Development of a dynamic motion platform with two independent drive systems for radiotherapy

Abstract

There are some motion platforms for radiotherapy quality assurance. However, no platform with two drive systems that can move along three axes is available. The purpose of this study is to develop a dynamic motion platform with two drive systems capable of three-axis motion and to evaluate its motion performance. The developed moving platform had two drive systems that use the same equipment. Each axis of the platform used can support a maximum load of 10kg. The motors for moving the platform in each direction are capable of a drive stroke up to 40mm. The drive speed is 30mm/s at maximum load fluctuation. To evaluate the static positional accuracy of this system with an arbitrary input movement, the XYZ position of each axis was measured using a coordinate measuring machine operating from 0 to 40mm at 10mm intervals. In addition, the accuracy of dynamic motion was verified with Sine waveform inputs of different patterns to the three axes for approximately 60 s, and they were compared with the resulting detected signals by SyncTrax. The two drive systems were successfully operated on three axes by using independent control systems. For static position, the accuracies were within 0.2mm, 0.05mm, and 0.14mm for lateral, longitudinal, and vertical directions, respectively. For dynamic motion, the mean absolute errors in the X, Y, and Z axes between the platform inputs and SyncTrax detected signals were 0.14±0.10mm, 0.16±0.12mm, and 0.16±0.11mm, respectively. A new dynamic platform for radiation therapy with two drive systems capable of three-axis motion was developed, and the positional accuracy of the drive axes was confirmed to be less than 0.2mm.