JPS5951346A - Code conversion circuit of ultrasonic tomographic imaging apparatus - Google Patents

Abstract

PURPOSE:To correct the shift of a tomographic image, by adding an offset amount to information related to the position and the direction of the display scanning line of each vibrator when the shift of the tomographic image is generated by the attaching errors of a plurality of ultrasonic vibrators in a single probe. CONSTITUTION:The reference slot pulse from the rotary encoder 2 attached to the rotary shaft of a single probe having two vibrators assembled therein is subjected to the shaping of a wave form by a wave form shaping circuit 3 to generate an initiating pulse which in turn initiate a counter 4 and the pulse P2 subjected to wave form shaping is clocked to generate a display scanning line number M prior to correction. From the count value, a scanning judging circuit 5 judges whether either one of two vibrators is used in the transmission or the reception of ultrasonic waves and a selection signal S (a) is used as the selection input of a data selector 6 while either one of offset amount A, B indicated by SWA, SWB is selected to add a correction amount to a scanning line number M' prior to correction in an adder 9. By this mechanism, the shift of a tomographic image is corrected.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an ultrasonic tomographic imaging apparatus, and in particular has a plurality of ultrasonic transducers in one probe, and mechanically converts the transducers. The present invention relates to a code conversion circuit for using an electronic circuit to remedy the low mechanical precision of mounting a transducer in an apparatus that obtains tomographic images by changing the transmission and reception direction of an ultrasonic beam by rotating or swinging the ultrasonic beam.

[Prior art to the invention]

Conventionally, as an example of introducing multiple transducers into the same probe, for example, as shown in Fig. 1(a), one rotation center 1
There is a device in which two vibrators A and B are arranged in parallel around the same radius of rotation r and on a straight line passing through the center of rotation. When these transducers are rotated to change the direction of ultrasonic transmission and reception as shown in FIG.
9) A fan-shaped display scanning line as shown in (c) is obtained. At this time, the direction of ultrasonic beam transmission and reception is determined by moving a rotary encoder 2, which has slots S1 arranged at equal intervals on the circumference and slots S2 indicating a reference position, to a rotating shaft 1, as shown in FIG. 1(d), for example. The counter value can be obtained by attaching the output to the optical slot detection circuit that generates a pulse for each slot as a clock and operating the counter kit. Suffice it to say, this counter may be initialized to a specific value each time the rotary encoder rotates once, using the output of the reference position slot detection circuit. Below, we will take as an example a mechanical rotary probe using a rotary encoder type position detection mechanism shown in Figure 1.
The details of the present invention will be described.

Assume now that two vibrators A and B are mechanically accurately attached around the rotation axis as shown in FIG. 2(a).

At this time, for example, as shown in the figure, targets T1. If there is T2, the tomographic images produced by transducer A or B will be as shown in Figure 2 (b) or (C),9 respectively, and even if these two tomographic images are superimposed, the image of the target will not shift. O On the other hand, as shown in FIG. 3(a), for example, the vibrator A
If we consider a case where the transducer B is installed correctly but the angle of the transducer B is incorrect, the correct tomographic image obtained by the transducer A will be obtained as shown in FIG. 3(b). However, as shown in Example 3 - Figure 3(c), the image produced by transducer B is based on the display scanning line number (l in the figure) obtained from the encoder output and the actual transmission and reception direction of the ultrasound beam. (Converted to display scanning line number, i-△
N), a deviation (ΔN in terms of scanning line number) occurs. As a result, the image that should actually be displayed in the direction of the broken line in Figure 3(c) is displayed in the direction of the solid line.The 0N diagrams (d) and (e) also show when the rotation angle changes. A similar example is shown.In the end, the image produced by transducer B is shown in the same figure (f).
The target is displayed on a display scan line that is shifted by ΔN lines from the display scan line where it should originally be displayed. Therefore, when the images 't-3if' from the oscillators A and B are combined, the target will be seen twice as shown in FIG. 3(b).

This problem can be solved by sufficiently improving the mechanical precision when mounting the vibrator, but it may be difficult to do so in terms of cost.0 [Object of the Invention] Code conversion according to the present invention The circuit is, for example, A mentioned above,
, B To solve the problem when using two transducers, no correction is made for one display scanning line number of A4- However, as the display scanning line number of B, the display scanning line number output from the encoder pulse count circuit is By using the value obtained by subtracting ΔN from the value, the image in Fig. 3(f) can be converted to the image in Fig. 3(h).
This is done so that even if the image is superimposed on the image of the vibrator A as shown in FIG. 3(b), it will not look like 2N.

[Embodiments of the invention]

An embodiment of the present invention will be explained with reference to FIG.

In FIG. 4, the counter 4 is connected to the rotary encoder 2.
After being initialized (for example, set to 0) by an initialization pulse that is a waveform-shaped 0 reference slot pulse, the display scanning line number M before correction is set using a pulse P2 that is a waveform-shaped waveform of the circumferential slot pulse of the rotary encoder. Occur.

□The scanning line number determination circuit 5 determines from the value of the counter which of the two transducers A or B in FIG. 3(a) is used for transmitting and receiving the ultrasound beam, and outputs a determination output St
- occurs. The signal S is the selection input of the data selector 6, and the offset amount 0F specified by 9, SWA, and SWB.
Select either FSETA or 0FFSETB.

In the case of Figure 3, if it is taken on the gold side, the amount of correction for vibrator A is 0.
FFSET A 0FP before correction for FiO resonator B
SET B is -ΔN. The modified output ΔM selected by the data selector 6 is sent to the adder 9, where it is added to the scanning line number M' before modification, and the display scanning line number after modification M=M'
+ΔM is obtained.

In the case of the method described above, for example, considering the case of FIG. 3(e), if one ΔN is used instead of K as the number of the display scanning line as shown in FIG. Although the direction of the displayed scanning line is correctly expressed, the starting point of the scanning line is not the starting point P of the actual ultrasound beam (Fig. 5, broken a).
It moves to Q.

As a result, as shown in FIG. 5, there is an error of ΔX in the horizontal direction and ΔY in the * direction with respect to the position where it should originally be displayed. This means that the direction of the display scan line is corrected, but
The position will include an error.

When ΔN is small, this error is negligible; however, when ΔN becomes large, it is necessary to generate starting point correction information for each scanning line and send it to the deflection signal generator. There is. FIG. 6 shows a configuration diagram at this time. Numbers 2 to 9 in FIG. 6 represent all the same numbers as those in FIG. 4. In FIG. 6, a code converter 10 is added. ΔX and ΔY in FIG. 5 depend on both the value M' of the display scanning line number by the encoder and the correction amount ΔM.

The code converter 10 in FIG. 6 is from M9 and 6M to △X
and △Y, such as ROM or PLA.
It is realized using etc. M, ΔX.

ΔY is sent to the deflection signal generation circuit (in the case of an xy display), or is sent to the coordinate calculation circuit and used to calculate a memory address (in the case of a TV system).

In the explanation of FIG. 3, it was assumed that the vibrator A was mechanically installed correctly, but as shown in FIG. 7(a),
If the mounting angles of transducers A and B differ by ΔN and ΔNB, respectively, in terms of display scanning line numbers, transducer A
-, MNA and -Δ for the display scanning line numbers of and B, respectively.
It is clear that it is sufficient to give an offset amount of only NB, but if △NA + △NB = 7 = small, for example, using the image by transducer A as a reference,
If the display scanning line number of transducer B is offset by -(ΔNB-ΔNA) and displayed as shown in FIG. 7(d) K, the image obtained by transducer A shown in FIG. 7(b) will be approximately Needless to say, they overlap.

If this method is used, the image will no longer appear double, but as a whole, the IJC will be displayed at the position where it should have been displayed and where it has been scratched. If this is inconvenient, after giving only the offset amount to the above-mentioned transducer B (in the case of Figure 7 - (ΔNB - ΔNA)),
Equal amounts for both B (in the case of Figure 7 - △NA)
It is sufficient to give the offset ff. FIG. 8 shows a configuration using this method.

In FIG. 8, 2 to 9 are the same as those with the same numbers in FIG. A constant offset needle (0) is given for .

If the 99 output is directly used as the display scanning line number, an image in which FIGS. 7(b) and 7(d) are superimposed is obtained. switch 1
1 is the offset amount -△NA'r necessary to make the image as shown in Fig. 7-8-(e)
By adding this and the output of adder 9 in adder 12, an image as shown in FIG. 7(e) is obtained.

The advantages of setting the offset amount in two stages in this manner are as follows.

First, it is only necessary that the images formed by the plurality of vibrators overlap without deviation. In this case, fewer adjustments are required than when giving individual offsets to all the vibrators so that they are displayed at their original positions. Second, once the images of all the transducers are superimposed, the offset of the scanning line number relative to the overall image can be adjusted by adjusting only one location.

The above explanation was given only for the case where two transducers are included in one probe, but the case in which three or more transducers are included in one probe is also applicable as shown in Fig. 4. The output from the line number determination circuit 5 is set to 2 bits or more, the offset amount setting is increased from the two of 5Wft7°8, and the input port of the data selector 6 is changed to )
Mouth q kA + y mouth resistance − ↓ event is obvious.

Also, the above explanation was given only for the case where a rotary encoder is used as the position detection mechanism, but if the angle is detected using a potentiometer, then a differential transformer is used after converting rotational motion into linear motion. It can also be applied to cases where position detection is performed by detecting an angle. In these cases, the detected angle signal (analog)
When performing A/D conversion, in the configuration shown in Fig. 4, the output of the A/D converter or the output of the A/D converter is converted into a display scanning line number by appropriate sign conversion. You can use When processing analog signals as they are, use the output of a potentiometer or differential transformer in place of the counter 4, a voltage comparator and appropriate comparison voltage source in place of the transducer number determination judgment circuit 5, and a data selector 60. Instead, use an analog multiplexer and switch 7.
A variable voltage source may be placed in place of 8, and an analog adder may be placed in place of digital adder 9.

〔Effect of the invention〕

When incorporating the probe into one probe, if it is difficult to achieve a certain level of mechanical precision due to cost, the lack of pattern precision can be compensated for at low cost using a circuit.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams explaining the operation of a general probe, Figure 3 is a diagram explaining the operation of an embodiment of the present invention, Figure 4 is a block diagram of an embodiment of the invention, and Figure 5. FIG. 6 is an operational explanatory diagram and a block diagram of the second embodiment of the present invention, and FIGS. 7 and 8 are an operational diagram and a block diagram of the third embodiment of the present invention, respectively. 2 Figure (C) Figure 5 AXAY M Figure 6 (α) (1)), (C) (i) Ce
) -Figure 7

Claims (3)

[Claims] (1) Ultrasound that transmits and receives ultrasound while mechanically rotating or swinging multiple ultrasound transducers within a single probe, and displays tomographic images on a display using brightness modulation or color modulation pressure. In a tomographic imaging device, the mechanical position and/or direction of the transducer currently performing transmission and reception is detected by a mechanical position detection mechanism such as a mechanical or optical encoder, a differential transformer, or a potentiometer, In an ultrasonic tomography apparatus that determines the position and/or direction of a display scanning line, each vibration is added to the information regarding the position and/or direction of each vibrator obtained directly from the output of the mechanical position detection mechanism. any offseller)i independently for the child
ie, a code conversion circuit for an ultrasonic tomographic imaging apparatus, which additionally modifies information regarding the position and/or direction of a display scanning line for each transducer; (2) If a deviation occurs in tomographic images obtained by different transducers due to mechanical errors in the mounting accuracy of multiple ultrasonic transducers, the amount of offset described in paragraph 1 may be determined by using a certain transducer. Determining the position or direction of the optical scanning line of a transducer other than the transducer, or both, based on the amount of offset such that the tomographic image produced by the other transducer exactly conforms to the reference tomographic image, using the tomographic image obtained by the transducer as a reference. A code conversion circuit for an ultrasonic tomographic imaging apparatus according to claim 1, wherein the code conversion circuit is provided to perform the following steps. (3) If the transducer itself, which is based on the above standard, includes mechanical errors in its installation, the amount of offset that should be added to the display scanning line number in order to compensate for the mechanical errors should be applied to all of the transducers in the probe. A code conversion circuit for an ultrasonic tomographic imaging apparatus according to claim (2), characterized in that the code conversion circuit applies equal power to the transducers.