Study On In Vivo Photoacoustic Detection Miniaturization System For Early Metastasis Of Melanoma

Melanoma is a kind of a malignant tumor of melanocytes with the properties of high mortality and high metastasis rate.Circulating tumor cells(CTCs)is the sign of cancer metastasis,recurrence and therapeutic effect.The circulating melanoma cells with the high content of melanin can be detected by light absorption to diagnose and treat cancer at an early stage.Based on the principle of In vivo Photoacoustic Flow Cytometry(PAFC)and ergonomics,an in vivo photoacoustic detection miniaturization system was designed.The volume of the detection system was greatly reduced by simplifying the design of optical pathway.The vascular positioning system was designed by frequency doubling crystal.The photoacoustic effect of melanoma cells was collected through photoacoustic effect.Finally,melanoma CTCs were calculated and analyzed to monitor the metastasis process of melanoma,so as to reduce the mortality rate of cancer.The system design mainly includes photoacoustic signal excitation system,vascular positioning system,photoacoustic signal detection system and photoacoustic signal processing system.The vascular positioning system can accurately locate the location of blood vessels by multiplying the frequency of 1064 nm laser to 532 nm through a frequency multiplier crystal.Photoacoustic signal excitation system connects 1064 nm high-frequency pulse laser successively with optical fiber,collimator and lens to form a light spot to focus on the location of blood vessels,and activates the photoacoustic signal generated by the detected sample.The photoacoustic signal detection system collects the photoacoustic signal through ultrasonic transducer and converts it into electrical signal,which is then amplified by the amplifier and transmitted to the data acquisition and storage unit.The photoacoustic signal processing system uses threshold method,difference method,single-period signal analysis and other methods to process and store data,and finally confirms that the photoacoustic signal is from the detected object.In vivo photoacoustic detection miniaturization system is suitable for the detection of CTCs,providing a new method for the early diagnosis of cancer in clinical practice.Compared with traditional In vivo Flow Cytometry(IVFC),In vivo photoacoustic detection miniaturization system uses melanoma cells to replace fluorescent dyes as biomarkers and collects Photoacoustic Signal(PA)signals in a non-invasive manner,which is realtime,unmarked,non-invasive and portable.In order to distinguish PA signal and background noise effectively,wavelet denoising method is adopted to reduce background noise.Photoacoustic detection miniaturization system realizes the flexible transmission of laser,which can realize the isolation between equipment and patients,avoid patients’ fear of large diagnostic equipment,and its small portability greatly promotes the clinical transformation and application of PAFC.