Journal: Proceedings of SPIE--the International Society for Optical Engineering

Article Title: Automated Web-based Software for CT Quality Control Testing of Low-contrast Detectability using Model Observers

doi: 10.1117/12.3008777

Figure Lengend Snippet: User interface of the CHO calculation module and database on the CTPro website. (a) The user interface of the CHO module displays the images and key DICOM information and calculates the index of detectability (d’) and area under the ROC curve (AUC) for the 6-, 5-, and 4-mm low-contrast objects of the ACR phantom. (b) Image data query from CTPro database. The images were selected with Siemens Alpha PCD-CT, ACR phantom, CTDIvol at 6 mGy, 144x0.4 mm collimation (SR scan mode), T1 for spectral information (T3D reconstruction mode), and with an IR reconstruction (QIR, Br44-3 kernel).

Article Snippet: The results of d’ and AUC for the low-contrast objects at contrast of 6 HU are obtained after CHO calculation, which can be exported for further use. shows database query result with Siemens/Alpha PCD-CT/ACR phantom from the web-based CTPro platform on Python WebApp Server.

Techniques:

Journal: Proceedings of SPIE--the International Society for Optical Engineering

Article Title: Automated Web-based Software for CT Quality Control Testing of Low-contrast Detectability using Model Observers

doi: 10.1117/12.3008777

Figure Lengend Snippet: (a) Example images of the ACR low-contrast module from the standard resolution (SR, 144x0.4 mm collimation) and ultra-high-resolution (UHR, 120x0.2 mm) scans modes combined with threshold-low (T3D) and virtual-monoenergetic-image at 70 keV reconstruction modes on PCD-CT at 12 mGy with IR (Br44-3) reconstructions, along with the EID-CT images at matched dose and reconstruction methods. Ensemble average image of EID-CT with IR and PCD-CT UHR-T3D with IR are displayed with the signal (red) and background ROIs (blue and yellow). (b) d’ for the four scan-reconstruction modes on PCD-CT (SR-T3D, SR-70keV, UHR-T3D, and UHR-70keV) and EID-CT with both FBP and IR reconstructions. The d’ distribution came from 10 independent d’ measurements with repositioning of the ACR phantom.

Article Snippet: The results of d’ and AUC for the low-contrast objects at contrast of 6 HU are obtained after CHO calculation, which can be exported for further use. shows database query result with Siemens/Alpha PCD-CT/ACR phantom from the web-based CTPro platform on Python WebApp Server.

Techniques:

Journal: Medical Physics

Article Title: A simple approach to measure computed tomography (CT) modulation transfer function (MTF) and noise-power spectrum (NPS) using the American College of Radiology (ACR) accreditation phantom

doi: 10.1118/1.4800795

Figure Lengend Snippet: Averaged phantom image corresponding to the third module of the ACR phantom using a typical adult head protocol (see Table ​Table1).1). Regions enclosed inside the boxes in red correspond to ball-bearing locations, Teflon rings on the phantom stand, and the patient bed, and were not used in the MTF calculation. Image window and level have been adjusted to show noise within the cylinder.

Article Snippet: The authors would like to thank Mahadevappa Mahesh Ph.D. for the generous use of the ACR phantom as well as Elliot Fishman M.D., Beatrice Mudge, and Vince Blasko for their time and help in acquiring the CT images, all of whom are affiliated with the Russell H. Morgan Department of Radiology and Radiological Science at the Johns Hopkins Medical Institutes.

Techniques:

Journal: Medical Physics

Article Title: A simple approach to measure computed tomography (CT) modulation transfer function (MTF) and noise-power spectrum (NPS) using the American College of Radiology (ACR) accreditation phantom

doi: 10.1118/1.4800795

Figure Lengend Snippet: (a) The axial modulation transfer function (MTF) as a function of spatial frequency using a typical adult head protocol (see Table ​Table1)1) and calculated using data from −6° to 6° (x-dir), 84° to 96° (y-dir), 0° to 360° (radial), and 0° to 360° but only using half the axial slices in the measurement (reduced ROI radial). The curve drops to a value of 0.1 at a frequency of 0.62 mm−1. (b) ACR phantom bar pattern viewed using a window of 100 and optimized level of 1100. The patterns correspond to frequencies of (from top going clockwise): 1.2, 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, and 0.4 mm−1. An axial resolution (for example, the frequency at which the MTF falls to ∼0.1) between 0.6 and 0.7 mm−1 is indicated.

Article Snippet: The authors would like to thank Mahadevappa Mahesh Ph.D. for the generous use of the ACR phantom as well as Elliot Fishman M.D., Beatrice Mudge, and Vince Blasko for their time and help in acquiring the CT images, all of whom are affiliated with the Russell H. Morgan Department of Radiology and Radiological Science at the Johns Hopkins Medical Institutes.

Techniques:

Journal: Medical Physics

Article Title: A simple approach to measure computed tomography (CT) modulation transfer function (MTF) and noise-power spectrum (NPS) using the American College of Radiology (ACR) accreditation phantom

doi: 10.1118/1.4800795

Figure Lengend Snippet: Three representative planes from the three-dimensional NPS as measured using images from the third module of an ACR phantom. Slices shown correspond to a typical adult head protocol (see Table ​Table1).1). The general shape of the NPS is consistent with that expected of filtered-backprojection reconstruction. Note that the resolution of the NPS in the z direction depends on the slice thickness and size of Δz in the ROIs used, and is expected to be worse than the radial (axial) direction due to the limited 4 cm width of the module.

Article Snippet: The authors would like to thank Mahadevappa Mahesh Ph.D. for the generous use of the ACR phantom as well as Elliot Fishman M.D., Beatrice Mudge, and Vince Blasko for their time and help in acquiring the CT images, all of whom are affiliated with the Russell H. Morgan Department of Radiology and Radiological Science at the Johns Hopkins Medical Institutes.

Techniques:

Journal: Quantitative Imaging in Medicine and Surgery

Article Title: Qualitative and quantitative reproducibility of 3D MERGE and SNAP sequences for carotid vessel wall imaging across Siemens and Philips 3T scanners

doi: 10.21037/qims-24-2124

Figure Lengend Snippet: Phantom experiment to compare Siemens and Philips image quality. Two ACR phantoms (one in the Siemens site and the other in the Philips site) were used. Same coils and protocols as the human experiments were used here. Both 3D MERGE and SNAP have visually reasonable image qualities on both Philips and Siemens scanners, although they exhibit different uniformity patterns. SNR is measured in homogeneous ROIs on both left and right side for each image, defined by dividing the ROI-averaged signal intensity by the standard deviation. Results show that SNR (averaging left and right) is similar in both sequences (Philips vs. Siemens): 21.4 vs. 21.8 in 3D MERGE; 22.75 vs. 20.6 in SNAP. 3D, 3 dimensional; ACR, American College of Radiology; MERGE, motion-sensitized driven equilibrium prepared rapid gradient echo; ROI, region of interest; SNAP, simultaneous non-contrast angiography and plaque; SNR, signal to noise ratio.

Article Snippet: In addition to human data acquisition, we conducted a phantom experiment to compare the capability of the setups in Siemens and Philips scanners, using ACR phantom and same coils and protocols as the human experiments.

Techniques: Standard Deviation

Journal: Medical Physics

Article Title: A simple approach to measure computed tomography (CT) modulation transfer function (MTF) and noise-power spectrum (NPS) using the American College of Radiology (ACR) accreditation phantom

doi: 10.1118/1.4800795

Figure Lengend Snippet: Averaged phantom image corresponding to the third module of the ACR phantom using a typical adult head protocol (see Table ​Table1).1). Regions enclosed inside the boxes in red correspond to ball-bearing locations, Teflon rings on the phantom stand, and the patient bed, and were not used in the MTF calculation. Image window and level have been adjusted to show noise within the cylinder.

Article Snippet: The ACR phantom (model 464, Gammex-RMI, Middleton, WI), shown in Fig. , was carefully centered in the scanner and properly aligned using the method described by McCollough et al. with aid of the accompanying stand.

Techniques:

Journal: Medical Physics

Article Title: A simple approach to measure computed tomography (CT) modulation transfer function (MTF) and noise-power spectrum (NPS) using the American College of Radiology (ACR) accreditation phantom

doi: 10.1118/1.4800795

Figure Lengend Snippet: (a) The axial modulation transfer function (MTF) as a function of spatial frequency using a typical adult head protocol (see Table ​Table1)1) and calculated using data from −6° to 6° (x-dir), 84° to 96° (y-dir), 0° to 360° (radial), and 0° to 360° but only using half the axial slices in the measurement (reduced ROI radial). The curve drops to a value of 0.1 at a frequency of 0.62 mm−1. (b) ACR phantom bar pattern viewed using a window of 100 and optimized level of 1100. The patterns correspond to frequencies of (from top going clockwise): 1.2, 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, and 0.4 mm−1. An axial resolution (for example, the frequency at which the MTF falls to ∼0.1) between 0.6 and 0.7 mm−1 is indicated.

Article Snippet: The ACR phantom (model 464, Gammex-RMI, Middleton, WI), shown in Fig. , was carefully centered in the scanner and properly aligned using the method described by McCollough et al. with aid of the accompanying stand.

Techniques:

Journal: Medical Physics

Article Title: A simple approach to measure computed tomography (CT) modulation transfer function (MTF) and noise-power spectrum (NPS) using the American College of Radiology (ACR) accreditation phantom

doi: 10.1118/1.4800795

Figure Lengend Snippet: Three representative planes from the three-dimensional NPS as measured using images from the third module of an ACR phantom. Slices shown correspond to a typical adult head protocol (see Table ​Table1).1). The general shape of the NPS is consistent with that expected of filtered-backprojection reconstruction. Note that the resolution of the NPS in the z direction depends on the slice thickness and size of Δz in the ROIs used, and is expected to be worse than the radial (axial) direction due to the limited 4 cm width of the module.

Article Snippet: The ACR phantom (model 464, Gammex-RMI, Middleton, WI), shown in Fig. , was carefully centered in the scanner and properly aligned using the method described by McCollough et al. with aid of the accompanying stand.

Techniques: