bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐D‐207‐04: GPU‐Based 4D Cone‐Beam CT Reconstruction Using Adaptive Meshing Method
Authors: Zhong Z , Gu X , Iyengar P , Mao W , Guo X , Wang J 
Published: June 2015

Purpose:Due to the limited number of projections at each phase, the image quality of a four‐dimensional cone‐beam CT (4D‐CBCT) is often degraded, which decreases the accuracy of subsequent motion modeling. One of the promising methods is the simultaneous motion estimation and image reconstruction (SMEIR) approach. The objective of this work is to enhance the computational speed of the SMEIR algorithm using adaptive feature‐based tetrahedral meshing and GPU‐based parallelization.Methods:The first step is to generate the tetrahedral mesh based on the features of a reference phase 4D‐CBCT, so that the deformation can be well captured and accurately diffused from the mesh vertices to voxels of the image volume. After the mesh generation, the updated motion model and other phases of 4D‐CBCT can be obtained by matching the 4D‐CBCT projection images at each phase with the corresponding forward projections of the deformed reference phase of 4D‐CBCT. The entire process of this 4D‐CBCT reconstruction method is implemented on GPU, resulting in significantly increasing the computational efficiency due to its tremendous parallel computing ability.Results:A 4D XCAT digital phantom was used to test the proposed mesh‐based image reconstruction algorithm. The image Result shows both bone structures and inside of the lung are well‐preserved and the tumor position can be well captured. Compared to the previous voxel‐based CPU implementation of SMEIR, the proposed method is about 157 times faster for reconstructing a 10 ‐phase 4D‐CBCT with dimension 256×256×150.Conclusion:The GPU‐based parallel 4D CBCT reconstruction method uses the feature‐based mesh for estimating motion model and demonstrates equivalent image Result with previous voxel‐based SMEIR approach, with significantly improved computational speed.
SU‐D‐201‐05: Phantom Study to Determine Optimal PET Reconstruction Parameters for PET/MR Imaging of Y‐90 Microspheres Following Radioembolization
Authors: Maughan N , Conti M , Parikh P , Faul D , Laforest R 
Published: June 2015

Purpose:Imaging Y‐90 microspheres with PET/MRI following hepatic radioembolization has the potential for predicting treatment outcome and, in turn, improving patient care. The positron decay branching ratio, however, is very small (32 ppm), yielding images with poor statistics even when therapy doses are used. Our purpose is to find PET reconstruction parameters that maximize the PET recovery coefficients and minimize noise.Methods:An initial 7.5 GBq of Y‐90 chloride solution was used to fill an ACR phantom for measurements with a PET/MRI scanner (Siemens Biograph mMR). Four hot cylinders and a warm background activity volume of the phantom were filled with a 10:1 ratio. Phantom attenuation maps were derived from scaled CT images of the phantom and included the MR phased array coil. The phantom was imaged at six time points between 7.5–1.0 GBq total activity over a period of eight days. PET images were reconstructed via OP‐OSEM with 21 subsets and varying iteration number (1–5), post‐reconstruction filter size (5–10 mm), and either absolute or relative scatter correction. Recovery coefficients, SNR, and noise were measured as well as total activity in the phantom.Results:For the 120 different reconstructions, recovery coefficients ranged from 0.1–0.6 and improved with increasing iteration number and reduced post‐reconstruction filter size. SNR, however, improved substantially with lower iteration numbers and larger post‐reconstruction filters. From the phantom data, we found that performing 2 iterations, 21 subsets, and applying a 5 mm Gaussian post‐reconstruction filter provided optimal recovery coefficients at a moderate noise level for a wide range of activity levels.Conclusion:The choice of reconstruction parameters for Y‐90 PET images greatly influences both the accuracy of measurements and image quality. We have found reconstruction parameters that provide optimal recovery coefficients with minimized noise. Future work will include the effects of the body matrix coil and off‐center measurements.
SU‐D‐210‐01: Automated Depth of Penetration Measurements for Quality Assurance in Ultrasound
Authors: Rubert N , Zagzebski J 
Published: June 2015

Purpose:Subjective assessment of image quality metrics is a current limitation of most ultrasound quality assurance (QA) programs. Here, depth of penetration (DOP) assessments for sensitivity checks are routinely done. We demonstrate the performance of an automated method for DOP measurement for ultrasound QA.Methods:Subjective DOP was assessed by examining an image of a QA phantom and determining the depth where the echo data fades into noise. To assess DOP objectively, a phantom image was recorded followed by a second, “noise image” with the transducer held in air. Phantom and noise images were laterally averaged; the DOP was the depth where phantom image pixel value intersected 1.4X noise image values. During annual QA, DOP was evaluated subjectively by a single observer on a number of probes and compared with objective DOP measurements. Additionally, the objective method's measurement variance and sensitivity to transmit power was examined using a linear‐array transducer. To examine variance, the DOP measurement was repeated with 25 phantom images recorded at uncorrelated planes with transmit power at either 100% or 1%. DOP was also measured as the transmit power was varied in fine steps between 0.1% and 100%.Results:Agreement within 10% of the mean DOP was found between objective and subjective methods for most cases. A small number of cases showed a difference between 10% and 18%. Using the linear‐array, DOP was found to fall off as a power law with the transmit power. At 100% and 1% transmit power, the standard deviation of the DOP measurement was found to be 0.9 mm at DOP's of 8.16 and 6.30 mm on average.Conclusion:Objective image quality assessment is necessary to improve the utility of routine ultrasound QA. We found that objective DOP measurements show good agreement with subjective assessments of DOP while showing little variance.
SU‐D‐210‐05: The Accuracy of Raw and B‐Mode Image Data for Ultrasound Speckle Tracking in Radiation Therapy
Authors: O'shea T , Bamber J , Harris E 
Published: June 2015

Purpose:For ultrasound speckle tracking there is some evidence that the envelope‐detected signal (the main step in B‐mode image formation) may be more accurate than raw ultrasound data for tracking larger inter‐frame tissue motion. This study investigates the accuracy of raw radio‐frequency (RF) versus non‐logarithmic compressed envelope‐detected (B‐mode) data for ultrasound speckle tracking in the context of image‐guided radiation therapy.Methods:Transperineal ultrasound RF data was acquired (with a 7.5 MHz linear transducer operating at a 12 Hz frame rate) from a speckle phantom moving with realistic intra‐fraction prostate motion derived from a commercial tracking system. A normalised cross‐correlation template matching algorithm was used to track speckle motion at the focus using (i) the RF signal and (ii) the B‐mode signal. A range of imaging rates (0.5 to 12 Hz) were simulated by decimating the imaging sequences, therefore simulating larger to smaller inter‐frame displacements. Motion estimation accuracy was quantified by comparison with known phantom motion.Results:The differences between RF and B‐mode motion estimation accuracy (2D mean and 95% errors relative to ground truth displacements) were less than 0.01 mm for stable and persistent motion types and 0.2 mm for transient motion for imaging rates of 0.5 to 12 Hz. The mean correlation for all motion types and imaging rates was 0.851 and 0.845 for RF and B‐mode data, respectively. Data type is expected to have most impact on axial (Superior‐Inferior) motion estimation. Axial differences were <0.004 mm for stable and persistent motion and <0.3 mm for transient motion (axial mean errors were lowest for B‐mode in all cases).Conclusions:Using the RF or B‐mode signal for speckle motion estimation is comparable for translational prostate motion. B‐mode image formation may involve other signal‐processing steps which also influence motion estimation accuracy. A similar study for respiratory‐induced motion would also be prudent.This work is support by Cancer Research UK Programme Grant C33589/A19727.
SU‐D‐210‐06: Feasibility for Monitoring the Head of the Pancreas Motion Through a Surrogate Using Ultrasound During Radiation Therapy Delivery
Authors: Omari E , Noid G , Ehlers C , Erickson B , Quiroz F , Cooper D , Lachaine M , Li X 
Published: June 2015

Purpose:Substantial target motion during the delivery of radiation therapy (RT) for pancreatic cancer is well recognized as a major limiting factor on RT effectiveness. The aim of this work is to monitor intra‐fractional motion of the pancreas using ultrasound during RT delivery.Methods:Transabdominal Ultrasound B‐mode images were collected from 5 volunteers using a research version of the Clarity Autoscan System (Elekta). The autoscan transducer with center frequency of 5 MHz was utilized for the scans. Imaging parameters were adjusted to acquire images at the desired depth with good contrast and a wide sweep angle. Since well‐defined boundaries of the pancreas can be difficult to find on ultrasound B‐mode images, the portal vein was selected as a surrogate for motion estimation of the head of the pancreas. The selection was due to its anatomical location posterior to the neck of the pancreas and close proximity to the pancreas head. The portal vein was contoured on the ultrasound images acquired during simulation using the Clarity Research AFC Workstation software. Volunteers were set up in a similar manner to the simulation for their monitoring session and the ultrasound transducer was mounted on an arm fixed to the couch. A video segment of the portal vein motion was captured.Results:The portal vein was visualized and segmented. Successful monitoring sessions of the portal vein were observed. In addition, our results showed that the ultrasound transducer itself reduces breathing related motion. This is analogous to the use of a compression plate to suppress respiration motion during thorax or abdominal irradiation.Conclusion:We demonstrate the feasibility of tracking the pancreas through the localization of the portal vein using abdominal ultrasound. This will allow for real‐time tracking of the intra‐fractional motion to justify PTV‐margin and to account for unusual motions, thus, improving normal tissue sparing.This research was funding in part by Elekta Inc.
SU‐E‐E‐05: Improving Contouring Precision and Consistency for Physicians‐In‐Training with Simple Lab Experiments
Authors: Ma L , Larson D A 
Published: June 2015

Purpose:Target contouring for high‐dose treatments such as radiosurgery of brain metastases is highly critical in eliminating marginal failure and reducing complications as shown by recent clinical studies. In order to improve contouring accuracy and practice consistency for the procedure, we introduced a self‐assessed physics lab practice for the physicians‐in‐training.Methods:A set of commercially acquired high‐precision PMMA plastic spheres were randomly embedded in a Styrofoam block and then scanned with the CT/MR via the clinical procedural imaging protocol. A group of first‐year physicians‐in‐training (n=6) from either neurosurgery or radiation oncology department were asked to contour the scanned objects (diameter ranged from 0.4 cm to 3.8 cm). These user‐defined contours were then compared with the ideal contour sets of object shape for self assessments to determine the maximum areas of the observed discrepancies and method of improvements.Results:The largest discrepancies from initial practice were consistently found to be located near the extreme longitudinal portions of the target for all the residents. Discrepancy was especially prominent when contouring small objects < 1.0 cm in diameters. For example, the mean volumes rendered from the initial contour data set differed from the ideal data set by 7.7%±6.6% for the participants (p> 0.23 suggesting agreement cannot be established). However, when incorporating a secondary imaging scan such as reconstructed coronal or sagittal images in a repeat practice, the agreement was dramatically improved yielding p<0.02 in agreement with the reference data set for all the participants.Conclusion:A simple physics lab revealed a common pitfall in contouring small metastatic brain tumors for radiosurgical procedures and provided a systematic tool for physicians‐in‐training in improving their clinical contouring skills.Dr Ma is current a board member of international stereotactic radiosurgical society
SU‐E‐E‐07: An Adaptable Approach for Education On Medical Physics at Undergraduate and Postgraduate Levels
Authors: Miller‐Clemente R , Mendez‐Perez L 
Published: June 2015

Purpose:To contribute to the professional profile of future medical physicists, technologists and physicians, and implement an adaptable educational strategy at both undergraduate and postgraduate levels.Methods:The Medical Physics Block of Electives (MPBE) designed was adapted to the Program of B.S. in Physics. The conferences and practical activities were developed with participatory methods, with interdisciplinary collaboration from research institutions and hospitals engaged on projects of Research, Development and Innovation (RDI). The scientific education was implemented by means of critical analysis of scientific papers and seminars where students debated on solutions for real research problems faced by medical physicists. This approach included courses for graduates not associated to educational programs of Medical Physics (MP).Results:The implementation of the MPBE began in September 2014, with the electives of Radiation MP and Introduction to Nuclear Magnetic Resonance. The students of second year received an Introduction to MP. This initiative was validated by the departmental Methodological Workshop, which promoted the full implementation of the MPBE. Both postgraduated and undergraduate trainees participated in practices with our DICOM viewer system, a local prototype for photoplethysmography and a home‐made interface for ROC analysis, built with MATLAB. All these tools were designed and constructed in previous RDI projects. The collaborative supervision of University's researchers with clinical medical physicists will allow to overcome the limitations of residency in hospitals, to reduce the workload for clinical supervisors and develop appropriate educational activities.Conclusion:We demonstrated the feasibility of adaptable educational strategies, considering available resources. This provides an innovative way for prospective medical physicists, technologists and radiation oncologists. This strategy can be implemented in several regions without formal programs of MP, like most of developing countries. Starting with undergraduate students would allow to reach appropriate certification faster than most of traditional or alternative approaches for education on MP.The authors acknowledge Radiation Consulting Group, LLC, an Arizona Corporation which promotes the use of ionizing radiation in the healing arts, for the “Oscar Luis Caballero” travel grant. The authors thanks to professors Meisbel Daudinot, David Adame and Alexander Pascau for the practices through imagis, imageROC and ANGIODIN PD3000 respectively.
SU‐E‐E‐08: Applications of the Quantization of Coupled Circuits in Radiation Physics (design of Klystron, Bremsstrahlung, Synchrotron)
Authors: Ulmer W 
Published: June 2015

Purpose:During the past decade the quantization of coupled/forced electromagnetic circuits with or without Ohm's resistance has gained the subject of some fundamental studies, since even problems of quantum electrodynamics can be solved in an elegant manner, e.g. the creation of quantized electromagnetic fields. In this communication, we shall use these principles to describe optimization procedures in the design of klystrons, synchrotron irradiation and high energy bremsstrahlung.Methods:The base is the Hamiltonian of an electromagnetic circuit and the extension to coupled circuits, which allow the study of symmetries and perturbed symmetries in a very apparent way (SU2, SU3, SU4). The introduction resistance and forced oscillators for the emission and absorption in such coupled systems provides characteristic resonance conditions, and atomic orbitals can be described by that. The extension to virtual orbitals leads to creation of bremsstrahlung, if the incident electron (velocity v nearly c) is described by a current, which is associated with its inductivitance and the virtual orbital to the charge distribution (capacitance). Coupled systems with forced oscillators can be used to amplify drastically the resonance frequencies to describe klystrons and synchrotron radiation.Results:The cross‐section formula for bremsstrahlung given by the propagator method of Feynman can readily be derived. The design of klystrons and synchrotrons inclusive the radiation outcome can be described and optimized by the determination of the mutual magnetic couplings between the oscillators induced by the currents.Conclusions:The presented methods of quantization of circuits inclusive resistance provide rather a straightforward way to understand complex technical processes such as creation of bremsstrahlung or creation of radiation by klystrons and synchrotrons. They can either be used for optimization procedures and, last but not least, for pedagogical purposes with regard to a qualified understanding of radiation physics for students.
SU‐E‐E‐11: Novel Matching Module for Respiration‐Gated Motion Tumor of Cone‐Beam Computed Tomography (CBCT) to 4DCT
Authors: Yu P , Tsai Y , Nien H , Chiu Y , Chang H , Lin C , Fu P , Chang C , Wu C 
Published: June 2015

Purpose:Four dimensional computed tomography (4DCT) scans reliably record whole respiratory phase and generate internal target volumes (ITV) for radiotherapy planning. However, image guiding with cone‐beam computed tomography (CBCT) cannot acquire all or specific respiratory phases. This study was designed to investigate the correlation between average CT and Maximum Intensity Projection (MIP) from 4DCT and CBCT.Methods:Retrospective respiratory gating were performed by GE Discovery CT590 RT. 4DCT and CBCT data from CRIS Dynamic Thorax Phantom with simulated breathing mode were analyzed. The lung tissue equivalent material encompassed 3 cm sphere tissue equivalent material. Simulated breathing cycle period was set as 4 seconds, 5 seconds and 6 seconds for representing variation of patient breathing cycle time, and the sphere material moved toward inferior and superior direction with 1 cm amplitude simulating lung tumor motion during respiration.Results:Under lung window, the volume ratio of CBCT scans to ITVs derived from 10 phases average scans was 1.00 ± 0.02, and 1.03 ± 0.03 for ratio of CBCT scans to MIP scans. Under abdomen window, the ratio of CBCT scans to ITVs derived from 10 phases average scans was 0.39 ± 0.06, and 0.06 ± 0.00 for ratio of CBCT scans to MIP scans. There was a significant difference between lung window Result and abdomen window Result. For reducing image guiding uncertainty, CBCT window was set with width 500 and level‐250. The ratio of CBCT scans to ITVs derived from 4 phases average scans with abdomen window was 1.19 ± 0.02, and 1.06 ± 0.01 for ratio of CBCT to MIP scans.Conclusion:CBCT images with suitable window width and level can efficiently reduce image guiding uncertainty for patient with mobile tumor. By our setting, we can match motion tumor to gating tumor location on planning CT more accurately neglecting other motion artifacts during CBCT scans.
SU‐E‐E‐16: The Application of Texture Analysis for Differentiation of Central Cancer From Atelectasis
Authors: Gao M , Fan T , Duan J 
Published: June 2015

Purpose:Prospectively assess the potential utility of texture analysis for differentiation of central cancer from atelectasis.Methods:0 consecutive central lung cancer patients who were referred for CT imaging and PET‐CT were enrolled. Radiotherapy doctor delineate the tumor and atelectasis according to the fusion imaging based on CT image and PET‐CT image. The texture parameters (such as energy, correlation, sum average, difference average, difference entropy), were obtained respectively to quantitatively discriminate tumor and atelectasis based on gray level co‐occurrence matrix (GLCM)Results:The texture analysis results showed that the parameters of correlation and sum average had an obviously statistical significance(P<0.05).Conclusion:the results of this study indicate that texture analysis may be useful for the differentiation of central lung cancer and atelectasis.
SU‐E‐P‐03: The Australian Clinical Dosimetry Service, a Bespoke National Solution
Authors: Williams I , Lehmann J , Lye J , Kenny J , Alves A , Dunn L , Kron T 
Published: June 2015

Purpose:The Australian Clinical Dosimetry Service, (ACDS) was a pilot program to enable the Australian Government to determine whether a locally designed audit program was suitable for mitigating dosimetric error risk to radiotherapy patients within Australia. The outcomes from four years of operations will be presented and discussed with a focus why and how the pilot requirements were met. The consequnces of success will be considered, the lessons learnt from the pilot program and how they are impacting the future ACDS design, operation and engagement with stakeholders.Methods:The ACDS was designed over 2010/11 by experts drawn from the three professions in consultation with the national Department of Health. The list of outcomes required over a three year pilot was expressed in a Memorandum of Understanding, (MoU) between Health and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) which hosted the ACDS.Results:The ACDS has achieved all the MoU requirements. This paper describes how the staff within the ACDS engaged with the professional clinical workforce and provided a successful and functioning audit service. It identifies the strengths and weaknesses within the MoU and the ACDS structure and how the ACDS resolved a number of conflicting issues. It identifies the successes within the ACDS and how these were achieved. It provides details to assist and advise those seeking to design or modify national or regional auditing programs. Finally the paper reviews potential futures for the ACDS.Conclusion:The raw number of audits and outcomes indicate that the ACDS has met the MoU auditing requirements. The reasons for the ACDS’ success are highly dependent on: attracting quality staff who can respond with agility to changing situations, a high level of communication with the professional community, a high level of engagement by the community and an interested and engaged Federal Department.The Australian Clinical Dosimetry Service is a joint initiative between the Australian Department of Health and the Australian Radiation Protection and Nuclear Safety Agency.