JPH0477440B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides optimal imaging conditions under which an optimal image of an X-ray photograph can always be obtained regardless of changes in transparency due to changes in subject thickness, etc. X-ray photography equipment that can be automatically set from The present invention relates to an X-ray photographing apparatus that has a degree of freedom in setting optimal imaging conditions and can set optimal imaging conditions that also take into account the experience and knowledge-based preferences of a doctor or other surgeon who administers the procedure.

In order to obtain the optimal X-ray photograph, the imaging system (X
The most appropriate imaging conditions must be set for the radiation tube, object, film, photosensitive paper, etc.).

As one means for this purpose, a concept has been proposed in which optimal imaging conditions are obtained based on fluoroscopic conditions performed prior to X-ray photography.

This method of determining imaging conditions from fluoroscopic conditions first provides a fixed relationship between fluoroscopic conditions (tube voltage, tube current) and imaging conditions (tube voltage, tube current, exposure time). For example, when the fluoroscopic tube voltage is determined assuming that the fluoroscopic tube current is constant, the imaging tube voltage is determined based on a certain relationship, and at the same time, the imaging tube current imaging time is also uniquely determined. Moreover, this relationship can only change uniformly from a low fluoroscopy tube voltage to a high fluoroscopy tube voltage.

Therefore, since the fluoroscopy conditions and imaging conditions are uniquely determined, it is possible to determine the optimal imaging conditions (tube voltage, tube current, exposure time) to obtain the optimal X-ray image for all changes in the subject. Cannot be set.

In addition, there is no consideration given to the differences between the image forming systems of the fluoroscopy system and the imaging system, and the differences in film, intensifying screen, etc. that are selected depending on the purpose of imaging and the object to be photographed are not taken into consideration for each imaging system and for each tube voltage. It is practically impossible to set optimal photographing conditions. Furthermore, the image quality of an X-ray photograph is influenced by the experience and knowledge of the doctor or other operator who makes the diagnosis, and the optimal imaging conditions vary depending on this, but no consideration is given to this point. It is something.

In view of the above, this invention provides a degree of freedom in determining imaging conditions from fluoroscopic conditions in response to changes in the subject, and allows doctors to improve the The experience of the operator,
The doctor can determine the optimal X for diagnosis, which also reflects the knowledge
An object of the present invention is to provide an X-ray photographing apparatus that can automatically set optimal photographing conditions for taking a radiograph based on fluoroscopic conditions.

For this reason, the X-ray photographing apparatus of the present invention obtains the relationship between the thickness of the subject and the optimal fluoroscopy conditions through actual fluoroscopy. Furthermore, regarding photography, the surgeon (doctor)
The imaging system used by (X-ray tube, film,
The operator sets and memorizes the optimal relationship between the subject thickness and imaging conditions (tube voltage, tube current, exposure time) (tube voltage, tube current, exposure time) or actual measured data. The present invention is characterized in that practical data relating to fluoroscopy and photography are stored, and thereafter, photographing conditions are determined from the fluoroscopy conditions from the stored data in accordance with the thickness of the subject to be photographed through fluoroscopy.

Examples will be described below. FIG. 1 is a characteristic diagram showing the relationship between object thickness and fluoroscopic tube voltage using tube current as a parameter. Points A to C in the figure are the optimum fluoroscopic tube voltages obtained by a known fluoroscopic brightness automatic adjustment mechanism by actually using, for example, a human body equivalent phantom and changing the phantom thickness. ac corresponds to the points A to C when changing the fluoroscopic tube current. Obtaining this data is
It can be easily obtained by using Phantom.

FIG. 2a is a characteristic diagram showing the relationship between object thickness and imaging tube voltage, and FIG. 2b is a characteristic diagram showing the relationship between object thickness and tube current x imaging time. Points A' to C' and points A'' to C'' are conditions corresponding to the thicknesses of points A to C in FIG.

In this case, the imaging data corresponding to points A' to C' and A'' to C'' can be determined according to the operator's will. That is, the operator can consider the optimal conditions for one imaging system based on his experience and knowledge, or the imaging conditions for photographs that are easy to diagnose and desired by the operator, who has great significance in X-ray photography. In addition, in the imaging system, we used a phantom to collect data on A′ to C′, as well as data collection for fluoroscopic conditions.
It is also possible to “actually measure” and determine the data from A″ to C″. Although not shown, the tube current×imaging time (mA×sec) shown in FIG. 2b may be decomposed into mA and sec for determination.

A~C, A'~C' determined in this way,
Each data of A″ to C″ is stored in a memory described later. During actual photography, when a certain subject is viewed through, a fluoroscopic tube voltage is obtained that is adjusted to obtain the optimum fluoroscopic image by the automatic fluoroscopic brightness adjustment mechanism, and this tube voltage is calculated based on the fluoroscopic tube voltage, which takes into account the effects of scattered radiation, etc. gives an indication of the thickness of the Therefore, using this fluoroscopy tube voltage as an index, the object thickness can be determined from the characteristic diagram in Figure 1, and from this, Figures 2 a and b
The optimal tube voltage, tube current, and time for imaging can be determined according to the thickness of the subject by referring to the data of the characteristic diagram. Of course, points other than the stored data can also be calculated by linear interpolation or the like.

FIG. 3 is a block diagram showing the configuration of an apparatus for carrying out the present invention. In the figure, reference numeral 1 indicates an imaging control unit that sets and controls the tube voltage, tube current, and exposure time during imaging, and 2 indicates a fluoroscopy control unit that sets and controls the tube voltage and tube current during fluoroscopy. 3 is an X-ray high voltage generator, 4
is an X-ray tube, 5 is a subject, 6 is a photographic film holding device, 7 is an image amplifier amplifier (II),
Reference numeral 8 denotes a television camera and a camera control unit that captures the output image of II7 and converts it into an electrical signal, 9 a TV for monitoring, and 10 samples the electrical signal of the camera control unit 8 so that the TV image for monitor has a predetermined brightness. This is a signal processing unit for controlling the perspective control unit 2 and adjusting the perspective brightness. 11
is a microcomputer (arithmetic device), 12
is a memory connected to the microcomputer 11. In addition, the above II7, the TV camera and camera controller section 8, and the monitor TV9
It constitutes a TV fluoroscopy system.

In the above configuration, first, a phantom is inserted as the object to be examined in order to determine the fluoroscopy conditions. When the operator performs a fluoroscopy operation by controlling the fluoroscopy control section 2, the fluoroscopy control section 2 is controlled by the operation of the signal processing section 10 so that the image on the monitor TV 9 is optimized, and the fluoroscopy conditions (fluoroscopy tube voltage) are adjusted. Automatically set. At this time, the thickness of the phantom is not converted to the human body thickness if necessary, and the human body thickness and the fluoroscopy conditions at that time are stored in the memory 12 through the microcomputer 11 manually or automatically using a keyboard or the like.

Furthermore, the perspective conditions are actually measured at two to three points (the more data there is, the higher the accuracy of the system is) at various phantom thicknesses. Through this series of operations, the data shown in FIG. 1 is stored in the memory 12.

Next, in order to determine the photographing conditions, enter the phantom of the phantom thickness used when the fluoroscopic conditions were obtained first, and set the conditions in the photographing control unit 1 to obtain the desired photograph at each thickness. , take pictures. The optimal imaging conditions (tube voltage and tube current) obtained for each thickness in this way are stored in the memory 12 in the same way as for the fluoroscopic conditions. When determining the photographing conditions, it is also possible to determine the photographic conditions in such a way that a photograph containing much of the information required by the surgeon can be obtained. By memorizing the fluoroscopic imaging conditions for several points within the range of human body thickness that the surgeon is likely to use on a daily basis as described above, the operator's experience can also be used for imaging conditions for body thicknesses that have not been collected. , knowledge is reflected. In other words, by using a well-known interpolation method such as linear interpolation or functional interpolation between the data input and stored using the method described above, the operator's experience and knowledge reflected in the input data can be calculated using a microcomputer. This applies to each human body thickness. At this time, for example, if you want to keep the imaging time constant for a certain part regardless of body thickness, by making the imaging time term of the input data constant, the imaging time for other points corresponding to the human body thickness will also be constant. Can be done.

In this way, after storing the data regarding the optimal fluoroscopic view and the optimal imaging conditions for the thickness of the subject, that is, the characteristic diagrams shown in FIGS. 1 and 2, in the memory 12, by performing fluoroscopic photography of the subject, The optimal shooting conditions corresponding to the thickness are automatically set.

That is, the subject 5 is positioned in front of II7,
When the fluoroscopy switch (not shown) provided in the fluoroscopy control section 2 is closed with the film holding device 6 removed from the front of the II 7 (as shown), the X-ray tube 4 is energized and the subject 5 is exposed to X-rays. It is illuminated and fluoroscopy is performed.

At this time, due to the action of the signal processing section 10,
The fluoroscopic conditions, ie, the fluoroscopic tube voltage corresponding to the thickness of the subject 5, are automatically set so that the TV image has a predetermined brightness.

This automatically set fluoroscopic tube voltage is based on the data stored in the memory 12 and compared with the data interpolated by the microcomputer 11 to find the optimal imaging conditions (tube voltage, tube voltage, etc.) corresponding to the thickness of the subject 5. current and exposure time) are read out from the memory 12 and set in the imaging control section 1.

Thereafter, the film holding device 6 is positioned in front of the II 7, and the
When the radiation exposure switch is closed, a photograph can be taken under optimal photographing conditions corresponding to the thickness of the subject automatically set during the fluoroscopy process.

As described above, according to the present invention, when determining the imaging conditions from the fluoroscopic conditions, the experience and knowledge of the operator, a large amount of information regarding the imaging conditions for each region, and the image forming system of the fluoroscopy system and the imaging system are used to determine the imaging conditions. It is now possible to freely input information on the differences between images, and automatically set the optimal imaging conditions (tube voltage, tube current, exposure time) for the subject, regardless of the thickness or part of the subject. X-ray photographs with optimal image quality for X-ray diagnosis, reflecting the experience and knowledge of the doctor, can be obtained.

In the embodiment, an automatic fluoroscopic brightness adjustment mechanism was used in order to obtain the optimum fluoroscopic tube voltage corresponding to the thickness of the subject, but it may also be manually stored in the memory using a numeric keypad or the like.

In short, any method is sufficient as long as it automatically determines the imaging conditions using data input by the operator separately from the tube voltage and tube current of the fluoroscopy conditions. Furthermore, in the embodiment, it has been described that data regarding the optimum fluoroscopic condition for the thickness of the object is collected with the fluoroscopic tube current set at a certain value, but this value is changed depending on the object. Therefore, in practice, data on the relationship between human body thickness and fluoroscopy tube voltage is collected and stored for fluoroscopy tube currents at two or more points. If a fluoroscopic tube current that has not been collected or stored is set, the human body thickness may be determined from the optimal fluoroscopic tube voltage at that time using a data interpolation method, and the optimum imaging conditions may be calculated.

Furthermore, the human body thickness and optimal fluoroscopy conditions change due to changes in the image effective field of view of the image amplifier amplifier. Therefore, it is also possible to consider a method of treating this case in the same way as when the fluoroscopic tube current changes. Furthermore, if a phototimer is used during photographing, the photographing time automatically set by the apparatus of the present invention may be used for backup purposes. In this case, it is sufficient to store in memory the photographing conditions set to be slightly longer than the photographing time by the phototimer.

Furthermore, in the configuration of the embodiment, if a rewritable memory element such as C-MOS RAM is used as a memory element and is combined with a microcomputer, the optimum fluoroscopy conditions and the corresponding optimum imaging conditions can be arbitrarily rewritten as necessary. becomes possible.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the relationship between object thickness and imaging tube voltage, Figure 2a is a characteristic diagram showing the relationship between object thickness and imaging tube voltage, and Figure 2b is a characteristic diagram showing the relationship between object thickness and imaging tube voltage. A characteristic diagram showing the relationship, and FIG. 3 is a block diagram showing the configuration of an embodiment of the device of the present invention. 1: Imaging control unit, 2: Fluoroscopic control unit, 3: High voltage generator, 4: X-ray tube, 5: Subject, 6: Film holding device, 7: II, 8: Television camera and camera control unit, 9: TV for monitor, 10: Signal processing unit for adjusting perspective brightness, 11: Microcomputer, 12: Memory (arithmetic device).

Claims (1)

[Scope of Claims] 1. In an X-ray photography apparatus equipped with an X-ray TV fluoroscopy system, data regarding optimal fluoroscopy conditions corresponding to different thicknesses of a subject and optimal imaging conditions approximately corresponding to the thickness of the subject are stored. and an arithmetic unit that calculates optimal fluoroscopy conditions and optimal imaging conditions corresponding to the subject thickness that is not stored in the memory between each data based on the data stored in this memory by interpolation calculation such as linear interpolation. 1. An X-ray photographing apparatus, characterized in that the thickness of an object is determined from fluoroscopic conditions, and the optimum imaging conditions corresponding to the thickness of the object are automatically set. 2. The X-ray photography apparatus according to claim 1, wherein the memory is capable of externally setting and storing data regarding at least optimal imaging conditions corresponding to the thickness of the subject.