JP5265520B2 - Chemical injection device and method for controlling the chemical injection device - Google Patents

Description

  The present invention relates to a liquid medicine injection device for injecting a liquid medicine filled in a syringe into a blood vessel of a subject by pushing a piston of a syringe into a cylinder, and a control method thereof.

  Medical diagnostic imaging apparatuses include a CT (Computed Tomography) scanner, an MRI (Magnetic Resonance Imaging) apparatus, a PET (Positron Emission Tomography) apparatus, an angiographic apparatus, and an MRA (MR Angio) apparatus. When these devices are used, a chemical solution such as a contrast medium or physiological saline is often injected into the subject.

  Usually, the drug solution is filled in a syringe. Generally, a syringe has a cylinder containing a chemical solution and a piston inserted in the cylinder so as to be movable in the axial direction. An injection needle is connected to the cylinder via an extension tube. This injection needle is punctured into the blood vessel of the subject, and the piston is pushed into the cylinder in this state, whereby the drug solution in the syringe can be injected into the subject.

  A chemical solution used for diagnostic imaging often has a high viscosity, and a high pressure is required to inject such a high-viscosity chemical solution. Therefore, it is common to automatically inject a chemical solution into a subject using a chemical solution injection device. The chemical injection device has an injection head to which a syringe is detachably attached. The injection head includes a piston drive mechanism, and the piston drive mechanism pushes the piston of the syringe into the cylinder.

  Each of the syringe, the extension tube, and the injection needle has an allowable pressure, and if a pressure exceeding the allowable pressure is applied to the syringe, the extension tube, or the injection needle, the syringe, the extension tube, or the injection needle may be damaged. Therefore, it is necessary to inject the chemical solution so as not to exceed these allowable pressures.

  Therefore, Patent Document 1 discloses a chemical liquid injector in which a load cell for detecting a load for pressing a piston is provided in a piston drive mechanism. The chemical injection device measures and monitors the injection pressure of the chemical in real time based on the load detected by the load cell.

  In a chemical injection device that can monitor the injection pressure in real time, a pressure lower than the permissible pressure is set in advance as a set pressure, and the chemical injection device has a predetermined injection speed determined based on the subject's physical information, imaging region, etc. Inject the drug solution. During the injection operation of the chemical solution, the injection pressure is detected based on the output of the load cell. When the detected injection pressure exceeds the set pressure, the operation of the piston drive mechanism is stopped.

  Even if the operation of the piston drive mechanism is stopped, the internal pressure of the syringe is still high, and the drug solution in the syringe is injected into the subject by the pressure. As the drug solution is injected into the subject, the internal pressure of the syringe gradually decreases, and the injection pressure also decreases accordingly. When the injection pressure drops below the set pressure, the piston drive mechanism resumes operation, thereby pushing the piston further into the cylinder.

The chemical solution injection device can inject the chemical solution into the subject without exceeding the allowable pressure by repeatedly performing the above series of operations.
Patent Document 1: Japanese Patent Application Laid-Open No. 2003-290343

  However, in the conventional chemical liquid injector that detects the injection pressure, when the injection pressure reaches the set pressure, the operation and stop of the piston drive mechanism are repeated thereafter. Since the piston drive mechanism uses a motor as a drive source, the piston drive mechanism is operated and stopped by switching the motor on and off. By repeating the on / off switching of the motor, noise and vibration are generated in the injection head. Depending on the degree of noise and vibration of the injection head, the subject may feel uneasy. In particular, the vibration of the injection head may adversely affect the function of each component of the injection head.

  The present invention provides a chemical injection device that suppresses on / off switching of a motor in a case where on / off control of a motor of a piston drive mechanism is performed so that the injection pressure does not exceed a predetermined pressure, and a control method thereof. With the goal.

  In order to achieve the above object, a chemical liquid injector of the present invention is a chemical liquid injector that is equipped with a syringe having a cylinder and a piston, and injects a chemical liquid filled in the syringe by pushing the piston into the cylinder. The injection pressure detected by the injection pressure detection means has a piston drive mechanism having a motor as a drive source for pushing the piston into the cylinder and an injection pressure detection means for detecting the injection pressure of the chemical solution in real time. When the value exceeds a preset limit value, on / off control of the motor is controlled based on the limit value. In the chemical injection device that performs such motor switching control, in the present invention, in particular, when the injection pressure is stabilized by the switching control, the piston is configured so that the chemical solution is injected at a constant injection speed after which the injection pressure becomes stable. Control the operation of the drive mechanism.

In the present invention, in particular, during the motor switching control described above , it is determined in advance during a period between the time when the motor was turned on / off last time and the time when the motor was turned on / off at least once before. if injection pressure that deviates from a pressure range which is has not been detected by said injection pressure detecting means, said injection pressure you determined to be stable.

  In this case, the predetermined pressure range can be determined around the limit value. Further, it may be determined whether or not the injection pressure is stable when the motor is stopped by the on / off switching control of the motor. Furthermore, the constant injection rate is preferably the average injection rate during the period.

Furthermore, the present invention is equipped with a piston drive mechanism equipped with a motor as a drive source for injecting a chemical solution filled in the syringe by attaching a syringe having a cylinder and a piston and pushing the piston into the cylinder . providing an injection pressure detection means for detecting the injection pressure of liquid medicine in real time, and a control unit for controlling the piston drive mechanism based on the injection pressure detected by the injection pressure detecting means, a control method of a liquid injector for have a . According to the control method of the present invention, the control unit sets the limit value of the injection pressure of the chemical solution in advance, and the control unit uses the limit value as a reference when the injection pressure detected by the injection pressure detection means exceeds the limit value. Between the step of performing the motor on / off switching control, the time during which the motor on / off was last switched during the switching control, and the time during which the motor on / off was switched at least once before During the period, if the injection pressure outside the predetermined pressure range is not detected , the control unit determines that the injection pressure is stable, and if the injection pressure is determined to be stable, the subsequent steps are stable. as chemical is injected at a constant injection rate as the injection pressure, having the steps of the control unit controls the operation of piston driving mechanism.

In this case, the predetermined pressure range may be determined around the limit value. Further, the step of determining that the injection pressure is stable may be performed when the motor is stopped by the on / off switching control of the motor. Furthermore, it is preferable that the step of controlling the operation of the piston driving mechanism includes that the control unit obtains an average injection rate during the period as a constant injection rate.

  According to the present invention, the injection pressure of the chemical liquid is controlled so as not to exceed the predetermined pressure by switching on / off the motor of the piston drive mechanism. At that time, if the injection pressure is stabilized, the operation of the piston drive mechanism is controlled so that the chemical solution is injected at a constant injection speed at which the injection pressure becomes stable thereafter, so the number of on / off switching of the motor is suppressed. be able to. As a result, except for the initial period until the injection pressure is stabilized, noise and vibration associated with the on / off switching of the motor do not occur.

1 is a perspective view of an example of a chemical liquid injection system to which the present invention is applied. It is a perspective view of the chemical injection device shown in FIG. It is a perspective view which shows the injection | pouring head shown in FIG. 2 with the syringe with which it is mounted | worn. It is a block diagram of the electric system of the injection | pouring head shown in FIG. It is a flowchart which shows an example of the chemical | medical solution injection | pouring operation | movement by a chemical | medical solution injection apparatus. It is a graph which shows the example of the relationship between the injection | pouring time of chemical | medical solution, and injection | pouring pressure when inject | pouring a chemical | medical solution according to the flow shown in FIG. It is a flowchart which shows the other example of the chemical | medical solution injection | pouring operation | movement by a chemical | medical solution injection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Chemical solution injection apparatus 101 Injection control unit 110 Injection head 130 Piston drive mechanism 141 Control part 142 Motor control circuit 143 Motor driver 144 Motor 145 Rotary encoder 146 Load cell 200C, 200P Syringe 210 Cylinder 220 Piston 300 CT apparatus 1000 Chemical solution injection system

  Referring to FIG. 1, there is shown a chemical liquid injection system 1000 according to an embodiment of the present invention that includes a chemical liquid injection apparatus 100 and a CT apparatus 300 that is a fluoroscopic imaging apparatus. The CT apparatus 300 and the chemical liquid injector 100 are connected to each other so that information can be transmitted and received between them.

  The CT apparatus 300 includes a scanner 301 that executes an imaging operation, and an imaging control unit 302 that controls the operation of the scanner 301. In FIG. 1, all the components of the chemical injection system 1000 are shown to be arranged in the same room. However, when actually taking a fluoroscopic image of a subject, the imaging control unit 302 includes a scanner 301. In addition, the chemical solution injection device 100 is arranged in a separate room.

  For example, as shown in FIG. 2, the chemical solution injector 100 includes an injection head 110 mounted on the top of a stand 111 via an arm 112, and an injection control unit 101 connected to the injection head 110 via a cable 102. doing. The injection control unit 101 includes a main operation panel 103, a touch panel 104 serving as a display unit and an input unit, a hand unit 107 serving as an auxiliary input unit connected by a cable 108, and the like.

  As shown in FIG. 3, the injection head 110 has two concave portions 114 formed as syringe holding portions on the upper surface of the head main body 113, and the two syringes 200 </ b> C and 200 </ b> P are held in the concave portions 114. The syringes 200 </ b> C and 200 </ b> P have a cylinder 210 and a piston 220. For example, one syringe 200C is filled with a contrast medium as a chemical solution, and the other syringe 200P is filled with physiological saline. The distal ends of the two syringes 200C and 200P attached to the head main body 113 are connected by a connecting tube 230 that merges into one at the intermediate portion and is connected to an injection needle at the distal end.

  The injection head 110 is provided with two piston drive mechanisms 130 that are driven independently of each other in order to operate the syringes 200 </ b> C and 200 </ b> P held in the recess 114, corresponding to each recess 114.

  The piston drive mechanism 130 includes a rod 131 that can be moved forward and backward along the longitudinal direction of the recess 114, a gripper 132 that is provided at the tip of the rod 131 and grips the flange of the piston 220, and the rod 131. It has a motor that is a drive source that moves forward and backward, a power transmission device that converts rotation of the motor into linear motion and transmits it to the rod 131, and a load cell provided in the gripper 132. As the power transmission device, for example, a ball screw mechanism can be used. The load cell constitutes a part of pressure detection means for detecting the injection pressure of the chemical solution.

  The piston drive mechanism 130 is driven by a motor so as to advance the rod 131 in a state where the gripper 132 holds the flange of the piston. As a result, the syringes 200 </ b> C and 200 </ b> P mounted in the recesses 114 are operated so that the piston 220 is pushed into the cylinder 210. By operating the syringes 200C and 200P in this way, the contrast agent and physiological saline filled in the syringes 200P and 200C can be injected into the subject separately or simultaneously.

  Further, during the chemical liquid injection operation by the injection head 110, the pressure force applied to the piston 220 is detected by the pressure sensor provided in the gripper 132. From this pressing force, the injection pressure of the chemical solution can be obtained.

  As the mechanism for holding the syringes 200P and 200C and the piston drive mechanism 130 of the injection head 110, a known mechanism generally used for this type of injection device can be adopted.

  As above, the injection head 110 has been described focusing on the mechanical configuration. Next, the electrical configuration of the injection head 110 will be described.

  FIG. 4 shows a block diagram of the injection head 110 electrical system. FIG. 3 shows an auxiliary display and operation buttons, which are omitted in FIG. Each block shown in FIG. 4 may be configured as hardware or may be configured as a logic circuit.

  In FIG. 4, the control unit 141 controls the operation of the entire injection head 110. The control unit 141 receives a signal indicating the injection speed and limit pressure of the chemical solution from the injection control unit 101 (see FIG. 2). The injection speed is directly input to the injection control unit 101 or is determined by the injection control unit 101 based on the weight of the subject, the imaging region, and the like. The limit pressure is a standard that limits the injection pressure so that pressure exceeding the allowable pressure is not applied to the tools used for injection (syringe, extension tube, and injection needle), and injection control is performed as a value smaller than the allowable pressure of the tool used. From unit 101.

  The motor control circuit 142 controls the motor 144 via the motor driver 143 in accordance with the injection speed sent from the control unit 141. The rotation of the motor 144 moves the rod 131 (see FIG. 3) straight through the power transmission device described above. The moving speed of the rod 131 is proportional to the rotational speed of the motor 144, and the injection speed of the chemical solution from the syringe is proportional to the moving speed of the rod 131. Therefore, the rotational speed of the motor 144 and the injection speed of the chemical solution are in a proportional relationship with each other.

  A rotary encoder 145 is attached to the rotor of the motor 144. The rotary encoder 145 outputs a pulse signal at a frequency corresponding to the rotational speed of the motor 144, and the rotational speed of the motor 144 is determined from this pulse signal. The pulse signal output from the rotary encoder 145 is input to the control unit 141 and the motor control circuit 142, whereby the injection rate of the chemical solution is feedback controlled.

  The load cell 146 is provided in the above-described gripper 132 (see FIG. 3), and outputs an electrical signal corresponding to the stress received from the piston 220 when the gripper 132 presses the piston 220 (see FIG. 3). . The electric signal output from the load cell 146 is amplified by the amplifier 147 and input to the control unit 141. The controller 141 obtains the injection pressure of the chemical liquid based on the input electric signal.

  Next, a procedure for injecting a chemical solution by the chemical solution injection apparatus 100 according to this embodiment will be described.

  First, as preparation for injection, the operator connects the syringes 200 </ b> C and 200 </ b> P via the extension tube 230 to the injection needle punctured by the subject. In this state, the syringe 210C and 200P are mounted on the injection head 110 by holding the cylinder 210 in the recess 114 of the injection head 110 and holding the piston 220 by the gripper 132.

  Next, the operator inputs data necessary for injecting the chemical solution via the main operation panel 103 of the injection control unit 101 or the like. The data required for the injection of the chemical solution includes the subject's weight, sex, imaging site, injection amount of the chemical solution, the type of the chemical solution to be injected, the type of syringe 200C, 200P, the injection rate of the chemical solution, the limit pressure described above, and the like. . All of the data necessary for the injection of the chemical solution may be input by the operator, or only a part of the data is input, and the remaining data is obtained by the injection control unit 101 based on the input data. Also good.

  When the data necessary for the injection of the chemical solution is obtained, the injection control unit 101 sends the obtained injection speed and limit pressure as data to the injection head 110. The injection head 110 controls the operation of the two piston drive mechanisms 130 according to the injection speed and limit pressure sent from the injection control unit 101, and causes the syringe 200C, 200P to inject the drug solution into the subject.

  Hereinafter, the operation of the injection head 110 will be described with reference to the flowchart of FIG. Here, in order to simplify the description, the chemical solution injection operation for one syringe will be described, but the same applies to the other syringe.

  When the injection speed and limit pressure are sent as data to the injection head 110, the control unit 141 of the injection head 110 first sets the injection speed in the motor control circuit 142 (step S11), and sets the limit pressure to control the injection pressure. A reference value is set in the control unit 141 (step S12).

  Next, the control unit 141 issues an operation command to the motor control circuit 142. The motor control circuit 142 rotates the motor 144 at a rotation speed corresponding to the injection speed while feeding back the detection result from the rotary encoder 145 so that the chemical solution is injected at the set injection speed. Thereby, the injection of the chemical solution is started (step S13). Simultaneously with the start of injection, detection of the load by which the gripper 132 presses the piston 220 by the load cell 146 is started. The detection result in the load cell 146 is sent to the control unit 141 in real time, and is converted into injection pressure data by the control unit 141.

  Next, the control unit 141 compares the magnitude relationship between the set limit pressure and the injection pressure detected by the load cell 146 (step S14).

  If the detected injection pressure is below the limit pressure, the injection operation is continued. Specifically, it is determined whether or not the motor 144 is stopped (step S15). If the motor 144 is stopped, the motor 144 is rotated (step S16), and if it is rotated, the process proceeds to the next step. The rotation of the motor 144 is performed by sending a rotation command from the control unit 141 to the motor control circuit 142.

  On the other hand, if the detected injection pressure is greater than the limit pressure, the injection operation is interrupted. Specifically, it is determined whether or not the motor 144 is stopped (step S17). If it is operating, the motor 144 is stopped (step S18), and if it is stopped, the process proceeds to the next step. The motor 144 is stopped by sending a stop command from the control unit 141 to the motor control circuit 142.

  Next, the controller 141 determines whether or not the current chemical solution injection operation is in a state where the injection pressure is limited (step S19). In this embodiment, once the detected injection pressure exceeds the limit pressure, thereafter, on / off switching control of the motor 144 is performed to stabilize the injection pressure (steps S14 to S18). The state where the injection pressure is limited is a state where the on / off of the motor 144 is controlled to be switched. In other words, once the detected injection pressure exceeds the limit pressure, the injection pressure is limited thereafter.

  When the injection pressure is not limited, the control unit 141 determines whether or not the injection of the chemical solution is completed (step S20). The injection amount of the chemical liquid depends on the movement amount of the piston 220, that is, the number of rotations of the motor 144. Therefore, whether or not the injection of the chemical liquid has been completed can be determined by whether or not the rotation speed of the motor 144 has reached the rotation speed corresponding to the target injection volume of the chemical liquid. The rotational speed of the motor 144 can be detected by the rotary encoder 145.

  When the injection of the chemical liquid is not completed, the process returns to step S14 to compare again the magnitudes of the injection pressure and the limit pressure, and shifts to the subsequent steps according to the result. When the injection of the chemical liquid is completed, the motor 144 is stopped (step S24), and the chemical liquid injection operation is terminated.

  In step S19, when the injection pressure is in a restricted state, the control unit 141 determines whether or not the injection pressure is in a stable state (step S21). If the injection pressure is not stable, the process returns to step S14 to compare again the magnitude of the injection pressure and the limit pressure, and shifts to the subsequent steps according to the result. In other words, in a state where the injection pressure is limited, the motor 144 is switched on / off according to the magnitude relationship between the detected injection pressure and the limit pressure, whereby the injection pressure is gradually stabilized.

  On the other hand, if the injection pressure is stable, the injection rate of the chemical solution is changed to a constant injection rate so as to obtain a stable injection pressure (step S22). Thereafter, the injection rate is changed until the injection of the chemical solution is completed. The chemical solution is injected at the injection rate (steps S23 and S24), and the chemical solution injection operation is terminated.

  Here, with reference to FIG. 6 showing an example of a graph of the relationship between the time from the start of injection and the injection pressure, it is possible to determine whether the injection pressure of the chemical solution is in a stable state and to change the injection speed, while referring to FIG. explain in detail.

In the graph of FIG. 6, the horizontal axis indicates the time from the start of injection, and the vertical axis indicates the injection pressure. Further, "P _L" is the limit pressure described above, is set as smaller than the allowable pressure P _A. For example, the stable range R _S is defined within a predetermined range centered on the limit pressure P _L , such as the limit pressure P _L ± 5 psi.

The stable range R _S is a criterion for determining whether or not the controlled injection pressure is in a stable state. If the detected injection pressure falls within the stable range R _{S under} the conditions described later. The injection pressure is determined to be stable. The stable range R _S may be automatically set by the control unit 141 according to the limit pressure P _L or may be arbitrarily set by the operator.

A curve 410 in FIG. 6 shows an example of the transition of the injection pressure when the chemical solution is injected without the injection pressure reaching the limit pressure P _L. In this case, the injection pressure is not limited, and the chemical solution is injected to the end at the initially set injection rate.

A curve 400 in FIG. 6 shows an example of transition of injection pressure when the injection pressure exceeds the limit pressure P _L.

In the curve 400, since the injection pressure is equal to or lower than the limit pressure PL from the start of injection to time T1, the chemical solution is injected at the initially set injection speed. After time T1, the injection pressure exceeds the limit pressure P _L. At that time, a stop command is sent from the control unit 141 to the motor control circuit 142, whereby the motor 144 is stopped and the injection pressure is limited.

  When the motor 144 is stopped, the movement of the piston 220 is also stopped, so that the injection pressure is lowered. However, even if a stop command is sent from the control unit 141 due to inertia of the rotor of the motor 144, the rotational speed of the motor 144 does not immediately become zero. Therefore, the injection pressure starts to decrease after slightly increasing after time T1.

When the injection pressure decreases to the limit pressure P _L due to the stop of the motor 144, a rotation command is sent from the control unit 141 to the motor control circuit 142 at that time (time T2), and the motor 144 starts rotating again. When the motor 144 rotates, the piston 220 moves, and the injection pressure increases again. In this case, as in the case where the motor 144 is stopped, even if a rotation command is sent from the control unit 141 due to the inertia of the rotor, the motor 144 does not immediately start rotating. Therefore, the injection pressure starts to increase after slightly decreasing after time T2.

When the injection pressure increased by the rotation of the motor 144 exceeds the limit pressure P _L , at that time (time T3), the control unit 141 sends a stop command to the motor control unit 142 again to stop the motor 144.

Thereafter, the above-described on / off switching of the motor 144 is repeated. By repeatedly switching on / off of the motor 144 in this manner, the injection pressure repeatedly increases and decreases with the limit pressure P _L as a reference. During each motor stop period and during each motor rotation period, the increase and decrease _ranges of the injection pressure with respect to the limit pressure P _L are relatively large at first, but become smaller each time the motor 144 is switched on / off. Is included in the stable range R _{S of the first} .

The controller 141 stores the detected injection pressure along with the time. When the on / off of the motor 144 is switched, the control unit 141 stores the time (T1, T2, T3...) When the on / off of the motor 144 is switched. Then, in the step of determining whether or not the injection pressure is stable, the control unit 141 lastly switches the on / off of the motor 144, and switches on / off at least once before that time. If an injection pressure outside the stable range R _S is detected during the period between and, it is determined that the injection pressure is not in a stable state. In other cases, it is determined that the injection pressure is stable.

  For example, consider a case where step S14 in the flowchart of FIG. 5 is executed immediately after the time T4 has elapsed in the curve 400 of FIG.

At this time, since the detected injection pressure is smaller than the limit pressure P _L , the process proceeds from step S14 to step S15. If the motor 144 is rotating, it is continued, and if it is stopped, it is rotated (step S16). .

In the next step S19, since the injection pressure is already limited, the process proceeds to step S21, and it is determined whether or not the injection pressure is stable. Here, the time when the on / off of the motor 144 is switched last is T4, and the time when the motor 144 is switched once before is T3. It can be seen from the graph that the injection pressure outside the stable range R _S is detected during the period (T4-T3) between the last switching time T4 and the previous switching time T3.

  Therefore, at this stage, it is determined in step S21 that the injection pressure is not stable, and the process returns to step S14 to compare the injection pressure with the limit pressure. After that, the injection pressure once lowered increases again, and the same processing is repeated until the time T5 when the ON / OFF of the motor 144 is switched next elapses.

When the time T5 has elapsed, the detected injection pressure becomes greater than the limit pressure. Therefore, in the determination in step S14, the process proceeds to step S17, the motor 144 is stopped, and it is determined through step S19 whether the injection pressure is in a stable state (step S21). At this time, the last time the motor 144 was switched on / off is time T5. It can be seen from the graph that the injection pressure outside the stable range R _S is not detected during the period (T5-T4) between this time T5 and the time T4 switched to once before.

  Therefore, in step S21, the period used as a reference for determination is a period between the time when the motor 144 is finally switched on / off and the time when the on / off is switched once before that time. It is determined that the injection pressure is in a stable state.

On the other hand, if the period serving as a criterion for determination is a period between the time when the motor 144 was last switched on and off and the time when the on / off was switched twice before that time, as described above. In addition, during the period between the time T4 and the time T3, since the injection pressure outside the stable range R _S is detected, it is determined that the injection pressure is not in a stable state. In this case, after the next time T6 has elapsed, the injection pressure outside the stable range R _S is not detected during the period (T6-T4) between the time T6 and the time T4. At this stage, it is determined that the injection pressure is stable.

Here, in order to determine whether or not the injection pressure is in a stable state, a period for referring to whether or not the injection pressure is out of the stable range R _{S is set} to 1 from the time when the motor was turned on / off last. Although the example of the period up to the previous time or the time up to the second time has been shown, it may be the time period up to three times before or more than the previous time.

  If it is determined in step S21 that the injection pressure is in a stable state, then the control unit 141 changes the injection speed (step S22). In this step, the control unit 141 obtains the average injection rate of the chemical solution during the above-described period when it is determined that the injection pressure is in a stable state.

  As described above, the actual rotational speed of the motor 144 can be detected by the rotary encoder 145. The rotational speed of the motor 144 is proportional to the moving distance of the piston 220, and the moving distance of the piston 220 is proportional to the injection amount of the chemical solution. Therefore, if the relationship between the rotation speed of the motor 144 and the movement distance of the piston 220 and the relationship between the movement distance of the piston 220 and the injection amount of the chemical liquid are obtained in advance, the injection amount of the chemical liquid is obtained from the rotation speed of the motor 144. be able to. If the injection amount of the chemical solution is obtained, the average injection rate of the chemical solution can be obtained from the relationship with time.

  For example, when it is determined that the injection pressure is in a stable state in the period between time T5 and time T4 (T5-T4), the control unit 141 causes the motor 144 to be in the period (T5-T4). By calculating the injection amount of the chemical solution from the actual number of revolutions and dividing the determined injection amount by the period (T5-T4), the average injection speed in the period (T5-T4) is determined. When it is determined that the injection pressure is in a stable state during the period between time T6 and time T4 (T6-T4), the control unit 141 causes the motor 144 during this period (T6-T4). By calculating the injection amount of the chemical solution from the actual number of revolutions and dividing the determined injection amount by the period (T6-T4), the average injection speed in that period (T6-T4) is determined.

  In step S22, the chemical solution injection rate is changed to the average injection rate obtained as described above. That is, the control unit 141 sets the obtained average injection speed as a new injection speed in the motor control circuit 142, and the motor control circuit 142 controls the rotation speed of the motor 144 according to the setting. Thereafter, as described above, the chemical solution is injected at the injection speed until the injection of the chemical solution is completed (step S23), and when the injection of the chemical solution is completed, the motor is stopped (step S24).

As described above, in this embodiment, when the injection pressure exceeds the pressure limit P _L , the injection of the chemical solution is controlled in two stages, the first stage PH1 and the second stage PH2. That is, the first stage PH1 is an injection pressure control stage in which the ON / OFF switching of the motor 144 is repeated based on the pressure limit P _L from the start of the injection of the chemical liquid until the injection pressure of the chemical liquid enters the stable range R _S. The second stage PH2 is a constant speed injection stage after the injection pressure of the chemical liquid enters the stable range R _S.

Thus, after the injection pressure of the chemical liquid enters the stable range R _S , the number of times the motor 144 is turned on / off can be reduced by controlling the chemical liquid to be injected at a constant injection speed. In the second stage PH2, since the motor 144 is rotated at a constant speed until the injection of the chemical solution is completed, no noise or vibration associated with the on / off switching of the motor 144 occurs in the injection head 110 during that time.

Moreover, the injection rate of the liquid medicine in the second stage PH2, since the injection pressure of the drug solution is the average infusion rate in the presence within the stable range R _S, the injection pressure of liquid medicine in the second phase PH2 is stable range R _S Never exceed. Therefore, the injection pressure since kept below the allowable pressure P _A, also eliminates the syringe 200C, 200P, extension tube 230 and injection needle is damaged by the pressure of the liquid medicine.

  The present invention has been described above by taking typical embodiments as examples. However, the present invention is not limited to the above-described embodiments, and various modifications are made without departing from the technical idea of the present invention. be able to.

  For example, in the above-described embodiment, it is determined whether or not the injection pressure is stable in the “state where the injection pressure is limited”. The “state where the injection pressure is limited” includes both the case where the motor is rotating and the case where the motor is stopped. However, if the motor is stopped, it can be said that the injection pressure is limited. Therefore, for example, as shown in FIG. 7, it is determined whether or not the injection pressure is in a stable state only when the motor is stopped (step S21). If it is determined whether or not the injection has been completed (step S20), the determination of whether or not the injection pressure is in a restricted state can be omitted.

  In the above-described embodiment, the example in which the two liquid syringes 200P and 200C are mounted on the injection head 110 has been shown. However, the number of the liquid syringes that can be mounted on the injection head 110 may be one or three or more. It may be. In that case, the concave portions 114, the piston drive mechanisms 130, and the like are provided in a number corresponding to the number of chemical syringes to be mounted. The size of the chemical syringe that can be attached to the injection head 110 is also arbitrary, and the size of the recess 114, the stroke of the rod 131, and the like are set so as to match the size of the chemical syringe to be attached. When mounting a plurality of chemical solution syringes, the sizes of the chemical solution syringes may be different from each other.

  Furthermore, in the above-described embodiment, the chemical solution injection device 100 applied to the CT apparatus 200 has been described. However, the present invention is applicable even if the fluoroscopic imaging apparatus is an MRI apparatus, a PET apparatus, an angio apparatus, or an MRA apparatus. Can do.

Claims (11)

A syringe having a cylinder and a piston is mounted, and a liquid injector for injecting a liquid filled in the syringe by pushing the piston into the cylinder,
A piston drive mechanism having a motor as a drive source for pushing the piston into the cylinder;
Injection pressure detection means for detecting the injection pressure of the chemical solution in real time;
Have
When the injection pressure detected by the injection pressure detection means exceeds a preset limit value, on / off switching of the motor is controlled based on the limit value,
During the switching control, during a period between the time when the motor was turned on / off last time and the time when the motor was turned on / off at least once before, the predetermined pressure range was exceeded. If the injection pressure is not detected by the injection pressure detection means, it is determined that the injection pressure is stable,
The injection pressure is determined to be stable al, thereafter stable injection pressure to become constant liquid injector operation of the piston driving mechanism as chemical is injected is controlled by the injection rate. The chemical injection device according to claim 1 , wherein the predetermined pressure range is determined around the limit value. It said injection pressure judgment is made as to whether the stable when the motor is stopped by the switching control of the motor on / off, liquid injector according to claim 1 or 2. The chemical injection device according to any one of claims 1 to 3 , wherein the constant injection rate is an average injection rate during the period. The chemical solution injection device according to any one of claims 1 to 4, wherein the limit value is set as a value smaller than an allowable pressure of the syringe, the extension tube, or the injection needle. The chemical injection device according to any one of claims 1 to 5, further comprising the syringe filled with a chemical. A syringe having a cylinder and a piston is mounted, and a piston drive mechanism having a motor as a drive source for injecting the liquid medicine filled in the syringe by pushing the piston into the cylinder ; an injection pressure detection means for detecting the injection pressure in real time, a control method of a liquid injector for chromatic and a control unit for controlling the piston drive mechanism based on the injection pressure detected by said injection pressure detecting means ,
The controller presetting a limit value of the injection pressure of the chemical solution;
When the injection pressure detected by the injection pressure detection means exceeds the limit value, the control unit performs on / off switching control of the motor based on the limit value;
During the switching control, during a period between the time when the motor was turned on / off last time and the time when the motor was turned on / off at least once before, the predetermined pressure range was exceeded. The controller determines that the injection pressure is stable if no deviated injection pressure is detected ; and
When it is determined that the injection pressure is stable , the control unit controls the operation of the piston drive mechanism so that the chemical liquid is injected at a constant injection speed that becomes a stable injection pressure thereafter.
A control method for a chemical injection device having   The method for controlling a chemical liquid injector according to claim 7, wherein the predetermined pressure range is determined around the limit value. The method of controlling a chemical injection device according to claim 7 or 8, wherein the step of determining that the injection pressure is stable is performed when the motor is stopped by on / off switching control of the motor. 10. The chemical solution according to claim 7, wherein the step of controlling the operation of the piston driving mechanism includes the controller obtaining an average injection rate during the period as the constant injection rate. Control method of injection device. 11. The method according to claim 7, wherein the step of setting the limit value includes the control unit setting the limit value as a value smaller than an allowable pressure of the syringe, the extension tube, or the injection needle. The control method of the chemical | medical solution injection apparatus of description.

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