Noise reduction performance of a deep learning-based reconstruction in brain computed tomography images acquired with organ-based tube current modulation

• Published in: Australasian physical & engineering sciences in medicine Vol. 46; no. 3; pp. 1153 - 1162
• Main Authors: Watanabe, Shota, Kono, Yuki, Kitaguchi, Shigetoshi, Kosaka, Hiroyuki, Ishii, Kazunari
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.09.2023; Springer Nature B.V
• Subjects: Anthropomorphism; Biological and Medical Physics; Biomedical and Life Sciences; Biomedical Engineering and Bioengineering; Biomedicine; Biophysics; Brain; Computed tomography; Current modulation; Deep learning; Diameters; Fiber optics; Image acquisition; Image contrast; Image filters; Image quality; Image reconstruction; Iterative methods; Lenses; Medical and Radiation Physics; Medical imaging; Noise reduction; Radiation dosage; Scientific Paper; Scintillating fibers; Tomography; Transfer functions; Image quality assessment; Organ-based tube current modulation; Low contrast; Computed tomography; Deep learning-based reconstruction
• ISSN: 2662-4729; 0158-9938; 2662-4737; 1879-5447
• DOI: 10.1007/s13246-023-01282-z

We aimed to evaluate the image quality of brain computed tomography (CT) images reconstructed using deep learning-based reconstruction (DLR) in organ-based tube current modulation (OB-TCM) acquisition. An anthropomorphic head phantom and a cylindrical low-contrast phantom were scanned at the standard dose level for adult brain CT in axial volume acquisition without OB-TCM. Moreover, image acquisition with OB-TCM was performed. The radiation dose on the eye lens was measured using a scintillation fibre-optic dosimeter placed on the anthropomorphic phantom’s eye surface. The task transfer function (TTF), contrast-to-noise ratio (CNR), and low-contrast object specific CNR obtained from low-contrast phantom images reconstructed with filtered back projection (FBP), hybrid iterative reconstruction (HIR), and two types of DLR (DLR CTA and DLR LCD ) were compared. In result, OB-TCM achieved a 32.5% dose reduction in the eye lens. Although HIR, DLR CTA , and DLR LCD showed lower TTF than FBP, the difference in TTF at the highest contributing spatial frequency corresponding to the contrast rod diameter was < 10%. Despite the OB-TCM acquisition, DLR CTA and DLR LCD achieved significantly lower noise and a higher CNR than FBP without OB-TCM ( p  < 0.05). However, low-contrast object specific CNR was equivalent among all reconstruction methods for the objective diameter of 5 mm and slightly improved in DLR LCD for the objective diameter of 7 mm. DLR with OB-TCM acquisition enabled dose reduction for the eye lens and high CNR image appearance, whereas the low contrast detectability evaluated by low-contrast object specific CNR did not always improve.