Innovative electromagnetic coupling design and performance testing of a drive module for multi-leaf collimators

In radiotherapy, the multi-leaf collimator (MLC) significantly improves treatment efficiency compared to traditional blocks. However, the large number of motors within the MLC results in higher failure rates and costs for the drive modules.

To further enhance the performance of the MLC, this study proposes an innovative electromagnetic coupling drive module, which reduces the number of motors required, thereby lowering the failure rate.

The electromagnetic coupling drive module achieves synchronized control of the entire MLC leaf bank through a dual-motor cooperative drive mechanism. Based on an electromagnetic coupling drive module, novel single-layer and double-layer MLCs were developed. The design, manufacture, and performance testing of both types of MLCs were successfully completed. Meanwhile, a customized control algorithm was developed to enable MLC performance. For the novel double-layer MLC, the electromagnetic coupling drive module was structurally optimized, and the position feedback unit was improved, further enhancing leaf positioning accuracy.

Mechanical test demonstrated that the maximum leaf movement speed reached 3 cm/s, with a repeat positioning accuracy of 0.23 mm in single-layer MLC. The optimized electromagnetic coupling drive module in double-layer MLC further improved positioning accuracy to within 0.05 mm, with a maximum repeat positioning error of only 0.059 mm detected by the encoder. After MV image calibration, the average isocentric leaf projection positioning error was 0.06 mm.

The two types of MLCs proposed in this study significantly improve MLC performance through innovative drive module design, which has notably reduced the number of motors, potentially reducing failure rate and cost. These MLCs provide important support and are expected to play a significant role in clinical applications by enhancing treatment efficiency and reducing costs.