bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐F‐I‐49: Vendor‐Independent, Model‐Based Iterative Reconstruction On a Rotating Grid with Coordinate‐Descent Optimization for CT Imaging Investigations
Authors: Young S , Hoffman J , Noo F , McNitt‐Gray M 
Published: July 2016

Purpose:Iterative reconstruction methods show promise for improving image quality and lowering the dose in helical CT. We aim to develop a novel model‐based reconstruction method that offers potential for dose reduction with reasonable computation speed and storage requirements for vendor‐independent reconstruction from clinical data on a normal desktop computer.Methods:In 2012, Xu proposed reconstructing on rotating slices to exploit helical symmetry and reduce the storage requirements for the CT system matrix. Inspired by this concept, we have developed a novel reconstruction method incorporating the stored‐system‐matrix approach together with iterative coordinate‐descent (ICD) optimization. A penalized‐least‐squares objective function with a quadratic penalty term is solved analytically voxel‐by‐voxel, sequentially iterating along the axial direction first, followed by the transaxial direction. 8 in‐plane (transaxial) neighbors are used for the ICD algorithm. The forward problem is modeled via a unique approach that combines the principle of Joseph's method with trilinear B‐spline interpolation to enable accurate reconstruction with low storage requirements. Iterations are accelerated with multi‐CPU OpenMP libraries. For preliminary evaluations, we reconstructed (1) a simulated 3D ellipse phantom and (2) an ACR accreditation phantom dataset exported from a clinical scanner (Definition AS, Siemens Healthcare). Image quality was evaluated in the resolution module.Results:Image quality was excellent for the ellipse phantom. For the ACR phantom, image quality was comparable to clinical reconstructions and reconstructions using open‐source FreeCT_wFBP software. Also, we did not observe any deleterious impact associated with the utilization of rotating slices. The system matrix storage requirement was only 4.5GB, and reconstruction time was 50 seconds per iteration.Conclusion:Our reconstruction method shows potential for furthering research in low‐dose helical CT, in particular as part of our ongoing development of an acquisition/reconstruction pipeline for generating images under a wide range of conditions. Our algorithm will be made available open‐source as “FreeCT_ICD”.NIH U01 CA181156; Disclosures (McNitt‐Gray): Institutional research agreement, Siemens Healthcare; Past recipient, research grant support, Siemens Healthcare; Consultant, Toshiba America Medical Systems; Consultant, Samsung Electronics
SU‐F‐I‐50: Finite Element‐Based Deformable Image Registration of Lung and Heart
Authors: Penjweini R , Kim M , Zhu T 
Published: July 2016

Purpose:Photodynamic therapy (PDT) is used after surgical resection to treat the microscopic disease for malignant pleural mesothelioma and to increase survival rates. Although accurate light delivery is imperative to PDT efficacy, the deformation of the pleural volume during the surgery impacts the delivered light dose. To facilitate treatment planning, we use a finite‐element‐based (FEM) deformable image registration to quantify the anatomical variation of lung and heart volumes between CT pre‐(or post‐) surgery and surface contours obtained during PDT using an infrared camera‐based navigation system (NDI).Methods:NDI is used during PDT to obtain the information of the cumulative light fluence on every cavity surface point that is being treated. A wand, comprised of a modified endotrachial tube filled with Intralipid and an optical fiber inside the tube, is used to deliver the light during PDT. The position of the treatment is tracked using an attachment with nine reflective passive markers that are seen by the NDI system. Then, the position points are plotted as three‐dimensional volume of the pleural cavity using Matlab and Meshlab. A series of computed tomography (CT) scans of the lungs and heart, in the same patient, are also acquired before and after the surgery. The NDI and CT contours are imported into COMSOL Multiphysics, where the FEM‐based deformable image registration is obtained. The NDI and CT contours acquired during and post‐PDT are considered as the reference, and the Pre‐PDT CT contours are used as the target, which will be deformed.Results:Anatomical variation of the lung and heart volumes, taken at different times from different imaging devices, was determined by using our model. The resulting three‐dimensional deformation map along x, y and z‐axes was obtained.Conclusion:Our model fuses images acquired by different modalities and provides insights into the variation in anatomical structures over time.
SU‐F‐I‐52: An Approach to Estimate Noise in Patient Image by Computing the Minimal Difference in Neighborhoods
Authors: Maitree R , Curcuru A , Gach H , Yang D 
Published: July 2016

Purpose:To quantitatively evaluate and compare the accuracy of two advanced methods that can estimate the level of noise per voxel in patient images. These noise estimation methods show promises in: 1) assuring the performance of imaging systems and algorithms, 2) guiding image processing tasks for clinical and research applications, i.e. by optimization of the parameters, and 3) quantifying patient image quality and assisting image quality improvements.Methods:We conducted an experiment of 34 repeated MRI scans (TrueFISP sequence) of a swine head in order to obtain a ground truth noise dataset. Two published noise estimation methods were implemented in this study: 1) Minimal Difference in Neighborhoods (MDiN) and 2) high‐pass MDiN. Noise estimation accuracies of two methods were quantitatively measured using the ground truth data and patient MRI images with added Rician noise.Results:The experimental results with both swine head images and patient images showed that the MDiN method is more accurate. The high‐pass MDiN method is slightly less but still sufficiently accurate. The MDiN method could be obtained within a 90% accuracy when tested on the ground‐truth dataset.Conclusion:We verified the performance of two efficient methods to automatically estimate per voxel noise levels in patient images. Our results suggest that these methods could be confidently used to assist and guide clinical and research applications that require such noise information.Senior Author Dr. Deshan Yang received research funding form ViewRay and Varian.
SU‐F‐I‐54: Spatial Resolution Studies in Proton CT Using a Phase‐II Prototype Head Scanner
Authors: Plautz Tia E. , Johnson R. P. , Sadrozinski H. F.‐W. , Zatserklyaniy A. , Bashkirov V. , Hurley R. F. , Schulte R. W. , Piersimoni P. , Giacometti V. 
Published: July 2016

Purpose:To characterize the modulation transfer function (MTF) of the pre‐clinical (phase II) head scanner developed for proton computed tomography (pCT) by the pCT collaboration. To evaluate the spatial resolution achievable by this system.Methods:Our phase II proton CT scanner prototype consists of two silicon telescopes that track individual protons upstream and downstream from a phantom, and a 5‐stage scintillation detector that measures a combination of the residual energy and range of the proton. Residual energy is converted to water equivalent path length (WEPL) of the protons in the scanned object. The set of WEPL values and associated paths of protons passing through the object over a 360° angular scan is processed by an iterative parallelizable reconstruction algorithm that runs on GP‐GPU hardware. A custom edge phantom composed of water‐equivalent polymer and tissue‐equivalent material inserts was constructed. The phantom was first simulated in Geant4 and then built to perform experimental beam tests with 200 MeV protons at the Northwestern Medicine Chicago Proton Center. The oversampling method was used to construct radial and azimuthal edge spread functions and modulation transfer functions. The spatial resolution was defined by the 10% point of the modulation transfer function in units of lp/cm.Results:The spatial resolution of the image was found to be strongly correlated with the radial position of the insert but independent of the relative stopping power of the insert. The spatial resolution varies between roughly 4 and 6 lp/cm in both the the radial and azimuthal directions depending on the radial displacement of the edge.Conclusion:The amount of image degradation due to our detector system is small compared with the effects of multiple Coulomb scattering, pixelation of the image and the reconstruction algorithm. Improvements in reconstruction will be made in order to achieve the theoretical limits of spatial resolution.
SU‐F‐I‐55: Performance Evaluation of Digital PET/CT: Medical Physics Basis for the Clinical Applications
Authors: Zhang J , Miller M , Knopp MV 
Published: July 2016

Purpose:Replacement of conventional PMT‐based detector with next generation digital photon counting (DPC) detector is a technology leap for PET imaging. This study evaluated the performance and characteristics of the DPC system and its stability within a 1 year time window following its installation focusing on the medical physics basis for clinical applications.Methods:A digital PET/CT scanner using 1:1 coupling of 23,040 crystal: detector elements was introduced and became operational at OSU. We tested and evaluated system performance and characteristics using NEMA NU2‐2012. System stabilities in timing resolution, energy resolution, detector temperature and humidity (T&H) were monitored over 1‐yr. Timing, energy and spatial resolution were characterized across clinically relevant count rate range. CQIE uniformity PET and NEMA IEC‐Body PET with hot spheres varying with sizes and contrasts were performed. PET reconstructed in standard(4mm), High(2mm) and Ultra‐High(1mm) definitions were evaluated.Results:NEMA results showed PET spatial resolution (mm‐FWHM) from 4.01&4.14 at 1cm to 5.82&6.17 at 20cm in transverse & axial. 322±3ps timing and 11.0% energy resolution were measured. 5.7kcps/MBq system sensitivity with 24kcps/MBq effective sensitivity was obtained. The peak‐NECR was ∼171kcps with the effective peak‐NECR >650kcps@50kBq/mL. Scatter fraction was ∼30%, and the maximum trues was >900kcps. NEMA IQ demonstrated hot sphere contrast ranging from ∼62%±2%(10mm) to ∼88%±2%(22mm), cold sphere contrast of ∼86%±2%(28mm) and ∼89%±3%(37mm) and excellent uniformity. Monitoring 1‐yr stability, it revealed ∼1% change in timing, ±0.4% change in energy resolution, and <10% variations in T&H. CQIE PET gave <3% SUV variances in axial. 60%–100% recovery coefficients across sphere sizes and contrast levels were achieved.Conclusion:Characteristics and stability of the next generation DPC PET detector system over an 1‐yr time window was excellent and better than prior experiences. It demonstrated improved and robust system characteristics and performance in spatial resolution, sensitivity, timing and energy resolution, count rate and image quality.Michael Miller is an employee of Philips Healthcare
SU‐F‐I‐57: Evaluate and Optimize PET Acquisition Overlap in 18F‐FDG Oncology Wholebody PET/CT: Can We Scan PET Faster?
Authors: Zhang J , Natwa M , Hall NC , Knopp MU , Zhang B , Tung C , Knopp MV 
Published: July 2016

Purpose:The longer patient has to remain on the table during PET imaging, the higher the likelihood of motion artifacts due to patient discomfort. This study was to investigate and optimize PET acquisition overlap in 18F‐FDG oncology wholebody PET/CT to speed up PET acquisition and improve patient comfort.Methods:Wholebody 18F‐FDG PET/CT of phantoms, 8 pre‐clinical patients (beagles) and 5 clinical oncology patients were performed in 90s/bed on a time‐of‐flight Gemini TF 64 system. Imaging of phantoms and beagles was acquired with reduced PET overlaps (40%, 33%, 27%, 20%, 13% and no overlap) in addition to the system default (53%). In human studies, 1 or 2 reduced overlaps from the listed options were used to acquire PET/CT sweeps right after the default standard of care imaging. Image quality was blindly reviewed using visual scoring criteria and quantitative SUV assessment. NEMA PET sensitivity was performed under different overlaps.Results:All PET exams demonstrated no significant impact on the visual grades for overlaps >20%. Blinded reviews assigned the best visual scores to PET using overlaps 53%–27%. Reducing overlap to 27% for oncology patients (12‐bed) saved an average of ∼40% acquisition time (11min) compared to using the default overlap (18min). No significant SUV variances were found when reducing overlap to half of default for cerebellum, lung, heart, aorta, liver, fat, muscle, bone marrow, thighs and target lesions (p>0.05), except expected variability in urinary system.Conclusion:This study demonstrated by combined phantom, pre‐clinical and clinical PET/CT scans that PET acquisition overlap in axial of today's systems can be reduced and optimized. It showed that a reduction of PET acquisition overlap to 27% (half of system default) can be implemented to reduce table time by ∼40% to improve patient comfort and minimize potential motion artifacts, without prominently degrading image quality or compromising PET quantification.
SU‐F‐I‐58: Image Quality Comparisons of Different Motion Magnitudes and TR Values in MR‐PET
Authors: Patrick J , Tavallaei M , Thompson R , Stodilka R , Drangova M , Gaede S 
Published: July 2016

Purpose:The aim of this work is to evaluate the accuracy and sensitivity of a respiratory‐triggered MR‐PET protocol in detecting four different sized lesions at two different magnitudes of motion, with two different TR values, using a novel PET‐MR‐CT compatible respiratory motion phantom.Methods:The eight‐compartment torso phantom was setup adjacent to the motion stage, which moved four spherical compartments (28, 22, 17, 10 mm diameter) in two separate (1 and 2 cm) linear motion profiles, simulating a 3.5 second respiratory cycle. Scans were acquired on a 3T MR‐PET system (Biograph mMR; Siemens Medical Solutions, Germany). MR measurements were taken with: 1) Respiratory‐triggered T2‐weighted turbo spin echo (BLADE) sequence in coronal orientation, and 2) Real‐time balanced steady‐state gradient echo sequence (TrueFISP) in coronal and sagittal planes. PET was acquired simultaneously with MR. Sphere geometries and motion profiles were measured and compared with ground truths for T2 BLADE‐TSE acquisitions and real time TrueFISP images. PET quantification and geometry measurements were taken using standardized uptake values, voxel intensity plots and were compared with known values, and examined alongside MR‐based attenuation maps. Contrast and signal‐to‐noise ratios were also compared for each of the acquisitions as functions of motion range and TR.Results:Comparison of lesion diameters indicate the respiratory triggered T2 BLADE‐TSE was able to maintain geometry within −2 mm for 1 cm motion for both TR values, and within −3.1 mm for TR = 2000 ms at 2 cm motion. Sphere measurements in respiratory triggered PET images were accurate within +/− 5 mm for both ranges of motion for 28, 22, and 17 mm diameter spheres.Conclusion:Hybrid MR‐PET systems show promise in imaging lung cancer in non‐compliant patients, with their ability to acquire both modalities simultaneously. However, MR‐based attenuation maps are still susceptible to motion derived artifacts and pose the potential to affect PET accuracy.
SU‐F‐I‐59: Quality Assurance Phantom for PET/CT Alignment and Attenuation Correction
Authors: Lin T , Hamacher K 
Published: July 2016

Purpose:This study utilizes a commercial PET/CT phantom to investigate two specific properties of a PET/CT system: the alignment accuracy of PET images with those from CT used for attenuation correction and the accuracy of this correction in PET images.Methods:A commercial PET/CT phantom consisting of three aluminum rods, two long central cylinders containing uniform activity, and attenuating materials such as air, water, bone and iodine contrast was scanned using a standard PET/CT protocol. Images reconstructed with 2 mm slice thickness and a 512 by 512 matrix were obtained. The center of each aluminum rod in the PET and CT images was compared to evaluate alignment accuracy. ROIs were drawn on transaxial images of the central rods at each section of attenuating material to determine the corrected activity (in BQML). BQML values were graphed as a function of slice number to provide a visual representation of the attenuation‐correction throughout the whole phantom.Results:Alignment accuracy is high between the PET and CT images. The maximum deviation between the two in the axial plane is less than 1.5 mm, which is less than the width of a single pixel. BQML values measured along different sections of the large central rods are similar among the different attenuating materials except iodine contrast. Deviation of BQML values in the air and bone sections from the water section is less than 1%.Conclusion:Accurate alignment of PET and CT images is critical to ensure proper calculation and application of CT‐based attenuation correction. This study presents a simple and quick method to evaluate the two with a single acquisition. As the phantom also includes spheres of increasing diameter, this could serve as a straightforward means to annually evaluate the status of a modern PET/CT system.
SU‐F‐I‐60: ICC MIWG Displays: Final Recommendations for Visualization of Medical Content On Color Display Systems
Authors: Kimpe T , Green P , Revie C , Flynn M 
Published: July 2016

Purpose:Use of color images in medical imaging has increased significantly the last few years. There is no agreement yet on what is an appropriate visualization framework for color medical images. This lack of standardization results into large variability of color appearance and makes consistency and quality assurance a challenge. The ICC Medical‐Imaging‐Working‐Group (MIWG) has defined recommendations for visualization of medical content on color display systems, whereby DICOM GSDF images, pseudo color images and color accurate images can all be presented effectively on the same display.Methods:The MIWG characterized a wide range of color display systems (consumer, professional and medical), and collected representative greyscale and color medical images. Simulations and bench testing was done to quantitatively compare the performance of various architectures and imaging pipelines in an ICC framework context. This allowed making recommendations on imaging pipeline architectures, and defining minimum requirements to guarantee minimum performance levels.Results:The ICC framework specification supports many possible architectures, profile types and pipeline characteristics. Numerous experiments have been performed to understand the effects related to choice of System design choices such as architecture, profile type (matrix, LUT, device, …) and pipeline specifications (eg. bit depth, LUT size). The impact of inaccurate estimation of display luminance/contrast/tone rendering curve has also been studied. Specific recommendations have been made related to system configuration, ICC framework/CMM, and calibration process.Conclusion:There is a need to standardize how medical color images need to be visualized. The ICC Medical Imaging Working Group has defined recommendations for visualization of medical content on color display systems. It has been shown that it is possible to achieve accurate greyscale, pseudo color and absolute color visualization of medical images by means of the ICC framework, at least when appropriate choices are made related to profile specification, imaging pipeline and calibration procedure.Tom Kimpe, employee Barco NV
SU‐F‐I‐61: Assessment and Characterization of the Built‐in Internal Photometer of Primary Diagnostic Monitors
Authors: Ruuge A , Erdi Y , Mahmood U 
Published: July 2016

Purpose:The conformance of Primary Diagnostic Monitors (PDMs) to the DICOM GSDF is increasingly required by several state and city regulators. Our purpose was to quantitatively characterize the luminance performance of the internal, built in photometer of BARCO monitors against an externally calibrated luminance meter.Methods:Thirty one PDMs (BARCO) were included in our analysis. An externally calibrated photometer (RaySafe Solo Light) was used to measure the luminance and illuminance values. Measured monitors were located at various hospital sites, radiology physicians’ offices and radiology reading rooms. All measured PDMs were equipped with the manufacturer's built‐in photometers and connected to Barco MediCal QA web service for manual and automatic quality control measurements. PDM combinations included 1, 2 and 4 monitors depending on the location. TG‐18 and SMPTE test patterns were used to evaluate monitor performance.Results:All the PDMs exceeded the luminance ratio of 250:1, as required by NYC PDM guidelines. One PDM failed the NYC requirement for the minimal luminance level of 350 cd/m2. As compared to the external photometer, the difference in measurement of the maximum luminance with the built‐in photometer was found to exceed 5% on 6 of the PDM measured, with a maximum deviation of 10%. The age of the monitors that failed was on average 5 years. All monitors passed the luminance uniformity test, which was 30% from the center of the monitor to the 4 corner locations. Four PDMs failed the Gray Scale Display Function (GSDF) calibration.Conclusion:For the consistent display of medical images and continued conformance with the DICOM GSDF standard, it is essential to compare the performance of the built‐in photometer with an externally calibrated photometer for monitors that are older than 5 years.
SU‐F‐I‐65: Fatty Acid Quantification in High‐Fat‐Diet Induced Abnormal Intrahepatic Triglyceride Storage Using Internal Standard Method at 3.0 T
Authors: Song K‐H , Yoo C‐H , Lim S‐I , Choe B‐Y 
Published: July 2016

Purpose:The objective of this study was to determine the metabolic changes in a rat model of high‐fat‐diet‐induced non‐alcoholic fatty liver disease (NAFLD) by using single‐voxel 1H‐MRS with a 3.0 T MRI scanner.Methods:The examination were performed on a 3.0T scanner using a 4‐channel animal coil for higher resolution. This method used point‐resolved spectroscopy (PRESS) (repetition time (TR)/echo time (TE) = 6000/35 ms; number of signal averages (NSA) = 64). To measure the lipid content, we quantified total lipids ((‐CH2‐)n/noise), total saturated fatty acids (3(‐CH2‐)/2(‐CH3)), total unsaturated fatty acids (3(‐CH2‐C=C‐CH2‐)/4(‐CH3)), total unsaturated bonds index (3(‐CH=CH‐)/2(‐CH3)), and polyunsaturated bonds index (3(=C‐CH2‐C=)/2(‐CH3)) by separating each peak area of (CH2)n, CH2C=CCH, =CCH2C=, and CH=CH by CH3. The ‐CH3 (0.90 ppm) peak was used as an internal chemical shift reference.Results:Total lipids and total saturated fatty acids were substantially upregulated in high‐fat‐diet‐fed rats in comparison with baseline values (total lipids, 16.22±6.60×10−4; total saturated fatty acids, 10.26±1.91). The resulting data on lipid accumulation were statistically significant in terms of total lipids at 3 weeks (78.65±36.20, p = 0.002), 6 weeks (88.14±22.36, p < 0.001), 9 weeks (78.55±31.29, P < 0.001), and 15 weeks (107.87±39.95, p < 0.001) after initiation of the high‐fat diet.Conclusion:Our results of noninvasive in vivo MRS are based on accurate monitoring of the changes in lipid content, which were verified using the data on saturated fatty acids and unsaturated fatty acids. We can conclude that localized MRS holds promise as an indicator of fatty liver diseases in humans and in animal models for monitoring treatment.