Computer 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 the examination and treatment of patients by means of computed tomography. [Background technology]

[0002] A CT system is known, for example, from DE 10 2013 2019 676 A1. For a particular CT examination, the X-ray beam emitted by an X-ray tube of the CT system can be collimated, for example, by means of a diaphragm. Summary of the Invention

[0003] The problem on which the present invention is based is to further improve such CT systems with regard to functionality. This problem has the following characteristics: a) at least one X-ray beam source; b) at least one patient platform on which a patient lies; c) at least one collimator in a beam path of the x-ray beam from the x-ray beam source through the patient, whereby a directional x-ray beam is emitted from the entire x-ray radiation of the x-ray beam source to the patient; d) at least one X-ray detector, permanently or at least temporarily positioned 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 by which the collimator can be adjusted with respect to a direction of emission of the directional X-ray beam transmitted by the collimator relative to the patient and / or the X-ray detector; f) at least one electronic control mechanism adapted for automatic actuation of the drive mechanism; This can be solved by a CT system having

[0004] The CT system according to the invention can thus be improved by an active collimator, which allows for automatic auxiliary functions, such as automatic alignment of the directional X-ray beam by adjusting the collimator to a desired position, to assist in the examination and treatment with the CT system. In addition to this, further auxiliary functions are made possible, such as automatic tracking of instruments during patient interventions for dose reduction or volume of interest imaging, in which the automatic alignment of the directional X-ray beam by adjusting the collimator allows a precise transillumination of a specific body region to be captured, such as a specific organ, during and after the rotation of the gantry.

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

[0006] The X-ray detector may be formed, for example, as a multi-row detector. The multi-row detector combines the advantages of imaging with high dynamics (contrast resolution) and very accurate determination of the Hounsfield value with very short integration times. Additionally or alternatively, the X-ray detector may be formed as a planar detector, which has the advantages of very high spatial resolution and a large imaging range. A number of such X-ray detectors may be associated with the CT system, whereby one or the other X-ray detector may be utilized as required.

[0007] An important field of application of the invention is X-ray image-guided interventions in patients, such as needle placement for biopsies, instrument placement for tumor treatment, surgery, and catheter-based interventions for the treatment of blood vessels. In this regard, the CT system according to the invention allows the focusing of the X-ray beam source into a transmitted directional X-ray beam and the active automated layer and Image section tracking may be combined.

[0008] The electronic control mechanism may comprise, for example, a computer that performs certain control and / or regulation steps, for example by means of a computer program, which may be formed as a commercially available computer, for example as a PC, laptop, notebook, tablet or smartphone, or as a microprocessor, microcontroller or FPGA, or as a combination of such elements.

[0009] According to an advantageous embodiment of the invention, it is provided that the automatically actuatable drive mechanism is adapted for adjusting the collimator in at least two spatial directions 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. The drive mechanism may be formed for two-dimensional adjustment of the collimator, for example in the X- and Z-directions, for example by a mechanism similar to an industrial two-axis positioning system.

[0010] According to an advantageous embodiment of the invention, it is provided that the control mechanism is adapted to determine the position of an object in the area of ​​the patient couch and to adjust the collimator by means of a drive mechanism depending on the determined position so that the recognized object is in the area of ​​the directional X-ray beam transmitted by the collimator, in particular in the center of the directional X-ray beam. The object may be, for example, part of a medical instrument, for example for tumor treatment, catheter-based interventions or biopsy needles. In particular, it may be the distal end of such an instrument. In this way, an automatic function by the control mechanism ensures that the object or instrument is always within the imaging range of the CT system.

[0011] According to an advantageous embodiment of the invention, the control mechanism is adapted for automatic tracking of the recognized object when the object's position changes, and for moving the collimator, by means of the drive mechanism, to a changing position with respect to the emission direction of the directional X-ray beam. TrackingIt is contemplated that the X-ray beam may be adapted to automatically align a directional X-ray beam with an object, e.g., a medical instrument. Tracking This allows the user to perform a large amount of manual work. This automatic function of the control mechanism ensures that the object or instrument is still within the capture range of the CT imaging even if the object or instrument changes position.

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

[0013] To determine the location of an object using image processing, algorithms can be used to recognize the position and orientation from the projected or reconstructed images of the instrument. According to an advantageous embodiment of the invention, the control mechanism is adapted to control an external measuring device for capturing the position of the object. It is contemplated that the imaging system is adapted to determine a position of an object based on the data. Thus, object position capture may be performed either by external measuring equipment alone or additionally by external measuring equipment as a supplement to CT imaging.

[0014] According to an advantageous embodiment of the invention, it is provided that the control mechanism has access to a data set presenting a desired directional trajectory of the directional X-ray beam, the control mechanism being adapted to adjust the collimator by means of the drive mechanism using the data set, such that the directional X-ray beam has a directional trajectory corresponding to the directional trajectory of the data set. This directional trajectory is the time-varying beam direction of the directional X-ray beam. In this way, a specific pre-defined path along which the directional X-ray beam should move can be pre-defined by the automatic control. In this regard, not only the directional trajectory, but also the speed of the adjustment, generally the time response of the change in the direction of the directional X-ray beam, can be pre-defined depending on the embodiment. For example, it can be pre-defined that the directional X-ray beam will not move in a specific direction for a while until it is adjusted in another direction.

[0015] According to an advantageous embodiment of the invention, it is provided that the CT system has a further drive mechanism capable of automatically adjusting the position of the patient relative to the gantry of the CT system, and the electronic control mechanism is adapted for automatic actuation of the further drive mechanism. In general, the adjustment range of the collimator using the automatically actuable drive mechanism is defined by the maximum projection 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 than the collimator adjustment allows. For this, it is advantageous if the patient position can be adjusted automatically via the further drive mechanism, so that a desired position of the patient within the image capture range of the CT system can be defined. For example, the further drive mechanism may be adapted for adjusting the patient couch or at least the lying area of ​​the patient couch relative to the gantry.

[0016] According to an advantageous embodiment of the invention, it is provided that the drive mechanism and / or the further drive mechanism are formed as an electromechanical, hydraulic or pneumatic drive mechanism or as a combination of such drive mechanisms. This allows for a simple and inexpensive realization of a reliable drive mechanism. The drive mechanism may have, for example, an electric motor for the movement of the collimator or a hydraulically or pneumatically integrated adjustment cylinder or a combination of several such elements. The same applies to the further drive mechanism.

[0017] According to an advantageous embodiment of the invention, it is provided that the control mechanism is additionally adapted for controlling the X-ray beam source and evaluating the signal of the X-ray detector. In this way, all necessary data are available in the control mechanism, both regarding the signal of the X-ray detector and regarding the moment-to-moment position of the directional X-ray beam from the collimator. This allows additional information to be combined with each other, which leads to a simplification of the CT imaging and an improvement in the imaging quality.

[0018] According to an advantageous embodiment of the invention, it is provided that the CT system comprises at least one display unit for displaying the CT images obtained from the signals of the X-ray detector, so that on the display unit, for example on a screen, the CT images generated by the image reconstruction of the computer tomography can be displayed.

[0019] In the following, the invention is explained in more detail on the basis of exemplary embodiments using the drawings. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a side view of a portion of a CT system for a multi-detector row approach. [Diagram 2] FIG. 1 is a side view of a portion of a CT system for a multi-detector row approach. [Diagram 3] FIG. 2 is a side view of a portion of a CT system for a projection approach. [Figure 4] FIG. 2 is a side view of a portion of a CT system for a projection approach. [Diagram 5] FIG. 1 is a schematic block diagram of an entire CT system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0022] As can be seen in Fig. 1, a patient 16 is positioned on a patient couch (not shown) of the CT system. An X-ray beam source 1 emits an X-ray beam in a beam path 2 to a collimator 3, which blocks a portion of the X-ray radiation so that only a directional X-ray beam 4 is transmitted from the collimator 3 to the patient 16. On the side of the patient 3 opposite the X-ray beam source 1 or the collimator 3 there is an X-ray detector 7, for example a conventional multi-row detector as shown in Figs. 1 and 2. The collimator 3 can be adjusted by an automatically actuable drive mechanism 9 (not shown in Fig. 1) so that the radiation direction of the directional X-ray beam 4 relative to the patient 16 or the X-ray detector 7 is changed.

[0023] Figure 1 shows a first, in this case relatively left, region 14 of the X-ray detector 7 that is illuminated by the directional X-ray beam 4. The remaining region 15 of the X-ray detector 7 is not illuminated by the directional X-ray beam 4. If the collimator 3 is then adjusted as shown in Figure 2, the direction of the directional X-ray beam 4 changes, for example so that the illuminated region 14 of the X-ray detector 7 is now further to the right. The illuminated region 14 is no longer actively illuminated. Tracking It can be done.

[0024] In the examples of Figures 1 and 2, respectively, it is assumed that with the automatic assistance of the CT system, an object 5, e.g. a medical instrument, should be image-guided and moved from some starting point where the object 5 is located in Figure 1 to a target point 13. This means that by automatic control of the collimator 3 using an automatically actuatable drive mechanism 9 and electronic control mechanisms 8, 9, the directional X-ray beam 4 should be adjusted to constantly follow the position of the object 5, e.g. the distal end of the object 5. This automatic tracking function ensures that the object 5 is precisely tracked towards the target point 13, which is reached in Figure 2, by permanent imaging of the distal end of the object 5.

[0025] Figures 3 and 4 show views comparable to Figures 1 and 2 and the same process of tracking an object 5 from a starting point towards a target point 13. Unlike Figures 1 and 2, here another X-ray detector 7 is used, for example a planar detector. Unlike Figures 1 and 2, where a multi-row detector approach can be realised, in Figures 3 and 4 a 2D approach of instrument guidance can be realised.

[0026] Multidetector row approach: The goal is to continuously monitor the instruments required for treatment or the organs to be observed within the framework of (minimally invasive) image-guided interventions. Image section Inside Place it in The device is guided by the therapist either freehand or, for example, by means of a robot. Up to now, the patient has been centered by pushing the patient table with a manual control. The present invention solves the problem of needle imaging, for example, in fluoroscopic 3D images, by using the collimator 3 on the tube side. Active Layer Tracking This approach offers the advantage that the intervention can be performed without interruption and no manual alignment of the patient couch is required. In particular, automatic alignment of the directional X-ray beam using collimator adjustments allows automatic volume-of-interest imaging during and after gantry rotation, where specific areas of the patient's body to be captured, e.g. specific organs, are precisely fluoroscopy-enabled.

[0027] Fluoroscopic 3D imaging requires a detector someof layer It is only used because otherwise Fault Simultaneous display as an image is not possible. However, in this respect it is not important which detector row contributes to the interventional fluoroscopic imaging. The detector rows can be controlled individually. Just a few layers By using the width of the collimator, the beam is collimated, and this beam is then moved to the collimator's All Throughout the depths shift This can be up to 512 detector rows in state-of-the-art systems, which is about 256 mm for an exemplary pixel size of 0.5 mm. layer For needle guidance perpendicular to the patient bed, this means that the needle can be captured up to 256 mm without displacing the patient bed.

[0028] To enable image reconstruction, it is advantageous to know the needle path in advance or to capture it during imaging. Instead, the entire projection data set required for image reconstruction is stored in a fixed collimator. layer This allows for updates depending on the gantry rotation speed, which is 0.5Hz to 5Hz for most commercially available CT systems. Tracking may be performed on coordinates from image processing or external tracking methods (eg optical, electromagnetic). Being tracked The layer is the maximum size of Exceed case, In stages Automatic patient bed Tracking or gantry system of Positioning is advantageous. Therefore Layer Tracking may be formed in conjunction with the active collimator and the positioning of the gantry and / or patient couch.

[0029] 2D approach: Unlike the 3D approach, the 2D approach requires individual ofInstead of a layered display, an X-ray projection of a larger volume is performed. This method of imaging is applied, among others, in the case of vascular interventions and tumor treatment. The advantage over the 3D approach is the large area observation and understanding. The disadvantage is that no depth information is provided. In the context of 2D projections, active collimator systems should be utilized to reduce the fluoroscopic area in which the instruments (e.g. catheters) are located and thus reduce the dose to the patient.

[0030] 5 shows a schematic representation of the overall CT system. Here too, an X-ray beam source 1 can be seen together with a beam path 2 of an X-ray beam, which is narrowed by a collimator 3 into a directional X-ray beam 4. The directional X-ray beam 4 passes through a patient 16 and reaches an X-ray detector 7. layer 6 are acquired as projection images and possibly subsequently reconstructed into a 3D data set. The X-ray detector 7 transmits the acquired signals to a 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, which is adapted for controlling an automatically actuable drive mechanism 11.

[0031] The control unit 9 receives a control signal from the processing computer 8. In response to this control signal, the control unit 9 controls a drive mechanism 11, by which the collimator 3 is desirably adjusted. In addition to this, the control unit 9 may operate 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 couch may be adjusted by the drive mechanism 12.

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

Claims

1. The following characteristics: a) at least one X-ray beam source (1); b) at least one patient bed for lying on a patient (16); c) at least one collimator (3) in a beam path (2) of an X-ray beam passing from the X-ray beam source (1) through the patient (16), whereby a directional X-ray beam (4) is emitted from the entire X-ray radiation of the X-ray beam source (1) towards the patient (16); 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) passing from the collimator (3) through the patient (16); e) at least one automatically actuatable drive mechanism (11) by means of which the collimator (3) is adjustable with respect to a radiation direction of the directional X-ray beam (4) transmitted by the collimator (3) relative to the patient (16) and / or the X-ray detector (7); f) at least one electronic control mechanism (8, 9) adapted for said automatic actuation of said drive mechanism (11); 1. A computed tomography (CT) system comprising: the electronic control mechanism (8, 9) is adapted for determining a position of an object (5) in the area of ​​the patient couch and for adjusting the collimator (3) by means of the drive mechanism (11) in dependence on the determined position such that the object (5) is in the area of ​​the directional X-ray beam (4) transmitted by the collimator (3), said electronic control mechanism (8, 9) is adapted for automatic tracking of said object (5) when said position of said object (5) changes and for positioning, by means of said drive mechanism (11), said collimator (3) at said changing position with respect to said radiation direction of said directional X-ray beam (4); a stepwise automatic positioning of the patient couch or the gantry of the CT system is performed when the tracked layer exceeds a maximum dimension of the X-ray detector (7), and tracking of the layer is performed in cooperation with the collimation of the X-ray beam by the collimator (3) and the positioning of the gantry or the patient couch, 1. A computed tomography (CT) system, characterized in that the CT system has a further drive mechanism (11) capable of automatically adjusting the position of the patient (16) relative to a gantry of the CT system, and the electronic control mechanism (8, 9) is adapted for the automatic actuation of the further drive mechanism (11).

2. 2. The CT system according to claim 1, characterized in that the automatically actuable drive mechanism (11) is adapted for adjusting 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) relative to the patient (16) and / or the X-ray detector (7).

3. 2. The CT system according to claim 1, characterized in that the electronic control mechanism (8, 9) is adapted to determine the position of the object (5) by image processing on the basis of the projections and reconstructed 3D data sets obtained by the X-ray detector (7).

4. 2. The CT system according to claim 1, characterized in that the electronic control mechanism (8, 9) is adapted to determine the position of the object (5) on the basis of data of an external measuring device capturing the position of the object (5).

5. 5. The CT system according to claim 1, wherein 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) is adapted to adjust the collimator (3) by means of the drive mechanism (11) using the data set such that the directional X-ray beam (4) has a directional trajectory corresponding to the directional trajectory of the data set.

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

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

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

Images