Improving CT quality with optimized image parameters for radiation treatment planning and delivery guidance  Guang-Pei Chen, George Noid, An Tai, Feng Liu, Colleen Lawton, Beth Erickson, X. Allen Li  Physics and Imaging in Radiation Oncology  Volume 4, Pages 6-11 (October 2017) DOI: 10.1016/j.phro.2017.10.003 Copyright © 2017 The Authors Terms and Conditions

Fig. 1 Variation of CNR (a) and CNRD (b) for the CatPhan 500 versus effective tube current–time product for different tube voltages. (c) The obtained relationship between noise and the effective tube current–time product. (d) The CT number histograms (with mean CT number subtracted) from both simulation and phantom scan images at effective tube current–time product of 100 mAs. The histograms were both normalized to the total counts. Physics and Imaging in Radiation Oncology 2017 4, 6-11DOI: (10.1016/j.phro.2017.10.003) Copyright © 2017 The Authors Terms and Conditions

Fig. 2 Sample images scanned with standard clinical (a) and IQE (b) protocols for a prostate cancer patient. Contour variation (ratios of standard deviation over average of structure volumes) for the same patient: intra-observer (c) and inter-observer (d). Physics and Imaging in Radiation Oncology 2017 4, 6-11DOI: (10.1016/j.phro.2017.10.003) Copyright © 2017 The Authors Terms and Conditions

Fig. 3 A sample image (b) with noise level corresponding to 500 mAs, which was compared with the CTs acquired with the standard clinical (a, 210 mAs) and IQE (c, 1000 mAs) protocols. The line in (b) represents a strip of voxels which illuminate the gradient between prostate and bladder as described in the text. (d) The CT number crossing the boundary in images acquired with the IQE protocol (High), the standard clinical protocol (Low) and the simulated image generated from adding noise to the IQE protocol (Adjusted). Physics and Imaging in Radiation Oncology 2017 4, 6-11DOI: (10.1016/j.phro.2017.10.003) Copyright © 2017 The Authors Terms and Conditions