JP3635776B2 - X-ray equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an X-ray imaging apparatus that performs X-ray imaging on a film, and more particularly to an X-ray imaging apparatus having an automatic exposure control function.
[0002]
[Prior art]
An X-ray imaging apparatus is usually provided with an automatic exposure control function (also called a phototimer). That is, when photographing is performed by exposing X-rays to a subject and making the X-rays transmitted through the subject incident on the film for exposure, the X-rays transmitted through the subject are detected by an X-ray detector, When the output is integrated and the integrated value reaches the set value, it is determined that the film exposure (X dose) has reached a desired value, and an X-ray cutoff signal is generated to end the X-ray exposure. Thereby, it is possible to perform photographing at a constant film density.
[0003]
A semiconductor detector or the like is used as the X-ray detector for automatic exposure, but the conversion efficiency does not completely match and the output value may vary, and the output gain of the detector is adjusted for the correction. There is a need. In the conventional apparatus, the adjustment work for this correction is performed manually.
[0004]
That is, a conventional X-ray imaging apparatus is usually configured as shown in FIG. In FIG. 3, when an X-ray exposure signal is supplied from the controller 13 to the high voltage generator 12, the high voltage generator 12 generates a high voltage and applies it to the X-ray tube 11. Thereby, X-rays are emitted from the X-ray tube 11 toward the subject 10. Here, films 21, 22, and 23 (and intensifying screens) are held by three light receiving portions 31, 32, and 33 such as a standing position and a horizontal position, and subject 10 is placed on one of them, for example, film 21. The transmitted X-ray is exposed. Each of the light receiving units 31, 32, and 33 is a multi-lighting field having three lighting fields, and semiconductor X-ray detectors 41 to 49 are provided in each of the lighting fields. These detectors 41 to 49 detect X-rays that have passed through the subject 10 and convert them into electricity (current). The outputs of these detectors 41 to 49 are switched by a switch 50.
[0005]
Here, assuming that the light receiving unit 31 is used, the outputs of the detectors 41, 42, 43 of the light receiving unit 31 are selected by the switch 50, and the respective output currents pass through the protective resistors 51, 52, 53. Input to each of the current / voltage converters 61, 62, 63. The output converted into voltage is input to the integrators 81, 82, and 83 and integrated. The integrated output voltages Vs1, Vs2, and Vs3 correspond to the film exposure amount (X dose) and are input to the comparators 91, 92, and 93, respectively, and compared with the reference value (set voltage) Vref from the controller 13. When the integrated voltage reaches the reference value, an X-ray cutoff signal is sent to the controller 13. As soon as the controller 13 receives this X-ray cut-off signal, it controls the high voltage generator 12 to cut off the high voltage supplied to the X-ray tube 11 and stop the X-ray exposure.
[0006]
Since the conversion efficiencies of the detectors 41 to 49 do not completely match, the integrated outputs Vs1, Vs2, and Vs3 are not always the same even with the same X-ray dose. Therefore, by providing variable resistors in the current / voltage converters 61, 62, and 63 and adjusting them, variations in the detectors 41 to 49 are corrected so that the same integrated output can be obtained with the same X-ray dose. In this case, each of the three current / voltage converters 61, 62, and 63 receives three outputs from the selected light receiving unit, but since there are three light receiving units, each of them is for adjustment. The variable resistor is provided and switched with a switch.
[0007]
That is, since it is necessary to provide three variable resistors for each of the light receiving units 31 to 33 in each of the three current / voltage converters 61, 62, and 63, a total of nine variable resistors 111, 121, 131, and 112 are provided. , 122, 132, 113, 123, 133 are used by switching between the changers 211, 221, 231, 212, 222, 232, 213, 223, and 233. In order to adjust the output of each of the detectors 41 to 49, each of these nine variable resistors is manually adjusted.
[0008]
[Problems to be solved by the invention]
However, there is a problem that it is very troublesome and troublesome to manually adjust the output gain of the automatic exposure X-ray detector as in the prior art. That is, normally, the variable resistor knob for adjusting the output is not provided in an easily accessible place such as a panel surface of the controller, and is housed inside a cabinet such as the controller and cannot be easily adjusted. In particular, when there are multiple light receivers in a multi-lighting field, the number of locations to be adjusted becomes very large, and the work becomes complicated accordingly, which requires a lot of labor and time. become. Moreover, since it is manual adjustment at difficult places, it is difficult to adjust accurately.
[0009]
In view of the above, an object of the present invention is to provide an improved X-ray imaging apparatus so that adjustment for correcting variations in the output of an automatic exposure X-ray detector can be easily performed.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, in the X-ray imaging apparatus according to the present invention,
X-ray generation means, a plurality of light receiving sections each holding a film, a plurality of automatic exposure X-ray detection means provided for each of the light receiving sections, and the X-ray detection means according to the light receiving section used. A switch for selecting an output; a gain adjusting means for adjusting the gain of the output of the X-ray detection means that has passed through the switch according to a gain adjustment signal from the outside; an integrating means for integrating the adjusted output; Comparing means for comparing the integrated value with the set value and generating an X-ray cutoff signal when the integrated value reaches the set value; and a control means for changing the gain by giving a gain adjustment signal to the gain adjusting means. Is provided,
The control means repeats the X-ray exposure from the X-ray generation means under a reference X-ray condition, the integrated value for each X-ray detection means output reaches a reference set value, and the X-ray cutoff signal is The gain adjustment signal is changed so that the generated time converges to the reference exposure time, the gain adjustment signal at the time of convergence is stored for each of all the X-ray detection means, and the above-described gain adjustment signal is used according to the light receiving unit used. When the X-ray detection means output is selected by the switch, the gain adjustment signal stored for the selected X-ray detection means output is read to determine the gain of the gain adjustment means. ing.
[0011]
By giving a gain adjustment signal from the control means to the gain adjustment means, each output gain of the automatic exposure X-ray detection means is adjusted. Each gain adjustment signal is obtained in advance and stored in the control means. When the output of the X-ray detection means is selected by the switch according to the light receiving unit to be used, the selected X-ray detection signal is detected. The gain adjustment signal stored for the means output is read, and the gain of the gain adjustment means is determined. A plurality of X-ray detecting means for automatic exposure are provided for each of the plurality of light receiving units, and the number of automatic X-ray detection units is very large as a whole, and it is not possible to manually adjust the gain for correcting variations in output. Although it takes a lot of time and effort, since the gain is determined by reading out the gain adjustment signal obtained and stored in advance as described above and applying it to the gain adjustment means, such time and effort can be saved.
[0012]
Furthermore, the work of obtaining and storing gain adjustment signals for a number of X-ray detection means for automatic exposure in advance is automated and easy. The control means repeats the X-ray exposure from the X-ray generation means under the reference X-ray condition, and the time during which the integrated value for each X-ray detection means reaches the reference set value and the X-ray cutoff signal is generated The gain adjustment signal is changed so as to converge at the reference exposure time, and the gain adjustment signal at the time of convergence is stored for each of all the X-ray detection means, and the operation is automatically performed.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1, when an X-ray exposure signal is supplied from the controller 13 to the high voltage generator 12, the high voltage generator 12 generates a high voltage and applies it to the X-ray tube 11. Thereby, X-rays are emitted from the X-ray tube 11 toward the subject 10. X-rays transmitted through the subject 10 are exposed to, for example, the film 21. An intensifying screen or the like may be used in combination with the film 21. Here, the films 21, 22, and 23 (and the intensifying screen) are held by the three light receiving portions 31, 32, and 33 such as the standing position and the horizontal position. Each of the light receiving units 31, 32, and 33 is a multi-lighting field having three lighting fields, and semiconductor X-ray detectors 41 to 49 are provided in each of the lighting fields. These detectors 41 to 49 detect X-rays that have passed through the subject 10 and convert them into electricity (current). The outputs of these detectors 41 to 49 are output via a switch 50.
[0014]
Here, assuming that the light receiving unit 31 is used, the outputs of the detectors 41, 42 and 43 of the light receiving unit 31 are selected by this switch, and the respective output currents are passed through the protective resistors 51, 52 and 53 as currents. / Input to each of voltage converters 61, 62, 63. The output converted into the voltage is gain-adjusted by each of the analog computing units 71, 72, 73, and then input to the integrators 81, 82, 83 for integration. The integrated output voltages Vs1, Vs2, and Vs3 correspond to the film exposure amount (X dose) and are input to the comparators 91, 92, and 93, respectively, and compared with the set values (set voltages) from the controller 13, When the integrated voltage reaches a set value, an X-ray cutoff signal is sent to the controller 13. As soon as the controller 13 receives this X-ray cut-off signal, it controls the high voltage generator 12 to cut off the high voltage supplied to the X-ray tube 11 and stop the X-ray exposure.
[0015]
The reason why the detector output gain is adjusted by the analog calculators 71, 72, and 73 is to correct variations in the outputs of the detectors 41 to 49. When the detector of another light receiving unit is selected by the switch 50, a gain adjustment signal corresponding to the detector is sent from the controller 13 to the analog calculators 71, 72, 73, and appropriate correction is performed.
[0016]
Since the gain adjustment signal corresponding to each of the detectors 41 to 49 for performing the appropriate correction is generated from the controller 13, it is manually set to an arbitrary optimum value by an appropriate operation from the panel surface of the controller 13. Can be determined.
[0017]
Alternatively, the controller 13 may be configured to automatically obtain and hold the controller 13. In that case, first, the film 21, 22, 23 (and the intensifying screen) and the FID (distance from the focal point of the X-ray tube 11 to the film) are predetermined for all of the plurality of light receiving units 31, 32, 33. Fix it. The tube voltage and tube current applied to the X-ray tube 11 from the high voltage generator 12 are also set to predetermined values and fixed. Thereby, X-rays are emitted from the X-ray tube 11. As the subject, a reference material such as an acrylic plate having a thickness of 200 mm is used. At this time, the X-ray cutoff signal obtained from the outputs of the detectors 41 to 49 is not used, and automatic exposure control is not performed. Then, the exposure time when the film density becomes constant (Density becomes 1.3, for example) is measured by a separate means. When this exposure time is measured as T, the T is registered as a reference exposure time from the panel surface of the controller 13 or the like.
[0018]
Next, X-ray exposure and gain adjustment are performed according to the procedure shown in the flowchart of FIG. First, X-ray conditions such as films 21 to 23 (and intensifying screen), FID, tube voltage / tube current, etc. are not changed. . At this time, the automatic exposure control using the outputs of the detectors 41 to 49 is activated. A predetermined reference value Vref is used as a set value given to the comparators 91 to 93. The integration outputs Vs1, Vs2, and Vs3 from the integrators 81 to 83 are compared with the reference value Vref in the comparators 91, 92, and 93. When the former reaches the latter value, an X-ray cutoff signal is generated. X-ray exposure is blocked.
[0019]
At this time, the exposure time t until the X-ray cutoff signal is generated is obtained for each of the comparators 91, 92, and 93 (for this reason, the switch 50 is controlled so that only the detection signal of one detector is output). The t is compared with the reference exposure time T described above. If t is shorter than the reference exposure time T, a numerical value is input by operating the panel so as to increase the gain of the analog computing unit 71 (or 72, 73), and a gain adjustment signal corresponding to the numerical value is output. If t is longer than T, a numerical value that decreases the gain is input, and a gain adjustment signal corresponding to the numerical value is output. Then, the exposure time t is obtained again by X-ray exposure, and if this does not coincide with the reference exposure time T, an operation of inputting a numerical value for increasing or decreasing the gain and controlling the gain is repeated. By repeating this operation, t can be converged to match T within a range including an allowable error. If t can be matched with T in this way, the gain adjustment signal at that time is stored in the controller 13.
[0020]
Such an operation is first performed for the three detectors 41, 42, and 43 of the light receiving unit 31 while switching the switch 50, and then for the three detectors 44, 45, and 46 of the light receiving unit 32, and then the light reception is performed. This is performed individually for all the detectors of all the light receiving sections, such as for the three detectors 47, 48, 49 of the section 33, and the individual gain adjustment signals for all the detectors are stored in the controller 13.・ Hold it.
[0021]
Accordingly, X-ray exposure is performed several times only by an input operation on the panel surface of the controller 13, and correction values for correcting individual variations of a large number of automatic exposure X-ray detectors are obtained, stored and held. Can do. When the actual subject 10 is photographed, when the detector is selected by the switch 50, the correction value (gain adjustment signal) of the detector is read out, and the analog calculators 71, 72, 73 are accordingly read. Is adjusted, so that variations in detectors can be automatically corrected.
[0022]
In the above description, the number of the light receiving units is three, and each of the three lighting fields is provided. However, these numbers are merely examples, and the number of the light receiving units and the lighting fields (detectors) can be increased. . On the contrary, even in the case of a single lighting field (one lighting field and one detector), applying the present invention is effective in saving labor and time for correcting the output of the detector. Furthermore, although an analog computing unit is used to adjust the detector output gain, other circuits can be used as long as the gain can be adjusted by an external control signal. Further, the operation of obtaining, storing and holding correction values for correcting individual variations of a large number of automatic exposure X-ray detectors may be performed manually instead of automatically as described above.
[0023]
【The invention's effect】
As described above, according to the X-ray imaging apparatus of the present invention, the operation for correcting the output of the automatic exposure X-ray detector can be performed very easily, and the labor and time can be saved. Is possible. Since the output of the automatic exposure X-ray detector is corrected in this way, the photographing time by the automatic exposure control becomes appropriate, and the film density is always kept constant. In particular, operations for obtaining, storing and holding correction values for correcting individual variations of a large number of X-ray detectors for automatic exposure are automatically performed, so that the operation is easy and accurate.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of the present invention.
FIG. 2 is a flowchart showing an operation.
FIG. 3 is a block diagram showing a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Subject 11 X-ray tube 12 High voltage generator 13 Controller 21-23 Film 31-33 Light-receiving part 41-49 X-ray detector 50 for automatic exposure control 50 Switch 53-53 Protection resistance 61-63 Current / voltage converter 71-73 Analog computing units 81-83 Integrators 91-93 Comparators
111 to 113, 121 to 123, 131 to 133 Variable resistance
211-213, 221-223, 231-233 selector

Claims (1)

X-ray generation means, a plurality of light receiving sections each holding a film, a plurality of automatic exposure X-ray detection means provided for each of the light receiving sections, and the X-ray detection means according to the light receiving section used. A switch for selecting an output; a gain adjusting means for adjusting the gain of the output of the X-ray detection means that has passed through the switch according to a gain adjustment signal from the outside; an integrating means for integrating the adjusted output; Comparing means for comparing the integrated value with the set value and generating an X-ray cutoff signal when the integrated value reaches the set value; and a control means for changing the gain by giving a gain adjustment signal to the gain adjusting means. With
The control means repeats the X-ray exposure from the X-ray generation means under a reference X-ray condition, the integrated value for each X-ray detection means output reaches a reference set value, and the X-ray cutoff signal is The gain adjustment signal is changed so that the generated time converges to the reference exposure time, the gain adjustment signal at the time of convergence is stored for each of all the X-ray detection means, and the above-described gain adjustment signal is used according to the light receiving unit used. When an X-ray detection means output is selected by the switch, a gain adjustment signal stored for the selected X-ray detection means output is read to determine the gain of the gain adjustment means. X-ray imaging device.

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