Common computed tomography artifact: source and avoidance

Amel F Alzain,M E Elbashir,Amna Mohamed Ahmed,Nagwan Elhussein,Badria Awad Elamin,Ibtisam Abdallah Fadulelmulla

doi:10.1186/s43055-021-00530-0

Abstract

BackgroundArtifacts have significantly degraded the quality of computed tomography (CT) images, to the extent of making them unusable for diagnosis. The types of artifact that could be used are as follows: (a) streaking, which is commonly due to a discrepancy in a single measurement, (b) shading, which is due to a group of channels deviating gradually from the true measurement, (c) rings, which are due to errors in individual detector calibration and (d) distortion, which is due to helical reconstruction. It is occasionally possible to avoid scanning of a bony area, by means of changing the postion of the patient. Thus, this study aimed to evaluate the common artifacts that affect image quality and the method of correction to improve image quality.ResultsThe data were collected by distributing a questionnaire to the CT technologist at different hospitals about the most common type of artifacts in the CT images, source of artifacts and methods of correction. A total of 95 CT technologists responded to the questionnaire, which included 67% males and 33% females. Most of the participants (70%) were experienced CT technologists, and 61% of the participants had not done any subspecialty CT scan courses. The most common artifact used in the CT departments was motion artifact in brain CT (73%), and the best method to reduce motion artifact was patient preparation (87%).ConclusionsThe most common shown artifact in this study was motion artifact, and the common cause was the patient-based artifact. It is important to understand why objects occur and how they could be prevented or suppressed to improve image quality.

Highlights

Artifacts have significantly degraded the quality of computed tomography (CT) images, to the extent of making them unusable for diagnosis
Practical experiences of the participants were assessed, and it was found that 70% of the participants had the experience of 1–3 years, 15% of the participants had the experience of 5–10 years, while 9% had the experience of 3–5 years (Fig. 2)
The number of subspeciality CT scan courses taken by the participants was inquired, and it showed that 38% of the participants had taken such courses, whereas 61% of the participants did not take any such courses; one participant left the space blank (Fig. 3)

Summary

Introduction

Artifacts have significantly degraded the quality of computed tomography (CT) images, to the extent of making them unusable for diagnosis. The existence of high-density substances, such as dental stuffing, hardening and photon starvation [1], decreasing metal artifacts. These methods are extremely dependent on the arrangement of the metal material and might not be fully operative. At the most initial stage, a CT image artifact is an inconsistency amongst the recreated values in a CT image and is based on the material thickness and the simple geometry. They are characteristically manifested as bright or dark bands or shades that typically follow some sort of forecast outline. There are two initial categories of artifacts: one produced due to difficulties with the CT imaging setup (e.g. ring artifacts, under-sampling aka aliasing, sample movement, etc.) and the other one Alzain et al Egyptian Journal of Radiology and Nuclear Medicine (2021) 52:151 which is more sample dependent such as beam hardening, scattered radiation, and lack of x-ray infiltration [3]

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Conclusion