EP4081124A1

EP4081124A1 - Computer-assisted tomography system

Info

Publication number: EP4081124A1
Application number: EP20839257.1A
Authority: EP
Inventors: Georg Rose; Thomas Hoffmann; Mathias Leopold; Oliver Grosser; Maciej Pech
Original assignee: Otto Von Guericke Universitaet Magdeburg
Current assignee: Otto Von Guericke Universitaet Magdeburg
Priority date: 2019-12-23
Filing date: 2020-12-16
Publication date: 2022-11-02
Also published as: JP2023508915A; DE102019135782A1; US20220409148A1; WO2021130084A1

Abstract

The invention relates to a computer-assisted tomography (CT) system having the following features: a) at least one X-ray source, b) at least one patient couch for supporting a patient, c) at least one collimator in the ray path of the X-rays from the X-ray source through the patient, wherein a targeted X-ray from among the total X-ray radiation of the X-ray source is radiated by the collimator onto the patient, d) at least one X-ray detector, provided permanently or at least temporarily in the ray path of the targeted X-ray radiated by the collimator through the patient, e) at least one automatically actuable drive mechanism, using which the collimator can be moved with respect to the radiation direction of the targeted X-ray passing through the collimator, relative to the patient and/or to the X-ray detector, f) at least one electronic control device that is configured to automatically actuate the drive mechanism.

Description

Computed tomography system

The invention relates to a computed tomography system, hereinafter also referred to as a CT system, for computed tomographic examinations and treatments on patients.

A CT system is known, for example, from DE 1020132019676 A1. For certain CT recordings, the X-rays emitted by an X-ray tube of the CT system can be collimated, for example by means of diaphragms.

The invention is based on the object of further improving such a CT system in terms of functionality.

This object is achieved by a CT system with the following features: a) at least one X-ray source, b) at least one patient table for positioning a patient, c) at least one collimator in the beam path of the X-rays from the X-ray source through the patient, from the total X-rays from the X-ray source, a directed X-ray beam is emitted to the patient by the collimator, d) at least one X-ray detector which is permanently or at least temporarily arranged in the beam path of the directed X-ray beam from the collimator through the patient, e) at least one automatically actuated drive mechanism through which the The collimator is adjustable in terms of the emission direction of the directional X-ray beam passed by the collimator relative to the patient and / or to the X-ray detector, f) at least one electronic control device which is set up for automatic actuation of the drive mechanism i st. The CT system according to the invention can be improved in this way by an active collimator. Such an active collimator allows the support of examinations and treatments by means of the CT system through automatic support functions, for example the automatic alignment of the directed X-ray beam by adjusting the collimator to a desired position. It also enables other supporting functions, such as automatic tracking of instruments during interventions on the patient to reduce dose or volume-of-interest imaging, in which a certain area of the body to be captured by automatically aligning the directed X-ray beam by adjusting the collimator of the patient, e.g. a certain organ, during and after the rotation of the gantry is x-rayed in a targeted manner.

As can be seen from the preceding explanations, the collimator is a device with which a directed X-ray beam (also referred to as useful beam) is faded in with a certain solid angle and allowed to pass through to the patient from the entire X-ray radiation emitted by the X-ray source. The collimator can for example be designed as an adjustable diaphragm, for example in the form of mutually displaceable plates with openings.

The X-ray detector can be designed as a multi-line detector, for example. A multi-line detector combines the advantages of imaging with high dynamics (contrast resolution) as well as very precise determination of the Flounsfield values and very short integration times. Additionally or alternatively, the X-ray detector can also be designed as a flat detector, which has the advantage of a very high spatial resolution and a large imaging area. Several such X-ray detectors can also belong to the CT system, with one or the other X-ray detector being used as required.

An important field of application of the invention is the X-ray-guided image-guided intervention on the patient, such as needle placement for biopsy, in- instrument placement for tumor treatment, surgical interventions, and catheter-based interventions for treating blood vessels. By means of the CT system according to the invention, the insertion of the transmitted, directed X-ray beam from the X-ray source can be combined with active, automated tracking of slices and image sections.

The electronic control device can, for example, have a computer that executes certain control and / or regulation steps, for example by means of a computer program. The computer can be designed as a commercially available computer, e.g. as a PC, laptop, notebook, tablet or smartphone, or as a microprocessor, microcontroller or FPGA, or as a combination of such elements.

According to an advantageous embodiment of the invention, it is provided that the automatically actuatable drive mechanism is set up to adjust 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 to the X-ray detector. The drive mechanism can e.g. be designed for two-dimensional adjustment of the collimator in the X and Z directions, e.g. with a mechanism similar to an industrial two-axis positioning system.

According to an advantageous embodiment of the invention, it is provided that the control device is set up to determine the position of an object in the area of the patient table and, depending on the determined position, to adjust the collimator by means of the drive mechanism in such a way that the detected object is in the area of the Collimator is transmitted directional X-ray, especially in the center of the directional X-ray. The object can, for example, be part of a medical instrument, for example for tumor treatment, catheter-based intervention or a biopsy needle. In particular, it can be the distal end of such an instrument. To this The automatic function by means of the control device ensures that the object or the instrument is always in the area of the imaging of the CT system.

According to an advantageous embodiment of the invention, it is provided that the control device is set up to automatically track the detected object when the position of the object changes, and to track the collimator to the changing position by means of the drive mechanism with respect to the emission direction of the directed x-ray beam. This allows the directional X-ray beam to be automatically tracked with the object, for example the medical instrument. In this way, the user is relieved of manual activities even more. The automatic function of the control device ensures that the object or the instrument is still in the detection area of the CT imaging even if the position changes.

According to an advantageous embodiment of the invention, it is provided that the control device is set up to determine the position of the object by means of image processing based on the projections and reconstructed 3D data records obtained by means of the X-ray detector. This has the advantage that no additional sensory elements are required for detecting the position and possibly tracking the object. The projections and reconstructed 3D data sets captured by means of the CT image acquisition can be used directly. Depending on the type of X-ray detector used, a 3D approach or a 2D approach, for example, can be followed here, as will be explained below with the aid of examples. In particular, a multi-line detector allows a 3D approach when recognizing and tracking an object in the CT images, that is, three-dimensional coordinates of the object can be automatically determined from the CT images. To determine the position of the object by means of image processing, algorithms can be used which recognize the position and orientation from the projection or reconstruction images of the instruments.

According to an advantageous embodiment of the invention, it is provided that the control device is set up to determine the position of the object on the basis of data from an external measuring device that detects the position of the object. The position detection of the object can thus be carried out either only by the external measuring device or, in addition to the CT imaging, additionally by the external measuring device.

According to an advantageous embodiment of the invention, it is provided that the control device has access to a data set which specifies a desired directional course of the directed x-ray beam, the control device being designed to use the data set to adjust the collimator by means of the drive mechanism in such a way that the directional X-ray beam has a directional course which corresponds to the directional course of the data set. A directional course is understood to mean a beam direction of the directed x-ray beam that changes over time. In this way, by means of automatic control, a specific, predetermined path along which the directed X-ray beam is to be moved can be predetermined. Here, not only the course of the direction can be given, but depending on the embodiment also the speed of the adjustment and generally the time behavior of the change in the direction of the straightened X-ray. For example, it can be specified that the directed X-ray beam remains in certain directions for a period of time before it is adjusted in another direction.

According to an advantageous embodiment of the invention it is provided that the CT system has a further drive mechanism by which the position of the patient relative to the gantry of the CT system can be automatically adjusted, the electronic control device is set up for automatic actuation of the further drive mechanism. Due to the maximum projection area on the detector, the adjustment range of the collimator is usually limited by means of the automatically actuated drive mechanism. Depending on the type of examination or intervention on the patient, it may be necessary for CT imaging to take place over a larger area than the adjustability of the collimator allows. For this purpose, it is advantageous if the position of the patient can be adjusted automatically via the further drive mechanism, so that a desired position of the patient can be placed in the image acquisition area of the CT system. For example, the further drive mechanism can be set up to adjust the patient table or at least a lying area of the patient table relative to the gantry.

According to an advantageous embodiment of the invention it is provided that the drive mechanism and / or the further drive mechanism is designed as an electromechanical, hydraulic or pneumatic drive mechanism or as a combination of such drive mechanisms. This allows a simple and inexpensive implementation of a reliable drive mechanism. The drive mechanism can, for example, have an electric motor for moving the collimator, or a hydraulically or pneumatically entered actuating cylinder or a combination of several such elements. The same applies to the further drive mechanism.

According to an advantageous embodiment of the invention, it is provided that the control device is set up in addition to controlling the x-ray source and evaluating the signals from the x-ray detector. In this way, all the necessary data are available in the control device, both with regard to the signals from the X-ray detector and with regard to the current position of the directed X-ray beam from the collimator. This allows additional information to be combined with one another, which leads to a simplification of the CT imaging and an increase in the quality of the imaging. According to an advantageous embodiment of the invention, it is provided that the CT system has at least one display unit for displaying CT images obtained from the signals of the X-ray detector. The CT images generated by the image reconstruction of the computer tomography can thus be displayed on the display unit, for example a screen.

The invention is explained in more detail below with reference to exemplary embodiments using drawings.

Show it:

Fig. 1, 2 - a part of the CT system in side view with a multi-line detector approach and

Fig. 3, 4 - a part of the CT system in side view with a projection approach and

Fig. 5 is a schematic block diagram of the entire CT system.

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

As can be seen in FIG. 1, a patient 16 is on a patient table of the CT system that is not reproduced. The X-ray source 1 emits X-rays in a beam path 2 to the collimator 3. Part of the X-ray radiation is shielded by the collimator 3 in such a way that only one directed X-ray beam 4 is transmitted from the collimator 3 to the patient 16. On the side of the patient 3 facing away from the X-ray source 1 or the collimator 3, there is the X-ray detector 7, for example the conventional multi-line detector shown in FIGS. 1 and 2. By means of the automatically actuatable drive mechanism 9, not shown in FIG. 1, the collimator 3 can be adjusted in such a way that the emission direction of the directed X-ray beam 4 is changed relative to the patient 16 or relative to the X-ray detector 7.

FIG. 1 shows a first area 14 of the X-ray detector 7, which in this case lies relatively far to the left and irradiated by the directed X-ray beam 4. The remaining areas 15 of the X-ray detector 7 are not irradiated by the directed X-ray beam 4. If the collimator 3 is now adjusted, as shown in FIG. 2, the direction of the directed x-ray beam 4 changes, for example, in such a way that the irradiated area 14 of the x-ray detector 7 is now further to the right. The irradiated area 14 can be actively tracked.

In the examples of FIGS. 1 and 2, it is assumed that, through the automatic support of the CT system, an object 5, for example a medical instrument, from any starting point at which the object 5 is located in FIG Target point 13 is to be moved image-guided. This means that through the automatic control of the collimator 3 by means of the automatically actuable ble drive mechanism 9 and the electronic control device 8, 9 of the ge directed X-ray 4 is to be adjusted so that it is always the position of the object 5, for example the distal end of the Object 5 follows. By means of this automatic tracking function, the object 5 is tracked specifically to the target point 13, which is reached in FIG. 2, by permanent imaging of the distal end of the object 5.

FIGS. 3 and 4 show a representation comparable to that of FIGS. 1 and 2 and the same process of tracking the object 5 from a starting point to the target point 13. In contrast to FIGS. 1 and 2, a different X-ray is used here. gene detector 7 used, for example a flat panel detector. In contrast to FIGS. 1 and 2, in which a multi-line detector approach can be implemented, in FIGS. 3 and 4 a 2D approach to instrument guidance can be implemented.

Multi-line detector approach: The aim is to have the instrument required for treatment or the organ to be viewed continuously localized in the image section as part of a (minimally invasive) image-guided intervention. The practitioner guides the instrument free-hand or, for example, by means of a robot. Until now, the patient was centered using a manually controlled advance of the patient table. The invention addresses, for example, the problem of needle imaging in the fluoroscopic 3D image via active slice tracking of the tube-side collimator 3. This approach offers the advantage that the intervention can be carried out without interruption and no manual adjustment of the patient table is necessary. In particular, automatic volume-of-interest imaging is possible, in which a certain area of the patient's body to be recorded, e.g. a certain organ, is illuminated in a targeted manner during and after the rotation of the gantry by automatically aligning the directed X-ray beam by adjusting the collimator.

Only a few slices of the detector are used for fluoroscopic 3D imaging, since a simultaneous display as a slice image would otherwise not be possible.

However, it does not matter which detector rows contribute to the interventional fluoroscopic imaging. The detector lines can be controlled individually. By collimating the useful beam bundle, which is only a few layers wide, the bundle can be shifted over the entire depth of the collimator by changing the coordinates of the tube collimator. In current systems this can be up to 512 detector lines, which is approx. 256 mm with an exemplary pixel size of 0.5 mm. This means that with a collimated slice using a pendulous needle guide, the needle can be captured up to 256 mm without having to move the patient table. To enable the image reconstruction, it is advantageous to know the needle path in advance or to detect it during the imaging. Alternatively, it is possible for a complete projection data set required for image reconstruction to be recorded completely with one rotation with a constant collimator slice. This enables an update depending on the gantry speed, which is 0.5 Hz to 5 Hz with commercially available CT systems. The tracking of the collimator can take place on coordinates from image processing methods or external tracking methods (eg optical, electromagnetic). In the case of slices to be tracked that exceed the maximum depth of the detector, step-by-step automated tracking of the patient table or positioning of the gantry system is advantageous. The slice tracking can thus be designed as an interplay of active collimator and positioning of the gantry and / or the patient table.

2D approach: In contrast to the 3D approach, the 2D approach does not show individual patient layers, but rather radiographic projections of large volumes. This type of imaging is used, among other things, in vascular interventions and tumor treatments. The advantage over the 3D approach is the large-area viewing and overview. The disadvantage is that the depth information is not available. In the context of 2D projection, the active collimator system should be used to reduce the irradiated area in which an instrument (e.g. catheter) is located and thus to save the dose to the patient.

FIG. 5 shows schematically the entire CT system. The X-ray source 1 with the beam path 2 of the X-rays, which is delimited by the collimator 3 to form the directed X-ray 4, can again be seen. The directed x-ray beam 4 passes through the patient 16 to the x-ray detector 7. Here, the slices 6 are recorded as projection images and, if necessary, then reconstructed to form a 3D data set. The X-ray detector 7 transmits the detected signals to a host computer 8, which is set up, for example, to record the data, reconstruct and process images. The processing Computer 8 forms part of the electronic control device. The processing computer 8 is connected to a controller 9 which is set up to control the automatically actuatable drive mechanism 11. The controller 9 receives control signals from the host computer 8. The controller 9 controls the drive mechanism 11 in accordance with these control signals, so that the collimator 3 is adjusted in the desired manner. In addition, the control 9 can actuate a further automatically actuatable 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.

The host computer 8 is also coupled to the display unit 10. The CT images determined by means of the processing computer 8 can be shown on the display unit 10 in this way.

Claims

Patent claims:

1. Computed tomography (CT) system with the following features: a) at least one X-ray source (1), b) at least one patient table for positioning a patient (16), c) at least one collimator (3) in the beam path (2) of the X-rays from the x-ray source (1) by the patient (16), with a directed x-ray (4) being emitted to the patient (16) of the total x-ray radiation from the x-ray source (1) through the collimator (3), d) at least one x-ray detector (7) ), which is arranged permanently or at least temporarily in the beam path (2) of the directed X-ray beam (4) from the collimator (3) through the patient (16), e) at least one automatically actuatable drive mechanism (11) through which the collimator (3 ) is adjustable relative to the patient (16) and / or to the X-ray detector (7) with regard to the emission direction of the directed X-ray beam (4) transmitted by the collimator (3), f) at least one electronic control device device (8, 9), which is set up for automatic actuation of the drive mechanism (11).

2. CT system according to claim 1, characterized in that the automatically actuatable drive mechanism (11) is designed to move the collimator (3) relative to the patient (16) with regard to the radiation direction of the directional X-ray beam (4) transmitted by the collimator (3). and / or to adjust to the X-ray detector (7) in at least two spatial directions.

3. CT system according to one of the preceding claims, characterized in that the control device (8, 9) is set up to determine the position of an object (5) in the area of the patient table and as a function to adjust the collimator (3) from the determined position by means of the drive mechanism (11) in such a way that the detected object (5) is in the area of the directed x-ray beam (4) transmitted by the collimator (3), in particular in the center of the directed x-ray beam ( 4).

4. CT system according to claim 3, characterized in that the control device (8, 9) for automatic tracking of the detected object (5) is set up when the position of the object (5) changes, and the collimator (3 ) to track the changing position by means of the drive mechanism (11) with respect to the emission direction of the directed X-ray beam (4).

5. CT system according to claim 3 or 4, characterized in that the control device (8, 9) is set up to use the projections and reconstructed 3D data sets obtained by means of the X-ray detector (7) to determine the position of the object (5 ) to be determined by means of image processing.

6. CT system according to one of claims 3 to 5, characterized in that the control device (8, 9) is set up to use data from an external measuring device that detects the position of the object (5), the position of the object (5) to be determined.

7. CT system according to one of the preceding claims, characterized in that the control device (8, 9) has access to a data record which specifies a desired directional course of the directional X-ray beam (4), the control device (8, 9) for this purpose is set up to adjust the collimator (3) by means of the drive mechanism (11) by means of the data record in such a way that the directional X-ray beam (4) has a directional course which corresponds to the directional course of the data set.

8. CT system according to one of the preceding claims, characterized in that the CT system has a further drive mechanism (11), by means of which the position of the patient (16) relative to the gantry of the CT system can be automatically adjusted, the electronic control device (8, 9) being set up for automatic actuation of the further drive mechanism (11).

9. CT system according to one of the preceding claims, characterized in that the drive mechanism (11) and / or the further drive mechanism (11) is designed as an electromechanical, hydraulic or pneumatic drive mechanism (11) or as a combination of such drive mechanisms.

10. CT system according to one of the preceding claims, characterized in that the control device (8, 9) is also set up to control the X-ray source (1) and to evaluate the signals from the X-ray detector (7).

11. CT system according to one of the preceding claims, characterized in that the CT system has at least one display unit (10) for displaying CT images obtained from the signals of the X-ray detector (7).