Abstract:Soft tissue images from portable cone beam computed tomography (CBCT) scanners can be used for diagnosis and detection of tumor, cancer, intracerebral hemorrhage, and so forth. Due to large field of view, X-ray scattering which is the main cause of artifacts degrades image quality, such as cupping artifacts, CT number inaccuracy, and low contrast, especially on soft tissue images. In this work, we propose the X-ray scatter correction method for improving soft tissue images. The X-ray scatter correction scheme … Show more
“…Nowadays, many latest DR systems come with scatter correction software [ 17 – 20 ] that lower the dose and improve the image quality for this situation. The scatter correction software of BodiiRay [ 21 ] is forthcoming and will be soon available for upgrading.…”
Background. The National Science and Technology Development Agency (NSTDA) in Thailand researched and prototyped digital radiography systems under the brand name BodiiRay aiming for sustainable development and affordability of medical imaging technology. The image restoration and enhancement were implemented for the systems. Purpose. The image quality of the systems was evaluated using images from phantoms and from healthy volunteers. Methods. The survey phantom images from BodiiRay and other two commercial systems using the exposure settings for the chest, the abdomen, and the extremity were evaluated by three experience observers in terms of the high-contrast image resolution, the low-contrast image detectability, and the grayscale differentiation. The volunteer images of the chests, the abdomens, and the extremities from BodiiRay were evaluated by three specialized radiologists based on visual grading on 5-point scaled questionnaires for the anatomy visibility, the image quality satisfaction, and the diagnosis confidence in using the images. Results. BodiiRay phantom results were similar to those from the commercial systems. The overall performance averaged across the exposure settings showed that BodiiRay was slightly better than Fujifilm FDR Go in the low-contrast detectability (
p
=
0.033
) and in the grayscale differentiation (
p
=
0.004
). It was also slightly better than Siemens YSIO Max in the high-contrast resolution (
p
=
0.018
). The images of chest, pelvis, and hand phantoms illustrated comparable visual quality. For volunteer images, the percentage of the images scored ≥4 ranged from 61% to 99%, 23% to 92%, and 96% to 99% for the chest, abdomen, and extremity images, respectively. The average score ranged from 3.63 to 4.46, 3.18 to 4.21, and 4.41 to 4.51 for the chest, abdomen, and extremity images, respectively. Conclusion. The phantom image results showed the comparability of these systems. The clinical evaluation showed BodiiRay images provided sufficient image qualities for digital radiography of these body parts.
“…Nowadays, many latest DR systems come with scatter correction software [ 17 – 20 ] that lower the dose and improve the image quality for this situation. The scatter correction software of BodiiRay [ 21 ] is forthcoming and will be soon available for upgrading.…”
Background. The National Science and Technology Development Agency (NSTDA) in Thailand researched and prototyped digital radiography systems under the brand name BodiiRay aiming for sustainable development and affordability of medical imaging technology. The image restoration and enhancement were implemented for the systems. Purpose. The image quality of the systems was evaluated using images from phantoms and from healthy volunteers. Methods. The survey phantom images from BodiiRay and other two commercial systems using the exposure settings for the chest, the abdomen, and the extremity were evaluated by three experience observers in terms of the high-contrast image resolution, the low-contrast image detectability, and the grayscale differentiation. The volunteer images of the chests, the abdomens, and the extremities from BodiiRay were evaluated by three specialized radiologists based on visual grading on 5-point scaled questionnaires for the anatomy visibility, the image quality satisfaction, and the diagnosis confidence in using the images. Results. BodiiRay phantom results were similar to those from the commercial systems. The overall performance averaged across the exposure settings showed that BodiiRay was slightly better than Fujifilm FDR Go in the low-contrast detectability (
p
=
0.033
) and in the grayscale differentiation (
p
=
0.004
). It was also slightly better than Siemens YSIO Max in the high-contrast resolution (
p
=
0.018
). The images of chest, pelvis, and hand phantoms illustrated comparable visual quality. For volunteer images, the percentage of the images scored ≥4 ranged from 61% to 99%, 23% to 92%, and 96% to 99% for the chest, abdomen, and extremity images, respectively. The average score ranged from 3.63 to 4.46, 3.18 to 4.21, and 4.41 to 4.51 for the chest, abdomen, and extremity images, respectively. Conclusion. The phantom image results showed the comparability of these systems. The clinical evaluation showed BodiiRay images provided sufficient image qualities for digital radiography of these body parts.
“…2 . The in-house scatter correction algorithm [ 24 , 25 ] was applied to projection data before reconstruction to accurately estimate X-ray scatters. Fig.…”
Section: Methodsmentioning
confidence: 99%
“…The truncated data or incomplete projection images of the head phantom were acquired from the prototype. They were corrected for X-ray scattering [ 24 , 25 ] and reconstructed by fast iterative reconstruction with the proposed truncation effect reduction to obtain the reconstructed images. In this case, we focused on certain slices of reconstructed images in the upper part inside the FOV because they tend to degrade easier than other slices.…”
Background
Iterative reconstruction for cone-beam computed tomography (CBCT) has been applied to improve image quality and reduce radiation dose. In a case where an object’s actual projection is larger than a flat panel detector, CBCT images contain truncated data or incomplete projections, which degrade image quality inside the field of view (FOV). In this work, we propose truncation effect reduction for fast iterative reconstruction in CBCT imaging.
Methods
The volume matrix size of the FOV and the height of projection images were extrapolated to a suitable size. These extended projections were reconstructed by fast iterative reconstruction. Moreover, a smoothing parameter for noise regularization in iterative reconstruction was modified to reduce the accumulated error while processing. The proposed work was evaluated by image quality measurements and compared with conventional filtered backprojection (FBP). To validate the proposed method, we used a head phantom for evaluation and preliminarily tested on a human dataset.
Results
In the experimental results, the reconstructed images from the head phantom showed enhanced image quality. In addition, fast iterative reconstruction can be run continuously while maintaining a consistent mean-percentage-error value for many iterations. The contrast-to-noise ratio of the soft-tissue images was improved. Visualization of low contrast in the ventricle and soft-tissue images was much improved compared to those from FBP using the same dose index of 5 mGy.
Conclusions
Our proposed method showed satisfactory performance to reduce the truncation effect, especially inside the FOV with better image quality for soft-tissue imaging. The convergence of fast iterative reconstruction tends to be stable for many iterations.
“…2. The in-house scatter correction algorithm [24,25] was applied to projection data before reconstruction to accurately estimate the x-ray scatters.…”
Background: Iterative reconstruction for cone-beam computed tomography (CBCT) has been applied to improve image quality and reduce radiation dose. In a case where an object is larger than a flat panel detector, most CBCT images contain truncated data or incomplete projections, which degrade image quality. In this work, we propose the truncation effect reduction for fast iterative reconstruction in CBCT imaging inside the field of view (FOV).Methods: The volume matrix size of FOV and the height of projection images were extrapolated to a suitable size. These extended projections were reconstructed by fast iterative reconstruction. Moreover, a smoothing parameter for noise regularization in iterative reconstruction was also modified to reduce the accumulated error while processing. The proposed work was evaluated by image quality measurements and compared with the conventional filtered back projection (FBP) method. To validate the proposed method, we used a head phantom for evaluation and tested on real human head data. Results: In the experimental results, the reconstructed images from the head phantom can be enhanced apparently. In addition, fast iteration reconstruction can be run continuously while remaining the consistent mean-percentage-error (MPE) value with a large number of iterations. The CNR of the soft-tissue images was improved by the increased contrast and the decreased noise. Visualization of low contrast in the ventricle and soft-tissue images can be observed much clearer compared to those from FBP using the same effective radiation dose of 5 mGy. Conclusions: Our proposed work has satisfactory performance to reduce the truncation effect, especially inside the FOV with better image quality for soft-tissue imaging. The convergence of fast iterative reconstruction tends to be stable for many iterations.
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