A Method to Increase the Dose Rate of Medical Linear Electron Accelerators by Considering the Target and the Flattening Filter as a Whole System When Designing the Target

Abstract：

Generally, the design of the target used in the medical electron accelerator follows the thick-target rule, that is, using a target thicker than the electron range to make almost no electrons penetrating out of the target. In this article, a new rule of target design is proposed. The target and the relevant components (primary collimator and flattening filter) are considered as a whole system when designing the target, that is, using a thinner target to increase the dose rate and using the primary collimator and the flattening filter to reduce the contaminated electrons. To improve the dose rate in the treatment, an optimization is given to the target design of BJ-6, a 6MV medical linear electron accelerator, by using Monte Carlo method. By using MC codes of MCNP and BEAMnrc, simulations are given to calculate the percent depth dose profiles in the 10cm×10cm field and the 30cm×30cm field respectively. The surface dose satisfies the national standards and the dose rate in treatment increases 10 percent of that of the present thick-target. The feasibility of this method has been tested by experiment.