X-ray equipment and method for controlling it

X-ray equipment in which the X-ray source and X-ray detector can be moved in a simple and uncomplicated manner permits an X-ray picture to be taken only when the X-ray source and X-ray detector are aligned to match one another. This provides the user with information about how this appropriate alignment can be achieved, which helps to avoid failed exposures, and which conforms to radiation hygiene. The X-ray equipment comprises:

The invention relates to X-ray equipment with an X-ray source that can be altered in respect of its position and/or alignment, an aperture arrangement, a positioning device for positioning an object that is to be examined, an X-ray detector that can be altered in respect of its position and/or alignment, and a detection device for detecting the position and/or alignment of the X-ray source and/or of the X-ray detector. The invention also relates to a method for controlling the X-ray equipment.

From the German utility model DE-90 12 435 U1, we know of such X-ray equipment. The X-ray source and X-ray detector can be moved by means of adjusting slides, wherein position transmitters and adjusting elements are provided for determining or altering the spatial alignment of the X-ray source and X-ray detector. In DE-90 12 435 U1, it is proposed that the adjusting elements are acted on in such a way that a central axis of the X-ray source and a central axis of the X-ray detector coincide with one another. In the case of this X-ray equipment, it turns out to be disadvantageous that due to the combination of position transmitters and adjusting elements, it is very elaborate, and that furthermore the spatial alignment of the X-ray source and X-ray detector via a control desk and a computer is difficult and time-consuming.

European patent application EP 1 004 271 A1 likewise presents X-ray equipment as described above. The X-ray source and X-ray detector are movable, wherein via a control unit it is ensured that they are always aligned relative to one another in such a way that an X-ray picture is possible. In one embodiment, the X-ray source or the X-ray detector can be moved manually, and the control unit automatically guides the corresponding counterpart to follow it, in such a way that the source and the detector remain appropriately aligned to one another. With this system too, one disadvantage is the great expense that is required for determining the alignment and for the automatic movement.

US disclosure document US 2003/0194056 A1 discloses another X-ray system of the type named at the outset. Here, the X-ray source and the X-ray detector can be moved freely; release for taking an X-ray picture is given only when the X-ray source and the X-ray detector are aligned appropriately to one another for a desired X-ray picture. It proves to be a disadvantage here that the user is given no assistance by means of which he can find the appropriate alignment of X-ray source and X-ray detector that allows him to take an X-ray picture.

It is thus an object of the invention to define X-ray equipment of the type named in the introduction, in which the X-ray source and the X-ray detector can be moved in a simple and uncomplicated way, which permits an X-ray picture to be taken only when the X-ray source and X-ray detector are aligned to match one another, and which gives the user information about how this appropriate alignment can be achieved. The intention is to avoid failed exposures, and radiation hygiene is to be observed.

To achieve the object stated above, in the case of the X-ray equipment named at the outset, an evaluation device is provided for determining a trigger setting that is suitable for an X-ray picture, in which the X-ray source and the X-ray detector have such positions and alignments that an X-ray picture of the examination object can be taken using the X-ray equipment; also provided are a signal device for outputting signals that inform a user how a trigger setting is to be achieved, and a release device for releasing the X-ray equipment for an X-ray picture when the X-ray equipment has a trigger setting.

The invention is based on the idea that by determining the spatial data of the X-ray source and the X-ray detector, their position and alignment are not only compared with a desired or permitted position and alignment to see whether an X-ray picture of an examination object is possible, but that through the use of the current positions and alignments, it is possible both to determine trigger settings and to provide instructions about what changes to the settings for the X-ray equipment, for example to the position or alignment, are necessary in order to achieve a trigger setting. To safely achieve an X-ray picture, the X-ray source and X-ray detector must be aligned so that their middle verticals coincide. On the basis of a known, fixed aperture setting, a spatial distance between source and detector results, in which the detector can be used completely.

In a preferred design, the X-ray equipment according to the invention also has an adjustable aperture arrangement as well as a detection device for detecting the setting of the aperture arrangement. The evaluation device is provided in order to include, for the determination of a trigger setting, the setting of the aperture arrangement too. The trigger setting is thus one in which the X-ray source and the X-ray detector have such positions and alignments, and the aperture arrangement has such a setting, that an X-ray picture of the examination object can be taken using the X-ray equipment. Through the inclusion of a variable aperture setting in the determination of a trigger setting and a corresponding outputting of signals relating to how this trigger setting is to be achieved, including with changes to the setting of the aperture arrangement, the X-ray equipment can be used more flexibly, without entailing that through a wrong setting, only a part of the X-ray detector is exposed or used, i.e. that only a reduced resolution is achieved, or that a portion of the rays leaving the X-ray source do not hit the X-ray detector and under certain circumstances cause unnecessary radiation elsewhere.

In an advantageous design, the X-ray equipment according to the invention has an adjustable aperture arrangement, an aperture determination device for determining a trigger aperture setting that is appropriate for an X-ray picture, in which, with the X-ray source and X-ray detector in the trigger setting, an X-ray picture of the examination object can be taken using the X-ray equipment, and an aperture setting device for setting the aperture arrangement in the trigger aperture setting. With automatic setting of an aperture arrangement, the user needs only to bring the middle verticals of the X-ray source and the X-ray detector together. The setting of the aperture arrangement then takes place according to the spatial distance between the source and the detector, such that the X-ray detector it optimally utilized.

In a further development of the X-ray equipment according to the invention, also provided are a comparison device for comparing positions and/or alignments of the X-ray source and/or X-ray detector with the trigger setting, and a signal device for outputting signals that inform a user that positions and/or alignments of the X-ray source and/or X-ray detector lie in a predetermined range around the trigger setting and/or that the positions and/or alignments of the X-ray source and/or X-ray detector correspond to the trigger setting. Beyond the information about how a trigger setting is to be achieved, it is sensible for the user to obtain information about how close he is to a trigger setting, and when he has reached a trigger setting. Depending on the distance from a trigger setting, the user can then for example adjust the speed at which he moves the X-ray source or X-ray detector.

In a preferred design of the X-ray equipment according to the invention, the equipment has a brake device for fixing and/or releasing the position and/or alignment of the X-ray source and/or X-ray detector, and a control device for controlling the brake device. Once a position or alignment of the X-ray source or X-ray detector that is desired by the user has been reached, the user can fix this position or alignment by means of the control device through the brake device. A setting envisaged by the user for this is thus maintained, which makes it possible for example for him to fix the X-ray detector and then to bring the X-ray source into a trigger setting without the setting of the X-ray detector being altered in the course of this. The control device can also be subject to control by the X-ray equipment itself, i.e. it can function automatically.

The invention furthermore relates to a method for controlling X-ray equipment with an X-ray source that can be altered in respect of its position and/or alignment, an aperture arrangement, a positioning device for positioning an examination object, an X-ray detector that can be altered in respect of its position and/or alignment, with the steps:detection of the position and/or alignment of the X-ray source and/or of the X-ray detector,determination of a trigger setting that is suitable for an X-ray picture, in which the X-ray source and the X-ray detector have such positions and alignments that an X-ray picture of the examination object can be taken using the X-ray equipment,outputting of signals that inform a user how a trigger setting is to be achieved, andrelease of the X-ray equipment for an X-ray picture when the X-ray equipment has a trigger setting.

FIG. 1shows a block diagram of an embodiment of X-ray equipment1according to the invention. An X-ray source2can be altered in respect of position X1, Y1, Z1and alignment Alfa1, Beta1, and has an integrated aperture arrangement15. Integrated into a positioning device3for positioning an examination object (not shown) is an X-ray detector4that can be altered in respect of position X2, Y2, Z2and alignment Alfa2, Beta2. The X-ray source2and X-ray detector4are thus movable in the three spatial directions and around 2 axes, thus making any position and alignment possible.

A detection device5ais provided for detecting the position X1, Y1, Z1and alignment Alfa1, Beta1of the X-ray source2, and a detection device5bis provided for detecting the position X2, Y2, Z2and alignment Alfa2, Beta2of the X-ray detector4.

A control unit6has an evaluation device7, a comparison device8, a signal device9, a control device12and a release device14.

The evaluation device7serves to determine a trigger setting that is suitable for an X-ray picture, in which the X-ray source2and the X-ray detector4have such positions X1, Y1, Z1, X2, Y2, Z2and alignments Alfa1, Beta1, Alfa2, Beta2that an X-ray picture of the examination object can be taken using the X-ray equipment1. Two trigger positions result from the fact that the X-ray source2or X-ray detector4is intended to keep its position and alignment, and the respective counterpart is to be positioned and aligned in such a way that in the event of triggering, the central beam of the X-ray bundle emitted by the X-ray source2coincides with the middle verticals of the detector field or of the predetermined portion of the detector field of the X-ray detector4.

Via a signal device9, signals are output by means of a display device10for visual display and/or by means of a loudspeaker11for acoustic indication, which inform a user how a trigger setting is to be achieved, and/or that the current setting is in a predetermined range around a trigger setting, or that a trigger setting has been achieved. For this, signals are envisaged that are preferably different in each case. Proximity to the trigger setting can for example be indicated by a color change from red via yellow, in the case of proximity within the predetermined range, to green in the case of correspondence, or by different sound signals. The instruction as to how a trigger position is to be reached implicitly likewise contains the instruction as to how the second trigger position is to be reached. It can however be envisaged that explicitly separate instructions are given for the changes in position and alignment of the X-ray source2and the X-ray detector4, for which separate signal devices and display instruments would also be provided. Separate instructions for the individual setting possibilities can likewise be envisaged.

The control device12serves to control a brake device13afor fixing the X-ray source2and a brake device13bfor fixing the X-ray detector4. It can be both envisaged that the brake devices13aand/or13bundertake the fixing constantly and are actuated separately in order to release the fixing temporarily, or that the brake devices13aand/or13bfix the X-ray source2and the X-ray detector4temporarily only after separate actuation. A suitable method for fixing or locking is described in the European patent application EP 02102694.3 (PHDE 020295EP-P).

The release device14is provided to release the X-ray equipment1to take an X-ray picture when the X-ray equipment1has achieved a trigger setting. This release can for example consist in a power supply for the X-ray source2being cleared so that the X-ray source2can produce X-rays.

The aperture arrangement15can, as shown here, be integrated into the X-ray source2, or it can also be separate from the X-ray source2itself. Furthermore, the aperture arrangement15can also be designed such that it is adjustable. A detection device16can then be provided for detecting the setting of the aperture arrangement, and the evaluation device7for determining a suitable trigger setting can be designed so as to result in a method of working analogous to that described above. Furthermore, the aperture arrangement15can be connected to an aperture determination device17for determining a suitable trigger aperture setting, and to an aperture setting device18for automatic setting of the aperture arrangement15in this trigger aperture setting, in order to enable automatic adaptation of the aperture arrangement15to an appropriate trigger setting of X-ray source2and X-ray detector4. It can furthermore be envisaged that only one respectively predetermined portion of the overall surface of the X-ray detector4is used.

FIG. 2shows a flow chart for a method according to the invention, for controlling the X-ray equipment1. After the procedure is started in step20, in a first step21the brakes are activated, and the signal device9is set so that no signals are output. Alternatively, a “ready” signal can be output. By means of a comparison22, in the comparison device8the current setting of the X-ray equipment1is compared with a trigger setting. If they match, for example with a tolerance of 1% of the distance between the detector4and the source2, or in the fact that in the case of movement that is possible only in discrete steps, the greatest possible approximation to a trigger setting is achieved, a release23of the X-ray equipment1is effected by means of the release device14, and after a positive decision24, in step25a picture is taken. In the standard IEC 60601-1-3 (X-ray directive), more detailed conditions for a trigger setting are laid down. If no picture is to be taken, an inquiry26takes place as to whether a setting alteration is to be made to the X-ray equipment. In the method according to the invention, this inquiry26is also reached where the comparison22yields non-equality, via an intermediate step27in which it is ascertained that there is no release for the X-ray equipment1. Depending on whether, on the basis of this inquiry26, a movement of the X-ray source2or of the X-ray detector4should take place, there follows a movement28of the X-ray source or a movement29of the X-ray detector, after which we then proceed once more to comparison22, thus resulting in a loop.

In the case of the inquiry26, as a further alternative it can be envisaged that the aperture arrangement15is altered, and corresponding further steps then result from that. It can also be envisaged that not all the setting possibilities are realized, in other words that for example only the position X1, Y1, Z1and alignment Alfa1, Beta1of the X-ray source2and the alignment Alfa2, Beta2of the X-ray detector can be altered. The inquiry26can also take place such that no explicit inquiry takes place for example via a switching device, but that the detection devices5a,5bdetect a desired movement by a change in the setting of the X-ray source or X-ray detector. Furthermore, there can be further differentiation, in that the individual setting possibilities along an x, y or z axis or around rotational axes are individually distinguished, and further separated movements are possible.

FIG. 3shows a flow chart of a part of the method according to the invention as shown inFIG. 2, in particular the steps28or29. First of all a check is made to see whether the brake, for example a brake device13a,13b, is released. If not, in step41the brake is released, a timer is initialized, and this timer is started. In a delay loop42, we wait for a predetermined period of time to expire, which in this case is given as1second. This delay loop42provides an opportunity to enable the alteration of the current setting if this would not otherwise be possible on account of the subsequent steps. Where the current setting already corresponds to a trigger setting, the brakes would—as illustrated below—automatically be activated and thus any alteration of the setting would be prevented.

The delay loop42is followed by step43, as is also the case directly in the case of a released brake. In step43, the current setting is compared to a trigger setting. In this comparison43, it is checked whether the current setting corresponds to a trigger setting or is in proximity to it, and a method is established as to how a trigger setting can be reached.

By “proximity”, we mean a range around the trigger setting in which it can be achieved with minimal alteration of the setting. For example, proximity can mean that the current position deviates by no more than 10% of the distance between the source2and detector4(film focus distance, FFD), and the current alignment deviates not more than 10° from a trigger setting.

If the comparison43does not yield any proximity to a trigger setting, then in step44a signal is output which indicates to the user how a trigger setting can be achieved. Subsequently, a new comparison43takes place, wherein the user can have changed the current setting in the meantime.

If the comparison43yields the result that the current setting does lie in proximity to a trigger setting, then in step45a corresponding signal is output that indicates this proximity. Just as in step44, it is also indicated how a trigger position can be achieved. Next, the speed at which the respectively current setting may change is checked. If this speed V lies above a limit speed VRast, then a new comparison43takes place. The limit speed is that speed at which locking or fixing and stopping of the movement is still possible or desired. This speed results from the characteristics of the brake device13a,13band of the X-ray equipment1in general. If the speed V now lies below or at the limit speed, then a comparison47takes place between the current setting and a trigger setting. If this comparison47does not yield equality in the sense of the invention, then step43follows once more. In the case of equality, in other words if a trigger setting has been reached, then the current setting is fixed by means of braking48, and the procedure step for movement is concluded for the time being.

If the comparison43yields equality between the current setting and a trigger setting, then a corresponding signal is output (step49). If, analogously to step46, a check50yields the result that the speed is too high, then step43follows once more. If it is possible to fix the current setting, then this takes place in the following step48.

It can furthermore be envisaged that in the close range around a trigger setting, the movement is not stopped, but slowly braked. With this, fixing of the current setting in the event of equality would not take place completely abruptly. It is also possible to do without the automatic braking or automatic fixing48. The user would then have to effect fixing, or lifting of non-fixing, himself. The signals that are output can be of a lasting nature; in step43a respective lifting of these signals would then have to take place. The signals can also be so brief or short-lived that lifting is not necessary. It is also possible to envisage different limit speeds for the comparisons46and50.

The X-ray equipment according to the invention has suitable sensors for all the settings that are relevant for X-ray equipment (position, angle, possibly aperture setting). Since the geometric relation between the X-ray source and X-ray detector is thus known, this information can be used to locate a trigger setting that enables an X-ray picture to be taken safely and effectively, to provide the user with instructions as to how he can achieve such a setting, and to control the X-ray equipment in such a way that only safe and effective X-ray pictures are taken. By avoiding elaborate setting devices for the position and alignment of the X-ray source and X-ray detector, both the X-ray equipment itself as well as its use are simplified and the safety is improved. Greater degrees of freedom are available to the user, he obtains better support from the system, and can thus improve the performance and the throughput rate of the system.