Development Of Human Spect Mechanical System Operation Status Monitoring Device

Human SPECT is a large nuclear medical imaging device,which is widely used in disease examination and functional research of brain,lung,kidney,heart and other human organs.In SPECT,its mechanical system drives two detectors of several hundred kilograms around or close to the body to obtain functional images of the organ by detecting the distribution of radioactive tracers within the body.The reliability of SPECT system working state is directly related to personal safety,so it is necessary to monitor the working state of SPECT system to detect potential dangerous signals in advance and ensure the stable operation of the device.Based on analyzing the working characteristics of SPECT mechanical system,this paper presents a multiparameter monitoring scheme and develops a SPECT monitoring device based on STM32 single chip microcomputer.The device is mainly composed of signal acquisition,data processing,transmission,analysis and storage modules.The working state of SPECT mechanical system was monitored by measuring three parameters: vibration,noise and stress/strain.Vibration signal measurement scheme was used to monitor the running state of the main rotary motion mechanism,the translation and rotation mechanism of detector in SPECT mechanical system.Piezoelectric acceleration sensor is selected as vibration signal sensing device,which is installed at the monitoring point of motion mechanism by magnetic absorption to measure the vibration of the equipment when running.A single-chip microcomputer data acquisition system based on STM32F103 ZE and AD7606 is designed to collect the analog voltage signal output by the sensor,and then transmit the data to the top computer through serial port.LabVIEW software is used to design the data display and analysis program.Through the user interface,data waveform can be observed for statistical analysis,correlation analysis and power spectrum analysis.For the stress/strain monitoring of SPECT mechanical system,the finite element method was used to simulate and analyze the carrying condition of SPECT mechanical system.The resistance strain gauge is used as the sensor to build the measurement circuit of wheatstone bridge.The measurement signal is converted into analog voltage signal output by the integrated operational amplifier based on OP07 C.Then,the AD7606 chip is used for analog-to-digital conversion.STM32 single-chip microcomputer is used to transfer the converted data information to PC,and LabVIEW virtual software is used for stress/strain analysis of the processed data.The strain parameters are observed by oscilloscope.The stress parameters are analyzed by statistical analysis.In order to evaluate the running state of SPECT mechanical system,the noise acquisition module was designed to monitor the mechanical noise of the moving mechanism such as lead screw,gear and reducer,the electromagnetic noise of the driving motor,and the whole machine noise.Elector microphone is selected as the noise sensor,and an audio power amplifier circuit based on LM386 is built to convert the collected signal into an analog voltage signal.The ADC function module inside STM32 microcontroller is used for AD conversion and digital signal output,and the data are statistically analyzed by LabVIEW software.The system has been produced and monitored with SPECT mechanical system.The results show that the signal data collected by the device is relatively accurate and stable,and it can effectively monitor the running state of SPECT device and provide data support for evaluating the service life of SPECT system.