| With the rapid development of radio-therapy technology,the production of Volumetric Modulated Arc Therapy(VMAT)is to protect better the surrounding normal tissue and OAR from the excessive dose of irradiation,while ensuring tumors to accept higher dose,its frame can not only 360 degrees,but also have different speed of frame,dynamic multi-leaf collimator and different rate of dose.VMAT technology can almost compare with the IMRT dose distribution in clinic.The outstanding feature are reducing patients' treatment time considerably and avoiding patients getting discomfort for long time to keep fixed position to lead the shift of position,thereby reducing the chance of recurrence of tumor.PRECISE occupies a certain proportion in the national linear acceleratorequipment.Due to various reasons,there will be a lot of inconvenient factors to displace or acquire linear accelerator with the function of VMAT,then to upgrade the VMAT to provide a new way for developing new technology of VMAT.After upgrading,the most noteworthy is that the stability of performance parameter of linear accelerator and whether it can finish the missions that can be finished by RapidArc,VMAT and some others.If it is possible,that will give us more convenient and more available to carry out the technology of VMAT.Before and after upgrading,testing all aspects of linear accelerator's performance,as the result of parameters are basically stable,it can fit the bill basically.The position Accuracy of multi-leaf collimatorcan meet the requirements of clinical VMAT treatment.VMAT plan with double arc can remain a high 3%&3mm passing rate,VMAT plan with single arc is a little low with some fluctuations,and reach 90% mainly.The effect of simulating clinical dose is fine,according to requirements it can finish the mission that VMAT can do.For complex cases,it does not recommend using single arc plan.It is necessary for machines to check and maintain. |
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