Date of download: 9/20/2016 Copyright © 2016 SPIE. All rights reserved. (a) Photographs of the anthropomorphic phantom used in this study and (b) the inner vasculature to which synthetic nodules were attached. Figure Legend: From: Volume estimation of multidensity nodules with thoracic computed tomography J. Med. Imag. 2016;3(1): doi: /1.JMI

Date of download: 9/20/2016 Copyright © 2016 SPIE. All rights reserved. Regions of interest (ROI) from CT scans of the multidensity nodules with outer/inner shell diameters of 20/10 mm and outer/inner shell HU values of (a) 100/−630, (b) 10/−630 HU, (c) −630/100 HU, and (d) −630/−10 HU. These ROIs were extracted from scans acquired with 120 KVP, 100 mAs, 1.2 pitch, 16×0.65 mm slice collimation, and reconstructed with 0.75 mm slice thickness and a b40f reconstruction kernel. In addition to the four nodules shown here, the study utilized four nodules with corresponding HU values but outer/inner shell diameters of 10/5 mm. Note that due to the manufacturing process the spheres are not exactly concentric. Figure Legend: From: Volume estimation of multidensity nodules with thoracic computed tomography J. Med. Imag. 2016;3(1): doi: /1.JMI

Date of download: 9/20/2016 Copyright © 2016 SPIE. All rights reserved. Intensity profiles acquired vertically through the inner-core centers of the 20 mm/10 mm multidensity nodules, as indicated with arrows in Fig. 2. Pixel intensities are related to HU values as: pixel intensity=1000+HU. It can be seen that for the nodules with outer shell of −630 HU (bottom 2 nodules), a plateau for the outer shell at −630 HU is not clearly visible due to the modulation transfer function of the CT system. Figure Legend: From: Volume estimation of multidensity nodules with thoracic computed tomography J. Med. Imag. 2016;3(1): doi: /1.JMI

Date of download: 9/20/2016 Copyright © 2016 SPIE. All rights reserved. Schematic of the mixed-density template generation process. Figure Legend: From: Volume estimation of multidensity nodules with thoracic computed tomography J. Med. Imag. 2016;3(1): doi: /1.JMI

Date of download: 9/20/2016 Copyright © 2016 SPIE. All rights reserved. Cross-section of a mixed-density nodule and a set of sample of templates used in estimating the volume of the nodule’s inner core. (a) Cross-section of a synthetic nodule (20 mm, −630 HU) outer shell and (10 mm, +100 HU) inner core, scanned at 100 mAs and reconstructed at 0.75 mm slices. (a) Template with 20 mm/10 mm outer shell/inner core. (c) and (d) Templates with 10 mm inner core horizontal shifted of 1, and −1 pixel, respectively. (e) and (f) Templates with 20 mm/9.5 mm and 20 mm/10.5 mm outer shell/inner core, respectively. The other variables used to create a complete set of templates were shifts in the vertical and axial direction, and the ratio of outer shell to inner-core radiodensities in addition to horizontal shifts and changes in the inner core to outer shell size ratio. Figure Legend: From: Volume estimation of multidensity nodules with thoracic computed tomography J. Med. Imag. 2016;3(1): doi: /1.JMI

Date of download: 9/20/2016 Copyright © 2016 SPIE. All rights reserved. PB across slice thickness for the two nodule sizes used in the study (outer-shell/inner-core combinations of 20 mm/10 mm and 10 mm/5 mm). Slice thickness values were based on slice collimation of 16×0.75 mm except from those indicated with * (slice collimation of 16×1.5 mm). Top plot refers to the estimation of the entire object volume; bottom plot refers to the estimation of the inner-core volume. Error bars indicate 95% confidence intervals. Figure Legend: From: Volume estimation of multidensity nodules with thoracic computed tomography J. Med. Imag. 2016;3(1): doi: /1.JMI

Date of download: 9/20/2016 Copyright © 2016 SPIE. All rights reserved. SPE across slice thickness for the two nodule sizes used in the study (outer-shell/inner-core combinations of 20 mm/10 mm and 10 mm/5 mm). Slice thickness values were based on slice collimation of 16×0.75 mm except from those indicated with * (slice collimation of 16×1.5 mm). Top plot refers to the estimation of the entire object volume; bottom plot refers to the estimation of the inner-core volume. Error bars indicate 95% confidence intervals. Figure Legend: From: Volume estimation of multidensity nodules with thoracic computed tomography J. Med. Imag. 2016;3(1): doi: /1.JMI