition to this, the processing computer 8 is connected to a display unit 10. In this way, the CT image determined by the processing computer 8 can be displayed on the display unit 10.

Claims

1. the following features, namely a) at least one X-ray beam source (1), b) at least one patient couch for the patient (16) to lie on, c) at least one collimator (3) in the beam path (2) of the X-ray beam penetrating the patient (16) from the X-ray beam source (1), whereby a collimator (3) through which a directional X-ray beam (4) is emitted to the patient (16) from the entire X-ray emission of the X-ray beam source (1), d) at least one X-ray detector (7) permanently or at least temporarily arranged in the beam path (2) of the directional X-ray beam (4) penetrating the patient (16) from the collimator (3), e) at least one automatically operable drive mechanism (11), whereby the collimator (3) is adjustable with respect to the emission direction of the directional X-ray beam (4) transmitted by the collimator (3) for the patient (16) and / or the X-ray detector (7), f) at least one electronic control mechanism (8, 9) adapted for the automatic operation of the drive mechanism (11) A computed tomography (CT) system having the electronic control mechanism (8, 9) is adapted to use the drive mechanism (11) to adjust the collimator (3) depending on the determined position in order to determine the position of an object (5) in the region of the patient couch and so that the object (5) is in the region of the directional X-ray beam (4) transmitted by the collimator (3), the electronic control mechanism (8, 9) is adapted to use the drive mechanism (11) to place the collimator (3) in the changing position with respect to the emission direction of the directional X-ray beam (4) for automatic tracking of the object (5) when the position of the object (5) changes, When the layer to be tracked exceeds the maximum dimension of the X-ray detector (7), a stepwise automatic positioning of the patient table or the gantry of the CT system is performed, and the tracking of the layer is performed by the cooperation of the collimation of the X-ray beam by the collimator (3) and the positioning of the gantry or the patient table. The CT system has a further drive mechanism (11) that can automatically adjust the position of the patient (16) relative to the gantry of the CT system, and the electronic control mechanisms (8, 9) are adapted for the automatic operation of the further drive mechanism (11). A computed tomography (CT) system characterized by this.

2. The CT system according to claim 1, wherein the automatically operable drive mechanism (11) is adapted to adjust the collimator (3) in at least two spatial directions with respect to the radiation direction of the directional X-ray beam (4) transmitted by the collimator (3) with respect to the patient (16) and / or the X-ray detector (7).

3. The CT system according to claim 1, wherein the electronic control mechanisms (8, 9) are adapted to determine the position of the object (5) by image processing based on the projections obtained by the X-ray detector (7) and the reconstructed 3D data set.

4. The CT system according to claim 1, wherein the electronic control mechanisms (8, 9) are adapted to determine the position of the object (5) based on data from an external measuring device that captures the position of the object (5).

5. The electronic control mechanism (8, 9) has access to a data set presenting a desired directional trajectory of the directional X-ray beam (4), and the electronic control mechanism (8, 9) uses the data set to use the drive mechanism (11) so that the directional X-ray beam (4) has a directional trajectory corresponding to the directional trajectory of the data set. The CT system according to any one of claims 1 to 4, characterized in that it is adapted to adjust the collimator (3).

6. The drive mechanism (11) and / or the further drive mechanism (11) is formed as an electromechanical, hydraulic, or pneumatic drive mechanism (11), or a combination of such drive mechanisms. The CT system according to any one of claims 1 to 5, characterized in that

7. The electronic control mechanism (8, 9) is further adapted for the control of the X-ray beam source (1). The CT system according to any one of claims 1 to 6, characterized in that

8. The CT system has at least one display unit (10) for displaying a CT image obtained from the signal of the X-ray detector (7). The CT system according to any one of claims 1 to 7, characterized in that

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