DE20017274U1 - X-ray device - Google Patents

Description

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Von-dem-Bussche-MüVidi-Strasse^

32339 Espelkamp

X-ray device

The invention relates to a medical X-ray device for digital radiography with a radiation source, a detector unit for the emitted radiation which supplies digital output signals, a computer device connected downstream of the detector unit which processes the output signals, and an input and display device.

A medical X-ray device for digital radiography is known, DE 196 33 580 Al, which has a matrix detector that is located directly in the beam path of the X-rays and is therefore exposed to increased stress. Furthermore, its image quality only corresponds to that of conventional analog radiography.

The object of the invention is to provide an X-ray device that delivers digital X-ray images with optimal image quality while at the same time minimizing radiation exposure, providing maximum ease of use and cost-effectiveness.

The solution to this problem is achieved according to the invention in conjunction with the generic features by the technical teaching specified in the characterizing part of the main claim.

In addition to a required radiation source, the X-ray device has a detector unit, which comprises a housing with a fluorescent screen.

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as well as an optics connected downstream of it and a camera with which the X-rays converted into visible light by the fluorescent screen can be recorded and converted by a sensor into digital pulses.
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The use of optics enables the use of a small, highly sensitive sensor in a digital camera, which can be used to achieve high sharpness and a high depth of field in the images produced. The detector is installed inside the X-ray device instead of a moving grid unit in a conventional X-ray system. The same organ-related recording parameters are required for an X-ray image as are required for recording on X-ray film. The housing, which has universal fastening options and can be retrofitted to all known X-ray devices in any position, is lined with a bleaching layer on the inside to shield the X-ray radiation. Bucky tables, vertical stands or swivel bracket devices can be used as recording workstations. Such an X-ray device is advantageously used wherever fast and uncomplicated work with a high patient throughput is important. In practice, labor and material costs for film development and film archiving are eliminated. Another advantage for patients and operating personnel is the extremely low exposure dose of 4 μΘγ (measured behind the grid) or better.

Further advantageous embodiments of the subject matter of the invention result from and in combination with the following subclaims.

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It is advantageous if an anti-scatter grid is installed as a fixed grid with a correspondingly high number of grid slats per millimeter directly behind the outer cover of the detector, the detector cover, which is focused on the distance from the focus to the image plane. The anti-scatter grid is inserted into guide rails in the beam path in such a way that it can also be pulled out of the beam path, for example to take images of extremities without a grid, thus significantly reducing the patient dose.

A further advantage is an embodiment of the invention in which a measuring chamber is arranged behind the anti-scatter grid for switching off the radiation source after a required dose rate has been reached, so that a person to be X-rayed is not unnecessarily exposed to radiation.

According to another particularly preferred embodiment of the invention, the fluorescent screen which converts the X-rays into visible light consists of a film which has a trapezoidal characteristic curve of the illumination, the duration of the illumination and the afterglow over the excitation time. Compared to conventional fluorescent screens with an approximately sinusoidal characteristic curve, this film helps to produce images with excellent sharpness and image dynamics. The afterglow time of the film is extremely short and can be less than 60 ms, in particular 40 ms.

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In combination with the highly sensitive sensor, this enables an image resolution of 2.8 line pairs per millimeter (Lp/mm) and better.

A particular advantage here is the design of the extremely bright optics with lenses made of lead glass, which ensures that, with a correspondingly high lead equivalent of the optics, the X-rays are almost completely absorbed and thus all components downstream of the optics are protected from X-rays and their service life is increased many times over.

Downstream of the optics is a highly sensitive CCD sensor with an image matrix of 2000 x 2000 pixels or better and a preferred resolution of 12 bits per pixel, which corresponds to 4096 gray levels.

The downstream camera processes the electrical signal from the sensor into a digital signal, with the data being stored in a buffer. The sensor's pixels are read out at a clock frequency of 16 MHz during the entire recording time and the image information is stored in a fast buffer.

When viewing a pixel, the information of the pixel is first saved in a first readout cycle. In the second readout cycle, the new pixel information is added to the first and so on until the end of the recording. The entire image information that has accumulated in the buffer after the end of the recording is then converted into 16 Mbyte image information and pushed into a downstream working memory of the camera. From this working memory

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In turn, a grabber card from the computer unit reads 8 Mbytes of image information. This 8 Mbyte image information represents a raw image, which can then be further processed. Reading the sensor, temporarily storing the image information in the camera control system and displaying the X-ray image on a monitor takes less than 5 seconds. The doctor is shown the image that can be diagnosed within this time. This represents a significant time saving compared to conventional recording technology with X-ray films or storage plate systems.

According to a preferred embodiment, a so-called organ automation can be particularly advantageous, with which the recording process is considerably simplified. The computer unit of the X-ray device has optimized recording parameters for any number of organs, such as:

B. Recording voltage, mAs product, tube focus, recording workstation, measuring field of the 3-field measuring chamber, recording format to be displayed. These recording parameters are transmitted to the X-ray generator so that adjustments to the generator are no longer necessary. This minimizes incorrect settings and thus incorrect recordings and unnecessary radiation exposure to the patient. After the recording has been made, the recording parameters actually taken are read out of the X-ray generator by the computer unit and added to the X-ray image as a non-deletable part of the image.

It is particularly advantageous that the data line between the X-ray generator and the computer unit is designed as an optical fiber,

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which achieves galvanic isolation on the one hand and maximum interference immunity on the other.

Of particular advantage is also an embodiment of the subject matter of the invention in which a second camera unit comprising an optics, a CCD sensor and a camera control unit with buffer memory is arranged on the housing of the detector.

This camera unit can be designed in different ways for different image acquisition criteria. On the one hand, it can be designed so that, for example, a square recording field with half the edge length of the largest fluorescent screen format is imaged. While the first camera images the entire usable field of the fluorescent screen, e.g. 40 x 40 cm, the second camera is optically adjusted so that it only images the middle field, e.g. 20 x 20 cm. This means that the maximum spatial resolution in the small image format is doubled compared to the full fluorescent screen format. This enables the doctor to take an image of an organ region with particularly high resolution.

On the other hand, the second camera can be designed so that it is equipped with a CCD sensor of only 1000 x 1000 pixels. This results in a smaller amount of data per image with reduced spatial resolution. However, it is extremely advantageous that the camera in this design can take several images in a row in a short time, up to a frequency of 8 images per second. With the reduced amount of data per image, the computer unit can also display such a fast sequence of images almost in real time. This

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This gives the doctor the opportunity to follow, for example, the insertion of a catheter or the administration of an injection on the monitor with almost no delay.

The computer unit essentially includes patient data management, adjustment of the recording dynamics, contrast adjustment, brightness adjustment, black and white reversal, magnification, an electronic magnifying glass, calculation and display of the brightness characteristics, a measuring program for distances, angles, areas of image objects and photometry or density measurement in the form of computer programs, as well as recording programming as well as playback, processing, storage and archiving of the recorded digital X-ray images. The computer device also has an interface to the X-ray generator, which is electrically decoupled from the generator by means of a galvanic separation, and software for organ-programmed recording control of the generator at the click of a mouse. The recording parameters are communicated to the generator organ-related at the click of a mouse. Settings on the generator are therefore no longer required. The current recording parameters are logged in the patient recording file. In addition, various individual calculation parameters for image processing can be programmed for each organ program. This means that each image is processed organ-related and automatically as the user wishes as soon as it is fed into the computer.

An embodiment of the invention is described in more detail below with reference to drawings.

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Fig. 1 is an exploded view of a detector and

Fig. 2 is a schematic representation of the X-ray device.

The detector unit 2 consists of a multi-part housing 3 with detector cover 25 and camera cover 29, which encloses the following components and is lined with lead to protect against scattered radiation:

Firstly, an anti-scatter grid 9 as a fixed grid in guide rails for removing the anti-scatter grid 9 for images that are to be taken without a grid. Following the anti-scatter grid 9 is a 3-field ionisation chamber with a preamplifier which, in conjunction with the automatic exposure of the X-ray generator 13, stops the radiation when the required dose rate is reached. This is followed by the fluorescent screen 4 with a usable input field of 40 x 40 cm. The high-performance optics 5 optically match the fluorescent screen 4 and the CCD sensor and are made of lead glass to shield the subsequent components against X-rays. Behind the optics 5 is a highly sensitive sensor 6, in particular a CCD sensor which in this embodiment has an image matrix of 2000 x 2000 pixels. The downstream digital camera 7 processes the signal from the sensor 6 into a digital signal.

The schematic X-ray device consists of the radiation source 1, which is controlled by the X-ray generator 13 with control panel 14. The object to be examined 10 is located in the radiation field 11.

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The detector unit 2 described above is arranged in a manner that consists of the individual items rater 9, measuring chamber 8, fluorescent screen 7, detector housing 3, optics 5, sensor 6, camera 7 and buffer 12. The detector unit can optionally be equipped with a second camera 24. The signal line 22 between the detector unit and the X-ray generator 13 and the data line 25 between the computer and the X-ray generator 13 are made of galvanic isolators 15. Various peripheral devices can be connected to the computer 16, such as the input keyboard 21, mouse 20, microphone 19, loudspeaker 18, monitor 17 and printer 23.

Claims (14)

1. X-ray device for digital radiography with a radiation source, a detector unit for the emitted radiation which supplies digital output signals, a computer device connected downstream of the detector unit and which processes the output signals, and an input and display device, characterized in that the detector unit ( 2 ) has a housing ( 3 ) with a fluorescent screen ( 4 ), a downstream optics ( 5 ) and a camera ( 7 ) with a sensor ( 6 ) which converts visible light into digital pulses. 2. X-ray device according to claim 1, characterized in that the optics ( 5 ) contains lenses made of lead glass. 3. X-ray device according to claim 2, characterized in that the optics ( 5 ) contains so many lenses made of lead glass that the X-ray radiation is almost completely absorbed in front of the sensor ( 6 ). 4. X-ray device according to one of the preceding claims, characterized in that the fluorescent screen ( 4 ) which converts X-rays into visible light consists of a film which has an approximately trapezoidal characteristic curve of a flash, a lighting duration and an afterglow over an excitation time. 5. X-ray device according to claim 4, characterized in that the afterglow time of the film is extremely short. 6. X-ray device according to one of the preceding claims, characterized in that the resolution of an image displayed on a display device has a resolution of 2.8 line pairs per millimeter (Lp/mm) and better. 7. X-ray device according to one of the preceding claims, characterized in that a measuring chamber ( 8 ) for switching off the radiation source ( 1 ) after a required dose rate has been reached is arranged in front of the fluorescent screen ( 4 ). 8. X-ray device according to one of the preceding claims, characterized in that a static anti-scatter grid ( 9 ) can be inserted into the beam path ( 11 ) in front of the fluorescent screen ( 4 ) and in front of a measuring chamber ( 8 ) that can be placed in front of it. 9. X-ray device according to one of the preceding claims, characterized in that an intermediate storage device ( 12 ) is arranged in the camera ( 7 ). 10. X-ray device according to claim 9, characterized in that the buffer ( 12 ) has a memory depth of 24 bits. 11. X-ray device according to one of the preceding claims, characterized in that the radiation source ( 1 ) with a generator ( 13 ) and a control panel ( 14 ) is separated from the detector unit ( 2 ) and the computer device with its input and output devices via a galvanic isolator ( 15 ). 12. X-ray device according to one of the preceding claims, characterized in that the X-ray generator ( 13 ) is connected to the camera ( 7 ) via a galvanically isolated line ( 22 ), via which the recording duration can be transmitted from the X-ray generator ( 13 ) to the camera ( 7 ) by means of a signal. 13. X-ray device according to one of the preceding claims, characterized in that a second optics with a camera ( 24 ) is arranged on the side of the housing ( 3 ). 14. X-ray device according to one of the preceding claims, characterized in that the computer device has an organ automation by which optimized recording parameters for a selected organ such as recording voltage, mAs product, measuring field of the measuring chamber, size of the recording field with corresponding fade-in of the depth diaphragm can be set.