Scatter correction for multi-slice CT system

Wang, Yang; Stierstorfer, Karl; Petersilka, Martin; Grasruck, M.; Tian, Yi

doi:10.1117/12.2293117

Cited by 2 publications

(3 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Using parameters obtained with water phantom data, the clinical data of a patient scanned at position of about 10 cm off-center have been tested with the algorithm. The correction of object induced scatter signals is based on the algorithm described in (Wang et al 2018)…”

Section: Clinical Patient Resultsmentioning

confidence: 99%

“…Previously, simulations have been applied to determine the contribution of bowtie filter induced scatter signals (Liu et al 2021(Liu et al , 2013) and a kernel based correction algorithm has been already successfully applied to correct bowtie filter induced scatter signals (Wang et al 2019). The kernel based algorithm in the work of Wang et al makes use of several convolution operations and several parameters to estimate scatter signals based on projection data and attenuation profile of bowtie filter.…”

Section: Introductionmentioning

confidence: 99%

“…in equation (5) needs to be removed from measured projection data. Considering the similarity of physics behaviors, kernel based scatter correction algorithm used to correct object induced scatter signals (Ohnesorge et al 1999) can be also applied for the correction of bowtie filter induced scatter signals (Wang et al 2019) with the tuning of parameters. In this work, Gaussian convolution kernel has been used for convolution, since it can well approximate the distribution of scatter signals (Zhao et al 2015).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Correction of Bowtie filter induced scatter signals based on air scan data and object scan data

Zhang¹,

Wang²,

Chen³

et al. 2022

Biomed. Phys. Eng. Express

Self Cite

View full text Add to dashboard Cite

In a cone beam CT system, a bowtie filter brings in additional scatter signals with respect to object induced scatter signals, which can degrade image quality and sometimes result in artifacts. This work aims to improve the image quality of CT scans by analyzing the contribution of bowtie filter induced scatter signals and removing them from projection data. Air calibration is a very useful preprocessing step to eliminate the response variations of detector pixels. Bowtie filter induced scattered X-ray signals of air scans are recorded in air calibration tables and therefore considered as a part of primary signals. However, scattered X-rays behave differently in scanned objects compared to primary X-rays. The difference should be corrected to eliminate the impact of bowtie filter induced scatter signals. A kernel based correction algorithm based on air scan data, named bowtie filter scatter correction algorithm, is applied to estimate and to eliminate the bowtie filter induced scatter signals in object scans. The scatter signals of air scans can be measured with air scans or retrieved from air calibration tables of a CT system, and can be used as input of the correction algorithm to estimate the change of scatter signals caused by the scanned objects in the scan field. Based on the assumption that the scatter signals in the projection data scanned with narrow collimation can be neglected, the difference signals between narrow and broad collimations can be used to estimate bowtie filter induced scatter signals for air scans with the correction of extra-focal radiations (EFRs). The calculated bowtie filter induced scatter signals have been compared with the results of Monte Carlo simulations, and the parameters of correction algorithm have been determined by fitting the measured scatter signal curves of phantom scans with calculated curves. Projection data have been reconstructed using Filtered BackProjection (FBP) method with and without bowtie filter correction to check whether the image quality is improved. Scatter signals can be well approximated with the bowtie filter scatter correction algorithm together with an existing object scatter correction algorithm. After removing the bowtie filter induced scatter signals, the dark bands in reconstructed images in the regions near the edges of scanned objects can be mostly eliminated. The difference signals of air scan data between narrow and broad collimations can be used to estimate the bowtie filter induced scatter for air scans. The proposed bowtie filter scatter correction algorithm using air scan data can be applied to estimate and to remove most of the bowtie filter induced scatter signals in

show abstract

Section: Clinical Patient Resultsmentioning

confidence: 99%