Compare conspicuity of ductal carcinoma in-situ (DCIS) to benign calcifications on unenhanced (bC... more Compare conspicuity of ductal carcinoma in-situ (DCIS) to benign calcifications on unenhanced (bCT), contrast-enhanced dedicated breast CT (CEbCT) and mammography (DM). The institutional review board approved this HIPAA-compliant study. 42 women with Breast Imaging Reporting and Data System 4 or 5 category micro-calcifications had breast CT before biopsy. Three subjects with invasive disease at surgery were excluded. Two breast radiologists independently compared lesion conspicuity scores (CS) for CEbCT, to bCT and DM. Enhancement was measured in Hounsfield units (HU). Mean CS±standard deviations are shown. Receiver operating characteristic analysis (ROC) measured radiologists' discrimination performance by comparing CS to enhancement alone. Statistical measurements were made using ANOVA F-test, Wilcoxon rank-sum test and robust linear regression analyses. 39 lesions (17 DCIS, 22 benign) were analyzed. DCIS (8.5±0.9, n=17) was more conspicuous than benign micro-calcifications (3.6±2.9, n=22; p<0.0001) on CEbCT. DCIS was equally conspicuous on CEbCT and DM (8.5±0.9, 8.7±0.8, n=17; p=0.85) and more conspicuous when compared to bCT (5.3±2.6, n=17; p<0.001). All DCIS enhanced; mean enhancement (90HU±53HU, n=17) was higher compared to benign lesions (33±30HU, n=22) (p<0.0001). ROC analysis of the radiologists' CS showed high discrimination performance (AUC=0.94) compared to enhancement alone (AUC=0.85) (p<0.026). DCIS is more conspicuous than benign micro-calcifications on CEbCT. DCIS visualization on CEbCT is equal to mammography but improved compared to bCT. Radiologists' discrimination performance using CEBCT is significantly higher than enhancement values alone. CEbCT may have an advantage over mammography by reducing false positive examinations when calcifications are analyzed.
Swarm Robotics refers to the application of Swarm Intelligence techniques where a desired collect... more Swarm Robotics refers to the application of Swarm Intelligence techniques where a desired collective behavior emerges from the local interactions of robots with one another and with their environment. In this paper, a modified Bees Algorithm is proposed for multi-target search and coverage by an autonomous swarm of robotic “bees”. The objective is to find targets in an unknown area, send their estimated locations and fitness values to other robots in swarm which then provide the coverage of the found targets in a self-organized, decentralized way. The robots are equipped with ultrasonic sensors for obstacle avoidance, thermal sensors for target detection, and ZigBee modules for local communication. For the experiments, a small swarm of robots was built to test the performance of the modified Bees Algorithm. The experimental results show that the swarm is self-organized, decentralized and adaptive, and it can be successfully applied to the unknown area search and coverage.
Dedicated breast computed tomography (bCT) technology for the purpose of breast cancer screening ... more Dedicated breast computed tomography (bCT) technology for the purpose of breast cancer screening has been a focus of research at UC Davis since the late 1990s. Previous studies have shown that improvement in spatial resolution characteristics of this modality correlates with greater microcalcification detection, a factor considered a potential limitation of bCT. The aim of this study is to improve spatial resolution as characterized by the modulation transfer function (MTF) via changes in the scanner hardware components and operational schema. Four prototypes of pendant-geometry, cone-beam breast CT scanners were designed and developed spanning three generations of design evolution. To improve the system MTF in each bCT generation, modifications were made to the imaging components (x-ray tube and flat-panel detector), system geometry (source-to-isocenter and detector distance), and image acquisition parameters (technique factors, number of projections, system synchronization scheme,...
Medical Imaging 2013: Physics of Medical Imaging, 2013
ABSTRACT Dedicated breast CT (bCT) technology may be useful for patients with high risk of develo... more ABSTRACT Dedicated breast CT (bCT) technology may be useful for patients with high risk of developing breast cancer. Previous studies have shown that bCT outperforms mammography in the visualization of mass lesions, however mammography is superior in identifying microcalcifications. The Breast Tomography Project at UC Davis has led to development of three dedicated breast CT scanners that produce high resolution, fully tomographic images, overcoming tissue superposition effects found in mammography while maintaining an equivalent radiation dose. Over 600 patients have been imaged in an ongoing clinical trial. The first patient scan was performed on the latest bCT scanner developed at UC Davis, called Cambria, on April 12, 2012. The main differences between Cambria and the previous scanners are in using a pulsed xray source (generator and tube) instead of continuous x-ray sources, and also in using the non-binning mode of the flatpanel fluoroscopic detector. The spatial resolution characteristics of the new scanner were investigated and the results show significant improvement in the overall MTF properties. Based on these results, it was concluded that using the pulsed x-ray tube, we were able to restore the MTF degradation caused by motion blurring effect that exists in previous generations of bCT. Moreover, MTF analysis shows that using the detector in the native acquisition mode (1 x 1) results in superior spatial resolution which will likely bring considerable improvement to the delineation of microcalcifications.
Compare conspicuity of ductal carcinoma in-situ (DCIS) to benign calcifications on unenhanced (bC... more Compare conspicuity of ductal carcinoma in-situ (DCIS) to benign calcifications on unenhanced (bCT), contrast-enhanced dedicated breast CT (CEbCT) and mammography (DM). The institutional review board approved this HIPAA-compliant study. 42 women with Breast Imaging Reporting and Data System 4 or 5 category micro-calcifications had breast CT before biopsy. Three subjects with invasive disease at surgery were excluded. Two breast radiologists independently compared lesion conspicuity scores (CS) for CEbCT, to bCT and DM. Enhancement was measured in Hounsfield units (HU). Mean CS±standard deviations are shown. Receiver operating characteristic analysis (ROC) measured radiologists' discrimination performance by comparing CS to enhancement alone. Statistical measurements were made using ANOVA F-test, Wilcoxon rank-sum test and robust linear regression analyses. 39 lesions (17 DCIS, 22 benign) were analyzed. DCIS (8.5±0.9, n=17) was more conspicuous than benign micro-calcifications (3.6±2.9, n=22; p<0.0001) on CEbCT. DCIS was equally conspicuous on CEbCT and DM (8.5±0.9, 8.7±0.8, n=17; p=0.85) and more conspicuous when compared to bCT (5.3±2.6, n=17; p<0.001). All DCIS enhanced; mean enhancement (90HU±53HU, n=17) was higher compared to benign lesions (33±30HU, n=22) (p<0.0001). ROC analysis of the radiologists' CS showed high discrimination performance (AUC=0.94) compared to enhancement alone (AUC=0.85) (p<0.026). DCIS is more conspicuous than benign micro-calcifications on CEbCT. DCIS visualization on CEbCT is equal to mammography but improved compared to bCT. Radiologists' discrimination performance using CEBCT is significantly higher than enhancement values alone. CEbCT may have an advantage over mammography by reducing false positive examinations when calcifications are analyzed.
Swarm Robotics refers to the application of Swarm Intelligence techniques where a desired collect... more Swarm Robotics refers to the application of Swarm Intelligence techniques where a desired collective behavior emerges from the local interactions of robots with one another and with their environment. In this paper, a modified Bees Algorithm is proposed for multi-target search and coverage by an autonomous swarm of robotic “bees”. The objective is to find targets in an unknown area, send their estimated locations and fitness values to other robots in swarm which then provide the coverage of the found targets in a self-organized, decentralized way. The robots are equipped with ultrasonic sensors for obstacle avoidance, thermal sensors for target detection, and ZigBee modules for local communication. For the experiments, a small swarm of robots was built to test the performance of the modified Bees Algorithm. The experimental results show that the swarm is self-organized, decentralized and adaptive, and it can be successfully applied to the unknown area search and coverage.
Dedicated breast computed tomography (bCT) technology for the purpose of breast cancer screening ... more Dedicated breast computed tomography (bCT) technology for the purpose of breast cancer screening has been a focus of research at UC Davis since the late 1990s. Previous studies have shown that improvement in spatial resolution characteristics of this modality correlates with greater microcalcification detection, a factor considered a potential limitation of bCT. The aim of this study is to improve spatial resolution as characterized by the modulation transfer function (MTF) via changes in the scanner hardware components and operational schema. Four prototypes of pendant-geometry, cone-beam breast CT scanners were designed and developed spanning three generations of design evolution. To improve the system MTF in each bCT generation, modifications were made to the imaging components (x-ray tube and flat-panel detector), system geometry (source-to-isocenter and detector distance), and image acquisition parameters (technique factors, number of projections, system synchronization scheme,...
Medical Imaging 2013: Physics of Medical Imaging, 2013
ABSTRACT Dedicated breast CT (bCT) technology may be useful for patients with high risk of develo... more ABSTRACT Dedicated breast CT (bCT) technology may be useful for patients with high risk of developing breast cancer. Previous studies have shown that bCT outperforms mammography in the visualization of mass lesions, however mammography is superior in identifying microcalcifications. The Breast Tomography Project at UC Davis has led to development of three dedicated breast CT scanners that produce high resolution, fully tomographic images, overcoming tissue superposition effects found in mammography while maintaining an equivalent radiation dose. Over 600 patients have been imaged in an ongoing clinical trial. The first patient scan was performed on the latest bCT scanner developed at UC Davis, called Cambria, on April 12, 2012. The main differences between Cambria and the previous scanners are in using a pulsed xray source (generator and tube) instead of continuous x-ray sources, and also in using the non-binning mode of the flatpanel fluoroscopic detector. The spatial resolution characteristics of the new scanner were investigated and the results show significant improvement in the overall MTF properties. Based on these results, it was concluded that using the pulsed x-ray tube, we were able to restore the MTF degradation caused by motion blurring effect that exists in previous generations of bCT. Moreover, MTF analysis shows that using the detector in the native acquisition mode (1 x 1) results in superior spatial resolution which will likely bring considerable improvement to the delineation of microcalcifications.
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Papers by Peymon Gazi