Nuclear Techniques ›› 2018, Vol. 41 ›› Issue (4): 40201-040201.doi: 10.11889/j.0253-3219.2018.hjs.41.040201

• LOW ENERGY ACCELERATOR, RAY AND APPLICATIONS • Previous Articles     Next Articles

Design of a proton spot scanning position control system

MIAO Chunhui1,2, LIU Ming1,2, SHU Hang1,2, YIN Chongxian1,2, ZHAO Zhentang1,2   

  1. 1. Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Jiading Campus, Shanghai 201800, China;
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2017-12-12 Revised:2018-01-17 Online:2018-04-10 Published:2018-04-11
  • Supported by:

    Supported by the Youth Innovation Promotion Association of Chinese Academy of Sciences (No.2016238)

Abstract:

[Background] Spot scanning is adopted as the operating mode for the beam delivery system of the Shanghai Proton Therapy Facility. [Purpose] To meet the needs of dose rate and dose accuracy, a precise spot scanning position control system was developed. [Methods] Quadratic polynomial and smoothed thin-plate splines fitting has been adopted in mapping the relationship between the target scanning magnet strength and spot position at ISO center, and the relationship between the target scanning magnet strength and the spot position at ion chamber. During the treatment process, the target magnetic field is calculated according to the target spot position at ISO center given by the treatment planning system. A feed forward magnet strength control strategy is used in controlling the scanning magnetic to reach the target magnetic field. The position of the following spot is corrected through comparing the target spot position and the spot position readout from the ion chamber. [Results] Beam test showed that the maximum position error in X and Y direction was 0.8 mm and 0.6 mm respectively, and both of the root-mean-square were 0.2 mm. [Conclusion] Accurate spot scanning has been achieved by the spot scanning position control system.

Key words: Proton therapy, Spot scanning, Scanning position control, System design

CLC Number: 

  • TL99