Artifacts could degrade the image quality in the computed tomography, and sometimes making them diagnostically unusable; so, this study aimed to evaluate the common artifacts that effect on the image quality and the method of correction to improve image quality.
In this study, the common artifacts that appeared in the CT scan images was motion artifact (73%); however, this result was in contrast with Boas and Fleischmann ; they said, “Metal streak artifacts are very common, seen in 21% of scans in one sequence”,, because the motion artifact could be eliminated by rapid screening, and it depends on the CT technologist’s experience , while in this study, the majority of the CT technologists’ experience was between 1 and 3 years. On the other hand, the result was relevant to Yan et al. ; they reported, “In the procedure of CT scanning data collection, if in the fault the analyte have shifted, would lead to the projection data inconsistency so motion artifacts would be produced . Normally, when scanning the patient, the patient’s moving, physiological movements such as the heart beating, breathing, and gastrointestinal peristalsis and the object entering or leaving the scanning plane. Severely injured patients or children frequently move during scanning, causing motion artifacts”.
The participants in this study were also asked about the common source of artifact in the CT departments; 78% of the participants answered the patient-based source, this is a logical result because the motion artifact was a common artifact in the CT departments; this finding was relevant to the study reported by Barrett ; he said, “the patient–based artifacts sources like metallic materials artifacts, which the presence of metal objects in the scan field could lead to severe streaking artifacts, and patient motion artifacts could cause mis-registration artifacts, which usually appeared as shading or streaking in the reconstructed image” .
Analysis has shown in this study that 62% of motion artifacts were presented in the brain CT because it was easier for the patient to move the head during CT exam; the second highest percentage was the abdomen by percentage 26% due to involuntary movement in the abdomen; these results were similar to Veikutis et al.’s ; they reported, “Analysis shown 29.9 % of artifacts presented in cerebral CT investigations, 24.3 % – thoracic, 16.6 % – spinal, 5.8 % – pelvic, and 2.0 % – abdominal . The authors suggested that head is more prominent to motion; it’s easier for a patient to accidentally move head during CT scanning.”
Another study was reported by Kim et al. ; they said, “One of the major sources of image artifacts in computed tomography (CT) is patient motion, which created inconsistencies between acquired projections, leading to distortion and blurring when images are reconstructed . These motion artifacts might lead to false diagnosis, or in extreme cases, render images uninterpretable.”
In the current study, the CT technologist considered that the patient preparation and communication are the appropriate techniques that they utilized in order to avoid or reduce the motion artifact; there is a research that has been taken by Boas and Fleischmann ; the authors mentioned that “Motion (patient, cardiac, respiratory or bowel) causes blurring and double images, as well as long-range streaks. The streaks occur between high-contrast edges and the x-ray tube position when the motion occurs . Fast scanners reduce motion artifact because the patient has less time to move during the acquisition. This could be accomplished with faster gantry rotation or more x-ray sources. More detector rows allowed a greater volume to be imaged in a single gantry rotation, thus increasing the distance between step-off artifacts from motion on coronal or sagittal reformats. Rigid body motion artifacts (mainly a problem with head CT, could be reduced using special reconstruction techniques. Respiratory motion in cone-beam CT with slow gantry rotation could be estimated and corrected, thus reducing artifacts”. There is another research that has been taken by Zhou et al. , in which the author has mentioned certain procedures to reduce the metal artifact; they said, “The smart metal artifact reduction software” (SMAR) improves the quality of images and reduces artifacts to allow anatomic visualization of structures hidden underneath the artifacts by both subjective and objective measurements . This results in improved diagnostic confidence in patients with a variety of implants.
In another study written by Wei et al. , they reported, “we found that compared to the 64-slice Discovery CT virtual monoenergetic images combined with MARS technique for image reconstruction, the 256-slice Revolution CT combined with Multi-material artifact reduction technique for image reconstruction is better to reduce metal artifacts and background standard deviation” .
There were some limitations of this study. Firstly, the number of the participants was only 95, as the questionnaire was distributed by social media, and there was no personal meeting with the CT technologist due to the current situation of the corona virus, thereby, larger samples are needed in further studies. Secondly, the results did not cover all the CT image artifacts due to the lack of available data; so, further studies should take into account all the CT scan image artifacts and the methods of correction.