Effect of miscentering and low-dose protocols on contrast resolution in computed tomography head examination

Rahmat, Said Mohd Shaffiq Said and Karim, Muhammad Khalis Abdul and Isa, Iza Nurzawani Che and Abd Rahman, Mohd Amiruddin and Noor, Noramaliza Mohd and Hoong, Ng Kwan (2020) Effect of miscentering and low-dose protocols on contrast resolution in computed tomography head examination. Computers in Biology and Medicine, 123. ISSN 0010-4825, DOI https://doi.org/10.1016/j.compbiomed.2020.103840.

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Background: Unoptimized protocols, including a miscentered position, might affect the outcome of diagnostic in CT examinations. In this study, we investigate the effects of miscentering position during CT head examination on the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Method: We simulate the CT head examination using a water phantom with a standard protocol (120 kVp/180 mAs) and a low dose protocol (100 kVp/142 mAs). The table height was adjusted to simulate miscentering by 5 cm from the isocenter, where the height was miscentered superiorly (MCS) at 109, 114, 119, and 124 cm, and miscentered inferiorly (MCI) at 99, 94, 89, and 84 cm. Seven circular regions of interest were used, with one drawn at the center, four at the peripheral area of the phantom, and two at the background area of the image. Results: For the standard protocol, the mean CNR decreased uniformly as table height increased and significantly differed (p < 0.05) at +20 cm for MCS (435.70 +/- 9.39) and 20 cm for MCI (438.91 +/- 10.94) from the isocenter. Similarly, significant reductions (p < 0.05) were also noted for SNR for MCS (at +20 cm) and MCI (at -20 cm). For the low dose protocol, both CNR and SNR were significantly reduced (p < 0.05) at table heights of +20 and 20 cm from the isocenter. Conclusion: Miscentering is proven to significantly affect the image quality in both low and standard dose protocols for head CT procedure. This study implies that accurate patient centering is one of the approaches that can improve CT optimization practice.

Item Type: Article
Funders: Geran Putra of Universiti Putra Malaysia [Grant No: GP/IPM/UPM/9619800]
Uncontrolled Keywords: CT head; Miscentered position; Image quality; SNR; CNR
Subjects: Q Science > QA Mathematics > QA75 Electronic computers. Computer science
R Medicine > R Medicine (General)
Divisions: Faculty of Medicine
Depositing User: Mrs. Siti Mawarni Salim
Date Deposited: 19 Sep 2022 02:25
Last Modified: 19 Sep 2022 02:25
URI: http://eprints.um.edu.my/id/eprint/31695

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