Based On EPID System Of Medical Accelerator Quality Control

PurposeThis study of the A-SI EPID amorphous silicon electronic portal imaging device (AMORPHOUS SILICON ELECTRONIC PORTAL IMAGING DEVICE), use it as a conventional accelerator radiotherapy dosimetry quality control testing of rapid tool for routine radiation oncology dosimetry quality control testing, that is absolute dose measurement, flatness and symmetry, the light field and radiation field consistency, multi-leaf diaphragm in place monitoring the accuracy of measurement.Establishment of the system using a-Si EPID dose characteristics of medical accelerator quality evaluation system, and as a quick reference standard two-dimensional dose measurement system to address the quality assurance process is very time-consuming and use a lot of valuable work time and human machine resources to traditional methods.MethodTo this end, the author first electronic portal imaging system for quality testing, including anti-collision chain, the detector motion and image quality checks. With the film law and through the comparison of traditional methods to prove the use of electronic portal imaging system detects a dose characteristics is feasible. Including conventional dose measurements, are the symmetry and flatness measurement applications, optical field consistency detection portal, multi-leaf collimator leaves in place of the accuracy. EPID detector test chain collision, the detector movement and use of Las Vegas phantom camera, images were compared with the standard for image quality inspection, and can check the image geometric accuracy. The use of different machines will have to determine the number of hops corresponding to the absorbed dose to the calibration of the EPID for dose, absorbed dose calculated EPID blackness and EPID dose values between the calibration curve. Different dose range, try to fit the curve obtained and analyzed fitting error. EPID software analysis by using the RT113data collected to test the accelerator output dose, both flatness and symmetry, the light field radiation field consistency, accuracy of detection of multi-leaf diaphragm in place.Summed up the system using a-Si EPID dose characteristics of the quality of medical accelerators evaluation system.ConsultsThrough the above experiment, confirmed that the system using a-Si EPID dose characteristics of the quality of medical accelerators evaluation system is feasible. Can effectively carry out quality assurance of medical accelerators work of conventional dose, this quality assurance system in the EPID can be used in conjunction with relevant dose measurement analysis software to do testing. By comparing the traditional film method proved the system can use conventional EPID dosimetry, both the symmetry and flatness measurement applications, optical field consistency detection portal, multi-leaf collimator leaf position accuracy of validation testing instead of the traditional test methods. A certain frequency by the detection of a reliable running of the machine state, so as to ensure the accuracy of clinical radiation oncology.ConclusionRegular quality assurance and control is an important task. Each radiation therapy center in the use of accelerators must be a complete set of QA system. The experimental results of the study suggest that routine use of Elekta iViewGT EPID dosimetry, the symmetry and flatness were measured, the light field consistency detection portal, multi-leaf collimator leaf position accuracy of validation testing is feasible, the use of a-Si EPID System accelerator dose characteristics of medical quality evaluation system can be better applied to the daily radiation therapy quality assurance testing, the process can be very time-consuming traditional methods to solve and use a lot of valuable working time machine and human resources shortcomings, detection accuracy canAmerican Medical Association to the physical (AAPM) Report recommended TG142requirements. Consider conformal radiotherapy and intensity modulated radiation therapy requires a higher accuracy, the use of a-Si EPID system accelerator dose characteristics of the quality of medical evaluation system for the adjustment and calibration time. Regular monitoring helps to ensure accurate data to ensure the radiotherapy treatment.