bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐G‐IeP4‐09: Method of Human Eye Aberration Measurement Using Plenoptic Camera Over Large Field of View
Authors: Lv Yang , Wang Ruixing , Ma Haotong , Zhang Xuanzhe , Ning Yu , Xu Xiaojun 
Published: July 2016

Purpose:The measurement based on Shack‐Hartmann wave‐front sensor(WFS), obtaining both the high and low order wave‐front aberrations simultaneously and accurately, has been applied in the detection of human eyes aberration in recent years. However, Its application is limited by the small field of view (FOV), slight eye movement leads the optical bacon image exceeds the lenslet array which result in uncertain detection error. To overcome difficulties of precise eye location, the capacity of detecting eye wave‐front aberration over FOV much larger than simply a single conjugate Hartmann WFS accurately and simultaneously is demanded.Methods:Plenoptic camera's lenslet array subdivides the aperture light‐field in spatial frequency domain, capture the 4‐D light‐field information. Data recorded by plenoptic cameras can be used to extract the wave‐front phases associated to the eyes aberration. The corresponding theoretical model and simulation system is built up in this article to discuss wave‐front measurement performance when utilizing plenoptic camera as wave‐front sensor.Results:The simulation results indicate that the plenoptic wave‐front method can obtain both the high and low order eyes wave‐front aberration with the same accuracy as conventional system in single visual angle detectionand over FOV much larger than simply a single conjugate Hartmann systems. Meanwhile, simulation results show that detection of eye aberrations wave‐front in different visual angle can be achieved effectively and simultaneously by plenoptic method, by both point and extended optical beacon from the eye.Conclusion:Plenoptic wave‐front method possesses the feasibility in eye aberrations wave‐front detection. With larger FOV, the method can effectively reduce the detection error brought by imprecise eye location and simplify the eye aberrations wave‐front detection system comparing with which based on Shack‐Hartmann WFS. Unique advantage of the plenoptic method lies in obtaining wave‐front in different visual angle simultaneously, which provides an approach in building up 3‐D model of eye refractor tomographically.Funded by the key Laboratory of High Power Laser and Physics, CAS Research Project of National University of Defense Technology No. JC13‐07‐01; National Natural Science Foundation of China No. 61205144
SU‐G‐IeP4‐10: Microimaging for Different Degrees of Human Cavernous Hemangioma of Liver by Using In‐Line Phase‐Contrast Imaging CT
Authors: Duan J 
Published: July 2016

Purpose:Cavernous hemangioma of the liver (CHL) is the most common benign solid tumor of the liver. In this study, we quantitative assessment the different degrees of CHL from microscopic viewpoint by using in‐line phase‐contrast imaging CT (ILPCI‐CT).Methods:The experiments were performed at x‐ray imaging and biomedical application beamline (BL13W1) of Shanghai Synchrotron Radiation Facility (SSRF) in China. Three typical specimens at different stages, i.e., mild, moderate and severe human CHL were imaged using ILPCI‐CT at 16keV without contrast agents. The 3D visualization of different degrees of CHL samples were presented using ILPCI‐CT. Additionally, quantitative evaluation of the CHL features, such as the range of hepatic sinusoid equivalent diameters in different degrees of CHL samples, the ratio of the hepatic sinusoid to the CHL tissue, were measured.Results:The planar image clearly displayed the dilated hepatic sinusoids in microns. There was no normal hepatic vascular found in the all CHL samples. Different stages of CHL samples were presented with vivid shapes and stereoscopic effects by using 3D visualization. The equivalent diameters of hepatic sinusoids in three degrees CHL were different. The equivalent diameters of the hepatic sinusoids in mild CHL, range from 60 to 120 µm. The equivalent diameters of the hepatic sinusoids in moderate CHL, range from 65 to 190 µm. The equivalent diameters of the hepatic sinusoids in severe CHL, range from 95 to 215 µm. The ratio of the hepatic sinusoid to the mild, moderate and severe CHL tissue were 3%, 16% and 21%, respectively.Conclusion:The results show that the high degree of sensitivity of the ILPCI‐CT technique and demonstrate the feasibility of accurate visualization of different stage human CHL. ILPCI‐CT may offers a potential use in non‐invasive study and analysis of CHL.
SU‐G‐IeP4‐13: PET Image Noise Variability and Its Consequences for Quantifying Tumor Hypoxia
Authors: Kueng R , Manser P , Fix M K , Driscoll B , Stampanoni M F M , Keller H 
Published: July 2016

Purpose:The values in a PET image which represent activity concentrations of a radioactive tracer are influenced by a large number of parameters including patient conditions as well as image acquisition and reconstruction. This work investigates noise characteristics in PET images for various image acquisition and image reconstruction parameters.Methods:Different phantoms with homogeneous activity distributions were scanned using several acquisition parameters and reconstructed with numerous sets of reconstruction parameters. Images from six PET scanners from different vendors were analyzed and compared with respect to quantitative noise characteristics. Local noise metrics, which give rise to a threshold value defining the metric of hypoxic fraction, as well as global noise measures in terms of noise power spectra (NPS) were computed. In addition to variability due to different reconstruction parameters, spatial variability of activity distribution and its noise metrics were investigated. Patient data from clinical trials were mapped onto phantom scans to explore the impact of the scanner's intrinsic noise variability on quantitative clinical analysis.Results:Local noise metrics showed substantial variability up to an order of magnitude for different reconstruction parameters. Investigations of corresponding NPS revealed reconstruction dependent structural noise characteristics. For the acquisition parameters, noise metrics were guided by Poisson statistics. Large spatial non‐uniformity of the noise was observed in both axial and radial direction of a PET image. In addition, activity concentrations in PET images of homogeneous phantom scans showed intriguing spatial fluctuations for most scanners. The clinical metric of the hypoxic fraction was shown to be considerably influenced by the PET scanner's spatial noise characteristics.Conclusion:We showed that a hypoxic fraction metric based on noise characteristics requires careful consideration of the various dependencies in order to justify its quantitative validity. This work may result in recommendations for harmonizing QA of PET imaging for multi‐institutional clinical trials.
SU‐G‐JeP4‐03: Anomaly Detection of Respiratory Motion by Use of Singular Spectrum Analysis
Authors: Kotoku J , Kumagai S , Nakabayashi S , Haga A , Kobayashi T 
Published: July 2016

Purpose:The implementation and realization of automatic anomaly detection of respiratory motion is a very important technique to prevent accidental damage during radiation therapy. Here, we propose an automatic anomaly detection method using singular value decomposition analysis.Methods:The anomaly detection procedure consists of four parts:1) measurement of normal respiratory motion data of a patient2) calculation of a trajectory matrix representing normal time‐series feature3) real‐time monitoring and calculation of a trajectory matrix of real‐time data.4) calculation of an anomaly score from the similarity of the two feature matrices. Patient motion was observed by a marker‐less tracking system using a depth camera.Results:Two types of motion e.g. cough and sudden stop of breathing were successfully detected in our real‐time application.Conclusion:Automatic anomaly detection of respiratory motion using singular spectrum analysis was successful in the cough and sudden stop of breathing. The clinical use of this algorithm will be very hopeful.This work was supported by JSPS KAKENHI Grant Number 15K08703.
SU‐G‐JeP4‐05: Effects of Irregular Respiratory Motion On the Positioning Accuracy of Moving Target with Free Breathing Cone‐Beam Computerized Tomography
Authors: Li X , Yang G , Ma R , Yorke E , Mageras G , Tang X , Xiong W , Chan M , Reyngold M , Gewanter R , Wu A , Deasy J , Hunt M 
Published: July 2016

Purpose:Average or maximum intensity projection (AIP or MIP) images derived from 4DCT images are often used as a reference image for target alignment when free breathing Cone‐beam CT (FBCBCT) is used for positioning a moving target at treatment. This method can be highly accurate if the patient has stable respiratory motion. However, a patient's breathing pattern often varies irregularly. The purpose of this study is to investigate the effect of irregular respiration on the positioning accuracy of a moving target with FBCBCT.Methods:Eight patients’ respiratory motion curves were selected to drive a Quasar phantom with embedded cubic and spherical targets. A 4DCT of the moving phantom was acquired on a CT scanner (Philips Brilliance 16) equipped with a Varian RPM system. The phase binned 4DCT images and the corresponding MIP and AIP images were transferred into Eclipse for analysis. CBCTs of the phantom driven by the same breathing curves were acquired on a Varian TrueBeam and fused such that the zero positions of moving targets are the same on both CBCT and AIP images. The sphere and cube volumes and centrioid differences (alignment error) determined by MIP, AIP and FBCBCT images were compared.Results:Compared to the volume determined by FBCBCT, the volumes of cube and sphere in MIP images were 22.4%±8.8% and 34.2%±6.2% larger while the volumes in AIP images were 7.1%±6.2% and 2.7%±15.3% larger, respectively. The alignment errors for the cube and sphere with center‐center matches between MIP and FBCBCT were 3.5±3.1mm and 3.2±2.3mm, and the alignment errors between AIP and FBCBCT were 2.1±2.6mm and 2.1±1.7mm, respectively.Conclusion:AIP images appear to be superior reference images than MIP images. However, irregular respiratory motions could compromise the positioning accuracy of a moving target if the target center‐center match is used to align FBCBCT and AIP images.
MO‐A‐BRC‐02: TG167 Report ‐ Detailed Description
Authors: Rivard M. 
Published: July 2016

Although a multicenter, Phase III, prospective, randomized trial is the gold standard for evidence‐based medicine, it is rarely used to evaluate innovative radiotherapy devices because of many practical and ethical reasons. It is usually sufficient to compare the dose distributions and dose rates for determining equivalence of the innovative device to an existing one. Thus, quantitative evaluation of the dosimetric characteristics of an innovative brachytherapy device or application is a critical part in which physicists are actively involved. The physicist's role, along with physician colleagues, in this process is highlighted for innovative products or applications and includes evaluation of 1) dosimetric considerations for clinical implementation (including calibrations, dose calculations, and radiobiological aspects) to comply with existing societal dosimetric prerequisites for sources in routine clinical use, 2) risks and benefits from regulatory and safety perspectives, and 3) resource assessment and preparedness. Further, calibration methods should be traceable to a primary standards dosimetry laboratory such as NIST in the U.S. or to other primary standards dosimetry laboratory located elsewhere. Clinical users should follow standards as approved by their country's regulatory agencies that approved such a brachytherapy device. Integration of this system into the medical source calibration infrastructure of secondary standard dosimetry laboratories such as the ADCLs is encouraged before a source is introduced into widespread routine clinical use. The AAPM and GEC‐ESTRO have developed guidelines for the safe and consistent application of brachytherapy using innovative brachytherapy devices and applications. The current report covers regulatory approvals, calibration, dose calculations, radiobiological issues, and overall safety concerns that should be addressed during the commissioning stage preceding clinical use. These guidelines are based on review of requirements of the U.S. NRC, FDA, Department of Transportation, International Electrotechnical Commission Medical Electrical Equipment Standard 60601, European Commission for CE Marking, and institutional review boards and radiation safety committees.

Learning Objectives:
Understand the necessary dosimetric considerations for clinical implementation (including calibrations, dose calculations, and radiobiological aspects) to comply with existing societal dosimetric prerequisites for sources in routine clinical use.
Evaluate risks and benefits from regulatory and safety perspectives.
Identify necessary resources and create a plan for clinical introduction of innovative brachytherapy device or applications.Consultant for Theragenics Corp.; R. Nath, Consultant to Theragenics Corp.
MO‐AB‐BRA‐01: A Global Level Set Based Formulation for Volumetric Modulated Arc Therapy
Authors: Nguyen D , Lyu Q , Ruan D , O'Connor D , Low D , Sheng K 
Published: July 2016

Purpose:The current clinical Volumetric Modulated Arc Therapy (VMAT) optimization is formulated as a non‐convex problem and various greedy heuristics have been employed for an empirical solution, jeopardizing plan consistency and quality. We introduce a novel global direct aperture optimization method for VMAT to overcome these limitations.Methods:The global VMAT (gVMAT) planning was formulated as an optimization problem with an L2‐norm fidelity term and an anisotropic total variation term. A level set function was used to describe the aperture shapes and adjacent aperture shapes were penalized to control MLC motion range. An alternating optimization strategy was implemented to solve the fluence intensity and aperture shapes simultaneously. Single arc gVMAT plans, utilizing 180 beams with 2° angular resolution, were generated for a glioblastoma multiforme (GBM), lung (LNG), and 2 head and neck cases—one with 3 PTVs (H&N3PTV) and one with 4 PTVs (H&N4PTV). The plans were compared against the clinical VMAT (cVMAT) plans utilizing two overlapping coplanar arcs.Results:The optimization of the gVMAT plans had converged within 600 iterations. gVMAT reduced the average max and mean OAR dose by 6.59% and 7.45% of the prescription dose. Reductions in max dose and mean dose were as high as 14.5 Gy in the LNG case and 15.3 Gy in the H&N3PTV case. PTV coverages (D95, D98, D99) were within 0.25% of the prescription dose. By globally considering all beams, the gVMAT optimizer allowed some beams to deliver higher intensities, yielding a dose distribution that resembles a static beam IMRT plan with beam orientation optimization.Conclusions:The novel VMAT approach allows for the search of an optimal plan in the global solution space and generates deliverable apertures directly. The single arc VMAT approach fully utilizes the digital linacs’ capability in dose rate and gantry rotation speed modulation.Varian Medical Systems, NIH grant R01CA188300, NIH grant R43CA183390.
MO‐AB‐BRA‐02: Modeling Nanoparticle‐Eluting Spacer Degradation During Brachytherapy Application with in Situ Dose‐Painting
Authors: Boateng F , Ngwa W 
Published: July 2016

Purpose:Brachytherapy application with in situ dose‐painting using gold nanoparticles (GNP) released from GNP‐loaded brachytherapy spacers has been proposed as an innovative approach to increase therapeutic efficacy during brachytherapy. This work investigates the dosimetric impact of slow versus burst release of GNP from next generation biodegradable spacers.Methods:Mathematical models were developed based on experimental data to study the release of GNP from a spacer designed with FDA approved poly(lactic‐co‐glycolic acid) (PLGA) polymer. The diffusion controlled released process and PLGA polymer degradation kinetics was incorporated in the calculations for the first time. An in vivo determined diffusion coefficient was used for determining the concentration profiles and corresponding dose enhancement based on initial GNP‐loading concentrations of 7 mg/g.Results:The results showed that there is significant delay before the concentration profile of GNP diffusion in the tumor is similar to that when burst release is assumed as in previous studies. For example, in the case of burst release after spacer administration, it took up to 25 days for all the GNP to be released from the spacer using diffusion controlled release process only. However, it took up to 45 days when a combined model for both diffusion and polymer degradation processes was used. Based on the tumor concentration profiles, a significant dose enhancement factor (DEF >20%), could be attained at a tumor distances of 5 mm from a spacer loaded with 10 nm GNP sizes.Conclusion:The results highlight the need to take the slow release of GNP from spacers and factors such as biodegradation of polymers into account in research development of GNP‐eluting spacers for brachytherapy applications with in‐situ dose‐painting using gold nanoparticles. The findings suggest that I‐125 may be the more appropriate for such applications given the relatively longer half‐live compared to other radioisotopes like Pd‐103 and Cs‐131.
MO‐AB‐BRA‐06: Dynamic FLT PET for Investigating Potential Synergistic Therapeutic Targets During Anti‐Angiogenic Treatment
Authors: Scarpelli M , Simoncic U , Perlman S , Liu G , Jeraj R 
Published: July 2016

Purpose:Novel treatment strategies for metastatic cancer patients involve synergistically combining treatments with the hope of improving outcomes. This study investigated changes in tumor proliferative and vascular characteristics derived from dynamic [F‐18]FLT PET during antiangiogenic treatment with the goal of identifying synergistic treatment opportunities.Methods:Patients with various solid cancers underwent continuous three‐week cycles of anti‐angiogenic treatment with intermittent dosing (two‐weeks‐on/one‐week‐off). Patients received up to six dynamic FLT PET/CT scans (days 0, 14, and 21 of cycle 1 (C1) and cycle 3 (C3)). Tumor proliferative (Kflt, net uptake rate) and vascular parameters (K1 blood‐to‐tissue transfer; Vb, vascular fraction) were calculated using a two‐tissue compartment four‐rate parameter kinetic model. Relative changes in these parameters, from day 0 to 14 (TxResp) and day 14 to 21 (offTxResp), were calculated. Significant differences were tested using Wilcoxon signed‐rank test and significant correlations were tested using Spearman correlation.Results:Thirty patients were evaluable for C1 offTxResp with median values for Kflt, K1, and Vb of +30%, +35% and +30%, respectively. The fractions of patients with positive C1 offTxResp were: 21/30 for Ki, 24/30 for K1, 21/30 for Vb, and 12/30 had positive offTxResp for all three kinetic parameters. The offTxResp in C3 was not significantly different from C1 for any of the kinetic parameters. Significant correlations were found between TxResp and offTxResp in C1 for Kflt (ρ=‐0.52, p=0.014), K1 (ρ=−0.61, p=0.003) and Vb (ρ=−0.80, p<0.001). Similar correlations were found for Kflt (ρ=‐1, p=0.017) and K1 (ρ=−1, p=0.017) for the five patients evaluable in C3.Conclusion:Dynamic FLT PET showed evidence of distinct vascular and proliferative increases during off treatment weeks that could potentially be targeted with synergistic therapy. Early changes in kinetic parameters were correlated with later changes suggesting potential for early prediction of vascular and proliferative changes during off treatment weeks.
MO‐AB‐BRA‐08: A Modular Multi‐Source X‐Ray Tube for Novel Computed Tomography Applications
Authors: Walker B , Radtke J , Petry G , Swader R , Chen G , Eliceiri K , Mackie T 
Published: July 2016

Purpose:To develop and build a practical implementation of an x‐ray line source for the rapidly increasing number of multi‐source imaging applications in CT.Methods:An innovative x‐ray tube was designed using CST Particle Studio, ANSYS, and SolidWorks. A slowly varying magnetic field is synchronized with microsecond gating of multiple thermionic electron sources. Electrostatic simulations were run to optimize the geometry of the optics and prevent electrode arcing. Magnetostatic simulations were used for beam deflection studies and solenoid design. Particle beam trajectories were explored with an emphasis on focusing, acceleration, deflection, and space charge effects. Thermal constraints were analyzed for both transient and steady‐state regimes. Electromagnetic simulations informed the design of a prototype unit under construction.Results:Particle tracking simulations for a benchtop system demonstrate that three 80 keV electron beams are able to be finely controlled and laterally swept a combined distance of 15 cm over a stationary target with an oscillating magnetic field in the hundreds of gauss. The beams are pulsed according to scanning sequences developed for implementation in a mock stationary CT scanner capable of a 30 ms temporal resolution. Beam spot diameters are approximately 1 mm for 30 mA beams and the stationary target stays well within thermal limits. The relevant hardware and control circuits were developed for incorporation into a physical prototype.Conclusion:A new multi‐source x‐ray tube was designed in a modular form factor to push the barriers of high‐speed CT and spur growth in emerging imaging applications. This technology can be used as the basis for a stationary high‐speed CT scanner, a system for generating a virtual fan‐beam for dose reduction, or for reducing scatter radiation in cone‐beam CT utilizing a tetrahedron beam CT geometry. A 2.4 kW benchtop system is currently being built to show proof of concept for the tube.Support for this research was provided by the University of Wisconsin Madison, Office of the Vice Chancellor for Research and Graduate Education with funding from the Wisconsin Alumni Research Foundation.