bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐D‐12A‐01: An Inter‐Projection Interpolation (IPI) Approach for the Synchronized Moving Grid (SMOG) to Reduce Dose in Cone Beam CT
Authors: Zhang H , Kong V , Ren L , Jin J 
Published: July 2014

Purpose:Synchronized moving grid is a promising technique to reduce scatter and ghost artifacts in cone beam computed tomography (CBCT). However, it requires 2 projections in the same gantry angle to obtain full information due to signal blockage by the grid. We proposed an inter‐projection interpolation (IPI) method to estimate blocked signals, which may reduce the scan time and the dose. This study aims to provide a framework to achieve a balance between speed, dose and image quality.Methods:The IPI method is based on the hypothesis that an abrupt signal in a projection can be well predicted by the information in the two immediate neighboring projections if the gantry angle step is small. The study was performed on a Catphan and a head phantom. The SMOG was simulated by erasing the information (filling with “0”) of the areas in each projection corresponding to the grid. An IPI algorithm was applied on each projection to recover the erased information. FDK algorithm was used to reconstruct CBCT images for the IPI‐processed projections, and compared with the original image in term of signal to noise ratio (SNR) measured in the whole reconstruction image range. The effect of gantry angle step was investigated by comparing the CBCT images from projection sets of various gantry intervals, with IPI‐predicted projections to fill the missing projection in the interval.Results:The IPI procession time was 1.79s±0.53s for each projection. SNR after IPI was 29.0db and 28.1db for the Catphan and head phantom, respectively, comparing to 15.3db and 22.7db for an inpainting based interpolation technique. SNR was 28.3, 28.3, 21.8, 19.3 and 17.3 db for gantry angle intervals of 1, 1.5, 2, 2.5 and 3 degrees, respectively.Conclusion:IPI is feasible to estimate the missing information, and achieve an reasonable CBCT image quality with reduced dose and scan time.This study is supported by NIH/NCI grant 1R01CA166948‐01
SU‐D‐12A‐04: Investigation of a 2D Antiscatter Grid for Flat Panel Detectors
Authors: Altunbas C , Zhong Y , Shaw C , Kavanagh B , Miften M 
Published: July 2014

Purpose:To improve CT number accuracy and contrast sensitivity, a novel 2D antiscatter grid (ASG) for flat panel detector (FPD) based CBCT imaging was evaluated. Experiments were performed to characterize the scatter rejection and contrast sensitivity performance of ASG. The reduction in primary transmission for various ASG geometries was also evaluated by a computational model.Methods:The 2D ASG design was based on multi‐hole collimators used in Nuclear Medicine. It consisted of abutted hexagon shaped apertures with 2.5 mm pitch and 32 mm height, and separated by 0.25 mm thick lead septa. Scatter‐to‐primary ratio (SPR), contrast‐to‐noise ratio (CNR), and mean primary transmission were measured using a benchtop FPD/x‐ray source system. Acrylic slabs of varying thicknesses were imaged with a contrast‐detail phantom to measure CNR and SPR under different scatter conditions. Primary transmission was also measured by averaging pixel values in flood field images without the phantom. We additionally explored variation of primary transmission with pitch and septum thickness using a computational model of our ASG.Results:Our 2D ASG reduced the SPR from 3.3 to 0.12, and improved CNR by 50% in 20 cm thick slab phantom projections acquired at 120 kVp. While the measured primary transmission was 72.8%, our simulations show that primary transmission can be increased to 86% by reducing the septum thickness to 0.1 mm. Primary transmission further increases to 93% if septum thickness of 0.1 mm is used in conjunction with an increased pitch of 4 mm.Conclusion:The 2D ASG appears to be a promising scatter rejection device, offering both superior scatter rejection and improved contrast sensitivity. Though its lead footprint reduced primary transmission, our work shows that optimization of aperture pitch and septum thickness can significantly improve the primary transmission.
SU‐D‐12A‐06: A Comprehensive Parameter Analysis for Low Dose Cone‐Beam CT Reconstruction
Authors: Lu W , Yan H , Bai T , Zhou L , Gu X , Jiang S , Jia X 
Published: July 2014

Purpose:There is always a parameter in compressive sensing based iterative reconstruction (IR) methods low dose cone‐beam CT (CBCT), which controls the weight of regularization relative to data fidelity. A clear understanding of the relationship between image quality and parameter values is important. The purpose of this study is to investigate this subject based on experimental data and a representative advanced IR algorithm using Tight‐frame (TF) regularization.Methods:Three data sets of a Catphan phantom acquired at low, regular and high dose levels are used. For each tests, 90 projections covering a 200‐degree scan range are used for reconstruction. Three different regions‐of‐interest (ROIs) of different contrasts are used to calculate contrast‐to‐noise ratios (CNR) for contrast evaluation. A single point structure is used to measure modulation transfer function (MTF) for spatial‐resolution evaluation. Finally, we analyze CNRs and MTFs to study the relationship between image quality and parameter selections.Results:It was found that: 1) there is no universal optimal parameter. The optimal parameter value depends on specific task and dose level. 2) There is a clear trade‐off between CNR and resolution. The parameter for the best CNR is always smaller than that for the best resolution. 3) Optimal parameters are also dose‐specific. Data acquired under a high dose protocol require less regularization, yielding smaller optimal parameter values. 4) Comparing with conventional FDK images, TF‐based CBCT images are better under a certain optimally selected parameters. The advantages are more obvious for low dose data.Conclusion:We have investigated the relationship between image quality and parameter values in the TF‐based IR algorithm. Preliminary results indicate optimal parameters are specific to both the task types and dose levels, providing guidance for selecting parameters in advanced IR algorithms.This work is supported in part by NIH (1R01CA154747‐01)
SU‐E‐E‐03: Developing Solutions to Critical Radiation Oncology Challenges in Tanzania
Authors: Kenton O , Dachi J , Metz J , Avery S 
Published: July 2014

Purpose:Develop solutions to critical medical physics challenges in Tanzania.Methods:In September of 2013 we began working with Jumaa Bin Dachi, a Therapy Physicist at the Ocean Road Cancer Institute in Dar es Salaam, Tanzania. We developed a bi‐lateral learning partnership over the course of eight qualitative Skype meetings with Jumaa. From these meetings we have ascertained that there is a gap between the installation of new equipment and treating patients. This gap has often been overlooked by international partners attempting to improve radiation therapy access. Relationships with academic institutions abroad can fill these gaps, and lead to sustained care of patients needing radiation.Results:Our efforts are best given in a supporting role to help develop solutions and new technology that can reduce the burden on the Medical Physicist. Solutions may include: training material, support for radiation therapy classes, development of appropriate local protocols, and peer‐review on documents being produced. New technology needs to focus around simple and easy field shaping, improved patient imaging systems, and systems for patient set‐up. We believe our work can help alleviate some of the burdens faced by this institute.Conclusion:While we are just in the beginning stage of this partnership, we believe there is great potential for success between both parties. We hope that the Ocean Road Cancer Institute will benefit from potential funding and resources by partnering with a High Income Country to develop affordable solutions to clinical problems in Tanzania.
SU‐E‐E‐06: Teaching Medical Physics in a Radiology Museum
Authors: Bednarek D , Rudin S 
Published: July 2014

Purpose:To enhance the learning process in the teaching of medical physics by providing a venue to experience the historical equipment and devices of radiology.Methods:We have created a museum by assembling a large collection of equipment and artifacts related to radiology and medical physics. As part of a learning‐in‐context educational approach, classes for a survey course in medical physics are held in the museum so that students are able to visually and tangibly experience the implements of radiology, while related topics are discussed. The students learn how x‐ray equipment and techniques evolved throughout the years and they learn to appreciate the differences and similarities between current x‐ray technology and that of the early days. The collection contains items dating from the era of the discovery of x‐rays up to recent times and includes gas x‐ray tubes, hand‐held fluoroscopes, generators, spark‐gap kV meters, stereoscopes, glass‐plate radiographs, a photofluorographic unit, wood‐interspaced grid, flat‐panel detector, linear‐accelerator klystron, and brachytherapy radium applicators, as well as an extensive library containing some of the seminal literature of the field so that students can delve deeper into the technology. In addition to the classes, guided tours are provided for radiologic‐technology, bioengineering, physics and medical students, as well as group and individual tours for the general public.Results:Student course assessments have consistently included positive expressions of their experience in the museum. Numerous students have volunteered to assist with display preparation and have learned by researching the content. Many individuals have been attracted on a walk‐in basis and have expressed a deep curiosity in the technology, with positive feedback.Conclusion:The museum and its artifacts have been invaluable in stimulating interest in the history and technology of medical physics. Students and visitors alike obtain a deeper appreciation of the contribution physics has made to medicine.
SU‐E‐E‐07: When the Old Ways Are the Best Ways: In Defense of Didactic Training
Authors: Sensakovic W 
Published: July 2014

Purpose:Physics education for residents has taken on a more prominent role due to the new ABR examination format. We present a curriculum for a new radiology residency entering its second year. This curriculum favors an extensive traditional didactic teaching approach. The curriculum is designed to minimize the amount of independent learning that is necessary outside the classroomMethods and Materials:idactic training repeats yearly for all four years of residency and consists of two 1‐hour lectures per week and several in‐class tests. The impact of physics on clinical practice is introduced gradually throughout the residency using specific clinical cases. The extensive time spent with the residents allows lectures to be taught at a deep (almost physicist) level and reduces the necessity of learning base concepts outside of lecture. This frees the resident to use resources (e.g., AAPM/RSNA physics modules) to cement concepts through repetition or to learn a slightly confusing concept from a different teaching perspective. Consistent testing reduces the traditional resident studying technique of physics “cramming.”Results:On average, the first year residents scored in the 98th percentile on the American College of Radiology Diagnostic Radiology In‐Service Training Exam (ACR DXIT). Feedback from the new first year residents was very positive and suggestions are constantly solicited and incorporated. For example, based on resident feedback, short‐format quizzes each lecture were eliminated and replaced interactive questions during lecture. Residents felt they have advanced rapidly and have a better understanding of radiologic physics, though they have expressed concern that the 1‐hour lecture block may not be optimal for learning physics.Conclusion:An extensive, physicist‐led series of didactic lectures is effective in the teaching of physics to residents.
SU‐E‐P‐09: Radiation Transmission Measurements and Evaluation of Diagnostic Lead‐Based and Lead‐Free Aprons
Authors: Syh J 
Published: July 2014

Purpose:This study was conducted to ensure that various lead shield apron manufacturers provided accurate attenuation factors regardless of whether the apron was made of lead‐based or lead‐free equivalent material.Methods:A calibrated ionization survey meter was placed at chest height and 36 cm horizontally away from a solid water phantom on a simulator couch. Measurements were done with or without apron. Radiation field was set to 24cmx24cm with the phantom at 100cm source‐to‐surface distance. Irradiation time was set for 1 minute at voltages of 60, 80, 100 and 120 kVp. Current was set at 6mA.Results:Between 60 kVp and 120 kVp, the transmission through 0.50 mm of lead‐based apron was between 1.0% and 6.5% with a mean value of 3.2% and a standard deviation (s.d.) of 1.4%. The transmissions through the 0.50 mm lead‐free aprons were 1.0 % to 12.0% with a mean value of 6.1% and s.d. of 2.6%. At 120 kVp, the transmission value was 6.5% for 0.50 mm lead‐based apron and 11.1% to 12.0% for 0.50 mm lead‐free aprons. The radiation transmissions at 80 kVp, measured in two different 0.5 mm lead‐free aprons, were 4.3% each. However, only 1.4% transmission was found through the lead‐based apron. Overall, the radiation transmitted through the lead‐based apron was 1/3 transmission of lead‐free at 80kVp, and half value of lead‐free aprons at 100 and 120 kVp.Conclusion:Even though lead‐based and lead‐free aprons all claimed to have the same lead equivalent thickness, the transmission might not be the same. The precaution was needed to exercise diligence in quality assurance program to assure adequate protection to staff who wear it during diagnostic procedures. The requirement for aprons not only should be in certain thickness to meet state regulation but also to keep reasonably achievable low exposure with the accurate labeling from manufacturers.
SU‐E‐I‐03: A Kinect‐Based Method of Bone and Soft Tissue Image Separation Using Object Thickness Measurement
Authors: Fukuyoshi R , Kurata T , Sato S , Kozono K , Ono M , Toyofuku F 
Published: July 2014

Purpose:Currently, dual energy subtraction is used for the separation of the soft tissue and bone. There are two methods of calculation: the filter method and the double tube voltage method. However, there are problems with these methods, such as an increase of exposure (double tube voltage method), and image quality degradation due to attenuation of x‐rays (filter method). In the present study, we have developed a new method of separating bone and soft tissue by using a single x‐ray exposure combined with object thickness measurement using the Microsoft Kinect sensor.Methods:We used a hand phantom as an object and measured the thickness of the object from a depth image obtained with the Microsoft Kinect. X‐ray images were taken at different tube voltages (40 kV, 60 kV, 80 kV), and thicknesses of the two components were calculated from x‐ray attenuation equation. A software program for an ImageJ Plugin was developed to obtain separated images, and the separated bone image was compared with the original image by visual evaluation and profile data. The thicknesses of the separated phalanx bones were also compared with those measured from CT images.Results:It was possible to obtain separated bone and soft tissue images using a single x‐ray exposure. The gray values of the bone were greatly enhanced while those of soft tissue were diminished. A comparison with the CT images showed that the bone thickness error was less than 20.0% in phalanx bones.Conclusion:It was shown that the image separation of bone and soft tissue was made possible by using a single x‐ray exposure combined with object thickness measurement. This method will be useful for the accurate evaluation of bone changes after a fracture without using any additional x‐ray exposure.
SU‐E‐I‐05: A Novel Application of SIFT Technique to Microcalcification Detection
Authors: Wang Y , Lin S , Lu C , Lue K , Lai L , Chuang K 
Published: July 2014

Purpose:This work applies Lowe's Scale Invariant Feature Transform (SIFT) to detect micro‐calcification on mammograms. The objective of this study is to expand the function of SIFT, which has originally been used to match objects by matching the detected feature points, and to provide a new method for micro‐calcification detection.Methods:First, variables in SIFT, the scaling factor between levels of the image, the radiuses of the areas for maximum comparison within current scale and neighboring scales, and the threshold value for maximum search, were adjusted to allow nearly all the micro‐calcification to be detected as the feature points. Second, to reject feature points which are not micro‐calcification, four features of sixty‐five feature points, determined by physicians as micro‐calcification, curvature of scale space, elements of Hessian matrix, used for the discrimination of prominence and shapes, and Contrast to neighboring pixels, Size on image used to reject points on blob‐like dense tissue, were analyzed to determine the specific ranges for selecting feature points on micro‐calcification.Results:Ninety region of interest (ROI) images (268 × 268 pixel) selected from 85 mammograms (3,540 × 4,740 pixel) were employed to test the proposed method. Of the 90 ROI images, 30 images were biopsy‐verified by a physician to present a cluster of micro‐calcification. The other 60 ROI images are selected from normal mammograms. The performance of the study is evaluated by a receiver operating characteristic curve (ROC). An area under the ROC curve of 94.2%, sensitivity of 93.3%, and specificity of 95% was achieved.Conclusion:The proposed system based on SIFT accurately detects micro‐calcification in mammograms with various brightness, size, and breast density, without preprocessing them. Our findings merit further investigation for its potential to classify benign and malignant calcification.
SU‐E‐I‐15: Comparison of Radiation Dose for Radiography and EOS in Adolescent Scoliosis Patients
Authors: Schueler B , Walz‐Flannigan A 
Published: July 2014

Purpose:To estimate patient radiation dose for whole spine imaging using EOS, a new biplanar slot‐scanning radiographic system and compare with standard scoliosis radiography.Methods:The EOS imaging system (EOS Imaging, Paris, France) consists of two orthogonal x‐ray fan beams which simultaneously acquire frontal and lateral projection images of a standing patient. The patient entrance skin air kerma was measured for each projection image using manufacturer‐recommended exposure parameters for spine imaging. Organ and effective doses were estimated using a commercially‐available Monte Carlo simulation program (PCXMC, STUK, Radiation and Nuclear Safety Authority, Helsinki, Finland) for a 15 year old mathematical phantom model. These results were compared to organ and effective dose estimated for scoliosis radiography using computed radiography (CR) with standard exposure parameters obtained from a survey of pediatric radiographic projections.Results:The entrance skin air kerma for EOS was found to be 0.18 mGy and 0.33 mGy for posterior‐anterior (PA) and lateral projections, respectively. This compares to 0.76 mGy and 1.4 mGy for CR, PA and lateral projections. Effective dose for EOS (PA and lateral projections combined) is 0.19 mSv compared to 0.51 mSv for CR.Conclusion:The EOS slot‐scanning radiographic system allows for reduced patient radiation dose in scoliosis patients as compared to standard CR radiography.
SU‐E‐I‐16: Comparison of the Blue Part of the Spectral Power Distribution in a Medical Liquid‐Crystal Display for Different Color Temperature Settings
Authors: Akamine H , Kuramoto T , Kato T , Awamoto S , Nakamura Y , Hashimoto N , Morishita J 
Published: July 2014

Purpose:The effects of blue light exposure on visual fatigue have received much attention in recent years. There have been attempts to reduce the blue part of the spectral power distribution in a display's output by using commercial films and glasses. However, reducing the blue part of the spectral power distribution in medical liquid‐crystal displays (LCDs) by changing the color temperature settings may prove to be a simpler solution. Our study aimed to quantitatively compare the blue part of the spectral power distribution of a medical LCD in different color temperature settings.Materials and Methods:We used two color LCDs (RadiForce RX340, 400 cd/m2, EIZO). The spectral power distribution, chromaticity, and correlated color temperature were measured for LCDs with different color temperature settings (6500, 7500, and 8500 K). The default color temperature setting of the medical LCDs used in this study was 7500 K. A spectroradiometer (CS‐2000, KONICA MINOLTA) and original gray‐scale test patterns with 18 different luminance levels were used for the measurements.Results:The blue parts of the spectral power distribution (380–495 nm) were different for each color temperature setting. The integrated power values over the blue of the spectral power distribution decreased by 9% from 8500 to 7500 K and 13% and from 7500 to 6500 K. The correlated color temperature changed by approximately 1000 K depending on the color temperature setting. The difference in the chromaticity was 0.011 between 8500 and 7500 K and between 7500 and 6500 K.Conclusion:Our results quantitatively indicate that the blue part of the spectral power distribution of the medical LCDs tested varies for different settings of color temperature.
SU‐E‐I‐26: Development and Characterization of a Temporally Stable Tissue‐ Mimicking Photoacoustic‐Ultrasonic Phantom
Authors: Mitcham T , Lynch J , Cook J , Emelianov S , Bouchard R 
Published: July 2014

Purpose:To quantify the tissue‐mimicking properties and temporal stability of a novel tissue‐mimicking photoacoustic‐ultrasonic (PAUS) imaging phantom.Methods:Nine phantoms containing titanium wire targets were formulated from a Zerdine base with varying degrees of Intralipid and India ink dye to generate distinct scattering and absorption characteristics. India ink was included in three concentrations (0.01%, 0.005%, or 0.0025% by mass), while Intralipid comprised 12.5%, 25%, or 37.5% of the sample by mass. These scattering/absorption agents were combined in a 3×3 matrix to generate unique properties for each phantom. Speed‐of‐sound (SOS), acoustic absorption and optical scattering/absorption measurements were obtained for each formulation to characterize tissuemimicking properties. PAUS imaging was performed on each phantom at four time points, in approximately 2‐month intervals, to assess temporal stability. Images were analyzed to provide data regarding target signal strength, target contrast, signal‐to‐noise ratio (SNR) and contrast‐to‐noise ratio (CNR). All PAUS imaging was performed on a Vevo 2100‐LAZR system (FUJIFILM VisualSonics Inc., Toronto, Canada) at 808 nm using a 20‐MHz US transducer.Results:Each phantom formulation provided unique acoustic absorption and optical scattering/absorption; the range of tested formulations provided scattering/absorption/SOS characteristics that accurately mimic tissue. Examination of the longitudinal PAUS data demonstrates that none of the phantoms experienced significant temporal change over the 6‐month testing period. Target signal, contrast, SNR, and CNR changed less than 10% from the initial baseline for an individual phantom through 2, 4, and 6‐month follow‐up imaging sessions.Conclusion:This work indicates that the investigated phantom formulations accurately approximate tissue for photoacoustic‐ultrasonic imaging purposes. Additionally, adequate temporal stability is demonstrated over a six‐month period, allowing for construction of a long‐term tissuemimicking PAUS imaging phantom that could be utilized for preclinical technical development or clinical quality assurance purposes in the future. John Lynch is an employee of CIRS, Inc.