Design Of Respiratory Gating System Based On Visual Guidance

Radiotherapy is one of the main methods for the treatment of cancer at present.Among them,the radiotherapy method based on proton heavy ions is based on its high relative biological effect,high dose uniformity,and good protection ability to normal tissues.showed good results during the treatment.However,proton heavy ion radiotherapy also faces some difficulties.For many tissues and organs located in the chest and abdomen of the human body,during the radiotherapy process,there will be implicated movement along with the patient’s breathing movement.This movement causes deviations in the position of the tumor target volume,which in turn leads to a series of problems,such as uneven dose distribution in the target volume,undesired geometric omission of the target volume,and unnecessary irradiation of surrounding normal tissues,which have a negative impact on the outcome of the treatment.In order to solve these problems,this paper studies the control problem of respiratory movement during radiation therapy,and after comparing and summarizing the existing solutions,a visual feedback respiratory gating system with specific guidance function based on laser displacement sensor is designed to solve the problem of deviation of target position under respiratory movement.The system uses a laser displacement sensor to monitor the patient’s breathing movement.During the actual radiotherapy process,the system generates a specific guide curve according to the movement waveform of the monitored patient under free breathing,and then instructs the patient to adjust his breathing movement to keep pace with the guide curve.It can meet the requirements of treatment precision.The software part of the system is developed based on Lab VIEW.Compared with the current mainstream respiratory motion monitoring methods,the optical tracking method has the advantages of high accuracy,large tracking range,easy patient tolerance and strong anti-interference ability.In order to evaluate the application prospect and development potential of this solution,the Polaris Vega infrared optical tracking system is selected in this paper,and based on its original characteristics,the tracking function for a single optical marker is developed with the help of the application program interface of the spatial position sensor.In the subsequent experiments,while testing the respiratory gating system based on the laser displacement sensor designed in this paper,we tried to use the secondary developed infrared tracking system to obtain the spatial motion data of the body surface.A total of 16 young volunteers were invited to participate in the simulation experiment in this system.The volunteers used the system to simulate the entire treatment process and test the completion of each function in the system.A total of 16 respiratory motion trajectories with a length of 600 seconds,240 spatial motion traces of optical markers with a length of 600 seconds,2 phantom motion traces with a length of 60 seconds,and 18 specific guide curve waveforms were obtained through the experiment.Then,based on the data obtained from the experiment,this paper gradually carried out the following work: verify the accuracy and validity of the specific guidance curve;test the performance of the respiratory gating system in terms of respiratory synchronization ability,breath-hold execution ability and tolerance changes;and evaluating the application prospect of the optical tracking system,this part focuses on analyzing the spatial motion relationship of each marker in the optical tracking system,as well as the motion relationship between the representative markers of each part and the respiratory trace.