The Research Of Isocenter Measurement In Proton Radiotherapy Gantry

The measurement of isocenter is a key step to measure the designed accuracy of the proton radiotherapy gantry.With the application of proton radiotherapy technology in cancer treatment,higher requirements are placed on the accuracy of isocenter and its measurement technology in order to ensure radiation depth accuracy in proton radiotherapy.The field of isocenter measurement and proton radiotherapy technology started at the same time abroad,nearly ten years earlier than China.And the introduction of proton therapy equipment in China is late and research on isocenter and its measurement is fewer.However,since the isocenter measurement technology is a part of proton radiotherapy technology,the relevant research is needed.Based on the measurement requirements for isocenter in 'Proton Radiotherapy Rotary Gantry Design' project,this paper proposes a method which is based on laser and CCD camera for isocenter measurement.The method uses the laser imaging isocenter movement trajectory,while using the CCD camera to record and transmit the data to measurement software running in the background for analysis and calculation to get the isocenter error,which has the advantage of better accuracy and convenience.This thesis focuses on the design of the isocenter measurement method and discusses the design of its different components,including lasers,CCD cameras,measurement software,and rotating platforms.The main analysis is the introduction of theoretical errors and the design verification of the rotating platform to ensure the reliability.At the same time,the overall design and development of the isocenter measurement software are studied.A method with laser threshold segmentation method and the gravity method for center calculating to obtain the laser center location and the scattered point circle fitting algorithm for the isocenter error are proposed.Based on the above method design,relevant isocenter error measurement experiments are designed to verify the accuracy and feasibility of the isocenter measurement method.