JPH02502868A - Device for contrast equalization of X-ray images - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Method and device for contrast equalization of X-ray images The present invention Contra of radiographs of the body with locally different penetration to X-ray radiation A method for equalizing the X-ray beams by using a flat fan-shaped X-ray beam. A slit photo with a slit diaphragm where the body is scanned a device for; and interacts with the slit diaphragm and thereby allows the fan-shaped x-ray beam to be At least one controllable absorption device for each section affected This absorption device is momentarily transmitted sector by sector through the body. The amount of radiation transmitted within a particular sector through the absorption device as a function of the amount of radiation is the first threshold (threshold) of the body transparency value that occurs momentarily within the sector; threshold) and is controlled to decrease as it increases upward from the X made with a roller absorption device! ! Methods for equalizing contrast in photos and a slit photographic device for equalized radiography.

Sunshine on hands Xa! A common problem when taking photographs is that the amount of radiation falling on the X-ray detector is Imaging means that can utilize a dynamic range, especially the dynamic XIi film It must be greater than the range.

'For example, when taking an X-ray of the thorax, changes in the transparency of the thorax to XIl radiation is much greater than the variations reproducible by the X-ray film normally used for radiography. big.

As a result, in most cases it is necessary to use several Several X-ray photographs will be required. If the lungs appear to have good contrast reproduction Once the photograph has been taken, it is usually no longer nearly possible to identify the abdominal area. If the photo was taken as well as possible, then the contrast reproduction may be insufficient. It's a minute.

All of this is also related to film selection, processing method and XvA tube settings. be.

Taking multiple photographs can also result in overexposure of the patient to radiation.

Attempts have already been made in the past to eliminate the above problems. death Thus, for example, Dutch patent application No. 8401411 describes This device allows you to examine the patient's thorax, other parts of the body, or the object to be examined. body into a flat fan-shaped x'a beam transmitted by a slit diaphragm. Therefore, scanning in the direction perpendicular to the longitudinal direction of the slot of the slit diaphragm A device for slit photography is described. In addition, slit diaphragm An absorption device is provided which does not interact with the ram and has an absorption element, The absorption element absorbs the influence of the electrical signal generated by the quantity detection means on which the radiograph is taken. The detection means locally detects the radiation dose reaching the patient or object. to the patient at each moment within each sector to match the patient transparency at that point. Therefore, the amount of transmitted radiation is detected.

In this way, the amount of radiation in the radiation transmitted by the patient (or the object to be examined) Match the dynamic range to the dynamic range of available image forming means Is possible. This technique is actually called contrast equalization.

According to the technique described in Dutch Patent Application No. 8401411, the patient or is the attached absorbing element ( (singular or plural) always corresponds to the exposure of the screen forming means attached to said specific value. It is considered to be a state.

In a real situation this means that the exposure of the imaging means, such as X-ray film, may be at a low value. Starting from above which the exposure remains constant as the value of patient transparency increases further. . This averages the image intermediate of all areas corresponding to absorbing elements in that photo. X-rays whose tone is essentially equal to that of all other regions corresponding to the absorbing element Resulting in getting a photo. In this type of photography, the absorbing element provides instantaneous light. Details that fall within the area being barred are clearly visible, e.g. experienced in a pneumothorax. Contrast differences that occur over large areas such as It is difficult to differentiate.

Such pictures are somewhat confusing since the local darkening is no longer proportional to the local patient transparency. It's also unnatural.

Therefore, natural photographs and contrast differences over relatively large areas are A need has arisen for an equalization method to produce photographs that allow detection in minutes. came.

几美ヱJ1ke It is an object of the present invention to meet the said need and to improve the contrast of X-ray images in general. The objective is to provide a reliable and efficient method for cost equalization. For this purpose To this end, according to the invention, a method of the above type: Above that threshold, the higher the transparency value, the more water is transmitted through the body. radiation dose at least within the appropriate range of radiographs to a certain extent (increase rate). It is characterized by an increase in

A slit photographic device for equalizing radiography, comprising an X-ray source and a flat fan. a combination with a slit diaphragm for forming a shaped X-ray beam; The body is therefore scannable; X-ray detector and Ni to collect radiation transmitted through the body at least one absorber located near the slit diaphragm, where appropriate Slit diaphragm instantaneously in each sector of the fan beam under the influence of a strong control signal. at least one element capable of influencing the amount of x-ray radiation transmitted through the system. an absorption device; Detects the amount of X-ray radiation transmitted momentarily through the body for each sector of the fan beam. a detection means for transmitting an input signal to a control device, the detection means transmitting an input signal to a control device; The position forms an output signal that acts as a control signal for the absorption device, and this control device from the first threshold of the amount of radiation transmitted through the body in a particular sector. emitting radiation and absorbing equipment such that the radiation dose presented within said sector is partially absorbed. detection means provided for forming a control signal for controlling the position; A slit photographic device for equalized radiography includes: radiation transmitted through the body; Above the threshold of radiation dose, the higher the value, the more appropriate the radiograph is at least. to correspond to an essentially higher transparency at that point for a given degree within the region. Features.

The invention will be explained in more detail below using the accompanying drawings.

Ward Jshinl direct connection] 笈月 1 is a schematic side view of the apparatus for slit photography; FIG. 2 is a schematic side view of the device for slit photography; FIG. One embodiment of a suitable control circuit for controlling a storage element; FIG. 3 shows the screen radiation dose and patient penetration or is a diagram of the relationship between film blackening; Figures 4 and 5 are diagrams of the modification of the device according to the invention; Show details.

cold 1st master FIG. 1 schematically shows a side view of a device for slit radiography.

The illustrated apparatus includes an XIl source 1 with an X-ray focus F, with a slit duct in front of the X-ray source. Earphragm 2 is placed and this causes XI! fairly flat directed towards detector 4 A fan-shaped X-ray beam 3 is formed. As shown in Figure 1, the X-ray beam 3 is viewed from the side. It has a somewhat wedge-shaped shape, but the height at the X-ray detector position is approximately For example, the width of the beam in the direction perpendicular to the drawing plane is 40 cw. Therefore, it is generally called a flat Xti beam.

The X-ray source and slit diaphragm are designed such that the Xtt beam is perpendicular to the width direction of the beam. angularly, i.e. vertically in the drawing plane as indicated by the double arrow 5. They are movable together to perform a scanning motion. Such a scanning movement The combination with the slit diaphragm is passed through the Xti focal point F and perpendicular to the drawing plane. easily by pivoting as shown by arrow 6 around an axis extending in the angular direction. It is possible to have this done. However, a flat fan performing a scanning motion Shaped beams can also be used, for example as described in Dutch Patent Application No. 8401411. It is also possible to obtain it by other methods.

In the illustrated embodiment, the X-ray detector 4 is vertically stratified during the scanning movement of the X-ray beam. It is a regular large image cassette with a lip-like exposure. Large static images like this Instead of an image cassette, it is possible to convert the incident X-ray radiation into a strip-like light image while strip type x-ray detector where images are used to expose photographic film It would also be possible to use such a strip type X! Application of i-detector An example is shown in Dutch Patent Application No. 8401411.

the patient to be examined or the specimen 7 at a particular moment and in a particular section of the X-ray beam. As a result, XI! Detector compatible section In order to ensure that the exposure of the slit diaphragm 2 is also controlled, An absorption device 8 is placed in the X-ray beam. The absorber is a section of the x-ray beam. The amount of radiation transmitted per sensor and at each instant is controlled under the influence of appropriate control signals. It is set up so that it can be easily accessed.

Some examples of suitable absorption devices are described in Dutch Patent Application No. 8400845. It is listed. - For example, a number of tongues juxtaposed to each other e) An absorber containing 9 is shown in Figure 1, one of which is shown here. The tongue is visible. The tongue is under the influence of the control signal XI! absorb some of the radiation It has a free end that can be introduced into the x-ray beam to varying degrees.

Control signals for the absorber are provided by control circuit 10 . The control circuit 10 is fan-shaped X! ! X-ray radiation transmitted through the patient or specimen 7 per sector of the beam Input from the detection device 11 that instantaneously detects the dose and outputs a corresponding electrical output signal. Receives force signal.

The detection device is placed between the patient or object and the Xi detector 4 as shown in FIG. However, in principle it is also possible to place it behind the X-ray detector 4. In both cases, the detection device responds directly to the incident X-ray radiation or in direct response to optical radiation generated by an x-ray detector in response to incident x-ray radiation Either.

If the detection device is placed between the patient or specimen 7 and the X-ray detector 4, the detection The device is designed to ensure that the final X11 image is as little influenced as possible by the detection device It should be as transparent as possible to line radiation. A suitable detection device is For example Dutch patent application no. 8503152 and Dutch patent application no. 8503 It is described in No. 153.

FIG. 2 shows an embodiment of a control circuit 10 suitable for use in the present invention. 0 forms the connection between the detection device and the absorption device and in principle a set of said subcircuits, including ancillary subcircuits for each set of corresponding parts of the storage device; Although only one of them is shown in the diagram, this will be referred to as the control circuit for simplicity. shall be. Some parts of the control circuit can be connected to all subcircuits by multiplexing techniques. It is noteworthy that they can be used in common.

The control circuit shown in Figure 2 is essentially the control circuit shown in Dutch Patent Application No. 8401411. It is the same as the control circuit. On the one hand, the control circuit 10 is connected via a conductor 20 to a part of the detection device. on the other hand, and an output signal to the corresponding part of the absorber via conductor 21 on the other hand. I will provide a. The control circuit includes a comparator, which in this example includes a reference amplifier 23. including.

A signal proportional to the input signal of the control circuit is input to one of the reference amplifiers via conductor 24. a reference signal, which is also provided by potentiometer 25 in the illustrated embodiment. signal is fed to the other input.

The output signal of the amplifier 23 is at least in polarity the signal supplied to the two inputs. correspond to the difference between The output of the amplifier 23 is connected to the input of the amplifier 26, but the amplification Depending on the type of absorption device used, the amplifier 26 can be a voltage amplifier or a current amplifier. Amplifier 26 may also provide appropriate output signals for control of appropriate portions of the absorber. Form. This output signal is such that the difference between the reference amplifier input signals is reduced to zero. In the illustrated embodiment, the control circuit 10 includes no other inputs. It further includes a power amplifier 27, the output signal of which is supplied to the reference amplifier 23.

The control circuit described here is illustrated and described in Dutch Patent Application No. 8401411. corresponds to the illustrated circuit. Transparency aside, using a circuit like this The final X-rays influenced by a particular part of the absorber over all areas A constant average image halftone (optical density) of the photograph is obtained. The image halftone is potentiometer 25 settings. If the potentiometers 25 of all subcircuits are of the same general the final radiograph is therefore averaged over the entire image area. The image has an octopus halftone.

As already pointed out above, in some situations relatively large parts of the radiograph There is a need to be able to sufficiently detect the contrast between According to the present invention If the difference between the input signals of the reference amplifier is not completely canceled and There continues to be some proportionality between the physical patient transparency and the local image midtones of the radiograph. It is possible to be satisfied by being maintained.

Reference is made to FIG. 3 for a more detailed explanation. Figure 3 shows the horizontal axis in the left half. Patient penetration (or specimen penetration) to X-ray radiation plotted along Screen showing the relationship between T and screen radiation dose S plotted along the vertical axis. The phosphorus radiation dose is the amount of XtI radiation that reaches the X-ray detector.

The left half of Figure 3 shows the screen radiation dose and the image on the X-ray film obtained from it. The relationship between the image halftone (optical density D) and the image halftone (optical density D) is shown. The graph shown is (film (after the image is developed) forms a feint image for low exposures and for high exposures Therefore, so-called reversal, which forms a dark image for high X-ray radiation doses, It is used between films. However, the present invention is applicable to other types of films or is equally applicable to the use of other image forming means.

In the right-hand part of FIG. 3, the thorax is also depicted for illustrative purposes. lung area The area is indicated by I, the abdominal region is indicated by ■7, and the lungs are the most sensitive to X-ray radiation. It is highly permeable, with the abdomen being the least permeable. For illustration purposes, it is also shown in the graph. The associated patient transmission range or optical density range is also indicated by ■ and ■. Ru.

The right-hand part of FIG. 3 shows a number of characteristic curves 30, 31, 32 and 33. Line 30 indicates scan XI! during patient penetration and photography. Any form of influence on the beam Shows the relationship between screen radiation dose in the absence of screen radiation. Therefore the characteristic curve 30 is essentially a straight line. Patient transparency within the abdominal area (hatched area■) corresponds to the screen radiation dose SI, while the screen radiation dose S1 corresponds to the screen radiation dose SI of the film used. It can be seen that the concentration range corresponds to . The range is the film characteristic curve 3 shown in the figure. 4 is essentially a straight line in that range, indicated by W. Although it is not completely within the range, range S1 corresponds to a relatively wide range, so It can be seen that contrast reproduction within this range is good.

On the other hand, for the same general definition of the XII source, the patient penetration in the lung region (hatched region I) is quite large and corresponds to the screen radiation dose range S2, while the range S2 is the concentration Corresponds to range D2. However, the screen radiation dose range S2 It is located well outside the suitable operating range, so if the screen radiation dose is in this range, overexposure will occur. As a result, an extremely dark photograph is obtained, and the area D2 Contrast reproduction is extremely blurred, as evidenced by the relatively small width of It is.

From the graph shown, it can be seen that one and the same photo Show both the lungs and abdomen directly above with sufficient clarity and contrast. That is not easily possible.

A solution to this problem, described in Dutch patent application no. 840i411, is that the straight line 30 and a portion 31a substantially coincident with the inflection point 31e and essentially water It is represented by a curve 31 consisting of a flatly extending portion 31b.

Portion 31a corresponds to a range of low patient permeability, within which the absorption device is activated. not in operation or in actual operation.

However, beyond the inflection point 31e, the detection device, control circuit, absorption device and The control loop formed by the X-ray beam is controlled by the configuration of the reference signal generator 25 (FIG. 2). The goal is an averaged image halftone determined by the If the absorber part (and Such control would result in a uniform gray image if An image will be obtained, however, each of the parts of the absorber at any moment For example, if the area on the X-ray detector has non-negligible dimensions of 4×4ci, give a sound. As a result of this, contrast differences within such a range are As a result of this, the contours also remain visible. However, differences in concentration between the left and right lungs, such as occurs in pneumothorax, It is not possible to see the contrast between such large areas. Actually perfect balance It can be said that equalization has been achieved. In this case, furthermore, the portion of the final radiograph showing the lungs is It is not natural at all, and this can be said to be a drawback. On the other hand, this control method This eliminates overexposure.

According to the invention, therefore, a control curve as shown as 32 is used, but , the part of this curve 32 beyond the same inflection point 31c as before has a slope of a straight line. It has a slope that exists between the slope and the horizontal portion 31b of the curve 31. If something like this If a control curve is used, the patient transparency increases and the film darkens more intensely. The final radiograph retains its natural characteristics, as overexposure does not occur even when It will be done. Therefore, the patient penetration range corresponding to lung region I is the screen for curve 32. corresponding to the radiation range S, which falls within the working range W of the film and which results in The blackening of the fruit film falls within the density range.

Such a control curve completes the difference between the reference amplifier input signals in the control circuit of FIG. This can be achieved by not controlling to zero.

All this is done in fact by configuring the amplifier 26 with a gain control device. It is achievable. The set gain determines the slope of the control curve beyond the inflection point.

More generally, the slope of control curve 32 depends on the x-ray beam, detection device, control circuitry and and by appropriate adjustment of the loop gain in the circuit formed by the absorber. It may be divided into sections.

In addition, the X-ray source also and the contrast that occurs therein can be fully reproduced as is by film. The screening radiation dose should be adjusted so that it still occurs. is clear. This is actually usually the case when taking equalized thoracic photographs. This means that a larger x-ray tube current is used than is used. For example 30 125wcA is used instead of mA.

The functions of the above control circuits can also be performed by a suitably programmed microprocessor. It is pointed out that it is achievable.

The above control method also ensures that the patient permeability range corresponding to the patient's lung region is the control curve 3. Actuation of the film while having even better contrast reproduction than for 2 It is also possible to modify it so that it is played back within the range W.

In FIG. 3, contrast reproduction in lung region I is caused by a steepening of the slope of the control curve 32. It is clearly understandable that the further the improvement, the better. Therefore, at this time The screen radiation dose of the genus is larger, and as a result the attached concentration range D3 is also larger. Become. However, to achieve this effect, if the gain control of amplifier 26 is If the slope of curve 32 is selected to a large angle by appropriate adjustment, the corresponding The screen radiation dose range S is moved out of the working range W of the film. death Therefore, steepening the slope of the control curve within the patient permeability range corresponding to the lung region must be achieved in a different way.

According to the invention, for this purpose the absorption device is provided in which the absorption element comprises a slit diaphragm. The slit of the slit diaphragm is affected only on a predetermined portion of the height of the slit of the diaphragm. It is configurable so that it can give an impact. This applies for example to absorbing elements. mechanical strip that prevents the absorption element from completely closing the slit diaphragm. This can be achieved by using a topper. A similar effect can be achieved by electronic methods or Also by properly programming the microprocessor that controls the absorption elements. It is also achievable.

Suitable mechanical stops can be configured in different ways depending on the type of absorption element used. It is Noh. If a pivoting tongue or sliding element is used If so, a cord (thread) that is connected to the absorbing element and limits its deflection. may be used. This is all shown in FIG. Code in stretched state is indicated by 40, and the dormant code is indicated by 40''. Therefore, the slit S of the slit diaphragm 2 is within the range of part “A” of the overall height. will always remain open.

A similar effect can also be achieved with a stopper 50 as shown in FIG. vinegar Since the topper is placed in front of the slit S, the stopper is transparent to X-ray radiation. The stopper must be made of perspex, for example. It may be manufactured from.

By using such a mechanical stop or an equivalent electric stop, the A control curve of the type shown at 33 in FIG. 3 is formed. This curve is the first part 3 1a, and the portion 31a is a region in which the absorption device is not yet activated or is almost inactive and the screen radiation dose increases in proportion to patient penetration. However, it corresponds to the curve 31. After passing the inflection point, absorption occurs in that range. There follows a 33m sloped section where the collection equipment is in operation. Inclination angle of portion 33a As mentioned above, it is adjustable. After passing the stop point 33b, a section 33e follows, and within the section 33e there is an absorber. The position always has the maximum effect and the screen radiation dose also increases with the opening of the diaphragm slit. Due to the presence of the releasing portion, it increases proportionally to the increase in patient permeability. Therefore, part 3 3e is in principle parallel to straight line 30. If the stopper point 33 as shown in FIG. b is appropriately selected, i.e. at a value of patient permeability lower than the patient permeability within the lung region. If selected, screen radiation dose is proportional to patient penetration throughout the lung region. . Therefore, radiographs are also sensitive to patient transparency seen within the abdominal region. and patient penetration values found within lung region I. As long as the X-ray film used is sufficiently capable of handling the attached screen radiation dose values. Has natural properties.

This latter example is indeed the case of interest. The screen radiation dose range S, has already been As mentioned above, curve 33 also corresponds to the range of patient penetration values attached to the lung region ■. Enter the point corresponding to the point that intersects the enclosure. Therefore, good contrast reproduction is ensured be done.

By adjusting the inclination angle of the curve 33 obtained and the selection of the stopper point 31b (step It is pointed out that it is adjustable by adjusting the topper 40 or 50).

Therefore, the inclination angle of the portion 33a is such that the portion 33a matches the portion 31b of the curve 31. It is pointed out that it is adjustable to In fact, at this time the Dutch patent A system of the type described in application no. The points may be provided electrically or mechanically.

In FIG. 3, a portion 33c of the curve 33 is drawn parallel to the straight line 30. theory Specifically, it is possible to provide the portion 33c with different inclination angles. Absorption device operation A gentler slope can be obtained by increasing the value slightly beyond the stopper point 33b. It is possible to obtain a slope 9. If a mechanical stop device is used, this by dividing the mechanical stopper device into parts corresponding to different absorption elements. and in a spring manner so that displacement is possible under the influence of the force exerted by the absorbing element This is achieved by setting a stopper section. This all takes the form shown in Figure 4. This can be achieved by including a (tension) spring within the coupling member 40.

Similarly, in the configuration of FIG. 5, for example (compression) springs 51 can be used. .

For the slit S section Aj, a second absorption device with an attached control circuit is used. It is also possible to exist.

If electrical stop points are used, this all applies to stop point 33b. The gain of amplifier 26 for screen radiation doses higher than the attached screen radiation dose. or by changing the operation of the microprocessor This can be achieved by

However, in general, the portion 33e is made to stand even steeper than the straight line 30, and as a result, It is important to do this because it will improve contrast reproduction.

The steeper slope of section 33c causes the influence of the absorber to be maximum at point 33b, Reduce again for screen radiation dose values higher than the value attached to stop point 33b. It is possible to obtain it by This effect can be programmed properly, e.g. This can be accomplished by a microprocessor or electronically.

A similar effect can normally be achieved by closing a certain height range of the slit S, but the first absorption The screen gradually opens beyond the stop point of the device, increasing the screen radiation dose. This is achieved by using a second absorption device.

For example, modification of the circuit 10 or modification of the stopper device described above. It is pointed out that various modifications of will be apparent to those skilled in the art.

Therefore, in particular a microprocessor is used to control the absorption device. If so, to achieve a control curve with more than one inflection point and stop point is possible. one or more additional absorbers controlled using separate control signals. A similar effect can be achieved by using For example, on the opposite side of slit S It is possible to place a second absorption device, which lies beyond the slit point 33b. It would be possible to have an inflection point.

At this time, it is possible to form a stopper point in the same way after passing such an inflection point. cormorant.

Such modifications are considered to be within the scope of this invention.

international search report l proboscis snlnMI ass-heavy-e-H・PCT/EP 8g100274 international Investigation report international search report

Claims (23)

[Claims] 1. Radiographic composition of the body with locally varying penetration to X-ray radiation. A method for trust equalization, whereby a flat fan-shaped x-ray beam a slit with a slit diaphragm, through which the body is scanned using photographic equipment; and interacts with the slit diaphragm and thereby allows the fan-shaped x-ray beam to be At least one controllable absorption device for each section affected This absorption device is momentarily transmitted sector by sector through the body. The amount of radiation transmitted within a particular sector through the absorption device as a function of the amount of radiation is the first threshold (threshold) of the body transparency value that occurs momentarily within the sector; thrceshold) is controlled to decrease as it increases upward from the value However, a method for equalizing the contrast of X-ray photographs consisting of an absorption device and; In law; Above that threshold, the higher the transparency value, the more water is transmitted through the body. radiation dose at least within the appropriate range of radiographs to a certain extent (increase rate). A method for equalizing the contrast of radiographs, characterized by an increase in contrast. 2. Above a second threshold of local transparency, which is higher than the first threshold, the fan beam A fan beam whose corresponding sector is not affected by the absorber to more than a predetermined maximum degree The absorption device controls such that a predetermined portion of the The method according to claim 1, characterized in that: 3. The pair of fan beams increases as the local transmittance increases starting from the second threshold. The absorption device is controlled such that the influence of the corresponding sector is reduced starting from said maximum degree. 3. The method according to claim 2, characterized in that: 4. As the local permeability increases starting from a second threshold that is higher than the first threshold, This means that the influence of the corresponding sector of the fan beam on transmittance values lower than the second threshold is also 2. A method according to claim 1, characterized in that the increase is to a different extent than the . 5. As the transmittance value increases, the amount of radiation transmitted through the body is inherently higher. Claims 1 to 4, characterized in that the predetermined degree of the change is adjustable. Method described. 6. 6. The method according to claim 2, wherein the second threshold value is adjustable. Law. 7. A slit photographic device for equalizing radiography, comprising: an X-ray source; Thus, in order to form a flat fan-shaped X-ray beam through which the body can be scanned, a combination body with a slit diaphragm; an X-ray detector for collecting radiation transmitted through the body; at least one absorber located near the slit diaphragm, where appropriate The slit diaphragm is activated momentarily in each sector of the fan beam under the influence of a strong control signal. at least one element capable of influencing the amount of x-ray radiation transmitted through the system. an absorption device; Detects the amount of X-ray radiation transmitted momentarily through the body for each sector of the fan beam. a detection means for transmitting an input signal to a control device, the detection means transmitting an input signal to a control device; The position forms an output signal that acts as a control signal for the absorption device, and this control device from the first threshold of the amount of radiation transmitted through the body in a particular sector. emitting radiation and absorbing equipment such that the radiation dose presented within said sector is partially absorbed. detection means provided for forming a control signal for controlling the position; A slit photographic device for equalized radiography comprising: Above the threshold of radiation dose, the higher the value, the lower the radiation dose corresponds to an essentially higher transparency at that point to a given extent within the appropriate range of A slit photographic device for equalized X-ray photography, characterized in that: 8. characterized in that the control device includes a suitably programmed microprocessor; 8. The apparatus according to claim 7. 9. In the circuit formed by the X-ray beam, detection means, control device and absorption device Claim 7 or 8, characterized in that it comprises means for adjusting the loop gain of the The device described. 10. The controller compares the input signal with a predetermined reference signal representative of the first threshold. including a comparison circuit capable of; and The output of the comparator circuit is such that its gain factor determines the predetermined degree of absorption. 10. A device according to claim 7 or 9, characterized in that it is connected to an amplifier. 11. 11. The method according to claim 9 or 10, characterized in that the gain coefficient is adjustable. Device. 12. Higher than the first threshold of the amount of X-ray radiation transmitted in the sector through the body Starting from a second threshold, more than a fixed maximum portion of X-ray radiation is A control device shall be provided to control the absorption device so that it is not absorbed. toto; and the remainder of the radiation represented within said sector is freely transmitted; 12. A device according to any one of claims 7 to 11, characterized in that: 13. The absorption device includes an absorption element that interacts with the slit of the slit diaphragm. The absorbing element is placed in front of the slit under the influence of the signal from the control device to a certain degree. Although there is a difference, it is possible to move the slit in a direction perpendicular to the longitudinal direction of the slit. In the device according to claim 12, the roller; The second threshold corresponds to the extreme position of the absorbing element, and the slit has a predetermined height range. 13. Device according to claim 12, characterized in that the remains transparent. 14. At least a characteristic of the value of the radiation dose transmitted through the body in a particular sector within a certain range, caused by the control signal and the absorber in response to the control signal. The relationship between the effect on the X-ray beam and the 14. Device according to any one of the preceding claims, characterized by means capable of. 15. at least one stop element for determining the ultimate position of the absorption element in the absorption device; 15. The device according to claim 13 or 14, characterized in that it is provided with a. 16. Placed at a location higher than the first threshold of the amount of X-ray radiation transmitted through the body. Of the radiation dose represented in said sector, starting from a second threshold placed The absorption device is controlled so that the portion corresponding to the second threshold is absorbed to a predetermined degree. a control device is provided so as to represent a residual amount within said sector; the radiation is absorbed to a predetermined second degree; The device according to any one of claims 7 to 11 or 14 or 15, characterized in that: 17. A stop element for each absorbing element is moved by a predetermined resistance by the absorbing element. 16. The stopper according to claim 15, characterized in that it comprises separate stops that can be moved. Device. 18. The stop element for each absorbing element must be transparent to X-ray radiation. element whose element corresponds to a specific deflection of the absorbing element under the influence of a spring force. is pushed into the rest position, but the absorbing element pushes it out of the rest position against the spring force. Claim 1 characterized in that it comprises an element that can be moved out. 7. The device according to 7. 19. If the stop element for each absorption element is an elastic connection between the fixing point and the absorption element 18. Device according to claim 17, characterized in that it has a spring element of: 20. Is the value of the amount of X-ray radiation transmitted within the sector through the body the second threshold? Starting from a second threshold corresponding to the position of maximum absorption as the absorption increases A control device is provided to control the absorber so that the absorber is proportionally reduced by 16. A device according to any one of claims 12 to 15. 21. characterized by at least one second absorption device controlled by a control device 21. The device according to any one of claims 7 to 20. 22. If the amount of X-ray radiation transmitted through the body within a particular sector is If it is greater than the threshold of 3, starting from the rest position, actuate the second absorption device. 22. Apparatus according to claim 21, characterized in that a control device is provided so as to 23. 23. The third threshold corresponds to the second threshold. equipment.