Human Body Verification Of Respiratory Phase Detection System In Tumor Radiotherapy

With the development of modern medical technology,a variety of accurate radiotherapy techniques have been applied in clinical practice,which has significantly improved the survival and quality of life of patients after receiving radiotherapy.There are many uncertain factors in clinical practice which seriously restrict the implementation of precise radiotherapy,and the most significant effect is the patient's semi-autonomous breathing exercise.Target region located in the patient's chest will have larger displacement with every breath,if could not be effective filtered,will influence the radiation physician's judgment on the size and location of the tumor,causing target region outline is not accurate,missing the region of interest under the radiotherapy.It can be seen that the whole treatment process is affected by the human respiratory movement and even leads to the failure of treatment,and the respiratory gating technique is an effective method to deal with such situation clinically.The real-time position management(RPM)system of Varian is one of the proven methods in clinical practice.RPM system exist some disadvantages in clinical applications,such as physicians do not match the repeated placement of fluorescence module may produce error of the final results,the modules placed on the chest may increases the stability of the tension of patients with respiratory,additional equipment will also improve treatment costs,etc.This study was based on the principle of heart impact and designed a new type of respiratory phase detection system.The set of equipment using poly(vinylidene fluoride)(PVDF)piezoelectric film produced by the back pressure sensor to collect collective dynamic signals.After the electronics system treatment,the patients' respiratory signal as respiration gating guide patients with radiation therapy.Electronics system with functions of signal amplification,reduce noise,filtering and so on.Mainly includes the charge sensitive amplifier,high-low pass filter,50 Hz trap and MCU module,etc.The respiratory phase detection system and the Varian RPM system simultaneously collect CT scan data,and through the actual test and related clinical trials,it is proved that the respiratory signal can be collected effectively.The qualitative comparison of respiratory signals showed that the pressure breathing signal was significantly better than the RPM signal.Quantitative contrast analysis adopts the generalized cross-correlation algorithm,and the conclusion is reliable for the two signal acquisition equipment.For the 4D-CT image evaluation,the two systems will produce artifacts in different degrees,and the imaging results of the self-research equipment are more accurate.This study verified the reliability of the system and tested the feasibility for respiration gating technology could control the breathing movement,comparing with the RPM system,this system has lower cost,much more vulnerable to patients and better clinical applicability.