X-ray device, method for operating an X-ray device, computer program and data carrier
阅读说明：本技术 X射线装置及其运行的方法、计算机程序和数据载体 (X-ray device, method for operating an X-ray device, computer program and data carrier ) 是由 斯文-马丁·苏特 于 2019-08-28 设计创作，主要内容包括：本发明涉及X射线装置及其运行的方法、计算机程序和数据载体。在用于运行用于记录图像序列的X射线装置(8)的方法中,所述图像序列尤其用于透视监视患者(9)的记录区域,透视图像借助记录速率和记录剂量获取并且借助帧率为用户在显示装置(16)处示出,其中根据在当前的、彼此相随的透视图像之间的图像内容变化自动地选择记录剂量。(The invention relates to an X-ray device, a method for operating the same, a computer program and a data carrier. In a method for operating an X-ray device (8) for recording a sequence of images, in particular for fluoroscopic monitoring of a recording region of a patient (9), the fluoroscopic images are acquired by means of a recording rate and a recording dose and are displayed for the user on a display device (16) by means of a frame rate, wherein the recording dose is automatically selected as a function of the image content between the current fluoroscopic images following one another.)
1. A method for operating an X-ray device (8) for recording a sequence of images, in particular for fluoroscopic monitoring of a recording region of a patient (9), wherein fluoroscopic images are acquired with the aid of a recording rate and a recording dose and are displayed for a user at a display device (16) with the aid of a frame rate,
it is characterized in that the preparation method is characterized in that,
the recording dose is automatically selected as a function of image content changes between the current fluoroscopic images that follow one another.
2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,
it is characterized in that the preparation method is characterized in that,
when the recorded dose is reduced, a display image is determined from a plurality of respective fluoroscopic images recorded one behind the other and is output on the display device (16), said display image corresponding to the maximum usable basic dose (5).
3. The method of claim 2, wherein the first and second light sources are selected from the group consisting of,
it is characterized in that the preparation method is characterized in that,
in the determination of the display images, the frame rate is reduced, in particular by a factor which corresponds to the number of combined perspective images in disjoint groups of perspective images to be combined.
4. The method according to any one of the preceding claims,
it is characterized in that the preparation method is characterized in that,
the selection of the recording dose is also based on a gradient of the image content changes with respect to more than two successive images of the current fluoroscopy.
5. The method according to any one of the preceding claims,
it is characterized in that the preparation method is characterized in that,
the variation of the recording dose is performed in discrete steps depending on whether the image content variation exceeds or falls below at least one variation threshold.
6. The method of claim 5, wherein the first and second light sources are selected from the group consisting of,
it is characterized in that the preparation method is characterized in that,
in the case of more than two stages, at least one stage is skipped if the image content variation gradient likewise taken into account according to claim 2 exceeds at least one threshold value.
7. The method according to any one of the preceding claims,
it is characterized in that the preparation method is characterized in that,
a comparison measure between the two most recent fluoroscopic images, which is selected in particular by application, is selected as a measure for the change in the image content.
8. The method according to any one of the preceding claims,
it is characterized in that the preparation method is characterized in that,
the fluoroscopic images are recorded for monitoring a minimally invasive procedure performed with an instrument, in particular a catheter, and/or a contrast agent diffusion in the patient (9).
9. An X-ray device (8) having a display device (16) and a control device (15) configured for carrying out the method according to any one of the preceding claims.
10. A computer program for performing the steps of the method according to any one of claims 1 to 8, when the computer program is executed on a control device (15) of an X-ray device (8).
11. An electronically readable data carrier on which a computer program according to claim 10 is stored.
Technical Field
The invention relates to a method for operating an X-ray device for recording a sequence of images, in particular for fluoroscopic monitoring of a recording region of a patient, wherein fluoroscopic images are acquired at a recording rate and a recording dose and are displayed to a user at a frame rate at a display device. Furthermore, the invention relates to an X-ray device, a computer program and an electronically readable data carrier.
Background
X-ray imaging is commonly used in the prior art to monitor dynamic processes in a recording area within a patient. An example of such a dynamic procedure is the so-called roadmapping procedure, in which a medical instrument, such as a catheter or a guide wire, is to be moved to a target position within the patient, so that as little damage as possible to the patient occurs. Another example is an imaging process with contrast agents, wherein the contrast agent surge should be monitored, for example, by means of transmission images. In such monitoring procedures, the fluoroscopic images of the patient are recorded with a specific recording rate and are shown directly or after a specific reprocessing, which means that the representation of the fluoroscopic images on the display device does not necessarily exclude a prior processing of the fluoroscopic images. For example, it is known to highlight specific features, such as medical instruments to be tracked, etc. The most common recording technique for recording image sequences for monitoring the recording area of a patient is fluoroscopy, but other uses can also be considered, for example when recording image sequences for digital radiography.
When recording image sequences of fluoroscopy images for monitoring, the patient is subjected to X-ray radiation approximately continuously, so that a dose reduction for the patient is an important subject of such a monitoring process, in particular fluoroscopy. In this case, different possibilities have been proposed in order to reduce or keep the dose load for the patient as small as possible. First of all, such fluoroscopic images for monitoring are usually produced with an extremely small recording dose, since important features to be observed, such as contrast agents and/or medical instruments, are imaged sufficiently clearly even at low doses. In addition, in order to obtain a sufficiently accurate view of the anatomical structure, it is proposed that the fluoroscopic image or a display image derived therefrom be superimposed in the view with, for example, previously interfered image data that clearly shows the anatomy of the patient. It is also proposed that the radiation field is only targeted at the absolutely necessary regions.
In another approach, which is also known from the prior art, it is proposed that the recording rate of the fluoroscopic images is reduced if no or only small changes occur between the fluoroscopic images. For this purpose, for example, a measure for the change in image content between the two most recent fluoroscopic images can be determined and compared with a change threshold value in order to switch back from a basic recording rate of 30fps to a recording rate of 10fps or less, for example. If a strong image content change then occurs again between the latest fluoroscopic images, it is possible to switch back again to a faster recording speed, i.e. in this example to the basic recording rate. By switching between the different recording rates, the frame rate with which the image data of the fluoroscopic image are displayed also changes.
This approach has the disadvantage that it may not be possible or not possible to react quickly enough to sudden, rapidly occurring changes in the image content, so that the user may ignore important information or the information cannot be recognized with sufficient quality.
Disclosure of Invention
The invention is therefore based on the following object: the possibility is proposed for reducing the dose to the patient when recording the image sequence for monitoring, which still enables a fast reaction to the strong image content changes that occur.
In order to achieve the object, according to the invention in a method of the type mentioned at the outset, a recording dose is automatically selected as a function of the image content changes between the current fluoroscopic images that follow one another. In particular, when the image content changes less, a lower recording dose can be selected than when the image content changes more strongly.
In order to react as quickly as possible to a strong type of sudden image content change, in particular by increasing the frame rate displayed on the display device, it is proposed: in the case of slight changes in the image content, the recording rate itself is not reduced, but rather the recording dose is dynamically adjusted, in particular the recording dose per fluoroscopic image is reduced, so that such changes in the image content can nevertheless be determined extremely quickly at the relevant image content, but the quality of the fluoroscopic image itself may be significantly reduced.
In this case, however, a particularly advantageous development of the invention provides that, when the recorded dose is reduced, a display image is determined from a plurality of respective fluoroscopic images recorded one behind the other, which display image corresponds to the maximum usable basic dose and is output on a display device. In this case, it can be provided in particular that the fluoroscopic images are combined by addition to form a display image. This means that, in particular, a frame rate reduction, which is familiar to the operator in a known manner, can still occur, at least with regard to the display on the display device. In this case, it can be provided that, when the display images are determined, the frame rate is reduced, in particular by a factor which corresponds to the number of combined perspective images in disjoint groups of perspective images to be combined. In other words, the recording dose can be suitably reduced, so that a plurality of fluoroscopic images are combined, in particular must be added before they can again be shown with sufficient quality at the display device. Thus, there is an image impression known to the operator, but additionally there can also preferably be a frame rate conversion known to the operator. In this case, the blocks/groups of the fluoroscopic images recorded one after the other are always combined, in particular by adding, to the display image, so that after a certain number of the fluoroscopic images to be combined are recorded in each case, a new display image can be output, so that the frame rate is reduced by a factor which corresponds to the number of the fluoroscopic images to be combined.
Although the combination of the fluoroscopic images into a display image is particularly preferred, the control device of the X-ray apparatus separately analyzes the fluoroscopic images recorded with the reduced recording dose, in respect of changes in the image content, and possibly readjusts the recording dose, in particular for renewed increase to the base dose, more precisely as soon as sufficiently strong changes in the image content occur.
In summary, it is therefore proposed to adjust the recording dose per fluoroscopic image as a function of the dynamic image content changes between the fluoroscopic images during the sequential recording, and in particular also to select the image display frequency, i.e. the frame rate, at the display device accordingly. The control device of the X-ray device is thus able to react quickly to dynamic changes in the image content, for example after injection of a contrast agent bolus and/or when the medical instrument is moving relatively quickly in the recording area.
In a particularly preferred development of the invention, it can be provided that the selection of the recording dose is also carried out as a function of a gradient with respect to a change in the image content of more than two successive fluoroscopy images. Whereby the type of speed of the change of the image content is finally taken into account. In particular, it is possible here to predict future minimum image content changes taking into account the gradient of the image content change and to select a new recording dose as a function of this.
For this purpose, for example, a prediction algorithm can be used, which can be selected in particular in an application-dependent manner, i.e., for example, with regard to the typical diffusion speed of contrast agents which can penetrate into the recording region, which can be directed and/or which can be evaluated with the aid of medical instruments, in particular at different points of the workflow, for a common working speed. Here, machine learning techniques or generally artificial intelligence can also be considered.
It is to be noted here that it is also conceivable in principle to associate the image content change or the image content change interval with the respective recording dose, in particular application-dependent, for example in a look-up table and/or by a mathematical relationship.
It is particularly expedient within the scope of the invention, however, to record the dose variation in discrete steps depending on whether the image content changes above or below at least one variation threshold. The stages can then be selected in particular such that the following impression is produced by combining, in particular adding, an integer number of perspective images recorded after one another: the resulting display images are recorded with the aid of the base dose, so that the image impression of the base dose, apart from possibly slightly increased noise, remains unchanged for the user in the simplest possible manner, in particular if the frame rate is reduced at the display device. The graduation of the recorded doses can thus be selected in a targeted manner such that, by combining, in particular adding, a set of perspective images following one another, the impression of recording by means of the base dose is created again. In this case, it is conceivable, in particular, for the recording dose to be reduced by an integer factor starting from the basic dose, so that a suitable display image is generated by adding the number of fluoroscopic images corresponding to the integer factor.
In a simple embodiment, two stages, and thus two discrete doses, can thus be provided. In this case, it can be provided that, when a reduction criterion is met, which indicates that the image content change between the images following one another falls within a first change threshold, the recording dose is reduced from the base dose, and, when an increase criterion is met, which indicates that the image content change between the fluoroscopic images following one another is above a second change threshold, the recording dose is increased again to the base dose. In the simple exemplary embodiment, a corresponding adjustment of the frame rate is also possible.
However, in an advantageous embodiment, more than two stages can be used, which means that more than two discrete values of the dose are recorded. This is particularly suitable in the following cases: the selection of the recording dose should also be based on the gradient of the image content changes with respect to more than two current fluoroscopic images recorded one after the other. It can therefore be provided that at least one level is skipped when the image content variation gradient exceeds a threshold value. If the speed of the change of the image content therefore shows: in the future, even stronger changes in the image content can be taken into account, and a switch can likewise be made to a step in which the recording dose is further reduced, wherein the same applies in contrast. However, in the case of two-stage, it may be useful to take into account the image variation gradient, for example in order to be able to reduce the recording dose in time or to increase the recording dose to the base dose.
As a measure for the change in the image content, a comparison measure can be selected which is selected in particular application-dependent between the two latest fluoroscopic images. In this case, entirely different comparison measures are taken into account, for example, by local analysis of the contents of the blood vessel in the case of contrast agents, its movement in the tracked medical instrument, etc. Of course, a comparison measure for global evaluation of the image data of the fluoroscopic image can also be used in the following cases: these comparison measures react only sensitively enough to relevant changes of the respective application.
In particular, it can be proposed as an application, for example, to record fluoroscopic images, to monitor minimally invasive procedures performed with instruments, in particular catheters, and/or to monitor the diffusion of contrast agents in a patient. The invention can of course be used in other application cases where dynamic changes to be monitored by means of fluoroscopic images, in particular fluoroscopic images, may occur in the patient.
In addition to the method, the invention also relates to an X-ray device which, in addition to at least one recording device having an X-ray emitter and an X-ray detector, also has a control device which is designed to carry out the method according to the invention. The control device can also be designed to control the operation of the X-ray device in other cases and has at least one processor and a memory means. In particular, the control device can also comprise a comparison unit for ascertaining changes in image content and an adjustment unit for adjusting the recording dose, in addition to a recording unit for controlling the recording operation of the X-ray apparatus, in order to carry out the method according to the invention. In a preferred embodiment of the invention, the combination unit can also be used to combine a plurality of perspective images recorded with a reduced recording dose following one another into a display image. The X-ray device further comprises a display device, for example a monitor, on which the fluoroscopic images are output, optionally in a time-combined manner, as display images.
The computer program according to the invention can be loaded directly, for example, into a memory of a control device of an X-ray apparatus and has a program mechanism in order to carry out the steps of the method according to the invention when the computer program is executed in the control device of the X-ray apparatus. The electronically readable data carrier according to the invention comprises electronically readable control information stored thereon, which control information comprises at least one computer program according to the invention and is designed such that, when the data carrier is used in a control device of an X-ray apparatus, it executes a method according to the invention. The data carrier can in particular be a non-transitory data carrier, such as a CD-ROM.
Drawings
Further advantages and details of the invention emerge from the examples of embodiment described below and from the figures.
Shown here are:
figure 1 shows a conventional flow chart of an embodiment of a method according to the invention,
FIG. 2 shows possible variation curves of different variables during perspective monitoring, an
Fig. 3 shows an X-ray device according to the invention.
Detailed Description
In the following, an embodiment of the method according to the invention is shown on the basis of a fluoroscopic monitoring during application to a patient, for example, in a minimally invasive procedure with the aid of a medical instrument. In this case, an X-ray device is used, which has a recording device, for example a C-arm, via which a fluoroscopic image of the patient is recorded with an already small base dose as the recording dose, which shows the dynamically changing features to be monitored in the recording region of the patient sufficiently clearly. Thus, an image sequence of the fluoroscopy images, in this case of the fluoroscopy images, is recorded. In order to reduce the dose stress of the patient, the recording dose is reduced from the base dose without changing the recording rate, and the plurality of fluoroscopic images are combined in sequence to form a display image in order to obtain a quality corresponding to the base dose again during the display, wherein the frame rate is reduced at the respective display device.
Fig. 1 shows a conventional flow chart of an embodiment of a method according to the invention. Step S1 here indicates that continuous monitoring takes place by continuous recording of the fluoroscopic images of the recording area by means of the X-ray device, with the recording rate being kept constant. If a new perspective image is present, a measure for the change in the image content is always determined in step S2, in particular application-specifically, by comparing the two latest perspective images, here by: an application specific comparison metric will be used for a pair of two up-to-date perspective images.
The image content changes thus ascertained are evaluated in step S3 by means of at least one evaluation criterion in order to determine whether an adjustment of the recording quantity, in particular a reduction from the basic value, is justified on account of only slow changes or no changes at all, or whether an increase in the recording quantity is justified on account of sudden/rapid/stronger image content changes occurring.
If a change in the recorded dose is reasonable, the change is performed in step S4. In the present exemplary embodiment, at least two, preferably more, doses of the recording medium to be used are provided, wherein the number of recording medium doses that can be reduced corresponds to an integer fraction of the basic dose. In particular, different intervals of image content variation are associated with a particular discrete value of the recording dose. In this context, it is to be noted in this connection that the interval can of course also be selected depending on the currently set recording dose, since in step S2 the two most recent fluoroscopic images are always compared with one another, which, depending on the recording dose, appear different and thus also result in different value ranges of the comparison measure. In particular, an image content change interval is therefore provided for each dose together with the associated dose, so that an association with a particular one of the intervals causes a switchover according to step S4.
In step S5, it is checked whether the patient has just worked with a reduced recording dose relative to the base dose, which is the maximum permissible recording dose for fluoroscopy. If this is not the case, in step S6 the current fluoroscopic image is shown on the display device, so that in particular the frame rate at the display device corresponds to the recording rate.
However, if the procedure is to be carried out with a reduced dose, in step S7 the multiple perspective images are combined to form a display image so that they correspond in their impression to the perspective image recorded with the basis dose. If, for example, the recording dose is reduced by a factor k as explained above, the disjoint groups of k fluoroscopic images are each combined into a further display image, which is subsequently shown in step S6.
It is to be understood that during the collection of the fluoroscopic images to be combined in step S2, however, further continuously monitored for the two latest fluoroscopic images, respectively, whether there is a relevant image content change. This means that even if the frame rate for the display is likewise reduced for the reason that the display image is generated only from all k fluoroscopic images in the case of a reduced recording dose, it is still possible to react very quickly to the sudden, strong image content changes that occur.
This is illustrated in detail by figure 2. First, a time axis 1 is shown, which has
As already mentioned, it is not absolutely necessary here to provide only two such stages, but three or more stages can also be considered. A suitable alternative refinement of steps S2 and S3, just as in this case, but also in the case of the use of only two stages, provides for the gradient of the image content change to be determined in step S2 additionally also with respect to more than two subsequent images of the current fluoroscopy. For example, the last two perspective image pairs up to ten recorded perspective image pairs can be considered in each case. It can be evaluated whether the image content changes that occur are, for example, only "outliers" relating to the perspective image pairs, so that an outlier detection can thus be carried out, wherein in the case of an outlier, in particular an individual event, being detected, a switching in step S3 need not be forced. Preferably, however, it is also possible in addition or alternatively to understand the gradient of the image content change as a trend, for example in the sense of describing a medical instrument which has been set in motion, so that a relevant estimation, in particular, can also be applied to what level of the image content changes the current dynamic process result. In this connection, for example, a step of the recording dose can be skipped and/or optionally, a switch to other, in particular also higher recording doses can be made earlier and preventively in step S3.
Fig. 3 finally shows an embodiment of an
The operation of the
Although the details of the invention have been shown and described in detail with reference to preferred embodiments, the invention is not limited to the examples disclosed but other variants can be derived therefrom by those skilled in the art without departing from the scope of the invention.
List of reference numerals:
1 time axis
2 recording the time of day
3 curve of change
5 basic dose
6 value
7 brackets
8X-ray device
9 patients
10 examining table
11C-shaped arm
12X-ray radiator
13X-ray detector
14 robot arm
15 control device
16 display device
17 recording unit
18 comparing unit
19 adjustment unit
20 communication unit
S1-S7 steps