Nuclear Techniques ›› 2019, Vol. 42 ›› Issue (6): 60202-060202.doi: 10.11889/j.0253-3219.2019.hjs.42.060202


Optimization design of a multilayer ionization chamber

Yaqiong GE1,2,Chongxian YIN2(),Zhen LI1(),Hanwen DU2   

  1. 1. Shanghai University, Shanghai 200444, China
    2. Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
  • Received:2019-03-27 Revised:2019-04-25 Online:2019-06-10 Published:2019-06-18
  • Contact: Chongxian YIN,Zhen LI;
  • About author:GE Yaqiong, female, born in 1995, graduated from University of South China in 2016, master student, focusing on nuclear detection technology

Abstract: Background

Multilayer ionization chamber (MLIC) can significantly reduce the measurement time of proton pencil beam dose depth distribution, which is of practical significance for improving the efficiency of daily quality assurance of proton therapy.


This study aims to optimize the design of a MLIC to realize fast and accurate dose verification.


Based on Monte-Carlo method, simulation of the MLIC was performed by using Geant4 codes. To evaluate the measurement uncertainties of the MLIC, materials of FR-4, polymethylmethacrylate (PMMA), Al were applied and the depth dose distribution in each material were compared with water phantom to evaluate the uncertainties caused by different material. Then the depth dose distribution was corrected by the collection efficiency of each layer of the MLIC in different sensitive area, and the deviation compared with water phantom after correction was calculated.


The final measurement accuracy of the optimized MLIC in the depth dose distribution is within ±5%, and range accuracy is within ±1 mm.


The optimized MLIC could replace the water tank to achieve fast daily quality assurance in clinical use.

Key words: Proton therapy, Monte-Carlo method, Multilayer ionization chamber

CLC Number: 

  • TL99