JP2003052693A - Ultrasonograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve transmission control by accurately estimating the temperatures of wave transmitting/receiving surfaces of probes in an ultrasonograph. SOLUTION: An ultrasonic probe 10 is provided with a temperature sensor 30 and based on an estimated temperature T' actually measured thereby and transmitting condition data to be outputted from a control part 34, a temperature estimating part 38 estimates the temperature T of a wave transmitting/ receiving surface 29A. The control part 34 executes the control of a reduction in transmission power or the like when the estimated temperature T is above the upper limit α of temperature.

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an ultrasonic diagnostic apparatus, and more particularly, to a surface temperature control of an ultrasonic probe. 2. Description of the Related Art In an ultrasonic diagnostic apparatus, a transmitting and receiving surface (usually, an acoustic lens surface) of an ultrasonic probe is brought into contact with the surface of a living body, and ultrasonic waves are transmitted and received in that state. You. An ultrasonic transducer as an electro-acoustic transducer is provided inside the ultrasonic probe, and the ultrasonic transducer transmits and receives ultrasonic waves. The ultrasonic transducer includes a single transducer, an array transducer, and the like. A transmission pulse is intermittently supplied to the ultrasonic transducer every transmission repetition period, and an electric transmission pulse is converted into an ultrasonic pulse in the ultrasonic transducer. The conversion efficiency in that case is, for example, about 10 to 20%, and the energy loss due to the conversion is heat energy. That is, if the transmission of the ultrasonic pulse is continuously performed, the ultrasonic transducer generates heat, and the ultrasonic probe itself containing the ultrasonic transducer also generates heat. [0004] From the viewpoint of safety, the upper limit of the temperature of the ultrasonic probe (temperature of the transmitting / receiving surface) which is brought into contact with the surface of a living body is set by laws, industry standards, and the like. When hitting a wave, transmission control is performed within a range where the temperature of the wave transmitting / receiving surface does not exceed its upper limit. Specifically, when the temperature of the ultrasonic probe reaches the upper limit, the control is such that the transmission power (transmission voltage) is forcibly reduced and the transmission is stopped. In the transmission control described above, it is ideal to provide a temperature sensor directly on the transmitting / receiving surface of the ultrasonic probe. In such a configuration, however, the temperature sensor is inevitably provided by the ultrasonic sensor. An obstacle to propagation. On the other hand, if the temperature sensor is provided on the side of the ultrasonic probe other than the transmitting and receiving surface, for example, and the temperature detected there is regarded as the temperature of the transmitting and receiving surface, an error easily occurs with respect to the actual temperature of the transmitting and receiving surface. By the way, without using such a temperature sensor, it is necessary to estimate the temperature of the transmitting and receiving wave surface from the transmission conditions (transmission voltage, transmission pulse width, transmission repetition period, elapsed time from the start of transmission, etc.) using a temperature estimation formula. Is also possible. However, in this case, since a uniform temperature estimation formula is used for each device, various conditions such as variations in the characteristics of the ultrasonic vibrator and aging of the ultrasonic vibrator (decrease in conversion efficiency) must be sufficiently satisfied. Therefore, there is a problem that satisfactory temperature estimation accuracy cannot be ensured as a result. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide an ultrasonic probe having a transmitting / receiving surface without directly providing a temperature sensor on the transmitting / receiving surface (body contact surface). An object of the present invention is to estimate an actual temperature with high accuracy, thereby realizing optimum transmission control. In order to achieve the above object, the present invention provides an ultrasonic probe having a wave transmitting / receiving surface abutting on a living body and transmitting and receiving an ultrasonic wave, and the ultrasonic probe A temperature sensor provided at a temperature reference position in the probe, and a temperature estimating unit for estimating a temperature of a transmitting / receiving surface of the ultrasonic probe based on a temperature of the temperature reference position detected by the temperature sensor; Temperature control means for performing transmission restriction based on the estimated temperature of the transmission / reception wavefront. According to the above configuration, a temperature sensor is provided at a temperature reference position (a reference measurement position different from the transmission / reception plane) on the ultrasonic probe, and using the detected temperature (reference temperature), for example, By using the temperature estimation formula in consideration of the transmission condition, it is possible to estimate the actual temperature of the transmission / reception wave surface with high accuracy. The above configuration is positioned as a combination of the actual measurement method and the estimation method. When the estimated temperature of the transmitting and receiving wave surface reaches or approaches the temperature upper limit, transmission control similar to the conventional one such as transmission power down is performed, whereby the temperature of the transmitting and receiving wave surface is maintained below the upper limit. You. According to the present invention, in the conventional device, it is possible to avoid excessive transmission power limitation caused by a temperature estimation error, and to realize reliable temperature management. Preferably, furthermore, in a state where ultrasonic waves are being transmitted and received by the ultrasonic probe, the ultrasonic probe contacts the transmitting and receiving surface of the ultrasonic probe and detects the actual temperature of the transmitting and receiving surface. It is also possible to provide a temperature sensor and use the actual temperature of the transmitting / receiving surface to confirm that the temperature detection and the temperature estimation are normal, for example, during ultrasonic diagnosis. In this case, means for comparing the actual temperature of the transmitting and receiving surface with the reference temperature at the temperature reference position to determine a temperature detection error, and means for comparing the actual temperature of the transmitting and receiving surface and the estimated temperature to determine an estimation error The reliability and safety of the apparatus can be further improved by providing such means. Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of an ultrasonic diagnostic apparatus according to the present invention. In FIG. 1, the ultrasonic diagnostic apparatus is roughly composed of an apparatus main body 12, an ultrasonic probe 10, an operation panel 14, and a display device 16. The ultrasonic probe 10 is connected to the apparatus main body 12 by a cable 18. Specifically, a connector 20A is provided at an end of the cable pulled out from one end of the ultrasonic probe 10, and the connector 20A is connected to a connector 20B provided on the apparatus main body 12. The cable 18 is a multi-core cable composed of a plurality of signal lines.
8 includes a signal line drawn from a temperature sensor 30 described later in the present embodiment. Note that the signal line from the temperature sensor 30 may be separately routed from the ultrasonic probe 10 to the apparatus main body 12 without being included in the cable 18. An array transducer 22 including a plurality of transducers is provided in the ultrasonic probe 10. The array transducer 22 transmits and receives ultrasonic waves, and an ultrasonic beam is formed by the array transducer 22. A backing layer 24 is provided on the back side of the array transducer 22, and a matching layer 26 and an acoustic lens 30 are provided on the living body side of the array transducer 22. The surface of the acoustic lens 30 constitutes a wave transmitting / receiving surface 29A, and the wave transmitting / receiving surface 29A is in contact with the living body surface 100. Therefore, for the living body surface 100,
The heat generated in the array vibrator 22 is transmitted via the transmitting / receiving surface 29A, that is, it is important to control the temperature of the transmitting / receiving surface 29A. For this reason, in the present embodiment, a temperature sensor 30 is buried at a predetermined position (different from the transmitting / receiving surface but preferably near the transmitting / receiving surface) in the case of the ultrasonic probe 10, and the temperature of the transmitting / receiving surface 29A is Is indirectly detected. Specifically, the temperature at the position where the temperature sensor 30 is provided (temperature reference position) is detected, and a signal indicating the temperature is sent to the apparatus main body 12. In the apparatus main body 12, the transmission section 32 functions as a transmission beamformer for supplying a transmission signal to a plurality of vibrating elements constituting an array transducer, thereby forming a transmission beam. Receiver 36
Performs a phasing addition process on received signals output from a plurality of vibrating elements constituting an array vibrator, thereby functioning as a receive beam former for electronically forming a receive beam. The phasing-added received signal output from the receiving section 36 is input to an image forming section 40, and the image forming section 40 converts an ultrasonic image, for example, a B-mode image, based on the received signal. After the image data is formed and sent to the display processing unit 42, the image data is output to the display device 16 through necessary processing. An ultrasonic image is displayed on the display device 16. Incidentally, the display processing unit 42 is, for example, a digital scan converter (DS).
C) and the like. The control unit 34 includes a transmission unit 32 and a reception unit 36
Operation control. In particular, the control unit 34
2, transmission power (transmission voltage), transmission frequency, transmission repetition period, transmission pulse width,
Conditions such as transmission time are set. The transmission condition data 200 is also separately output to the temperature estimating unit 38. The temperature estimating section 38 is provided with the transmitting / receiving wave surface 29A.
Is a calculation unit for estimating the temperature T. In the temperature estimation, the reference temperature T ′ detected by the temperature sensor 30 is used as a parameter. Specifically, the temperature estimating unit 38 has a temperature estimating function, and includes a reference temperature T ′ as one parameter in the temperature estimating function. Here, the temperature estimation function is, for example, T = f
(A, b, c..., T ′), where a, b, c.
00 corresponds to each condition value. That is, the temperature estimating unit 38 estimates the temperature of the transmitting and receiving surface using the temperature estimating equation according to the transmission condition, as in the conventional estimation method. At this time, the actually measured reference parameter is used as a correction parameter. The temperature T 'is used, that is, a more reliable temperature (estimated temperature) T of the transmitting / receiving surface 29A is estimated by a combination of the temperature estimation and the actual temperature measurement. As will be described later with reference to FIG. 2, when the estimated temperature T exceeds the temperature upper limit α, the control unit 34
The transmission condition given to the transmission unit 32 is adjusted, and more specifically, the transmission condition is corrected so that the transmission power is reduced. By such feedback control, the temperature of the transmitting / receiving surface 29A is always maintained at or below the temperature upper limit α, and the transmitting / receiving of ultrasonic waves is continuously performed within the range. The operation panel 14 is an input means for performing various user settings on the control section 34. Also,
The display device 16 is configured as a display on which an ultrasonic image is displayed. The apparatus main body 12 is provided with a probe holder 50 (the probe holder 50 is conceptually shown in FIG. 1). In the probe holder 50, the ultrasonic probe 10 is placed on the body surface 100. Ultrasonic probe 1 during non-ultrasonic diagnosis that is not in contact
0 is stored and held. As a modification of the present embodiment, a temperature sensor 52 is provided in the probe holder 50,
With respect to the ultrasonic probe continuously transmitting and receiving the ultrasonic wave by the temperature sensor 52, the transmission and reception surface 29
The actual temperature (actual temperature) Ta of A is actually measured. FIG. 2 is a flowchart showing the transmission restriction control of the control unit 34 shown in FIG. First,
In S101, when the transmission and reception of the ultrasonic wave are started in the ultrasonic probe 10, in S102, it is determined whether to end the transmission and reception of the ultrasonic wave, and the transmission and reception of the ultrasonic wave are continued. The temperature sensor 30 in S103
In step S104, the temperature estimating unit 38 detects various transmission conditions and the reference temperature T ′.
, The temperature (estimated temperature) T of the transmitting / receiving surface 29A is obtained. In S105, it is determined whether or not the estimated temperature T is equal to or higher than the temperature upper limit α. If the estimated temperature T is equal to or higher than the temperature upper limit α, the transmission condition is corrected in S106, that is, the transmission power is reduced. .
As a result, the energy supplied to the ultrasonic probe is reduced, and the amount of heat generated there is also reduced. Therefore, according to the above embodiment, it is possible to more accurately estimate the temperature of the transmitting / receiving surface 29A as compared with a simple temperature estimation or a simple indirect temperature detection. To improve the operation reliability and safety of the ultrasonic diagnostic apparatus. Next, a modification of the above embodiment will be described with reference to FIGS. FIG. 3 shows the concept of the probe holder 50 provided in the apparatus main body shown in FIG. The probe holder 50 has a concave portion for receiving the ultrasonic probe 10 as described above, and the bottom surface 50A is provided with a temperature sensor 52. The temperature sensor 52 comes into contact with the transmitting / receiving surface 29A of the accommodated ultrasonic probe 10 and directly detects the surface temperature (actual temperature) Ta. Even in a state where the ultrasonic probe 10 is housed in the probe holder 50, the transmission and reception of ultrasonic waves are usually repeatedly performed, that is, a state in which heat generation is continued. Therefore, for example, the ultrasonic probe 1
When 0 is stored in the probe holder 50, the actual temperature Ta of the transmitting / receiving surface 29A can be detected. As shown in FIG. 1, the detected actual temperature Ta is sent to a temperature estimating unit 38, and the temperature estimating unit 38 executes an error determination as described in detail below. FIG. 4 shows a configuration example of the temperature estimating section 38. The estimation calculation unit 60 is a circuit that calculates the estimated temperature T from the reference temperature T ′ according to the above-described temperature estimation function. The subtractor 62 subtracts the actual temperature Ta from the reference temperature T ′, and outputs ΔT1, which is the difference value. In the absolute value calculator 66, the absolute value of the difference value ΔT1 is calculated, and the calculation result is compared in the detection error determiner 70 with a predetermined determination value K1. The absolute value of the difference value ΔT1 is equal to the determination value K.
If it becomes larger than 1, for example, the temperature sensor 30
Is considered to be a detection error because of possible malfunction of the device. On the other hand, in the subtractor 64, the actual temperature Ta
Is subtracted from the estimated temperature T, and the difference value is output as ΔT2. The absolute value calculator 68 calculates the absolute value of the difference ΔT2, and outputs the calculation result to the estimation error determiner 72.
Is compared with a predetermined determination value K2. Here, when the absolute value of the difference value ΔT2 is larger than the determination value K2,
It is determined that there is a large error in the temperature estimation calculation or the like in the temperature estimating unit 38, so that the estimation is determined to be an error. When the detection error or the estimation error is determined, the control unit 34 controls the display device 6 as necessary.
An error is displayed at 0 or a predetermined error signal is output. According to the above modification, the appropriateness of the operation of the temperature sensor 30 and the temperature estimation can be constantly monitored. Since the notification can be made, there is an advantage that the operation reliability and safety of the ultrasonic diagnostic apparatus can be further improved. As described above, according to the present invention,
There is an advantage that the temperature control of the ultrasonic probe can be performed more appropriately.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an overall configuration of an ultrasonic diagnostic apparatus according to the present invention. FIG. 2 is a flowchart showing an operation when performing temperature management. FIG. 3 is a diagram showing a configuration of a modified example. FIG. 4 is a diagram showing signal processing contents of a modified example. [Description of Signs] 10 ultrasonic probe, 12 device main body, 14 operation panel, 16 display device, 18 cable, 22 array vibrator, 30 temperature sensor, 34 control unit, 38 temperature estimation unit.

Claims (1)

Claims: 1. An ultrasonic probe in which a wave transmitting / receiving surface is in contact with a living body to transmit and receive an ultrasonic wave, and a temperature sensor provided at a temperature reference position in the ultrasonic probe. Temperature estimating means for estimating the temperature of the transmitting / receiving surface of the ultrasonic probe based on the temperature of the temperature reference position detected by the temperature sensor; anda transmission limit based on the estimated temperature of the transmitting / receiving surface. An ultrasonic diagnostic apparatus, comprising: a temperature control unit that executes.