Varian TrueBEAM Radiotherapy Linear Accelerator

The Varian TrueBEAM Radiotherapy Linear Accelerator provides not only 6MV and 10MV high-energy photon beams at a traditional dose rate (600 MU/min), but also special high intensity modes in 6MV and 10 MV-FFF (Flattening Filter Free). The maximum output dose can reach 2400 MU per minute, which is four times the normal mode of 600 MU per minute, thus dramatically decreasing treatment time for patients. Furthermore, the accuracy in mechanical movements and beam control of TrueBEAM is also the most advanced among all accelerator equipment. This device uses an all- digital method to combine radiotherapy and image-guided positioning to provide the best quality of radiotherapy to patients with the simplest operations. Due to the high dose rate, the radiation shielding plan has to be carefully re-evaluated for the operation venue in order to ensure protection from radiation for both staff and patients. At the same time, the high- precision mechanical apparatus and high-accuracy digital control system require a more comprehensive verification procedure to ensure the high quality of the equipment.

For quality verification, according to the standard operating procedure for testing received by medical physicists, the verification includes the complete testing of the following: mechanical movement accuracy of each component, energy of the output beam, validity of dose distribution, and effectiveness of each operative function. Overall, the mechanical movement accuracy of TrueBEAM is < 1 mm and the beam energy accuracy is < 0.5%. The level of accuracy is sufficient for executing stereotactic radiotherapy, stereotactic radiosurgery (SRT/SRS) or even stereotactic body radiotherapy (SBRT), which requires the highest accuracy.