Nuclear Techniques ›› 2019, Vol. 42 ›› Issue (11): 110202-110202.doi: 10.11889/j.0253-3219.2019.hjs.42.110202


Evaluation and improvement of acceleratior's flatness and symmetry by six sigma capability and control technology

Xianya LI1,2,Wenjie LIANG1,Haiming YANG1,Yongjing GUAN2,Shaohan SUN3,Qingguo FU1()   

  1. 1. Guangxi Medical University Affiliated Tumor Hospital, Nanning 530021, China
    2. School of Physical Science and Technology, Guangxi University, Nanning 530004, China
    3. Wuming Hospital of Guangxi Medical University, Nanning 530199, China
  • Received:2019-04-17 Revised:2019-06-18 Online:2019-11-10 Published:2019-11-18
  • Contact: Qingguo FU
  • About author:LI Xianya, female, born in 1991, graduated from Guangxi University with a master's degree in 2017, major in nuclear physics
  • Supported by:
    National Natural Science Foundation of China(11665006);Guangxi Health Commission Scientific Research Project(Z20180635);Guangxi Health Commission Scientific Research Project(Z2013415)

Abstract: Background

Six sigma capability and control technology has been used to analyze the data of synergistic linear accelerator and evaluate the stability and controlled state. Uniformity of accelerator irradiation field is an important performance parameter of intensity-modulated radiation therapy (IMRT) with linear accelerator.


This study aims to employ six sigma capability and control technology in IMRT to keep the beam uniformity stable for a long time.


X-ray uniformity data were collected and recorded for 9 consecutive months, once a week. A data record includes four types of parameters: X-direction flatness, X-direction symmetry, Y-direction flatness and Y-direction symmetry. First of all, the correlation between symmetry and flatness in the X, Y direction in the irradiation field of X-ray beam were analyzed. At the same time, a reasonable multiple regression model was established to search an optimal solution of beam uniformity. Then, the uniformity of accelerator would be adjusted to the optimal solution. Finally, the Individual and Moving Range Charts (I-MR) were applied to monitor the uniformity, and to provide timely warnings when unstable conditions exist.


Through the above improvements, the uniformity performance is better and stable. The results reflect the instability of beam uniformity.


This technology can change the quality control of the accelerator from the pattern of passive detection mode to the active prevention mode.

Key words: Linear accelerator, Six sigma capability and control technology, Quality control, Beam uniformity

CLC Number: 

  • TL53