Study On Detection & Analysis Methods Of Exhaled Breath In Patients With Lung Cancer Based On PTR-MS

Proton transfer reaction mass spectrometry(PTR-MS)is the trace volatile organic compounds in recent years,the rapid development of the detection technology(VOCs),due to its high sensitivity,fast response,good specificity,no need of sample pretreatment,has great advantages in detecting VOCs.Human exhalation gas has a large number of important physiological information,and to a certain extent,it reacts to the metabolic process of the human body.And exhalation detection technology has the advantages of nondestructive sampling and simple operation,which is a hot research field in the field of medical examination.In this paper,the key technical parameters of PTR-MS are studied by theoretical analysis and experimental evaluation based on the topic of "proton transfer reaction mass spectrometer development and application demonstration",which is a major scientific instrument and equipment in Ministry of science and technology.By using mathematical deduction and experimental verification,we analyze and compare the multi physical field simulation methods in the ion optics analysis software SIMION,and then use the reasonable simulation method to design and optimize the ion transmission lens structure.The simulation algorithm of proton transfer reaction process is designed.A clinical experimental scheme for the study of VOCs in exhaled gas of lung cancer patients was proposed by PTR-MS.Taking the lung cancer patients in Peking University People’s Hospital as the research subjects,normal healthy people as controls,the difference of VOCs expression in exhaled gas was studied.Artificial neural network,random forest,support vector machine and two element Logistic regression were used to detect lung cancer expiratory data.Several characteristic respiratory VOCs markers of lung cancer were selected as candidate targets for early diagnosis of lung cancer,and a corresponding classification model was established.This research is the first time to study the multi physical field simulation method of PTR-MS for the first time in China.In view of the screening of expiratory markers in patients with lung cancer using PTR-MS,a more perfect clinical trial plan was proposed.And a variety of data mining methods are used to analyze the exhalation expression spectrum.The results show that the exhaled VOCs diagnostic model can be used as one of the screening and early warning methods for high risk population.Of course,the value of the above diagnostic models in the early diagnosis of lung cancer needs further evaluation,such as further enlarging the sample size,expanding the data dimension and improving the sensitivity of the detection system.Meanwhile,the mechanism of respiratory VOCs metabolic pathway will become the focus of later research,which will provide a scientific basis for the large-scale screening of characteristic VOCs in lung cancer.