Study On Semi-automatic Transcranial Doppler System For CBFV Searching

Transcranial Doppler ultrasound has been introduced since twenty years ago. Nowmanual searching is the main method. Manual operation has a lot of disadvantage, suchas poor reproducibility, strict demand and it is difficult to achieve long-term monitoring.As these considered, this paper proposes a cerebral blood flow detection and monitoringsystem which is easily to operate.We design a semi-controlled robotic holder which can accomplish the whole actionof manual searching. The probe holder is consisted of three sections, including planarlocation, orientation position and pressure adjustment. Here we take advantage of CADsoftware to make sure the mechanism rationality in kinematics and dynamics. Forexample, the simulation of the probe’s rotation range is done by MATLAB and the keycomponents’ force analysis is done by ANSYS.Most DOFs of Transcranial Doppler detection can be controlled separately. Asevery DOF must keep a certain holding force, we selected three servo motor and a DCmotor with worm drive. Considering the PWM output control signal, the AVRmicrocontroller is chosen. We made PC software to control motors easily. To search theposition of the blood vessel effectively, the paper introduces the possible trajectory ofthe probe. For the implementation of automatic search, this paper describes the principleand process of ultrasound signal processing. The detected signal can shows vividly byPC software. And by treating the analyzing signal data as the feedback of motor, wewill ultimately achieve the purpose of automation detection.Experiments show that the system can complete all the action of manual searchingand can be done by key operation. The probe can reach the area of general temporalwindow, including a circle area with18mm radius. By adjusting the orientation of theprobe around X and Y axis, the angle between the probe and blood vessel will be theminimum. The probe can automatically move when rotation. In the detection process,the blood flow signal can be display on the monitor and the main parameters such asmaximum speed, average speed can be calculated.The semi-automated intracranial blood flow detection system can replace the currentmainstream way and provides hardware prerequisite for future automation. TranscranialDoppler system of fully automation will effectively promote this technology in thefuture and make household possible.