JPS6348542B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention involves loading a dental film into the patient's oral cavity, and placing it on the floor or wall so that the central axis of Alternatively, the present invention relates to a dental X-ray photographing apparatus in which the diagnostic site is photographed using an X-ray generator suspended from the ceiling by a flexible arm.

In general, in an X-ray device that takes X-ray images on intraoral dental film, a base is fixed on the floor or the like, and the tip of a flexible arm mechanism such as a spring balance type that bends, rotates, and expands and contracts is rotatably supported by a hanger at the end of the arm mechanism. The relative angle with respect to the X-ray generator is always kept constant regardless of the above-mentioned refraction, rotation, expansion and contraction, etc. In other words, the X-ray generator (hereinafter referred to as head) maintains the X-ray emission central axis horizontally and moves the head vertically and horizontally according to the patient's body position, and then positions the diagnostic area from the front of the patient's head. This is done using an X-ray irradiation tube in the head. By this positioning operation, the X-ray emission central axis of the head is set at any angle of elevation or depression with respect to the horizontal axis on the interlocking plane. This angle is called the average vertical angle formed by the perpendicular plane in the direction of the diagnostic site in the oral cavity, and is approximately constant depending on the diagnostic site in the relationship shown in FIG. For example, as shown in Figure A, in the case of maxillary anterior teeth 2, 1, 1, 2, the X-ray radiation central axis
The angle of depression formed is 50 degrees, and the angle of elevation is 15 degrees with respect to A-A' in the case of the mandibular anterior teeth 2, 1, 1, 2 as shown in Figure J. In FIGS. 1A to 1J, each tooth is classified by a number from 1 to 8, and the number with a (-) above it is the lower jaw tooth, and the number below it is the upper jaw tooth. As you can see in the figure, the front teeth are thin and the molars are thick, so the imaging conditions are naturally different, but the imaging conditions for this type of X-ray equipment are set by keeping the tube voltage and tube current of the X-ray tube constant, and depending on the area to be imaged. Therefore, it is usual to change the photographing time within a range of 0 to 4 seconds, for example. After positioning the diagnosis area using the above procedure, the operator reads the elevation angle or depression angle on the angle scale on the side of the head using the indicator on the head support bearing of the hanger, and determines the imaging time X that suits the tooth. It is determined based on the load characteristics of the ray tube, the imaging condition table, etc., and is set using the timer of the X-ray control device. However, this dental
The quality of the video image of a radiography device is determined more by the accuracy of the positioning operation of the region to be imaged than by the length of the imaging time due to individual differences. Therefore, after completing accurate aiming through careful operation, the surgeon must read the angle of the head and the load on the A series of operations such as calculations and timer settings must be performed, which is troublesome and troublesome for the operator.

This invention has been made in view of the above-mentioned current situation, and includes setting of imaging conditions in a conventional X-ray imaging device that takes X-ray images of teeth on an intraoral dental film, that is, imaging time that is mainly changed for each region to be imaged. This eliminates the drawback of leaving the indexing work to the surgeon, and allows the surgeon to automatically set the optimal imaging conditions after accurately positioning the imaging area. The present invention aims to provide an X-ray imaging device that can quickly take good images and has high diagnostic efficiency. In other words, before loading an X-ray film into the patient's oral cavity and obtaining an X-ray image, the entire upper and lower jaw is divided into multiple imaging areas in advance.
This device stores three imaging conditions for each area to be imaged: tube voltage, tube current, and imaging time of the X-ray tube, and selects an appropriate condition from these according to the area to be imaged. , the plurality of preset imaging regions are identified as symbols, figures, or imaging conditions by the angle of elevation or depression formed by the central radiation axis of the X-ray tube facing the imaging region with respect to the horizontal axis of the occlusal plane. means for displaying the elevation angle or depression angle as an electrical signal, and signal selection means for selecting one of the plurality of angle signals specific to the imaging site based on the detected angle signal; The present invention relates to a dental X-ray imaging apparatus characterized in that it is provided with means for automatically setting optimal imaging conditions stored in advance according to a selected signal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be explained below with reference to the drawings. FIG. 2 is an external perspective view showing an example of the dental X-ray imaging apparatus according to the present invention as a mobile type;
1 is a trolley, and 12 is a main column of the apparatus, which supports an X-ray controller 13 and a spring-balanced flexible arm 14. 15 is an X-ray generator (hereinafter referred to as head)
It houses a main transformer, a wire heating transformer, and an X-ray tube, and is rotatably held, for example, by 300 degrees with respect to a hanger 14H at the tip, as shown in the figure. Hanger 1
The relative angle between 4H and head 15 remains constant regardless of the movement of the flexible arm, such as bending, rotation, expansion and contraction, and for example, as shown in the figure, the central axis of X-ray radiation in the direction of arrow X remains horizontal to the floor surface. It is designed to move in front of the subject's head. Reference numeral 16 denotes an X-ray irradiation tube, which has an open front tube generally called a dental cone to irradiate only the main radiation cone of the X-rays emitted from the focal point of the X-ray tube to the imaged area of the patient (see Figure 1). It is cylindrical in shape and has been devised in various ways to make it easier for the surgeon to position the area to be imaged, such as one that emits a ring-shaped visible light beam from its front edge. Using such an irradiation tube, the first
When the teeth shown in Figures A to J are correctly positioned, the elevation angle (-Θ°) formed by the head's X-ray emission center axis X with respect to the hanger bearing portion 14B.
Alternatively, the depression angle (+Θ°) can be read from a base line (usually one horizontal scale line) 17 provided on the hanger 14H and a ring-shaped angle scale 18 on the side surface of the head. Using this scale 18, the operator confirms the above (±Θ°) with respect to the horizontal axis A-A' of the occlusion plane shown in Figure 1, and as mentioned above, the thickness of the jaw and the The configuration and operation of conventional equipment is to determine an appropriate imaging time based on the load characteristics of This device is different from the conventional device in that the bearing portion 14B is provided with the mechanism explained in FIGS. 3A and 3B, and this is the first essential part of the invention. FIG. 3A is a sectional view showing the structure of a hanger 14H that rotatably supports the head 15.
It is a -' cross section of side view B. Figure B shows a state in which the central axis of X-ray radiation is kept parallel to the floor surface in the direction of arrow X. 19 in Fig. A is an inner box that seals the high voltage transformer, wire heating transformer, and X-ray tube built into the head in oil, and 20 is a shaft washer that is integrated with 19 above and knocks the shaft neck of 21. They are connected and supported in an appropriate manner. The shaft neck 21 is integrally engaged with the outer case 22 of the head 15 at its outer periphery (the outer case 22 is firmly connected to the inner case 19 at a portion not shown), and A display disk 23 is slidably fitted into the neck 21. This display disk 23 is normally locked to the outer case 22 by a stopper 24 made of balls and springs provided on the outer case 22, and rotates integrally with the outer case 22 and the shaft neck 21, which will be described later. When correcting the angle of the display disk 23, it is rotated around the shaft neck 21 against the elastic force of the spring of the stopper 24, so that its position can be shifted by a certain angle. Reference numeral 14B is a bearing portion that slidably supports the shaft neck 21 at the tip of the hanger 14H. This bearing portion 14B includes, for example, a ball snap mechanism 25.
are provided so that the head is properly stopped and stabilized by frictional pressure at positions corresponding to the respective aiming angles (elevation angles and depression angles in FIG. 1) of the imaging region described below. Reference numeral 26 denotes an angle detector whose center is fixed at a position offset by (d) mm from the center point of the concave portion of the shaft neck 21, and is, for example, a multi-rotation potentiometer or several rotary plates of a rotary encoder. . 27 is a pinion attached to the central axis of the angle detector 26, and this pinion is connected to the hanger 14.
It engages with an internal gear 28 fixed concentrically to the shaft neck 21 in the recess at the tip of the H. The dashed-dotted lines 27C and 28C in Fig. B indicate the pitch circles of the pinion 27 and the internal gear 28, respectively. With this configuration, when the head is in an elevation angle, the pinion 27 rolls in the direction of the arrow a, and when the head is in a depression angle, it rolls in the direction of the arrow b. Due to this rolling, the movable contact or rotary plate of the 26 angle detectors detects the positional displacement as an electric signal, and this is the first essential part of the present invention. Reference numeral 29 denotes an electric line for the angle detector, and the inner hole 14P of this hanger 14H accommodates all lines between the head and the X-ray controller other than the line 29. 30 is a hanger bearing cover. Next, the method of displaying the photographed region on the display disk 23 will be explained with reference to Figure B. The displayed numbers 1 to 8 indicate the teeth of the upper and lower jaws in Figure 1, and are the numbers 4 to 8 below the horizontal center line.
8, 3, 1.2 are each tooth 1 of the upper jaw row photographed with the radial center axis X of the head 15 set at an angle of depression (+Θ°)
~ 8 is divided into three types, for example, and the (+50°) in Figure 1 A, the (+45°) in Figure B, and the average angle (+30°) from Figures C to E are expressed with tooth symbols. This is what is displayed. 3 above the horizontal center line,
1.2, 4 to 8 are the first with the head at the elevation angle.
Teeth 4 to 8 at the average elevation angle (-5°) in Figures H to F, 1.2 in Figure J at (-15°), and 3 in Figure I (-20°)
The upper and lower jaws are separated by color-coding with the horizontal center line as the boundary. Note that the same numbers at symmetrical positions indicate the above-mentioned depression and elevation angles using tooth symbols when the radiation center axis X of the head 15 is directed to the opposite side to that shown in Figure B. 17
is a base line drawn on the slope of the tip of the hanger 14H, and if this matches the scale of the tooth symbol, the head is set at the above (±θ°). This is the second essential part of this invention.

Next, when photographing the subject's mandibular teeth, the subject's body position is tilted slightly backwards as shown in Figure 4, and the occlusion plane A-A'' is aligned with the horizontal axis A-
When tilted 20 degrees with respect to A', the radiation center axis of the head 15
Although the mandibular teeth 3 can be photographed while remaining horizontal, the base line 17 of the display disk does not point to 3 as shown in FIG. In such a case, if the angle correction handle 31 provided at the bottom of the display disc 23 is pushed strongly in the clockwise direction, the aforementioned restraint of the display disc stopper 24 can be released. By adjusting the acquisition scale 33 to an arbitrary angle, that is, the subject's body position change angle (-20° in the above example), the imaged area can be displayed correctly on the lower jaw 3.
, and other teeth can also be photographed as shown. Furthermore, display disk 2
The tooth display method of No. 3 is not limited to the six upper and lower jaw divisions shown in FIG. 3, but can also be displayed in ten divisions as shown in FIG. 1 A to J. Furthermore, Figure 5A,
Figure 1 shows the front tooth figures of 2, 1, 1, 2 as shown in B and C, the tooth figure of 3 is shown in figure B, and the tooth figures of 4 to 8 are shown in figure 3 as shown in figure C. Graphics may be displayed at different angular positions on the display disk 23, and it is also convenient for the operator to use both graphics and symbols. Note that the angle display may also display each set imaging time (sec) that is appropriate for the imaging site. The above is the structure and function of the head 15 and hanger 14H. Next, the signal processing circuit used until the electric signal detected by the angle detector 26 sets the imaging time of the X-ray controller will be explained.

In this invention, the above-mentioned signal processing includes both analog signal and digital signal methods, and FIG. 6A is a block diagram showing the basic structure of these methods. The angle detector 26 is a circuit including a multi-rotation potentiometer in the case of an analog type, and a set of three rotary encoder plates in the case of a digital type. Block 42 is a photographing time selection circuit that inputs the detection signal V of block 41 and selects the corresponding photographing time signal Vt. In the case of a digital signal, a 3-bit multiplexer is used. 43 blocks are 42
This is an imaging time setting circuit which receives the signal Vt selected in , and automatically sets an imaging time T suitable for the imaging region by combining a CR integration circuit with a switch element such as an N-gate thyristor and a relay. Block 73 shown by a dotted line is used when the radiation center axis X of the head is directed to the opposite side of the figure as explained in FIG. This is an input circuit, and is unnecessary when using a digital type.
The relationships among the above signals are shown in FIGS. 6B and 6C. Diagram B
The horizontal axis is the aiming angle (±θ°) of the head, the midpoint is the horizontal position (0°), the vertical axis V is the detection signal of the angle detector 26, and the maximum value is the power supply voltage (+Vcc). The current depression angle is 30° (see Figure 3), and when aiming, it is 2/3Vcc.
This indicates that the detection signal Vθ is output.
In Figure C, the horizontal axis is the above-mentioned angle proportional signal Vθ, the left side of the vertical axis is the shooting time setting signal Vt' for elevation angles up to 90°, and the right vertical axis is the shooting time setting signal Vt for depression angles up to 90°.
Even in the horizontal position, the voltage signal is low, and as the angle increases ±θ°, the voltage signal becomes higher, as shown in the figure, and the photographing time T is automatically set in proportion to this voltage. The characteristics of the curve in Figure C only show the tendency, and are not limited to these characteristics, and can be set arbitrarily. The above configuration constitutes the third and fourth essential parts of the present invention, and the circuit embodiment of the block will be explained with reference to FIG. 7 and subsequent drawings.

FIG. 7 is an embodiment of a circuit in which an analog electric signal is used as an angle detection signal, in which the block indicated by a dashed line 41 is the angle detector 26, 44 is a potentiometer resistor, and 45 is its movable contact. The midpoint of 44 corresponds to the horizontal position of the head 15 in Fig. 3, and the angle from the depression angle (-90°) to the elevation angle (+90°) of the head is (+
Vcc) DC voltage, for example 10V, is distributed,
Assuming that the movable contact 45 is now positioned at an angle of depression of (+30°), that is, teeth 4 to 8 in the upper jaw,
The voltage V.theta.=2/3 Vcc at that point is input to block 42 as shown in FIG. 6B. As mentioned above, the 42 shooting time selection circuits are composed of 12 OP amplifiers _A1 ~
Clamp the output of A ₁₂ with diodes D ₁ to D ₁₂ ,
This is a window comparator circuit that discriminates six categories of input voltage with high sensitivity, for example on the order of 1/10mV. Now when Vθ is input, A ₇ , D ₇ to determine this Vθ
The comparators A ₈ and D ₇ operate, and apply an output voltage Vθ' of, for example, several volts to the gate of S ₄ of the analog switches S ₁ to S ₆ of the next block 43.
74 is a correction voltage generated by the symmetrical position correction circuit 73 when the head direction is opposite as explained in FIG. 6A.
This is a circuit that inputs Vθα, shifts the set voltages of A ₁ to _{A 12} , and makes the output Vθ' the same regardless of the head direction, and the details are omitted from illustration. The analog switch is, for example, a voltage switch using a FET, ie, a field effect transistor. This S ₄
When turned on, the circuit is configured to generate an arbitrary voltage Vt depending on the resistance value set in advance in the variable resistor _V4 . This voltage Vt becomes the reference setting voltage for setting the time limit, that is, the photographing time, of the CR integral type time limit circuit described next. Here, the circuit configuration after analog switch S will be explained. Da, Db, Dc are diodes, 46 is an N-gate thyristor, 47 is a switching transistor, P ₁ , P ₂ , P ₃ are relays, P ₁ -a, P ₂ -
a, P ₃ -a is the a contact of relays P ₁ , P ₂ , P ₃ (always
OFF), P ₁ -b and P ₃ -b are b contacts (always ON) of relays P ₁ and P ₃ . _R1 is CR time constant setting resistor,
C is the same capacitor, _R2 is the X-ray tube series resistor, 48 is the AC power supply, Sx is the X-ray exposure switch,
49 is a main transformer, and 50 is an X-ray tube. In this configuration, when the operator presses Sx, P ₂ -a turns on and X
The ray tube 50 emits X-rays, a voltage Vx is generated at _R2 , and charging of the capacitor C is started through Dc. The parallel P ₁ -b of this C is open when P ₁ is ON. The voltage Vc integrated into this C is 46 N
The voltage is applied to the anode A of the gate thyristor while increasing over time. For example, the above-mentioned imaging time setting reference voltage Vt is applied to this 46 gate G.
Dc5V is already high, and when this Vt becomes equal to the above-mentioned Vc, the anode current I _A increases rapidly, turning on transistor 46 and turning on transistor 47 as well. P ₁ -a
is ON, so when 47 above turns ON, relay P ₃ conducts, P ₃ -a turns ON and P ₃ is self-held, and P ₃ - b turns OFF and P ₂ -a opens.
X-ray exposure will stop even if Sx is held down. By the above sequence operation, the X-ray exposure time T is determined by the gate voltage of 46 N-gate thyristors.
It can be automatically controlled by Vt. That is, the angle proportional signals Vθ and Vt shown in FIG. 6C,
By appropriately setting the characteristics with Vt′, it becomes possible to set the optimal time for the imaging area.

Next, a circuit in which a digital electric signal is used as an angle detection signal will be explained with reference to FIG. The dotted line block 41 is the aiming angle detection circuit shown in FIG.
As shown in the figure, six angle detection contacts C _A , C _B , and C _C are provided in six categories from (-20°) to (+50°) on a disc that rotates together with heads 1, 62, and 63 and head 15. There is. If the current angle of depression is (+30°), then (+Vcc)
With the power supply, 61 and 62 are ON and 1 and 63 are OFF and O.
A digital signal (011) is generated. In this way, the head angle (±θ°) is encoded into a 3-bit digital signal and input as Vθ to the A, B, and C terminals of 42 blocks. Reference numeral 42 denotes a photographing time selection circuit, which in this case is, for example, a 3-bit multiplexer, which selects the inputted V.theta. signals for each set reference voltage Vt, converts them from D to A, and outputs them to an output terminal Z. Variable resistors V ₁ -V ₆ connected to X ₁ -X ₆ are used to arbitrarily set the above-mentioned Vt, and operate in the same manner as V ₁ -V ₆ in FIG. The output signal Vt from this 42 is input to the photographing time setting circuit 43 described in FIG. 7, and operates in the same manner as described above. Compared to the analog type device shown in Figure 7, this digital type device has a simpler configuration and does not require high-precision parts, so it has the advantage of being inexpensive to manufacture, and is also less prone to malfunctions. Less and easier to maintain.

Next, as a problem common to both analog and digital types, we will discuss the CR of the photographing time setting circuit in block 43.
Two embodiments will be described in which the imaging time is automatically set by changing the time constant for each imaging site. In Figure 9, both ends of the series resistance _R2 of 50 X-ray tubes out of the 43 blocks in Figure 7 are N and E.
The rest are not shown, and the difference from Figure 7 is 46.
Instead of keeping the gate voltage Vt of the N-gate thyristor at a constant voltage with a variable resistor of 71, the time constant τ for integrally increasing the voltage Vx generated by the tube currents of N and E using the CR integration circuit is set using six time constants RI to RIV. This is the point where the resistance value of The 6 inputs of ~ are the 7th input.
These are voltage signals Vθ' output from D ₂ , D ₄ , D ₆ , D ₈ , D ₁₀ , and D ₁₂ in the figure, respectively. Other functions are the same as in FIG. 7. Figure 10 shows the change in the time constant τ of the CR integrator circuit with R ₁ constant and capacitor C.
This is a circuit in which the capacitances of six capacitors C _I to C _VI are changed, and the rest is the same as in FIG. 9. In addition, instead of Vx generated by X-ray exposure, the 7th, 8th,
Connect the DC power supply (+
Vcc) may be applied and the parts before Dc may be removed.

The above is an explanation of the structure and operation of the dental X-ray imaging apparatus according to the embodiment of the present invention, but it goes without saying that the present invention is not limited to what is shown in the drawings.

Since this invention is configured as described above,
Imaging conditions for conventional dental X-ray equipment that captures tooth images on intraoral dental film The imaging time, which is mainly set for each area to be imaged, is determined by the operator reading the elevation or depression aiming angle of the head relative to the hanger after completing positioning. This eliminates the trouble of determining the angle from an imaging chart and setting the timer on the X-ray controller, and divides the upper and lower jaw into multiple regions in advance, and sets the head's X-ray emission center axis to the divided imaging regions. By simply setting the aiming angle and using the irradiation tube, the surgeon can determine the correct position at this angle, and all conditions such as the jaw thickness of the area to be imaged and the load characteristics of the tube can be adjusted. A satisfactory optimum imaging time is automatically set, and the operator can perform imaging immediately after completing positioning, thereby providing an apparatus that can always quickly obtain good images and is highly efficient in diagnostic work.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the standard angle of elevation or depression formed by the X-ray radiation center axis with respect to the horizontal axis of the subject's occlusion plane for each tooth in the upper and lower jaws. Figures A to E are maxillary teeth, F
-J are views for the mandibular teeth. Fig. 2 is an external perspective view of the present invention applied to a mobile device, Fig. 3 is an explanatory diagram of the first essential part of the invention, which is a method for displaying the imaging area of the head and its aiming angle detection mechanism; The figure is an explanatory diagram of the case where the detected angle of the angle detector is corrected according to the posture of the subject, and Fig.
Figure 6A is a block diagram showing the configuration of an electric signal processing circuit for automatic imaging time setting according to the present invention, and Figure B is a diagram showing the configuration of an electric signal processing circuit for automatic imaging time setting according to the present invention. Figure C is a characteristic curve diagram showing the relationship between the detection signal and the photographing time setting signal, Figure 7 is a circuit diagram of an embodiment device in which the angle detection signal is an analog signal, and Figure 8 is the angle detection signal. Circuit diagram of the embodiment device using digital signal, No. 9
The figure is a circuit diagram of a method for changing R of the CR integral type time limit circuit of the shooting time setting circuit, and Figure 10 is the same.
FIG. 2 is a circuit diagram of a method for changing C of a CR integral type time limit circuit. 1 , 2 , 3 , 4 , 5, 6 , 7, 8 ... Upper jaw tooth symbol, 1, 2, 3, 4, 5, 6 , 7 , 8... Lower jaw tooth symbol, 13... X-ray controller, 14... Flexible Arm, 1
4H...Flexible arm end hanger, 14B...Head bearing part, 15...X-ray generator (head), 17...Display disc index, , 26... Angle detector, 27... Pinion of the central axis of 26 above, 28
...Internal gear fixed to the hanger, 31...Angle correction handle, A-A'...Horizontal axis of the head, A-A''...Changing elevation angle of the interlocking plane depending on the supine posture of the subject,
Θ゜...Aiming angle of the imaging site, V〓...Detection signal for the above Θ゜, Vt...Shooting time setting signal for the depression angle,
Vt′...Photography time setting signal for elevation angle, A ₁ to _{A 12}
…OP amplifier, S ₁ ~ S ₆ … Analog switch, V ₁ ~
V ₆ ...Variable resistor (shooting time setting reference voltage regulator), 44...Potentiometer slide resistance, 4
5... The above movable contact, 46... N-gate thyristor (semiconductor switch element), 47... Transistor,
R ₁ ...Resistor of integral type time-limiting circuit, C...Capacitor mentioned above, 61, 62, 63...Fixed terminal of encoder, C _A , C _B , C _C ... Contact of rotating plate of encoder (6 each), 71 ...N gate thyristor gate voltage setting variable resistor, N, E...Tube current detection resistor ( _R2 ) terminal, R _I ~ R _VI ...Resistor for shooting time setting,
～...Angle detection signal input terminal, C〓～C〓...Capacitor for shooting time setting.

Claims (1)

[Claims] 1. X-ray film is loaded into the mouth of the subject and
In order to obtain a line image, the entire upper and lower jaw is divided into multiple imaging areas in advance, and each imaging area is
In an apparatus that stores three imaging conditions: tube voltage, tube current, and imaging time of the wire tube, and selects an appropriate condition from these according to the area to be imaged, the device is configured to perform imaging while facing the area to be imaged. The plurality of preset imaging regions are displayed with symbols, figures, or numerical values of imaging conditions, based on the angle of elevation or depression that the central radiation axis of the X-ray tube forms with respect to the horizontal axis on the occlusion plane. , means for detecting the angle of elevation or depression as an electrical signal, and signal selection means for selecting one of the plurality of angle signals specific to the imaging site based on the detected angle signal;
A dental X-ray imaging apparatus characterized by comprising means for automatically setting optimal imaging conditions stored in advance based on the selected signal. 2. Claim 1, wherein the angle of elevation or depression formed by the central radiation axis of the X-ray tube facing the imaging site with respect to the horizontal axis on the occlusal plane is detected as an electrical signal of a rotary potentiometer. The dental X-ray imaging device described. 3. A dental clinic according to claim 1, in which the elevation angle or depression angle formed by the central radiation axis of the X-ray tube facing the imaging region with respect to the upper horizontal axis of the occlusion plane is detected as an electrical signal of a rotary encoder. X-ray imaging equipment.