Optimization of acquisition parameters for reduced-dose thoracic CT: A phantom study |
| |
Institution: | 1. Department of Radiology, Cochin Hospital, AP–HP Centre, 75014 Paris, France;2. Diagnostic and Interventional Radiology, University Hospital Zurich, 8008 Zurich, Switzerland;3. Université de Paris, Descartes-Paris 5, 75006 Paris, France;4. General Electric Healthcare, 78530 Buc, France;5. Center for Visual Computing, École Centrale Supelec, 91190 Gif-sur-Yvette, France |
| |
Abstract: | PurposeThe purpose of this study was to analyze the impact of different options for reduced-dose computed tomography (CT) on image noise and visibility of pulmonary structures in order to define the best choice of parameters when performing ultra-low dose acquisitions of the chest in clinical routine.Materials and methodsUsing an anthropomorphic chest phantom, CT images were acquired at four defined low dose levels (computed tomography dose index CTDIvol] = 0.15, 0.20, 0.30 and 0.40 mGy), by changing tube voltage, pitch factor, or rotation time and adapting tube current to reach the predefined CTDIvol-values. Images were reconstructed using two different levels of iteration (adaptive statistical iterative reconstruction ASIR®]-v70% and ASIR®-v100%). Signal-to-noise ratio (SNR) as well as contrast-to-noise ratio (CNR) was calculated. Visibility of pulmonary structures (bronchi/vessels) were assessed by two readers on a 5-point-Likert scale.ResultsBest visual image assessments and CNR/SNR were obtained with high tube voltage, while lowest scores were reached with lower pitch factor followed by high tube current. Protocols favoring lower pitch factor resulted in decreased visibility of bronchi/vessels, especially in the periphery. Decreasing radiation dose from 0.40 to 0.30 mGy was not associated with a significant decrease in visual scores (P < 0.05), however decreasing radiation dose from 0.30 mGy to 0.15 mGy was associated with a lower visibility of most of the evaluated structures (P < 0.001). While image noise could be significantly reduced when ASIR®-v100% instead of ASIR®-v70% was used, the visibility-scores of pulmonary structures did not change significantly.ConclusionFavoring high tube voltage is the best option for reduced-dose protocols. A decrease of SNR and CNR does not necessarily go along with reduced visibility of pulmonary structures. |
| |
Keywords: | Radiation dosage Tomography X-ray computed Thorax Phantoms"} {"#name":"keyword" "$":{"id":"kw0030"} "$$":[{"#name":"text" "_":"imaging |
本文献已被 ScienceDirect 等数据库收录! |
|