The goal of radiation therapy for tumors is to increase the dose of radiation therapy for tumors in order to kill tumor cells and reduce the dose to normal tissues around tumors as much as possible in order to reduce the toxic side effects caused by radiation therapy. Currently, radiation therapy for tumors has been pushed from the two-dimensional (2D) era to the three-dimensional era (Three-dimensional Conformal Radiotherapy, 3DCRT). Intensity Modulated Radiotherapy (IMRT) is better than 3DCRT in solving the problems of conformality and dose uniformity, and it can better avoid endangering organs, so it can better kill tumor cells and reduce the side effects of radiotherapy on normal tumor surrounding tissues. However, the MLC used in IMRT, whether step and shot or dynamic, has a much longer irradiation time than 3DCRT, which increases the irradiation time and increases the possibility of patient movement, resulting in a decrease in treatment accuracy. In addition, all organs in the human body are active and their positions are not exactly the same in different phases, and the location of tumors may also change. For example, the respiratory movement of lung, the pulsation of heart vessels, the different filling states of gastrointestinal tract and bladder, and the positioning error of each radiotherapy treatment will change the tumor position compared with the tumor image at the time of positioning. Image-guided radiotherapy (IGRT) is equipped with a Cone-beam CT (CBCT) on the side of the gas pedal head. CBCT is used to acquire real-time images of the patient before or during radiotherapy and adjust the treatment parameters according to the changes in the position of organs and tumors, so that the irradiation field closely “This allows the irradiation field to closely follow the tumor target area, thus solving the problem of decreased treatment accuracy caused by the patient’s position movement and human organ movement. Volumetric Intensity Modulated Arc Therapy (VMAT) is a radiotherapy technique based on IGRT, which can monitor the tumor and normal organs around the tumor with CT scan in real time before and during the CBCT radiotherapy treatment equipped with the gas pedal head. The dose rate, frame speed and MLC position are dynamically adjusted in a non-uniform manner while rotating the arc treatment. This non-uniform dynamic adjustment is adjusted according to the change of tumor and organ position, thickness and volume of tumor, etc., so that the radiation closely follows the tumor for precise treatment. In addition to adjusting the accuracy of tumor radiation dose at any time, overcoming the errors of respiratory movement, organ creep and daily positioning, and better protecting normal organs and tissues, this technology can also reduce the treatment time, shortening the 20-30 minutes of IMRT and IGRT treatment to less than 5 minutes. The biggest advantage of this technology is that it not only allows the radiation intensity to be adjusted according to the thickness of the tumor, but also gives the most suitable radiation intensity considering the different thickness of each part of the tumor volume, and avoids endangering the organs in the middle of the tumor to reduce the side effects after treatment. VMAT is a new type of high precision gas pedal with reverse optimized treatment plan design software and precise 3D and 2D dose verification equipment in one. This technology can meet the needs of tumor treatment in all parts of the body. It has few hardware changes from IGRT, mainly the control software upgrade, which can be upgraded by Synergy.