bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐I‐51: Use of Blade Sequences in Cervical Spine MR Imaging for Eliminating Motion, Truncation and Flow Artifacts
Authors: Mavroidis P , Lavdas E , Kostopoulos S , Ninos C , Strikou A , Glotsos D , Vlachopoulou A , Oikonomou G , Economopoulos N , Roka V , Sakkas G , Tsagkalis A , Statkahis S , Papanikolaou N , Batsikas G 
Published: July 2014

Purpose:To assess the efficacy of the BLADE technique to eliminate motion, truncation, flow and other artifacts in Cervical Spine MRI compared to the conventional technique. To study the ability of the examined sequences to reduce the indetention and wrap artifacts, which have been reported in BLADE sagittal sequences.Methods:Forty consecutive subjects, who had been routinely scanned for cervical spine examination using four different image acquisition techniques, were analyzed. More specifically, the following pairs of sequences were compared: a) T2 TSE SAG vs. T2 TSE SAG BLADE and b) T2 TIRM SAG vs. T2 TIRM SAG BLADE. A quantitative analysis was performed using the signal‐to‐noise ratio (SNR), contrast‐to‐noise ratio (CNR) and relative contrast (ReCon) measures. A qualitative analysis was also performed by two radiologists, who graded seven image characteristics on a 5‐point scale (0:non‐visualization; 1:poor; 2:average; 3:good; 4:excellent). The observers also evaluated the presence of image artifacts (motion, truncation, flow, indentation).Results:Based on the findings of the quantitative analysis, the ReCON values of the CSF (cerebrospinal fluid)/SC (spinal cord) between TIRM SAG and TIRM SAG BLADE were found to present statistical significant differences (p<0.001). Regarding motion and truncation artifacts, the T2 TSE SAG BLADE was superior compared to the T2 TSE SAG and the T2 TIRM SAG BLADE was superior compared to the T2 TIRM SAG. Regarding flow artifacts, T2 TIRM SAG BLADE eliminated more artifacts compared to the T2 TIRM SAG.Conclusion:The use of BLADE sequences in cervical spine MR examinations appears to be capable of potentially eliminating motion, pulsatile flow and trancation artifacts. Furthermore, BLADE sequences are proposed to be used in the standard examination protocols based on the fact that a significantly improved image quality could be achieved.
SU‐E‐I‐52: Validation of Multi‐Frequency Electrical Impedance Tomography Using Computed Tomography
Authors: Kohli K , Liu F , Krishnan K 
Published: July 2014

Purpose:Multi‐frequency EIT has been reported to be a potential tool in distinguishing a tissue anomaly from background. In this study, we investigate the feasibility of acquiring functional information by comparing multi‐frequency EIT images in reference to the structural information from the CT image through fusion.Methods:EIT data was acquired from a slice of winter melon using sixteen electrodes around the phantom, injecting a current of 0.4mA at 100, 66, 24.8 and 9.9 kHz. Differential EIT images were generated by considering different combinations of pair frequencies, one serving as reference data and the other as test data. The experiment was repeated after creating an anomaly in the form of an off‐centered cavity of diameter 4.5 cm inside the melon. All EIT images were reconstructed using Electrical Impedance Tomography and Diffuse Optical Tomography Reconstruction Software (EIDORS) package in 2‐D differential imaging mode using one‐step Gaussian Newton minimization solver. CT image of the melon was obtained using a Phillips CT Scanner. A segmented binary mask image was generated based on the reference electrode position and the CT image to define the regions of interest. The region selected by the user was fused with the CT image through logical indexing.Results:Differential images based on the reference and test signal frequencies were reconstructed from EIT data. Result illustrated distinct structural inhomogeneity in seeded region compared to fruit flesh. The seeded region was seen as a higherimpedance region if the test frequency was lower than the base frequency in the differential EIT reconstruction. When the test frequency was higher than the base frequency, the signal experienced less electrical impedance in the seeded region during the EIT data acquisition.Conclusion:Frequency‐based differential EIT imaging can be explored to provide additional functional information along with structural information from CT for identifying different tissues.
SU‐E‐I‐53: Variation in Measurements of Breast Skin Thickness Obtained Using Different Imaging Modalities
Authors: Nguyen U , Kumaraswamy N , Markey M 
Published: July 2014

Purpose:To investigate variation in measurements of breast skin thickness obtained using different imaging modalities, including mammography, computed tomography (CT), ultrasound, and magnetic resonance imaging (MRI).Methods:Breast skin thicknesses as measured by mammography, CT, ultrasound, and MRI were compared. Mammographic measurements of skin thickness were obtained from published studies that utilized standard positioning (upright) and compression. CT measurements of skin thickness were obtained from a published study of a prototype breast CT scanner in which the women were in the prone position and the breast was uncompressed. Dermatological ultrasound exams of the breast skin were conducted at our institution, with the subjects in the upright position and the breast uncompressed. Breast skin thickness was calculated from breast MRI exams at our institution, with the patient in the prone position and the breast uncompressed.Results:T tests for independent samples demonstrated significant differences in the mean breast skin thickness as measured by different imaging modalities. Repeated measures ANOVA revealed significant differences in breast skin thickness across different quadrants of the breast for some modalities.Conclusion:The measurement of breast skin thickness is significantly different across different imaging modalities. Differences in the amount of compression and differences in patient positioning are possible reasons why measurements of breast skin thickness vary by modality.
SU‐E‐I‐57: Evaluation and Optimization of Effective‐Dose Using Different Beam‐Hardening Filters in Clinical Pediatric Shunt CT Protocol
Authors: Gill K , Aldoohan S , Collier J 
Published: July 2014

Purpose:Study image optimization and radiation dose reduction in pediatric shunt CT scanning protocol through the use of different beam‐hardening filtersMethods:A 64‐slice CT scanner at OU Childrens Hospital has been used to evaluate CT image contrast‐to‐noise ratio (CNR) and measure effective‐doses based on the concept of CT dose index (CTDIvol) using the pediatric head shunt scanning protocol. The routine axial pediatric head shunt scanning protocol that has been optimized for the intrinsic x‐ray tube filter has been used to evaluate CNR by acquiring images using the ACR approved CT‐phantom and radiation dose CTphantom, which was used to measure CTDIvol. These results were set as reference points to study and evaluate the effects of adding different filtering materials (i.e. Tungsten, Tantalum, Titanium, Nickel and Copper filters) to the existing filter on image quality and radiation dose. To ensure optimal image quality, the scanner routine air calibration was run for each added filter. The image CNR was evaluated for different kVps and wide range of mAs values using above mentioned beam‐hardening filters. These scanning protocols were run under axial as well as under helical techniques. The CTDIvol and the effective‐dose were measured and calculated for all scanning protocols and added filtration, including the intrinsic x‐ray tube filter.Results:Beam‐hardening filter shapes energy spectrum, which reduces the dose by 27%. No noticeable changes in image low contrast detectabilityConclusion:Effective‐dose is very much dependent on the CTDIVol, which is further very much dependent on beam‐hardening filters. Substantial reduction in effective‐dose is realized using beam‐hardening filters as compare to the intrinsic filter. This phantom study showed that significant radiation dose reduction could be achieved in CT pediatric shunt scanning protocols without compromising in diagnostic value of image quality.
SU‐E‐I‐63: Quantitative Evaluation of the Effects of Orthopedic Metal Artifact Reduction (OMAR) Software On CT Images for Radiotherapy Simulation
Authors: Jani S 
Published: July 2014

Purpose:CT simulation for patients with metal implants can often be challenging due to artifacts that obscure tumor/target delineation and normal organ definition. Our objective was to evaluate the effectiveness of Orthopedic Metal Artifact Reduction (OMAR), a commercially available software, in reducing metal‐induced artifacts and its effect on computed dose during treatment planning.Methods:CT images of water surrounding metallic cylindrical rods made of aluminum, copper and iron were studied in terms of Hounsfield Units (HU) spread. Metal‐induced artifacts were characterized in terms of HU/Volume Histogram (HVH) using the Pinnacle treatment planning system. Effects of OMAR on enhancing our ability to delineate organs on CT and subsequent dose computation were examined in nine (9) patients with hip implants and two (2) patients with breast tissue expanders.Results:Our study characterized water at 1000 HU with a standard deviation (SD) of about 20 HU. The HVHs allowed us to evaluate how the presence of metal changed the HU spread. For example, introducing a 2.54 cm diameter copper rod in water increased the SD in HU of the surrounding water from 20 to 209, representing an increase in artifacts. Subsequent use of OMAR brought the SD down to 78. Aluminum produced least artifacts whereas Iron showed largest amount of artifacts. In general, an increase in kVp and mA during CT scanning showed better effectiveness of OMAR in reducing artifacts. Our dose analysis showed that some isodose contours shifted by several mm with OMAR but infrequently and were nonsignificant in planning process. Computed volumes of various dose levels showed <2% change.Conclusions:In our experience, OMAR software greatly reduced the metal‐induced CT artifacts for the majority of patients with implants, thereby improving our ability to delineate tumor and surrounding organs. OMAR had a clinically negligible effect on computed dose within tissues.Partially funded by unrestricted educational grant from Philips
SU‐E‐I‐64: X‐Ray Coherent Scatter Mammography Simulation
Authors: Hassan L R , MacDonald C A 
Published: July 2014

Purpose:Conventional mammography has poor contrast between healthy and cancerous tissues due to the small difference in attenuation properties. Coherent scatter potentially provides more information because interference of coherently scattered radiation depends on the average intermolecular spacing, and can be used to characterize tissue types. However, typical coherent scatter analysis techniques are not compatible with rapid low dose screening modalities. Coherent scatter slot scan imaging is a novel imaging technique which provides new information with higher contrast. In this work a simulation was performed of coherent scatter slot scan imaging to assess its performance and provide system optimization.Methods:In coherent scatter imaging, the coherent scatter is exploited using a conventional slot scan mammography system with anti‐scatter grids tilted at the characteristic angle of cancerous tissues. A Monte Carlo simulation was used to simulate the coherent scatter imaging. System optimization was performed across several parameters, including source voltage and filtration, tilt angle, source and grid distances, grid ratio, and shielding geometry.Results:The contrast was high and increased as the grid tilt angle was increased beyond the characteristic angle for the modeled carcinoma, and as the source voltage increased. Source filtration did not have a significant effect on contrast. Increasing grid ratio improved contrast at the expense of decreasing the signal to noise ratio (SNR). As the tumor size is decreased, additional shields to block the fat signal are necessary in order to detect the cancer signal.Conclusion:Coherent scatter analysis using a wide slot setup is promising as an enhancement for screening mammography.This work was supported by National Institutes of Health, # 7 R01EB009715
SU‐E‐I‐66: Radiomics and Image Registration Updates for the Computational Environment for Radiotherapy Research (CERR)
Authors: Apte A , Wang Y , Deasy J 
Published: July 2014

Purpose:To present new tools in CERR for Radiomics, image registration and other software updates and additions.Methods:Radiomics: CERR supports generating 3‐D texture metrics based on gray scale co‐occurance. Two new ways to calculate texture features were added: (1) Local Texture Averaging: Local texture is calculated around a voxel within the userdefined bounding box. The final texture metrics are the average of local textures for all the voxels. This is useful to detect any local texture patterns within an image. (2) Image Smoothing: A convolution ball of user‐defined radius is rolled over an image to smooth out artifacts. The texture metrics are then computed on the smooth image. Image Registration: (1) Support was added to import deformation vector fields as well as non‐deformable transformation matrices generated by vendor software and stored in standard DICOM format. (2) Support was added to use image within masks while computing image deformations. CT to MR registration is supported. This registration uses morphological edge information within the images to guide the deformation process. In addition to these features, other noteworthy additions to CERR include (1) Irregularly shaped ROI: This is done by taking intersection between infinitely extended irregular polygons drawn on any of the two views. Such an ROI is more conformal and useful in avoiding any unwanted parts of images that cannot be avoided with the conventional cubic box. The ROI is useful to generate Radiomics metrics. (2) Ability to insert RTDOSE in DICOM format to existing CERR plans. (3) Ability to import multi‐frame PET‐CT and SPECT‐CT while maintaining spatial registration between the two modalities. (4) Ability to compile CERR on Unix‐like systems.Results:The new features and updates are available via https://www.github.com/adityaapte/cerr.Conclusion:Features added to CERR increase its utility in Radiomics, Image‐Registration and Outcomes modeling.
SU‐E‐I‐67: X‐Ray Fluorescence for Energy Response Calibration of a Photon Counting Detector: A Simulation Study
Authors: Cho H , Ding H , Ziemer B , Molloi S 
Published: July 2014

Purpose:To investigate the feasibility of energy calibration and energy response characterization of a photon counting detector using x‐ray fluorescence.Methods:A comprehensive Monte Carlo simulation study was done to investigate the influence of various geometric components on the x‐ray fluorescence measurement. Different materials, sizes, and detection angles were simulated using Geant4 Application for Tomographic Emission (GATE) Monte Carlo package. Simulations were conducted using 100 kVp tungsten‐anode spectra with 2 mm Al filter for a single pixel cadmium telluride (CdTe) detector with 3 × 3 mm2 in detection area. The fluorescence material was placed 300 mm away from both the x‐ray source and the detector. For angular dependence measurement, the distance was decreased to 30 mm to reduce the simulation time. Compound materials, containing silver, barium, gadolinium, hafnium, and gold in cylindrical shape, were simulated. The object size varied from 5 to 100 mm in diameter. The angular dependence of fluorescence and scatter were simulated from 20° to 170° with an incremental step of 10° to optimize the fluorescence to scatter ratio. Furthermore, the angular dependence was also experimentally measured using a spectrometer (X‐123CdTe, Amptek Inc., MA) to validate the simulation results.Results:The detection angle between 120° to 160° resulted in more optimal x‐ray fluorescence to scatter ratio. At a detection angle of 120°, the object size did not have a significant effect on the fluorescence to scatter ratio. The experimental results of fluorescence angular dependence are in good agreement with the simulation results. The Kα and Kβ peaks of five materials could be identified.Conclusion:The simulation results show that the x‐ray fluorescence procedure has the potential to be used for detector energy calibration and detector response characteristics by using the optimal system geometry.
SU‐E‐I‐70: Quantification of Noise Reduction Dependency On Spatial Granularity With Adaptive Statistical Iterative Reconstruction
Authors: Zhou Y , Scott A 
Published: July 2014

Purpose:Adaptive statistical iterative reconstruction (ASIR) is often used for noise reduction. However, it may not be clear whether the noise reduction is uniform across different spatial scales. As this is important for lesion detection, we attempted to quantify the noise reduction dependency on spatial scales under different ASIR blending fractions.Methods:An abdomen phantom (CIRS TE‐07) simulating the medium sized patient was used. The phantom contains a cylindrical void of 4 cm diameter, filled with an insert containing six groups of cylindrical targets (1% and 2% contrast) of 1.2 mm to 7 mm. Helical scans were conducted using a GE 750HD with 120 kVp, 330 mAs and pitch of 1.375 (CTDI_vol = 18 mGy). The images were reconstructed to 5 mm thickness with filtered‐back projection (FBP) and with ASIR at blending fractions of 10% to 100%. The uniform sections of the contiguous slices were subtracted and the resulted regions were divided into matrices of cells matching the target size from 1.2 mm–7.0 mm. Standard deviations (sd) from the means of all cells were computed as a measure of noise at the target size. The noise reduction factor (NRF) was defined as the ratio of the sd from ASIR to the sd of FBP. The NRF was fitted to ASIR blending percentages (ASIRP) at different target sizes (d).Results:The NRF versus ASIRP was fitted to a linear relationship with an intercept of approximately 1.0 and a slope dependent on d (R square = 0.99). The slope versus d was fitted to a power relationship with a power index of – 0.80 and a proportion factor of −0.005 (R square = 0.978).Conclusion:The noise reduction with ASIR increases nonlinearly as the spatial scale (or target size) decreases. The result can be of help for ASIR use in target‐specific diagnoses.
SU‐E‐I‐72: First Experimental Study of On‐Board CBCT Imaging Using 2.5MV Beam On a Radiotherapy Linac
Authors: Xu Q , Li R , Yang Y , Xing L 
Published: July 2014

Purpose:Varian TrueBeam version 2.0 comes with a new inline 2.5MV beam modality for image guided patient setup. In this work we develop an iterative volumetric image reconstruction technique specific to the beam and investigate the possibility of obtaining metal artifact free CBCT images using the new imaging modality.Methods:An iterative reconstruction algorithm with a sparse representation constraint based on dictionary learning is developed, in which both sparse projection and low dose rate (10 MU/min) are considered. Two CBCT experiments were conducted using the newly available 2.5MV beam on a Varian TrueBeam linac. First, a Rando anthropomorphic head phantom with and without a copper bar inserted in the center was scanned using both 2.5MV and kV (100kVp) beams. In a second experiment, an MRI phantom with many coils was scanned using 2.5MV, 6MV, and kV (100kVp) beams. Imaging dose and the resultant image quality is studied.Results:Qualitative assessment suggests that there were no visually detectable metal artifacts in MV CBCT images, compared with significant metal artifacts in kV CBCT images, especially in the MRI phantom. For a region near the metal object in the head phantom, the 2.5MV CBCT gave a more accurate quantification of the electron density compared with kV CBCT, with a ∼50% reduction in mean HU error. As expected, the contrast between bone and soft‐tissue in 2.5MV CBCT decreased compared with kV CBCT.Conclusion:On‐board CBCT imaging with the new 2.5MV beam can effectively reduce metal artifacts, although with a reduced softtissue contrast. Combination of kV and MV scanning may lead to metal artifact free CBCT images with uncompromised soft‐tissue contrast.
SU‐E‐I‐73: Clinical Evaluation of CT Image Reconstructed Using Interior Tomography
Authors: Zhang J , Ge G , Winkler M , Cong W , Wang G 
Published: July 2014

Purpose:Radiation dose reduction has been a long standing challenge in CT imaging of obese patients. Recent advances in interior tomography (reconstruction of an interior region of interest (ROI) from line integrals associated with only paths through the ROI) promise to achieve significant radiation dose reduction without compromising image quality. This study is to investigate the application of this technique in CT imaging through evaluating imaging quality reconstructed from patient data.Methods:Projection data were directly obtained from patients who had CT examinations in a Dual Source CT scanner (DSCT). Two detectors in a DSCT acquired projection data simultaneously. One detector provided projection data for full field of view (FOV, 50 cm) while another detectors provided truncated projection data for a FOV of 26 cm. Full FOV CT images were reconstructed using both filtered back projection and iterative algorithm; while interior tomography algorithm was implemented to reconstruct ROI images. For comparison reason, FBP was also used to reconstruct ROI images. Reconstructed CT images were evaluated by radiologists and compared with images from CT scanner.Results:The results show that the reconstructed ROI image was in excellent agreement with the truth inside the ROI, obtained from images from CT scanner, and the detailed features in the ROI were quantitatively accurate. Radiologists evaluation shows that CT images reconstructed with interior tomography met diagnosis requirements. Radiation dose may be reduced up to 50% using interior tomography, depending on patient size.Conclusion:This study shows that interior tomography can be readily employed in CT imaging for radiation dose reduction. It may be especially useful in imaging obese patients, whose subcutaneous tissue is less clinically relevant but may significantly increase radiation dose.