JP2003290348A - Injection apparatus adaptable to mri - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection apparatus adaptable to MRI, capable of detecting the pressure of a medical solution injected to a subject without unnecessarily disturbing the magnetic field. <P>SOLUTION: A load cell 110 made of a non-magnetic material is formed of an alloy of phosphorus and bronze or the like. The stress for sliding a piston part of a syringe is detected by the load cell 110 and the stress is converted to the pressure of the medical solution injected to the subject. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection device for sliding a piston part of a syringe, and more particularly, an MR device for injecting at least a drug solution into a subject imaged by an MRI apparatus.
I-compatible injection device.

[0002]

2. Description of the Related Art MRI currently used in medical practice
The apparatus can take a tomographic image of a subject in real time by utilizing the magnetic resonance effect. In that case, an operator may inject a medical fluid such as a contrast agent or physiological saline into a subject at a desired timing, and an injection device that mechanically executes this injection is also in practical use. In addition, general ward and I
In some cases, a CU (Intersive Care Unit) or the like continuously injects a small amount of a medicinal solution into a subject, and an injection device that automatically performs this injection is also in practical use.

When using such an injection device, a cylinder portion of a syringe filled with a drug solution is connected to a subject by an extension tube, and the cylinder portion is held by a syringe holder. Since the piston portion of the syringe held in this manner is moved by the motor-driven slider mechanism, the drug solution is injected into the subject and aspirated if necessary.

However, since the influence of the magnetic field cannot be ignored in an MRI apparatus which takes a tomographic image by the magnetic resonance effect, the MR
The I-compatible implanter is required not to disturb the magnetic field as much as possible. Therefore, the inventor of the present invention uses a drive motor formed of a non-magnetic material so as not to disturb the magnetic field unnecessarily.
Corresponding injection device was developed.

[0005]

In the MRI compatible injection device using the above-mentioned drive 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 drug solution to be injected.

For example, in a CT injection device used with a CT (Computed Tomography) scanner, a pressure sensor is mounted on a slider mechanism that presses the piston portion of the syringe to detect the pressure that presses the piston portion. There is one that calculates the pressure of the chemical liquid. However, since such a pressure sensor disturbs the magnetic field, it is difficult to apply it to an MRI compatible injection device.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an MRI-compatible injection device capable of detecting the pressure of a chemical liquid to be injected without disturbing the magnetic field.

[0008]

In the MRI compatible injection device of the present invention, when the slider mechanism slides the piston portion of the syringe by the power of the drive motor, the stress is detected by the load cell and the liquid medicine injected into the subject is detected. Convert to pressure. However, the load cell is a phosphor bronze alloy (Cu + Sn +
P), titanium alloy (Ti-6Al-4V), magnesium alloy (Mg + Al +
Since it is made of a non-magnetic material such as Zn), it does not disturb the magnetic field unnecessarily.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The MRI-compatible injection device of the present embodiment has a syringe holder, a drive motor, a slider mechanism, a load cell, an initial setting means, and a pressure detecting means.

In the MRI compatible injection apparatus of this embodiment, the syringe holder holds the cylinder portion of the syringe, and the slider mechanism slides the held piston portion of the syringe by the power of the drive motor. The load cell is made of a non-magnetic material such as phosphor bronze alloy (Cu + Sn + P), and its electrical resistance changes according to the amount of strain. To occur.

The initial setting means acquires and holds the electric signal of the load cell in the initial state where the syringe is held by the syringe holder and the drive motor is not operating, and the pressure detecting means is the electric signal held by the initial setting means. The pressure of the chemical liquid is detected from the difference between the signal and the electric signal generated by the load cell in real time.

The various means referred to in the present invention may be formed so as to realize their functions. For example, dedicated hardware that exhibits a predetermined function, or a predetermined function is given by a computer program. The data processing device, a predetermined function realized by the computer program in the data processing device, a combination thereof, and the like may be used.

Further, the various means referred to in the present invention need not be independent of each other, but a plurality of means are formed as one device, and some means are part of other means. It is also possible that a part of a certain means and a part of another means overlap.

Further, the drug solution referred to in the present invention means a liquid to be injected into a subject in the vicinity of the MRI apparatus, for example, an MR contrast agent for MRI apparatus, physiological saline, blood,
Various chemicals, etc. are possible.

[Structure of Embodiment] As shown in FIG. 2, an MRI compatible injection device 100 comprises a head portion 101 and a device main body 102, which is mounted on the upper end of a stand 103. There is. An arm 104 is attached to a side portion of the apparatus body 102.
The head portion 101 is attached to the tip of the nozzle 4.

As shown in FIG. 3 and FIG. 3, the head portion 101 has a syringe holder 106, and the syringe holder 106 holds the replaceable cylinder portion 201 of the syringe 200. A slider mechanism 107 is formed behind the syringe holder 106, and the slider mechanism 107 holds and slides the piston portion 202 of the syringe 200 held by the syringe holder 106.

An ultrasonic motor 108 as a drive motor is built in the rear portion of the head portion 101, and the rotor portion of the ultrasonic motor 108 is connected to the slider mechanism 107 by a screw mechanism or the like (not shown). ), The slider mechanism 107 slides by the rotation of the ultrasonic motor 108.

Further, as shown in FIG. 5, the slider mechanism 107 has a load cell 110 made of a non-magnetic material. In the load cell 110, the slider mechanism 107 moves the piston portion 202 by the power of the ultrasonic motor 108. An electric signal corresponding to the pressing stress is generated.

More specifically, the load cell 110 is slidably mounted in a recess of a cell housing 111, and the cell housing 111 is a cell casing 112.
Is slidably mounted in the concave portion of the cell casing 112, and the load cell 110 is in contact with the bottom surface of the concave portion of the cell casing 112.

The cell housing 111 is the ultrasonic motor 1.
It is attached to the tip of a rod 113 that slides by the power of 08, and the cell housing 111 is attached to the syringe 200.
Since the piston portion 202 of the
7 is a piston portion 202 by the power of the ultrasonic motor 108.
The stress that presses acts on the load cell 110. The load cell 110 is made of a phosphor bronze alloy (Cu + Sn + P), and the electric resistance changes in accordance with the amount of strain, so that the electric resistance is acquired as an electric signal.

In the MRI compatible injection apparatus 100 of this embodiment, as shown in FIG.
21 and a liquid crystal display 122 are mounted, and as shown in FIG. 1, these are connected to a main CPU (Central Processing Unit) 123 together with the load cell 110.

The main CPU 123 includes a phase control circuit 124, an integrating circuit 125, and a VCO as a signal generating means.
A (Voltage Controlled Oscillator) 126, a signal generation circuit 127, and a motor drive circuit 128 are connected in order, and the motor drive circuit 128 is connected to the ultrasonic motor 108.
It is connected to the.

A rotary encoder 129 is mounted on the rotor portion of the ultrasonic motor 108, and the rotary encoder 129 is feedback-connected to the phase control circuit 124. The rotary encoder 129 detects the rotation speed of the ultrasonic motor 108 by outputting a detection signal having a frequency corresponding to the rotation speed of the ultrasonic motor 108.

The phase control circuit 124 stores data of a desired rotation speed of the ultrasonic motor 108 by a built-in register (not shown), and indicates the actual rotation speed of the ultrasonic motor 108 detected by the rotary encoder 129. Generate a drive voltage that matches the desired rotation speed.

The integrating circuit 125 integrates the drive voltage to obtain V
The CO 126 converts the integrated drive voltage into a drive signal having a corresponding frequency. The signal generation circuit 127 is shown in FIG.
As shown in, the drive signal is a four-phase DC (Direct Current)
Then, the motor drive circuit 128 converts the drive signal composed of a DC pulse into an AC (Alter) as shown in FIG.
nating Current) Convert to voltage.

The main CPU 123 comprises a one-chip microcomputer in which a processor section and a register section are integrated,
Predetermined data processing is executed corresponding to a computer program implemented by firmware or the like. When the desired injection speed is input from the operation panel 121, the main CPU 123 sets the injection speed to the ultrasonic motor 1.
Data is registered in the phase control circuit 124 after being converted into a desired rotation speed of 08.

Since a plurality of types of syringes 200 are interchangeably mounted on the syringe holder 106, the identification data of the syringe 200 mounted on the syringe holder 106 is input to the operation panel 121 serving as a type input means. Then, the main CPU 123 stores the data.

Then, the main CPU 123 acquires the electric resistance of the load cell 110 as an initial setting means in the initial state in which the syringe 200 is held by the syringe holder 106 and the ultrasonic motor 108 is not operating as described above. Hold. Further, the main CPU 123 responds to the input operation of the operation panel 121 by the ultrasonic motor 10.
When 8 is activated, the electric resistance of the load cell 110 is acquired in real time, and the pressure of the MR contrast agent, which is a drug solution, is detected as the pressure detecting means from the difference between the electric resistance and the electric resistance held in the initial state.

At this time, even if the stress acting on the load cell 110 is the same, the pressure of the MR contrast agent differs depending on the type of the syringe 200. Therefore, the main CPU 123 detects the pressure of the MR contrast agent corresponding to the identification data of the syringe 200. . In addition, the main CPU 123 uses the MR as described above.
When the pressure of the contrast agent is detected, a time-dependent graph of pressure is generated in real time as a pressure display means and is displayed on the liquid crystal display 122.

The MRI compatible injection apparatus 10 of the present embodiment.
0 is used near the imaging unit 301 of the MRI apparatus 300 as shown in FIG.
00 control unit 302. The control unit 302 is a computer system, which controls the operation of the imaging unit 301 and displays a tomographic image.

[Operation of the Embodiment] When the MRI-compatible injection device 100 of the present embodiment is used in the above-described configuration, the worker uses the extension tube to connect the syringe 200 to the subject located in the image pickup unit 301 of the MRI device 300. (Not shown), and as shown in FIG.
The cylinder portion 201 is held by the syringe holder 106 of the head portion 101, and the piston portion 202 is held by the slider mechanism 107.

When the identification data of the syringe 200 and the desired injection speed are input to the operation panel 121 of the apparatus main body 102 in such a state (steps S1 and S2), the main CP
The U123 stores the identification data (step S13), converts the injection speed into the rotation speed, and registers the data in the phase control circuit 124 (steps S14 and S15).

When the injection start is input in such a state,
(Step S3), the main CPU 123 acquires and holds the electric resistance of the load cell 110 without operating the ultrasonic motor 108 (steps S4 and S5), and after this is completed, the phase control circuit 124 instructs the ultrasonic motor 108 to operate. Is driven (step S6).

Then, the phase control circuit 124 generates a drive voltage corresponding to the registered rotational speed of the data, and the VCO 126 converts the drive voltage into a drive signal of a frequency corresponding thereto. The ultrasonic motor 108 is driven by this drive signal, so that the slider mechanism 107 slides the piston portion 202 of the syringe 200.

At this time, the rotary encoder 129 detects the actual rotation speed of the ultrasonic motor 108, and the phase control circuit 124 generates the drive voltage so that the actual rotation speed matches the desired rotation speed. MR of this embodiment
The I compatible injection device 100 injects the MR contrast agent in the syringe 200 into the subject at the set desired speed.

At the same time, the main CPU 123 acquires the electric resistance of the load cell 110 in real time (step S7), and based on the difference between the electric resistance and the electric resistance held in the initial state, it corresponds to the identification data of the syringe 200 by M.
The pressure of the R contrast agent is detected (step S8).

Further, from this pressure, the main CPU 123
Generates a time-lapse graph in real time and causes the liquid crystal display 122 to display this time-lapse graph as data.
(Step S10). Then, when the MRI compatible injection device 100 of the present embodiment detects the completion of injection of the MR contrast agent from the stroke of the slider mechanism 107 (step S11),
The driving of the ultrasonic motor 108 is stopped and the initial state is restored (step S12).

When the detected pressure of the MR contrast agent reaches a predetermined upper limit pressure (step S9), the main CPU 123
Forcibly stops driving the ultrasonic motor 108 (step S16), and displays an error guidance such as "abnormal pressure has occurred, check the syringe" on the liquid crystal display 122 (step S17).

Further, the MRI compatible injection apparatus 10 of this embodiment.
In 0, if the injection start is input without inputting the identification data of the syringe 200 and the injection speed of the MR contrast agent,
The above operation is executed with the previous registration data, and when the previous registration data does not exist, the above operation is executed with the default setting registration data.

[Effects of Embodiment] In the MRI-compatible injection device 100 of this embodiment, since the rotational speed of the ultrasonic motor 108 is feedback-controlled as described above, the syringe 20
An MR contrast agent of 0 can be injected into a subject at a predetermined rate, and the injection rate can be freely set as desired.

Moreover, the piston portion 20 of the syringe 200
The load cell 110 made of a non-magnetic material applies the stress that presses the
Since the pressure of the MR contrast agent to be injected is detected from the stress of the MR contrast agent, the pressure of the MR contrast agent can be detected without disposing the pressure sensor inside the syringe 200 and without disturbing the magnetic field unnecessarily. it can.

In particular, since the pressure of the MR contrast agent is detected corresponding to the identification data of the syringe 200, the pressure of the MR contrast agent can be accurately detected while the various syringes 200 are exchangeable. Moreover, the ultrasonic motor 108
Since the electric resistance of the load cell 110 is acquired in the initial state in which the MR contrast agent is not activated and the pressure of the MR contrast agent is detected from the difference from the electric resistance of the load cell 110 when the ultrasonic motor 108 is activated, the pressure of the MR contrast agent is detected. Can be accurately detected.

Further, since the detected pressure of the MR contrast agent is displayed in real time as a time-lapse graph, the leakage of the MR contrast agent can be detected by the pressure drop. Further, since the ultrasonic motor 108 is forcibly stopped when the detected pressure of the MR contrast agent reaches a predetermined upper limit pressure, it is possible to prevent the syringe 200 from being damaged due to abnormal pressure.

[Modification of Embodiment] The present invention is not limited to this embodiment, and various modifications are allowed without departing from the scope of the invention. For example, in the present embodiment, the operator inputs the identification data of the syringe 200 by the manual operation of the operation panel 121. However, for example, the type of the syringe 200 to which the syringe holder 106 is attached is detected and the identification data is obtained. It can also occur.

Further, in this embodiment, the main CPU 123 converts a desired injection speed input from the operation panel 121 into a desired rotation speed and registers the data in the phase control circuit 124, and the phase control circuit 124 registers the data. It has been illustrated that the actual rotation speed of the ultrasonic motor 108 is matched with the desired rotation speed. However, the main CPU 123 holds the desired injection pressure input from the operation panel 121 as data, and the phase control circuit 124 applies the drive voltage that matches the pressure detected by the load cell 110 with the desired pressure.
It is also possible to generate.

Further, in this embodiment, the slider mechanism 107 causes the piston portion 2 of the syringe 200 to operate by the load cell 110.
Although it has been exemplified that only the stress that presses 02 is detected and converted into the injection pressure of the MR contrast agent, for example, the load cell 11
It is also possible to detect the stress at which the slider mechanism 107 pulls out the piston portion 202 at 0 and convert it into the suction pressure of the MR contrast agent.

Further, in the present embodiment, the MRI compatible injection apparatus 100 exemplifies that the MR contrast agent is injected into the subject from one syringe 200 as the drug solution, but it is also possible to inject physiological saline as the drug solution, for example. It is also possible to appropriately inject the MR contrast agent and physiological saline from the two syringes 200.

The MRI-compatible injection device 10 of this embodiment is used.
Since 0 is used in the vicinity of the MRI apparatus 300 as described above, it is preferable to form each part with a non-magnetic material.
For example, the ultrasonic motor 108 and the slider mechanism 107 are
It is preferable to form it with a non-magnetic material such as stainless steel or free-cutting brass, and the housing of the head portion 101 and the like should be formed with a non-magnetic material such as resin or aluminum, or a magnetic-shielding material such as titanium or soft iron. It is preferable to form.

In this embodiment, an MRI-compatible injection device 100 called an MR contrast agent injection device for injecting an MR contrast agent into a subject imaged by the MRI apparatus 300 is exemplified. For example, FIGS. As shown in FIG. 9, an MRI-compatible injection device 500 called a chemical pump or a syringe pump, which continuously injects a small amount of a chemical solution containing a drug into a subject being treated, can also be implemented.

In this MRI compatible injection device 500, the slider mechanism 107 includes the gear train 501 and the screw shaft 5.
02 and a slider 503. Limit sensors 504 and 505 for detecting the initial position and the final position of the slider 503 are connected to the main CPU 123.

Such an MRI compatible injection apparatus 500 is
It is used to continuously inject a small amount of a drug solution into a subject in a general ward or ICU, regardless of the imaging by the MRI apparatus 300. However, this MRI compatible injection device 5
The subject who is injecting the drug solution at 00 may be imaged by the MRI apparatus 300, and even in such a case, the above-described MRI compatible injection apparatus 500 does not affect the magnetic field of the MRI apparatus 300.

[0052]

In the MRI-compatible injection device of the present invention, the stress for sliding the piston portion of the syringe is detected by the load cell made of a non-magnetic material, and this is converted into the pressure of the liquid medicine injected into the subject. The pressure of the drug solution can be detected without disturbing the magnetic field.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit structure of an MRI compatible injection device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the appearance of an MRI compatible injection device.

FIG. 3 is a perspective view showing a state in which the syringe is mounted on the head portion.

FIG. 4 is a partial cross-sectional view showing the structure of the load cell portion of the slider mechanism.

FIG. 5 is a perspective view showing the external appearance of the MRI apparatus.

FIG. 6 is a characteristic diagram showing a drive signal of an ultrasonic motor which is a drive motor.

FIG. 7 is a flowchart showing a processing operation of a main CPU.

FIG. 8 is a schematic block diagram showing an internal structure of an MRI-compatible injection device of a modified example.

FIG. 9 is a perspective view showing the appearance of an MRI-compatible injection device.

[Explanation of symbols] 100,500 MRI compatible injection device 106 syringe holder 107 slider mechanism 108 Ultrasonic motor that is a drive motor 110 load cell 121 Operation panel that functions as type input means 123 Main CPU that functions as various means 200 syringes 201 Cylinder part 202 Piston part 300 MRI device

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Claims (6)

[Claims] 1. An MRI-compatible injection device that slides a piston part of a syringe that at least injects a drug solution into a subject imaged by an MRI (Magnetic Resonance Imaging) device, and a syringe holder that holds a cylinder part of the syringe. A drive motor that generates power corresponding to the supplied electric power, a slider mechanism that slides the held piston portion of the syringe by the power of the drive motor, and the slider mechanism that is made of a non-magnetic material causes the piston portion to move. An MRI compatible injection device comprising: a load cell that generates an electric signal corresponding to a sliding stress; and pressure detection means that detects the pressure of the drug solution injected into the subject from the electric signal. 2. The pressure detecting means further comprises initial setting means for acquiring and holding an electric signal of the load cell in an initial state in which the syringe is held by the syringe holder and the drive motor is not operating. The MRI-compatible injection device according to claim 1, wherein the pressure sensor detects the pressure of the drug solution from the difference between the electric signal held by the initial setting means and the electric signal generated by the load cell in real time. 3. The syringe holder has a plurality of types of the syringes exchangeably mounted, and also has type input means for inputting identification data of the syringe held by the syringe holder, The MRI-compatible injection device according to claim 1 or 2, wherein the means detects the pressure of the drug solution from the electrical signal in response to the input identification data of the syringe. 4. The MRI-compatible injection device according to claim 3, further comprising a type detection unit that detects the type of the syringe held by the syringe holder and outputs identification data to the type input unit. 5. The MRI-compatible injection according to claim 1, further comprising feedback means for controlling the electric power of the drive motor corresponding to the pressure detected by the pressure detection means. apparatus. 6. The MRI-compatible injection device according to claim 1, further comprising pressure display means for displaying the pressure detected by the pressure detection means in real time data as a graph over time.