Research On Arbitrary Waveform Control Technology For Low-Intensity Ultrasound Therapy

Neurological diseases affect the health of millions of people.Traditional drug therapy has little effect on brain diseases,such as Alzheimer's disease.Physiotherapy provides a new means for these diseases.Low-intensity ultrasound(LIFU)is a non-invasive technique for nervous system diseases,which can be used for targeted drug delivery and the neuroregulation of the brain,and is expected to achieve the treatment of abnormal nerve loop function.Studies on the treatment of dual-frequency ultrasound,and the phase and amplitude distortion of transcranial ultrasound has led to higher requirements for ultrasound control.Most traditional ultrasound therapy systems have been based on single-frequency control technology.However,the amplitude could not be independently adjusted.Hence,there has been great limitations in the application of dualfrequency ultrasound and transcranial compensation.For this reason,an arbitrary waveform control system for low-intensity ultrasound therapy was proposed in this study.The ultrasonic shape can be defined according to the software definition,and the amplitude and phase can be independently modulated to meet the new ultrasonic therapy application.The study is presented,as follows:(1)The principle of treatment with low-intensity ultrasound was introduced.This included the use of ultrasonic cavitation to open the blood-brain barrier for targeted drug delivery,and the use of acoustic radiation for neural regulation.The present study introduced the ultrasound focusing technique,which appears to target the target brain region during the treatment,and the transcranial compensation method,explains its demand for amplitude and phase control according to the principle of transcranial ultrasound focusing and the application of new ultrasound therapy..(2)In order to meet the above application requirements for ultrasound therapy,an arbitrary waveform control array system for low-intensity ultrasound therapy was designed,which can support phase-controlled transducers with up to 128 array elements.This includes a waveform control system designed for ultrasonic targeting focusing,and an ultrasonic emission circuit for amplitude independent control.The waveform control system includes a digital control core for waveform generation,a beam synthesis system for ultrasonic focusing,a clock synchronization system for phase control accuracy,and a communication system for software operation and multisystem cascade.The ultrasonic transmitting circuit includes a power amplification circuit designed to achieve independent amplitude,a matching circuit designed to ensure maximum efficiency transmission,and a power detection circuit designed to monitor the output.(3)In order to verify whether the designed ultrasonic system can produce the ultrasonic output needed for ultrasonic therapy,the output of the system was tested in electronics and acoustics,respectively.According to "JJF1678-2017",the test platform was built,and the key parameters and output waveforms of the dual-frequency therapy experiment and transcranial attenuation test were tested.The acoustic scanning platform built according to "GB/T19890-2005" was introduced,and the sound field distribution of the system excitation transducer was quantitatively measured.(4)In order to prove that the control technology can be used for the treatment of lowintensity ultrasound,the designed ultrasound system was used to carry out treatment experiments in mice.The multi-point blood-brain barrier opening experiment on mice was carried out using the phase-controlled transducer to verify whether the system can realize the targeted drug delivery of multiple targets by controlling the ultrasonic focus position.In this experiment,the beam synthesis technique was used for ultrasonic focusing to stimulate three stimulation target areas of the mouse brain,respectively.By injecting dye into the blood,it was observed that the three stimulation areas of the mouse brain were stained with dye.The results revealed that the phasecontrolled focusing accuracy of the system can satisfy the targeted ultrasound therapy in different parts of the brain of mice.In summary,in order to meet the requirements for ultrasonic amplitude and phase control in low-intensity ultrasound therapy,an arbitrary control system for low-intensity ultrasound therapy was designed.This can support the phase-controlled ultrasonic transducer with 128 array elements,and the phase difference was less than 15 ns.The working frequency ranged within 0.5-5.0 MHz,and the range of acoustic focus was less than 6×6 mm.The multi-point blood-brain barrier opening experiment was carried out in mice,and the results revealed that the developed arbitrary waveform ultrasound control technology can be used in therapeutic application.