A simple instrument of HIFU piezo measurement

HIFU piezo for ultrasonc knife has the outstanding advantages of no pain, no surgery, short side effects, short treatment and recovery time, which has become a hot spot in the research of tumor treatment equipment. However, due to its therapeutic effect, it has yet to be extensively clinically tested.Based on promotion and application, with the continuous improvement of equipment technology and clinical application technology, high-energy ultrasonic knife will bring revolutionary changes for the traditional cancer treatment methods. The so-called "ultrasonic knife" uses secondary focusing technology to focus the ultrasonic waves emitted by multiple probes to form a high-intensity focusing piezo that approximates the size . The ultrasonic waves from the treatment body are formed from the outside of the patient's body through the human body.

The intensity of the high focus ultrasound piezo at the high focus piezo, and the local high temperature is generated enough to burn the cancer cells for therapeutic purposes. The ultrasonic intensity of a single probe is much lower and does not harm the human body. Since the focal spot intensity gradient of the single probe in the axial direction is too small to meet the requirements of the treatment, the high energy ultrasonic knife generally adopts the multi-probe secondary focusing mode, as is shown in FIG. Multiple probes are mounted in the spherical focusing body, depending on the geometry of the probe. The piezoelectric ceramic is used in the probe is a circular spherical plate with a thickness of about 2 mm. It is difficult to guarantee the geometric axis and acoustic axis of the probe for various reasons. Strictly coincident, the focal spots of multiple probes can not be accurately overlapped, and even multiple focal spots are formed, which greatly affects the quality of the focal spot.

The test of the sound field of the probe requires the design of a high-precision three-dimensional motion tester, which not only has a long design and manufacturing cycle, but also has high equipment cost and low usage rate. Therefore, we have made full use of the high-precision 3D motion positioning function of the device itself, and designed a set of ultrasonic field sound auxiliary testing tools to solve the problems encountered in the development process at a very low cost.

Multi-probe is to focus the geometrical axis of the positioning surface of multiple probes to one point by mechanical positioning method, which requires the acoustic axis of the single probe to exactly coincide with the geometric axis. Since the treatment requires a certain depth, the single probe has a small diameter relative to its "focal length", and its sound field does not form a point at the focal point like the optical lens, but forms a thin intermediate cylindrical shape near the focal point. The diameter of Hifu piezo crystal is smaller at the "focus", and the diameter of the "focus" becomes larger, but the change is not large. Therefore, the "focal length" of the sound field has little effect on the focus accuracy, and the coincidence degree of the acoustic axis and the geometric axis at the "focus" is treated. The focusing accuracy of the first multiple probes is greatest.

The ultrasonic knife device has a computer-controlled three-dimensional motion mechanism, which can drive the treatment head to achieve three-dimensional accurate positioning, the motion precision of Hifu piezo ceramic for ultrasonic knife is ±0.05mm, the movement range of each dimension movement is 250mm, and the center hole of the treatment head has a telescopic B-ultrasound is used to locate the lesion. Since the detection and treatment are performed by the same movement mechanism, there is no precision requirement for the treatment,which is supporting the patient as long as the position is kept unchanged during the treatment. To detect the coincidence of the acoustic axis of the probe with the geometric axis, it is necessary to establish the positional relationship between the positioning surface of the clamping probe and the motion mechanism that realizes the three-dimensional movement of the measuring head space.If the hydrophone of the test sound field is mounted on the treatment head of the exercise mechanism, the measurement of ultrasound piezoelectric transducer is placed on the treatment, and the probe is mounted on the underside of the pool, it is difficult to opposite the probe, and the replacement of the probe may also change the position of the treatment bed. 

The measurement method of the mechanism is: the probe is used for spatial three-dimensional motion, and the hydrophone for measuring the sound field is fixed in the pool and does not move. The method is to use an auxiliary measuring tool to mount the probe on the treatment head, and the positioning hole of the probe is positioned by the adjustment mechanism, so that the axis of the probe is positioning hole is parallel to the vertical direction z-axis, and the hydrophone is positioned by using the calibration test piece to make the water listen. The measuring head is located on the axis of the probe positioning hole, HIFU piezo crystal is replacing the calibration test piece, and installing the probe to be tested. The ultrasonic sound field is tested by a hydrophone, and the hydrophone is fixed in the pool. The probe or the treatment head is three-dimensionally moved in a certain way under computer control. The computer automatically measures and saves the data of each point in the sound field, and uses the software to process the measurement data into the desired result of the user.