Background:

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A dual-mode congeneric mid-energy accelerating waveguide for medical electron linac is a crucial device in imaging guided radiation therapy(IGRT) technology.

Purpose:

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To ensure the linac producing stable and high quality beam bunches for both imaging and treatment beams

a 14-MeV side-coupled standing wave waveguide accelerator structure for medical accelerator based on a novel microwave energy switch technology was developed in Shanghai United Imaging Healthcare Co.

Ltd(UIH).

Methods:

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First of all

the designs on the transverse focusing and the longitudinal bunching for the linac accelerating structure were generated using the beam dynamics simulation code Parmela to certify the optimization goal of the accelerating cavity structure which can be used in both dual-photon mode and multi-energy electron mode. Then the accelerating struc

ture was designed and the optimized microwave parameters were obtained by using the electromagnetic code Superfish and the commercial software CST(Computer Simulation Technology).

Results:

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A 1.3-m long π/2 mode standing-wave bi-periodic side-coupled accelerating wave-guide resonating at 2.998GHz was obtained. The accelerating structure can be adjusted to output both 3-MV imaging photon beam and dual-mode treatment photon beams

including 6-MV and 10-MV electron beam. In addition

multi-energy electron beams with maximum electron beam energy of 14MeV can be achieved.

Conclusion:

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So far

the accelerating waveguide was machined and brazed completely. It is found that the numerical design shows very good agreement with the microwave cold test result. Recently

the frequency tuning is achieved accurately and the RF conditioning is in progress.