Two decomposition algorithms of dual-energy cone beam CT and their dependence on the phantom sizes
10.3760/cma.j.cn112271-20211206-00471
- VernacularTitle:双能锥形束CT的分解算法和成像物体尺寸依赖性研究
- Author:
Chenguang LI
1
;
Tianye NIU
;
Li ZHOU
;
Jun DENG
;
Chengyuan ZOU
;
Sha LI
;
Hongjia LIU
;
Zhengkun DONG
;
Ling HUA
;
Yichen PU
;
Liangzi QU
;
Qiao LI
;
Yibao ZHANG
Author Information
1. 北京大学医学部医学技术研究院，北京 100191
- Keywords:
Dual-energy cone beam CT;
Image-domain decomposition;
Image quality;
Image guided radiotherapy
- From:
Chinese Journal of Radiological Medicine and Protection
2022;42(4):269-276
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To analyze the effects of two decomposition algorithms of dual-energy cone beam CT (DECBCT) (direct decomposition and iterative decomposition) on the image quality and material decomposition accuracy of different sizes of phantoms.Methods:Different sizes of imaging parts of patients were simulated using the combination of CatPhan604 phantoms and customized annuluses. CBCT with high energy of 140 kVp and low energy of 100 kVp were acquired using the Varian Edge CBCT system. Then the material decomposition of DECBCT images was performed using the two algorithms. The electron density (ED) and contrast-to-noise ratio (CNR) of each material in the CTP682 module were calculated. They were used to assess the decomposition accuracy and image quality of the two algorithms.Results:Based on the values in the Catphan604 manual, both algorithms have high ED accuracy. Only the ED accuracy of four materials of the smallest sized phantom showed statistical difference ( z = -4.21, 4.30, 2.87, 5.45, P < 0.05), but the average relative error was less than 1%. The CNR of the iterative decomposition algorithm was significantly higher than that of the direct decomposition, increasing by 51.8%-703.47%. The increase in the phantom size significantly reduced the accuracy of ED, and the increased amplitude of the relative error was up to a maximum of 2.52%. The large phantom size also reduced the image quality of iterative decomposition, and the decreased amplitude of CNR was up to a maximum of 39.71. Conclusions:Compared with the direct decomposition, the iterative decomposition algorithm can significantly reduce the image noise and improve the contrast without losing the accuracy of electron density in the DECBCT construction of different sizes of phantoms.
