JP2003235838A - Ultrasonic diagnostic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maximize a vibrator driving voltage on each photographing condition while suppressing within a safety specification value the rise of a temperature of a probe with driving of an ultrasonic vibrator. <P>SOLUTION: A controller 10 determines the voltage of a variable voltage source 13 in accordance with the photographing condition inputted from a keyboard 11 and corresponding to that voltage, a pulse driving circuit 15 performs pulse driving of the ultrasonic vibrator with an incorporated probe 17. A current measuring circuit 16 measures a flowing current and sends a measured value to the controller 10. The controller 10 calculates power consumption from that current value and the voltage value, predicts the rise of the temperature of the probe 17 by using a constant read out of a storage device 12 and controls the voltage of the variable voltage source 13 so that the predicted value can be settled within the safety specification value. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an ultrasonic diagnostic apparatus for managing the surface temperature of a probe. 2. Description of the Related Art An ultrasonic diagnostic apparatus obtains a tomographic image in a subject by irradiating an ultrasonic beam into a subject (body of a subject) and receiving a reflected wave of the beam. In addition, the velocity of a blood flow or the like is detected using the Doppler phenomenon.
In order to generate ultrasonic waves, the ultrasonic transducer is pulse-driven, and heat is generated based on power consumption there, and the surface temperature of the probe containing the ultrasonic transducer rises. In particular, in the Doppler mode, the number of transmitted pulses (wave number) is large, so that the temperature rises more than in the B mode or the M mode, and the temperature rises to such a degree that the user feels very hot. Therefore, some restrictions are required. Such a temperature rise is also a problem from the viewpoint of the safety of the subject, and in fact, a safety standard value is set for the probe surface temperature rise. [0003] On the other hand, the temperature of the inside of the subject rises due to the incidence of the ultrasound inside the subject, so that the safety of the ultrasonic power incident on the subject is also limited. However, since setting of various parameters and the like according to photographing conditions is generally complicated, it is difficult to set such that the probe surface temperature does not exceed a safety standard value. For example, in a Doppler mode that includes a color Doppler (a colorized Doppler image), various parameters such as a transmission pulse voltage, a repetition frequency, a wave number, a transmission focus position, and a transmission frequency are set according to imaging conditions. The setting, setting of an ROI (region of interest), setting of a sample volume, and the like are extremely complicated, and when combined with another mode, the complexity is doubled. In all sequences including these, it is not practical, if not impossible, to set parameters and the like so that the probe surface temperature is within the safety standard value and sufficient diagnostic information can be obtained. . [0005] Therefore, conventionally, as a simple method,
In many cases, a parameter is limited so that the temperature falls within the safety standard value under the imaging condition where the temperature rise is the largest, and the limitation is used also in other imaging conditions. Actually, among various parameters, the repetition frequency, transmission focus position, transmission frequency, ROI, and sample volume are left to the user's arbitrary settings, and a pulse drive voltage and the like are automatically set on the device side according to those settings. Limits so that the surface temperature does not exceed the safety standard value. [0006] However, when a method is adopted in which parameters are limited so that the temperature does not exceed a standard under photographing conditions in which the temperature rises as in the past, the parameter may be reduced under other photographing conditions. However, there is a problem that it cannot be used effectively and sufficient information cannot be collected. For example, when the position of the ROI is slightly changed, the voltage is limited even if a higher pulse driving voltage is used, even though the temperature rise falls within the standard, so that a high pulse driving voltage cannot be used. As a result, sufficient diagnostic information that would have been obtained by using a high pulse drive voltage cannot be obtained. [0007] In particular, the photographing conditions under which the temperature rises most are special ones that rarely seem to be used in ordinary inspections (for example, photographing that sets an ROI that is long in the azimuth direction and short in the depth direction). This condition is significant when (condition) is satisfied. In order to avoid this adverse effect, it is conceivable to individually determine, for each of all photographing conditions, a parameter limit that allows more diagnostic information to be obtained within a range where the temperature rise falls within the standard. For example, the setting of the ROI is innumerable, and it takes an enormous amount of time to find the parameter limit in advance for each. In addition, since an ultrasonic diagnostic apparatus generally allows a plurality of probes to be exchanged, it is necessary to determine parameter limits in advance for each probe, and this requires an excessively long time and labor. [0009] In order to achieve the above object, an ultrasonic diagnostic apparatus according to the present invention comprises an input device for inputting imaging conditions and a probe having a built-in ultrasonic transducer. A variable voltage type voltage source for driving the ultrasonic transducer, a pulse drive circuit for pulse driving the ultrasonic transducer using the voltage source according to input imaging conditions, and the probe From the limit value of the incident ultrasonic power to the subject, a storage device that stores a constant for the temperature rise of each probe and a safety standard value of the probe temperature, and a current detection circuit that detects a current flowing through the ultrasonic transducer, The voltage of the voltage source is determined according to the imaging conditions input within the range of the limit value of the incident ultrasonic power read from the storage device, and the pulse drive circuit is operated to input the ultrasonic wave. Is started, power consumption is obtained based on the current detected by the current detection circuit, and the temperature rise at the probe is estimated using the constant read from the storage device. It is characterized by comprising a controller for limiting the voltage of the voltage source so as to be within the standard value, and a signal processing circuit for processing a signal received by the ultrasonic transducer. When a user inputs photographing conditions via the input device, the controller sets various parameters according to the inputted photographing conditions and causes the probe to generate ultrasonic waves. However, the voltage of the variable voltage type voltage source for driving the ultrasonic transducer is determined so as not to exceed the limit value of the incident ultrasonic power read from the storage device. Then, the current flowing in the ultrasonic transducer at this time is detected by the current detection circuit, and the controller calculates the power consumption based on the detected current and a known voltage. Further, the controller estimates the temperature rise of the probe using the constant read from the storage device for the used probe. When a voltage is applied to the built-in ultrasonic vibrator, a current flows through the probe, and when the probe generates heat according to its power consumption, the temperature gradually increases with a predetermined time constant.
The relationship between this power consumption and the temperature rise of the probe differs for each probe, and since the shape of the probe is complicated,
It is determined in advance for each probe by an experiment, and a constant representing the relationship is stored in a storage device. In this way, the controller can accurately predict the temperature rise of the probe, and determines whether or not the temperature exceeds the safety standard value read from the storage device within the ultrasonic irradiation time, and does not exceed it. Then, continue the ultrasonic wave injection as it is, and if it exceeds, lower the voltage of the voltage source,
In the same manner, the voltage of the voltage source is controlled by detecting the current, estimating the temperature rise, and determining whether the safety standard value is exceeded. Therefore, the drive voltage can be increased within a range where the probe temperature does not exceed the safety standard value, and sufficient diagnostic information can be obtained. Next, embodiments of the present invention will be described in detail with reference to the drawings. In an ultrasonic diagnostic apparatus according to an embodiment of the present invention, as shown in FIG. 1, a controller 10 including a CPU, a keyboard as an input device, a storage device 12 such as a semiconductor memory or a magnetic disk device, a variable voltage A source 13, a pulse generating circuit 14, a pulse driving circuit 15, a current measuring circuit 16, a probe 17, a preamplifier 18, and a signal processing circuit 19 are provided. An ultrasonic transducer (not shown) is built in the probe 17, and a driving voltage is applied to the ultrasonic transducer to generate an ultrasonic wave, and the ultrasonic wave is incident on the inside of a subject (not shown). I do. The incident ultrasonic wave is reflected inside the subject, and the reflected wave returns. Therefore, the ultrasonic wave is received by the ultrasonic transducer in the probe 17, the received signal is amplified by the preamplifier 18, and the signal processing circuit 19 To output the signal, and use it for image display and the like (the reception signal system is omitted). A variable voltage source 13, a pulse generation circuit 14, and a pulse drive circuit 15 are provided for applying a pulse-like drive voltage to the ultrasonic transducer of the probe 17. The pulse drive circuit 15 shapes the drive voltage from the variable voltage source 13 into a pulse according to the pulse signal from the pulse generation circuit 14 and applies the pulse to the ultrasonic transducer of the probe 17. The output voltage of the variable voltage source 13 and the output pulse of the pulse generation circuit 14 are controlled by the controller 10. When the user operates the keyboard 11 to input photographing conditions, the controller 10 obtains and sets various parameters while referring to the information stored in the storage device 12. Regarding the transmission, these include, for example, the pulse repetition frequency, the delay time based on the focus position, the number of waves, the drive pulse voltage, the number of ultrasonic transducers in the probe used for transmission, and the drive pulse frequency. Among them, the pulse repetition frequency, the focus position, the number of waves, the number of ultrasonic transducers, and the like can be set directly or indirectly by the user. Depending on the composite mode, the ROI position in the color Doppler, the sample pull volume position in the Doppler mode, and the like, a complicated transmission sequence is obtained. As for the drive voltage, the controller 10 reads the limit value of the ultrasonic power stored in the storage device 12, obtains the limit value within a range not exceeding the limit value, and sends it to the variable voltage source 13 for setting. That is, a safety limit value is set for the ultrasonic power incident on the subject, and the limit value is stored in the storage device 12 in advance. The drive voltage value is limited so as not to exceed this limit value. When the setting of various parameters is completed, a pulse voltage is applied to the vibrator of the probe 17, and
Scanning for imaging (ultrasonic beam scanning) is started. At this time, the current flowing through the ultrasonic transducer of the probe 17 is measured by the current measuring circuit 16. As shown in FIG. 1, for example, the current measuring circuit 16 includes a current detecting resistor 21 inserted in a path through which a current flows, an amplifier 22 for amplifying a voltage generated at both ends thereof, and an A / D converter 23
The digitized value of the detected current value is sent to the controller 10. The controller 10 calculates power consumption from the input detected current value and the set voltage value of the variable voltage source 13. On the other hand, the probe 1 to be used is
7 is automatically recognized. Therefore, an identification code or the like is attached to the probe 17 in advance, and the probe 10 is automatically recognized by the controller 10 when the probe 17 is connected. The controller 10 stores the constant corresponding to the recognized probe 17 in the storage device 12.
And the temperature rise of the probe 17 is predicted. If the predicted temperature value is within the safety standard value read from the storage device 12, the controller 1
0 indicates that the scanning is continued with the parameters as they are, and if the value exceeds the safety standard value, the variable voltage source 1
Lower the set voltage of 3. Then, after the voltage is changed, the current is measured again, the temperature rise is similarly predicted, and the set voltage of the variable voltage source 13 is reduced until the predicted temperature value falls within the safety standard value. Since each current measurement can be performed within one second, the voltage of the variable voltage source 13 can be set in a relatively short time so that the predicted temperature rise value of the probe 17 does not exceed the safety standard value. The above description relates to one embodiment of the present invention, and it goes without saying that the specific configuration and the like can be variously changed without departing from the spirit of the present invention. For example, the controller 10 always calculates the power consumption (for example, at one-second intervals), determines whether the calculated power consumption has exceeded a predetermined limit value, and determines that the calculated power consumption has exceeded the limit value. Scanning may be stopped immediately upon determination. As a result, it is possible to improve safety by coping with a case where power consumption increases due to some abnormality. As described above, according to the ultrasonic diagnostic apparatus of the present invention, the pulse drive voltage can be increased within a range in which no danger due to temperature rise occurs under any imaging conditions. Thus, useful information for diagnosis can be sufficiently collected.

[Brief description of the drawings] FIG. 1 is a block diagram showing an embodiment of the present invention. [Explanation of symbols] 10 Controller 11 Keyboard 12 Storage device 13 Variable voltage source 14 pulse generation circuit 15 Pulse drive circuit 16 Current measurement circuit 17 Probe 18 Preamplifier 19 Signal processing circuit 21 Current detection resistor 22 Amplifier 23 A / D converter

Claims (1)

Claims: 1. An input device for inputting a photographing condition,
A probe having a built-in ultrasonic vibrator, a variable voltage type voltage source for driving the ultrasonic vibrator, and a pulse of the ultrasonic vibrator using the voltage source according to an input imaging condition. A pulse drive circuit to be driven; a storage device for storing a limit value of an ultrasonic power incident on the subject from the probe, a constant relating to a temperature rise for each probe, and a safety standard value of the probe temperature; A current detection circuit for detecting a current, and a pulse drive circuit is operated by determining the voltage of the voltage source according to the imaging condition input within the limit value of the incident ultrasonic power read from the storage device. Start the ultrasonic wave injection, calculate the power consumption based on the current detected by the current detection circuit, and estimate the temperature rise at the probe using the constant read from the storage device. A controller that limits the voltage of the voltage source so that the estimated temperature rise value falls within a safety standard value, and a signal processing circuit that processes a signal received by the ultrasonic vibrator. Ultrasound diagnostic device.