JP4276410B2 - MRI compatible injection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an injection apparatus that slides a piston portion of a syringe, and more particularly to an MRI-compatible injection apparatus that injects at least a drug solution into a subject imaged by an MRI apparatus.
[0002]
[Prior art]
Currently, an MRI apparatus used in a medical field can take a tomographic image of a subject in real time using a magnetic resonance effect. In that case, an operator may inject a medical solution such as a contrast medium or physiological saline into a subject at a desired timing, and an injection device that mechanically executes this injection has been put into practical use. In addition, in general wards and ICU (Intersive Care Unit), a chemical solution made of a medicine may be continuously injected into a subject little by little, and an injection apparatus that automatically executes this injection has been put into practical use.
[0003]
When using such an injection apparatus, the cylinder part of the syringe filled with the chemical solution is connected to the subject with an extension tube, and the cylinder part is held by the syringe holder. Since the piston part of the syringe held in this way is moved by a slider mechanism driven by a motor, the chemical solution is injected into the subject and sucked as necessary.
[0004]
However, since the influence of magnetism cannot be ignored in an MRI apparatus that captures a tomographic image using the magnetic resonance effect, the MRI-compatible injection apparatus is required not to disturb the magnetic field as much as possible. For this reason, the present inventor has developed an MRI compatible injection device that does not unnecessarily disturb the magnetic field by using an ultrasonic motor formed of a nonmagnetic material.
[0005]
[Problems to be solved by the invention]
In the MRI compatible injection device using the above-described ultrasonic motor, the liquid medicine in the syringe can be injected into the subject without disturbing the magnetic field as much as possible. However, in the field where such an MRI compatible injection device is used, it is desired to be able to monitor the pressure of the chemical solution to be injected.
[0006]
For example, in a CT injection device used together with a CT (Computed Tomography) scanner, a pressure sensor is mounted on a slider mechanism that presses the piston part of a syringe, thereby detecting the pressure that presses the piston part and detecting the pressure of the chemical solution. There is something to calculate. However, since such a pressure sensor is generally made of a magnetic material, it is difficult to apply it to an MRI compatible injection device.
[0007]
The present invention has been made in view of the above-described problems, and an object thereof is to provide an MRI-compatible injection device that can detect the pressure of a chemical solution to be injected or sucked without unnecessarily disturbing a magnetic field.
[0008]
[Means for Solving the Problems]
In the MRI-compatible injection device of the present invention, a driving signal having a specific frequency is input to an ultrasonic motor to rotate the rotor portion of the ultrasonic motor and slide the piston portion of the syringe, thereby injecting or sucking the drug solution into the subject. To do. At this time, the pressure of the chemical solution is reflected in the load of the ultrasonic motor, and this load is reflected in the difference between the planned rotation speed and the actual rotation speed based on the drive signal. Therefore, in the MRI compatible injection device of the present invention, the frequency of the driving signal or the driving voltage is converted into the pressure of the chemical solution in accordance with the actual rotational speed of the ultrasonic motor.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. The MRI-compatible injection device of the present embodiment includes a syringe holder, an ultrasonic motor, a slider mechanism, a rotary encoder, a voltage generation unit, a signal generation unit, and a pressure conversion unit.
[0010]
In the MRI compatible injection device of this embodiment, the ultrasonic motor rotates the rotor part at a speed corresponding to the frequency of the input drive signal, the syringe holder holds the cylinder part of the syringe, and the slider mechanism is held. The piston portion of the syringe is slid by the rotation of the rotor portion of the ultrasonic motor.
[0011]
The voltage generation unit generates a drive voltage, and the signal generation unit converts the drive voltage into a drive signal having a corresponding frequency and inputs the drive signal to the ultrasonic motor. As a result, the rotor part of the ultrasonic motor rotates, and the piston part of the syringe is slid to inject or suck the drug solution into the subject.
[0012]
At this time, the rotary encoder detects the rotation speed of the ultrasonic motor, and the pressure conversion means converts at least one of the frequency of the drive signal and the drive voltage into the pressure of the chemical solution corresponding to the rotation speed. The pressure of the chemical solution is detected without the need for a pressure sensor made of a magnetic material.
[0013]
The various means referred to in the present invention need only be formed so as to realize the function. For example, dedicated hardware that exhibits a predetermined function, a data processing apparatus provided with a predetermined function by a computer program A predetermined function realized in the data processing apparatus by a computer program, a combination thereof, or the like may be used.
[0014]
In addition, the various means referred to in the present invention do not have to be independent of each other, a plurality of means are formed as one device, and a certain means is a part of other means. It is also possible that a part of the means overlaps with a part of the other means.
[0015]
Furthermore, the chemical solution referred to in the present invention means a liquid that is injected into a subject in the vicinity of the MRI apparatus. For example, MR contrast agent for MRI apparatus, physiological saline, blood, various medicines, etc. are possible. It is.
[0016]
[Configuration of Example]
As shown in FIG. 2, the MRI compatible injection apparatus 100 of this embodiment includes a head unit 101 and an apparatus main body 102, and the apparatus main body 102 is attached to the upper end of a stand 103. An arm 104 is attached to a side portion of the apparatus main body 102, and a head portion 101 is attached to the tip of the arm 104.
[0017]
As shown in FIG. 3 and FIG. 3, the head portion 101 has a syringe holder 106, and holds the cylinder portion 201 of the syringe 200 that can be replaced by the syringe holder 106. A slider mechanism 107 is formed behind the syringe holder 106. The slider mechanism 107 grips and slides the piston portion 202 of the syringe 200 held by the syringe holder 106.
[0018]
An ultrasonic motor 110 is built in the rear portion of the head portion 101, and the rotor portion of the ultrasonic motor 110 is connected to the slider mechanism 107 by a screw mechanism or the like (not shown). Slide by the rotation of the ultrasonic motor 110.
[0019]
In the MRI compatible injection apparatus 100 of this embodiment, as shown in FIG. 2, an operation panel 111 and a liquid crystal display 112 are mounted on the apparatus main body 102. As shown in FIG. Unit) 113.
[0020]
A phase control circuit 114, an integration circuit 115, a signal generating means VCO (Voltage Controlled Oscillator) 116, a signal generation circuit 117, and a motor drive circuit 118 are sequentially connected to the main CPU 113. This motor drive circuit 118 is connected to the ultrasonic motor 110.
[0021]
A rotary encoder 120 is attached to the rotor portion of the ultrasonic motor 110, and the rotary encoder 120 is feedback-connected to the phase control circuit 114. Further, the VCO 116 and the rotary encoder 120 are sequentially connected to the frequency measurement circuit 121 and the sub CPU 122, and the sub CPU 122 is connected to the main CPU 113.
[0022]
Further, since a plurality of types of syringes 200 are interchangeably mounted on the syringe holder 106, when identification data of the syringe 200 mounted on the syringe holder 106 is input to the operation panel 111 serving as a type input means, The sub CPU 122 stores data.
[0023]
The phase control circuit 114 functions as a speed storage unit and a voltage generation unit, stores data on a desired rotation speed of the ultrasonic motor 110, and determines the actual rotation speed of the ultrasonic motor 110 detected by the rotary encoder 120. A drive voltage is generated that matches the desired rotational speed.
[0024]
The integration circuit 115 integrates the drive voltage, and the VCO 116 converts the integrated drive voltage into a drive signal having a corresponding frequency. The signal generation circuit 117 converts the drive signal into a four-phase DC (Direct Current) pulse as shown in FIG. 5A, and the motor drive circuit 118 generates a DC pulse as shown in FIG. 5B. Is converted into an AC (Alternating Current) voltage.
[0025]
The rotary encoder 120 detects the rotational speed of the ultrasonic motor 110 by outputting a detection signal having a frequency corresponding to the rotational speed of the ultrasonic motor 110. The frequency measurement circuit 121 measures the frequencies of the drive signal output from the VCO 116 and the detection signal of the rotary encoder 120, and the sub CPU 122 sets the frequency of the drive signal corresponding to the frequency of the detection signal to MR contrast that is a chemical solution. Data conversion into agent pressure.
[0026]
More specifically, the sub CPU 122 includes a one-chip microcomputer in which a processor unit and a register unit are integrated, and executes predetermined data processing corresponding to a computer program implemented by firmware or the like. Since the data table in which the pressure is set for each combination of the frequency of the detection signal and the drive signal is registered in the sub CPU 122 for each identification data of the syringe 200, the identification data of the syringe 200 is input as described above. Then, when the frequencies of the detection signal and the drive signal are input, one pressure is selected and data is output to the main CPU 113.
[0027]
The main CPU 113 is also composed of a one-chip microcomputer on which a computer program is mounted. When pressure is input from the sub CPU 122, a time graph of pressure is generated in real time as pressure display means, and the data is displayed on the liquid crystal display 112. Let When a desired injection speed is input from the operation panel 111, the injection speed is converted into a desired rotation speed of the ultrasonic motor 110 and registered in the phase control circuit 114.
[0028]
As shown in FIG. 4, the MRI compatible injection apparatus 100 of the present embodiment is used in the vicinity of the imaging unit 301 of the MRI apparatus 300 and connected to the control unit 302 of the MRI apparatus 300 as necessary. The control unit 302 includes a computer system, and controls the operation of the imaging unit 301 and displays a tomographic image.
[0029]
[Operation of the embodiment]
In the configuration as described above, when using the MRI compatible injection device 100 of the present embodiment, the operator connects the syringe 200 with an extension tube to a subject located in the imaging unit 301 of the MRI device 300 (not shown), As shown in FIG. 3, the cylinder portion 201 of the syringe 200 is held by the syringe holder 106 of the head portion 101 and the piston portion 202 is held by the slider mechanism 107.
[0030]
In this state, when the identification data of the syringe 200 and the desired injection speed are input to the operation panel 111 of the apparatus main body 102, the sub CPU 122 stores the identification data, and the main CPU 113 converts the injection speed into a rotational speed and the phase. Data is registered in the control circuit 114. When the injection start is input in such a state, the phase control circuit 114 generates a drive voltage corresponding to the rotation speed registered as data.
[0031]
The drive voltage is converted into a drive signal of a frequency corresponding to the VCO 116, and the ultrasonic motor 110 is driven by this drive signal. Thus, the slider mechanism 107 slides the piston portion 202 of the syringe 200. At this time, the rotary encoder 120 detects the actual rotational speed of the ultrasonic motor 110, and the phase control circuit 114 generates the drive voltage so that the actual rotational speed matches the desired rotational speed. The MRI compatible injection device 100 injects the MR contrast agent from the syringe 200 into the subject at a set speed.
[0032]
Furthermore, in the MRI-compatible injection device 100 of the present embodiment, the frequency measurement circuit 121 measures the frequency of the detection signal output from the rotary encoder 120 and the drive signal output from the VCO 116, respectively. Corresponding to the identification data, the sub CPU 122 converts the frequency of the drive signal into MR contrast agent pressure. From this pressure, the main CPU 113 generates a time graph in real time, and the liquid crystal display 112 displays this time graph as data.
[0033]
[Effect of Example]
In the MRI compatible injection apparatus 100 of the present embodiment, the rotational speed of the ultrasonic motor 110 is feedback-controlled as described above, so that the MR contrast agent in the syringe 200 can be injected into the subject at a predetermined speed. It can be set freely as desired.
[0034]
Moreover, since the pressure of the MR contrast medium injected from the drive signal of the ultrasonic motor 110 and the actual rotational speed is detected, the pressure of the MR contrast medium can be detected without the need for a pressure sensor made of a magnetic material. Can do. In particular, since the detected MR contrast agent pressure is displayed in real time as a graph over time, for example, leakage of the MR contrast agent can be detected by a pressure drop.
[0035]
[Modification of the embodiment]
The present invention is not limited to the present embodiment, and various modifications are allowed without departing from the spirit of the present invention. For example, in this embodiment, the drive voltage generated by the phase control circuit 114 is converted into a drive signal by the VCO 116, and the drive signal is converted into data of the MR contrast agent corresponding to the rotational speed of the ultrasonic motor 110. Illustrated.
[0036]
However, like the MRI compatible injection device 400 illustrated in FIG. 6, it is also possible to convert the drive voltage generated by the phase control circuit 114 into MR contrast agent pressure corresponding to the rotational speed of the ultrasonic motor 110. is there. In the figure, the drive voltage generated by the phase control circuit 114 is integrated by the integration circuit 115 and then amplified by the amplifier 401. However, the drive voltage generated by the phase control circuit 114 is directly converted into data of the MR contrast agent data. It is also possible to do.
[0037]
In the present embodiment, the operator inputs the desired injection speed by manual operation of the operation panel 111. However, for example, the rotation speed is registered for each of a plurality of types of syringes 200, and the syringe holder 106 is registered. It is also possible to automatically validate the corresponding rotation speed by detecting the type of the syringe 200 attached to the.
[0038]
Further, in this embodiment, the main CPU 113 converts the desired injection speed inputted from the operation panel 111 into the desired rotation speed and registers the data in the phase control circuit 114, and the phase control circuit 114 stores the desired registration speed. An example of matching the actual rotational speed of the ultrasonic motor 110 with the rotational speed is illustrated.
[0039]
However, the main CPU 113 registers the desired injection pressure input from the operation panel 111 in the phase control circuit 114, and the phase control circuit 114 sets a drive voltage that matches the pressure generated by the sub CPU 122 with the desired pressure. It is also possible to generate.
[0040]
In the present embodiment, only the detected MR contrast agent pressure is displayed as data over time. However, for example, the upper limit of the pressure is registered in advance and the detected pressure reaches the upper limit. It is also possible to forcibly stop the driving of the sonic motor 110.
[0041]
Furthermore, in the present embodiment, the MRI compatible injection device 100 exemplifies injecting an MR contrast agent as a drug solution from one syringe 200 to a subject. However, for example, physiological saline can be injected as a drug solution, It is also possible to appropriately inject MR contrast agent and physiological saline from the two syringes 200.
[0042]
Since the MRI compatible injection apparatus 100 of this embodiment is used in the vicinity of the MRI apparatus 300 as described above, it is preferable that each part is formed of a nonmagnetic material. For example, the ultrasonic motor 110 and the slider mechanism 107 are preferably formed of a nonmagnetic material such as stainless steel or free-cutting brass, and the housing of the head unit 101 is formed of a nonmagnetic material such as resin or aluminum. It is preferable to use a magnetic-shielding material such as titanium or soft iron.
[0043]
In the present embodiment, an MRI-compatible injection device 100 called an MR contrast agent injection device that injects an MR contrast agent into a subject imaged by the MRI device 300 is illustrated. For example, FIG. 7 and FIG. As described above, an MRI compatible injection device 500 called a chemical pump or a syringe pump that continuously injects a chemical solution made of a drug into a subject under treatment in small amounts can be implemented.
[0044]
In this MRI compatible injection device 500, the slider mechanism 107 is formed by a gear train 501, a screw shaft 502 and a slider 503, and limit sensors 504 and 505 for detecting the initial position and the final position of the slider 503, respectively, are the main CPU 123. It is connected to the.
[0045]
The slider 503 has a built-in load cell 506 made of a non-magnetic material such as phosphor bronze alloy (Cu + Sn + P), titanium alloy (Ti-6Al-4V), magnesium alloy (Mg + Al + Zn). The load cell 506 detects the pressure with which the slider 503 presses the piston member 202 of the syringe 200.
[0046]
Such an MRI compatible injection device 500 is used for continuously injecting a small amount of a drug solution into a subject in a general ward, ICU, or the like regardless of the imaging performed by the MRI device 300. However, the MRI compatible injection apparatus 500 may image a subject who is injecting a drug solution with the MRI apparatus 300. Even in such a case, the MRI compatible injection apparatus 500 does not affect the magnetic field of the MRI apparatus 300. .
[0047]
【The invention's effect】
In the MRI compatible injection device of the present invention, the drive frequency and the drive voltage are converted into the pressure of the chemical solution in accordance with the actual rotational speed of the ultrasonic motor that slides the piston portion of the syringe. Therefore, the pressure of the chemical solution can be detected with a simple structure.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a circuit structure of an MRI compatible injection apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view showing an appearance of an MRI compatible injection device.
FIG. 3 is a perspective view showing a state where a syringe is attached to a head portion.
FIG. 4 is a perspective view showing an appearance of an MRI apparatus.
FIG. 5 is a characteristic diagram showing a drive signal of an ultrasonic motor.
FIG. 6 is a block diagram showing a circuit structure of an MRI compatible injection device according to a modification.
FIG. 7 is a schematic block diagram showing an internal structure of an MRI compatible injection device according to a modification.
FIG. 8 is a perspective view showing an appearance of an MRI compatible injection device.
[Explanation of symbols]
100, 400 MRI compatible injection device 106 Syringe holder 107 Slider mechanism 110 Ultrasonic motor 111 Operation panel 113 functioning as type input means Main CPU functioning as pressure display means
114 Phase control circuit 116 functioning as speed storage means and voltage generation means VCO as signal generation means
122 Sub CPU functioning as pressure converting means
200 Syringe 201 Cylinder part 202 Piston part 300 MRI apparatus

Claims (9)

An MRI compatible injection device for injecting a drug solution into a subject imaged by an MRI (Magnetic Resonance Imaging) device,
A slider mechanism for sliding the piston part of the syringe;
An ultrasonic motor for driving the slider mechanism;
Signal generating means for generating a drive signal of a specific frequency and inputting it to the ultrasonic motor;
A rotary encoder that detects a signal having a frequency corresponding to an actual rotation speed of the ultrasonic motor as a detection signal ;
A data table in which pressure is set for each combination of the frequency of the drive signal and the detection signal;
By using the data table, pressure conversion means for detecting the pressure of the chemical solution from the planned rotation speed of the ultrasonic motor by the input drive signal and the rotation speed detected by the rotary encoder;
An MRI compatible injection device. It also has voltage generation means for generating a drive voltage,
The MRI compatible injection device according to claim 1, wherein the signal generating means converts the drive voltage into the drive signal having a corresponding frequency. It also has speed storage means for storing the desired rotational speed of the ultrasonic motor,
The MRI-compatible injection device according to claim 2, wherein the voltage generation unit generates a drive voltage that matches a rotation speed detected by the rotary encoder with the desired rotation speed. It also has pressure storage means for storing data of a desired pressure for injecting the chemical solution,
The MRI-compatible injection device according to claim 2, wherein the voltage generation unit generates a drive voltage that matches the pressure detected by the pressure conversion unit with the desired pressure. A plurality of types of syringes are mounted interchangeably,
It also has a type input means for inputting identification data of the mounted syringe,
The MRI-compatible injection device according to any one of claims 1 to 4, wherein the pressure conversion unit detects the pressure of the chemical solution in response to input identification data of the syringe. A plurality of types of syringes are mounted interchangeably,
In the speed storage means, the rotation speed is registered for each of a plurality of types of the syringes,
Type input means for inputting identification data of the mounted syringe,
Speed selection means for validating one of the plurality of rotational speeds registered in the speed storage means corresponding to the type of the input syringe,
The MRI-compatible injection device according to claim 3, comprising: A plurality of types of syringes are mounted interchangeably,
In the pressure storage means, the pressure is registered as data for each of the plurality of types of syringes,
Type input means for inputting identification data of the mounted syringe,
Pressure selecting means for validating one of the plurality of pressures registered in the pressure storage means corresponding to the type of the input syringe;
The MRI-compatible injection device according to claim 4, comprising:   The MRI-compatible injection device according to any one of claims 5 to 7, further comprising a type detection unit that detects a type of the mounted syringe and outputs identification data to the type input unit.   The MRI-compatible injection device according to any one of claims 1 to 8, further comprising pressure display means for displaying the pressure detected by the pressure conversion means in real time as a graph over time.

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