Journal of Radiation Research and Radiation Proces ›› 2015, Vol. 33 ›› Issue (3): 30201-030201.doi: 10.11889/j.1000-3436.2015.rrj.33.030202

• RADIOBIOLOGY AND RADIOMEDICINE • Previous Articles     Next Articles

Correlation analysis for modulation transfer function method and line pair method under loe dose conditions

GU Siyi1  WANG Xiaowa1  YUAN Baofeng2  LI Xiangyang1  SUN Liang1   

  1. 1(School for Radiological and Protection Sciences, Soochow University, Suzhou 215000, China)
    2(Yangzhou First People's Hospital, Yangzhou 225000, China)
  • Received:2014-12-04 Revised:2015-03-17 Online:2015-06-20 Published:2015-04-13

Abstract:

The aim of this study is to analyze the correlation of two spatial resolution of CT image acquisition method (modulation transfer function method and line pair method) under low dose conditions, which to provide an objective basis for spatial resolution evaluation of CT quality control. This research scanned located mid-line CPT 528 and 486 module of Catphan 500 phantom by using GE LightSpeed 16 CT under standard chest scanning conditions (120 kV, 200 mA) and low dose conditions (80 kV, 100 kV, 120 kV, and 140 kV four gears; 10−60 mA, 10 mA increased) separately, with CPT486 module measuring noise. Adjust the window wide and window level, observe distinguishable lines on the card under different scanning conditions (to illustrate the impact of subjectivity on the line pairs method, randomly selected parts of CPT528 scanned images were read by five testers and the results were statistically analyzed). The point spread function (PSF) on the different locations were measured via the program, and then on two-dimensional Fourier transformation of PSF to get modulation transfer function (MTF). Finally, we used SAS8.2 software statistical to analyze 10% MTF values and visual values in order to search the correlation between MTF method and line pairs method. The results show that when the MTF is 10% the corresponding spatial resolution and visual values obtained by lines pair method are consistent (t'=0.18, p=0.8556). Under low-dose conditions, part of MTF curves are influenced by noise, leading to increase of MTF value.

Key words: Low-dose chest CT, Modulation transfer function (MTF), Spatial resolution, Noise

CLC Number: 

  • R814.42,TL72