bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐P‐09: Compliance With Evidence‐Based Treatment Planning DVH Guidelines In An Academic Multi‐Site Radiation Oncology Practice Setting
Authors: D'souza W , Zhang B , Feigenberg S , D'souza G , Prado K , Regine W 
Published: June 2015

Purpose:To evaluate the compliance with evidence‐based treatment planning organ‐at‐risk (OAR) guidelines in a single institution with four practice sites.Methods:Two hundred thirteen head and neck cancer patients treated between September 2009 and September 2013 were retrospectively selected. Consensus treatment planning guidelines, including OAR dose constraints, were established based on institutional experience and published data. Data spanned a time period of 2 years prior to (n=112) and 2 years post‐enactment (n=101) of the guidelines. We investigated the differences in the frequency with which (1) OARs were contoured and (2) OAR DVH goals were met. Trends in the proportion with OAR contours over time was tested using linear regression. Trends in the proportion of contoured OARs achieving clinical DVH goals were similarly tested. The proportion of patients contoured and meeting DVH goals before and after guidelines was compared using a test of proportions.Results:When the proportion of cases with OAR contours before and after guidelines were compared, we observed an increase from 75% to 87% (p=0.02) for the brainstem, decrease from 97% to 88% (p=0.01) for the cord and increase from 47% to 77% (p<0.001) for the mandible. For the proportion of cases with OAR contours in which clinical goals were met, a significant decrease from 99% to 90% was observed for the cord V48<0.3% (p=0.001). A significant decrease in the proportion of cases with left parotid contours (from 92% to 73% (p=0.03)) was observed over 2 years after guideline enactment and the proportion meeting the clinical DVH goal of V30<50% increased significantly from 36% to 50% (p=0.007) over the 2 years after guidelines.Conclusion:The enactment of OAR planning guidelines resulted in an increase in OAR contour compliance, overall. In cases with OAR contours, there was little to no change in the proportion that met clinical goals.
SU‐E‐P‐11: Comparison of Image Quality and Radiation Dose Between Different Scanner System in Routine Abdomen CT
Authors: Liao S , Wang Y , Weng H 
Published: June 2015

PurposeTo evaluate image quality and radiation dose of routine abdomen computed tomography exam with the automatic current modulation technique (ATCM) performed in two different brand 64‐slice CT scanners in our site.Materials and MethodsA retrospective review of routine abdomen CT exam performed with two scanners; scanner A and scanner B in our site. To calculate standard deviation of the portal hepatic level with a region of interest of 12.5 mm × 12.5mm represented to the image noise. The radiation dose was obtained from CT DICOM image information. Using Computed tomography dose index volume (CTDIv) to represented CT radiation dose. The patient data in this study were with normal weight (about 65–75 Kg).ResultsThe standard deviation of Scanner A was smaller than scanner B, the scanner A might with better image quality than scanner B. On the other hand, the radiation dose of scanner A was higher than scanner B(about higher 50–60%) with ATCM. Both of them, the radiation dose was under diagnostic reference level.ConclusionThe ATCM systems in modern CT scanners can contribute a significant reduction in radiation dose to the patient. But the reduction by ATCM systems from different CT scanner manufacturers has slightly variation. Whatever CT scanner we use, it is necessary to find the acceptable threshold of image quality with the minimum possible radiation exposure to the patient in agreement with the ALARA principle.
SU‐E‐P‐15: Technique Factor Modulation and Reference Plane Air Kerma Rates in Response to Simulated Patient Thickness Variations for a Sample of Current Generation Fluoroscopes
Authors: Wunderle K , Rakowski J , Dong F 
Published: June 2015

Purpose:To evaluate and compare approaches to technique factor modulation and air kerma rates in response to simulated patient thickness variations for four state‐of‐the‐art and one previous‐generation interventional fluoroscopes.Methods:A polymethyl methacrylate (PMMA) phantom was used as a tissue surrogate for the purposes of determining fluoroscopic reference plane air kerma rates, kVp, mA, and spectral filtration over a wide range of simulated tissue thicknesses. Data were acquired for each fluoroscopic and acquisition dose curve within a default abdomen or body imaging protocol.Results:The data obtained indicated vendor‐ and model‐specific variations in the approach to technique factor modulation and reference plane air kerma rates across a range of tissue thicknesses. Some vendors have made hardware advances increasing the radiation output capabilities of their fluoroscopes; this was evident in the acquisition air kerma rates. However, in the imaging protocol evaluated, all of the state‐of‐the‐art systems had relatively low air kerma rates in the fluoroscopic low‐dose imaging mode as compared to the previous‐generation unit. Each of the newest‐generation systems also employ copper filtration in the selected protocol in the acquisition mode of imaging; this is a substantial benefit, reducing the skin entrance dose to the patient in the highest dose‐rate mode of fluoroscope operation.Conclusion:Understanding how fluoroscopic technique factors are modulated provides insight into the vendor‐specific image acquisition approach and provides opportunities to optimize the imaging protocols for clinical practice. The enhanced radiation output capabilities of some of the fluoroscopes may, under specific conditions, may be beneficial; however, these higher output capabilities also have the potential to lead to unnecessarily high dose rates. Therefore, all parties involved in imaging, including the clinical team, medical physicists, and imaging vendors, must work together to ensure that adequate but not excessive radiation doses are used.
SU‐E‐P‐16: A Feasibility Study of Using Eclipse AAA for SRS Treatement
Authors: Lim S , LoSasso T 
Published: June 2015

Purpose:To commission Varian Eclipse AAA for SRS treatment and compare the accuracy with Brainlab iPlan system for clinical cases measured with radiochromic film.Methods:A 6MV AAA clinical model for a Varian TrueBeam STx is used as baseline. The focal spot and field size of the baseline model(BASE) are (1.75,0.75) and 40×40cm2 respectively. Maximum field sizes, output factors(St), FWHM focal spot and secondary source sizes are systematically adjusted to obtain an optimized model(OPT) by comparing the calculated PDD's, profiles, and output factors with measurements taken with a stereotactic diode(SD) and, cc01 and cc04 ion chambers in Blue Phantom. In‐phantom dose distributions of clinical SRS fields are calculated using the OPT and the clinical Brainlab iPlan pencil‐beam. Within the 90% isodose‐line(ROI), the average dose difference between the calculations and radiochromic film measurements are assessed.Results:The maximum field, focal spot and secondary source sizes for the OPT are 15×15cm2, (0,0), and 32.3mm respectively. The OPT St input at 1.0 and 2.0cm fields are increased by 4.5% and 1.5% from BASE. The calculated output of the BASE and OPT underestimate by 16.1%–3.2% respectively at 0.5×0.5cm2 field and 3.1%−0.02% respectively at 1.0×1.0cm2 field. The depth doses at 10cm are within 3.5% and 0.4% of measurements for 0.5×0.5 and 1.0×1.0cm2. The ROI dose of OPT and iPlan are within 1.6% and 0.6% of film measurements for 3.0cm clinical fields. For 1.0cm fields, the ROI dose of OPT underestimate 0.0–2.0% and iPlan overestimates 1.7–2.9% relative to measurements.Conclusion:The small field dose calculation of Eclipse AAA algorithm can be significantly improved by carefully adjusting the input parameters. The larger deviation of the OPT for 0.5×0.5cm2 field from measurements can be attributed to the lowest 1.0cm field size input limit of AAA. The OPT compares reasonably well with the iPlan pencil‐beam and measurements.
SU‐E‐P‐19: A National Collaborative Academic Medical Physics Network: Structure, Activity and Outcomes
Authors: Thwaites D 
Published: June 2015

Purpose:A national Australian inter‐university medical physics (MP) group was formed in 2011/12, supported by Department of Health Better Access to Radiation Oncology BARO) seed funding. Core membership includes the six universities providing postgraduate MP courses. Objectives include increasing capacity, development and efficiency of national academic MP structures/systems and hence supporting education, clinical training and research, for the MP workforce support. Although the BARO scheme focuses on Radiation Oncology, the group has wider MP interests.Methods:Two further BARO seed grants were achieved: 1) for networked academic activities, including shared‐resource teaching, eg using virtual reality systems; MP outreach to schools and undergraduates; developing web‐based student and registrar education/resources, etc.; and 2) for conjoint ‘translational research’ posts between universities and partner hospitals, to clinically progress advanced RT technologies and to support students and registrars. Each university received 0.5 FTE post from each grant over 2 years (total: $1.75M) and leveraged local additional partner funds.Results:Total funding: $4–5M. Overall there have been 35 (mainly overseas) postholders bringing specific expertise, beginning in early 2013. Periods in Australia have been from 0.25–2 years (median=1). As well as the education activities, research projects include lung/spine SBRT, 4D RT, FFF beams, technology assessment, complex treatment planning, imaging for radiation oncology, DIR, adaptive breast, datamining, radiomics,etc. Observed positive impacts include: increased interest in MP courses, training support, translational research infrastructure and/or clinical practice in the hospitals involved, plus increased collaboration and effectiveness between the universities. Posts are continuing beyond grant end using leveraged funds, providing the basis for sustainability of some posts.Conclusion:The BARO‐funded projects have cost‐effectively produced a range of positive impacts on training, research and practice in hospitals and between universities. The evaluation of the specific post roles and activities, and their outcomes, has produced focused recommendations on continuation and sustainability.Funding was from the Australian federal Department of Health; leveraged funding was from partner universities and hospitals
SU‐E‐P‐30: Clinical Applications of Spatially Fractionated Radiation Therapy (GRID) Using Helical Tomotherapy
Authors: Zhang X , Penagaricano J , Liang X , Morrill S , Yan Y , Corry P , Griffin R , Paudel N , Vaneerat V Ratanatharathorn 
Published: June 2015

Purpose:To present the first clinical applications of Helical Tomotherapy‐based spatially fractionated radiotherapy (HT‐GRID) for deep seated tumors and associated dosimetric study.Methods:Ten previously treated GRID patients were selected (5 HT‐GRID and 5 LINAC‐GRID using a commercially available GRID block). Each case was re‐planned either in HT‐GRID or LINAC‐GRID for a total of 10 plans for both techniques using same prescribed dose of 20 Gy to maximum point dose of GRID GTV. For TOMO‐GRID, a programmable virtual TOMOGRID template mimicking a GRID pattern was generated. Dosimetric parameters compared included: GRID GTV mean dose (Dmean) and equivalent uniform dose (EUD), GRID GTV dose inhomogeneity (Ratio(valley/peak)), normal tissue Dmean and EUD, and other organs‐at‐risk(OARs) doses.Results:The median tumor volume was 634 cc, ranging from 182 to 4646 cc. Median distance from skin to the deepest part of tumor was 22cm, ranging from 8.9 to 38cm. The median GRID GTV Dmean and EUD was 10.65Gy (9.8–12.5Gy) and 7.62Gy (4.31–11.06Gy) for HT‐GRID and was 6.73Gy (4.44–8.44Gy) and 3.95Gy (0.14–4.2Gy) for LINAC‐GRID. The median Ratio(valley/peak) was 0.144(0.05–0.29) for HT‐GRID and was 0.055(0.0001–0.14) for LINAC‐GRID. For normal tissue in HT‐GRID, the median Dmean and EUD was 1.24Gy (0.34–2.54Gy) and 5.45 Gy(3.45–6.89Gy) and was 0.61 Gy(0.11–1.52Gy) and 6Gy(4.45–6.82Gy) for LINAC‐GRID. The OAR doses were comparable between the HT‐GRID and LINAC‐GRID. However, in some cases it was not possible to avoid a critical structure in LINAC‐GRID; while HT‐GRID can spare more tissue doses for certain critical structures.Conclusion:HT‐GRID delivers higher GRID GTV Dmean, EUD and Ratio(valley/peak) compared to LINAC‐GRID. HT‐GRID delivers higher Dmean and lower EUD for normal tissue compared to LINAC‐GRID. TOMOGRID template can be highly patient‐specific and allows adjustment of the GRID pattern to different tumor sizes and shapes when they are deeply‐seated and cannot be safely treated with LINAC‐GRID.
SU‐E‐P‐47: Evaluation of Improvement of Esophagus Sparing in SBRT Lung Patients with Biologically Based IMRT Optimization
Authors: Liang X , Penagaricano J , Paudel N , Zhang X , Morrill S , Corry P , Han E , Hardee M , Ratanatharathorn V 
Published: June 2015

Purpose:To study the potential of improving esophageal sparing for stereotactic body radiation therapy (SBRT) lung cancer patients by using biological optimization (BO) compared to conventional dose‐volume based optimization (DVO) in treatment planning.Methods:Three NSCLC patients (PTV (62.3cc, 65.1cc, and 125.1cc) adjacent to the heart) previously treated with SBRT were re‐planned using Varian Eclipse TPS (V11) using DVO and BO. The prescription dose was 60 Gy in 5 fractions normalized to 95% of the PTV volume. Plans were evaluated by comparing esophageal maximum doses, PTV heterogeneity (HI= D5%/D95%), and Paddick's conformity (CI) indices. Quality of the plans was assessed by clinically‐used IMRT QA procedures.Results:By using BO, the maximum dose to the esophagus was decreased 1384 cGy (34.6%), 502 cGy (16.5%) and 532 cGy (16.2%) in patient 1, 2 and 3 respectively. The maximum doses to spinal cord and the doses to 1000 cc and 1500 cc of normal lung were comparable in both plans. The mean doses (Dmean_hrt) and doses to 15cc of the heart (V15_hrt) were comparable for patient 1 and 2. However for patient 3, with the largest PTV, Dmean_hrt and V15_hrt increased by 62.2 cGy (18.3%) and 549.9 cGy (24.9%) respectively for the BO plans. The mean target HI of BO plans (1.13) was inferior to the DVO plans (1.07). The same trend was also observed for mean CI in BO plans (0.77) versus DVO plans (0.83). The QA pass rates (3%, 3mm) were comparable for both plans.Conclusion:This study demonstrated that the use of biological models in treatment planning optimization can substantially improve esophageal sparing without compromising spinal cord and normal lung doses. However, for the large PTV case (125.1cc) we studied here, Dmean_hrt and V15_hrt increased substantially. The target HI and CI were inferior in the BO plans.
SU‐E‐U‐01: Automatic Quantitative Analysis of Chronic Liver Disease Employing Shear Wave Ultrasound Elastography
Authors: Gatos I , Tsantis S , Skouroliakou A , Theotokas I , Zoumpoulis P , Kagadis G 
Published: June 2015

Purpose:The purpose of this study was to quantify liver elastic heterogeneity in Shear Wave Elastography (SWE) by using textural features and evaluating their diagnostic performance on differentiating healthy from chronic liver disease patients, taking biopsy results as the gold standard.Methods:Clinical material includes 16 healthy (F0) and 15 with Chronic Liver Disease (F1,F2,F3,F4) patients according to the Metavir staging system. All exams were performed using the Aixplorer ultrasound system with a SuperCurved SC6‐1 transducer. From the SWE‐QBox the RGB displayed elasticity data of Young's modulus were transformed from RGB color space into an elasticity matrix of gray tones, whose values varied from zero to the maximum elasticity measurement. Every pixel with no RGB‐values was set to ‘−1’ due to non‐valid elasticity value for that pixel. From the elastogram map 185 textural features were computed (5 from the gray‐tone histogram, 26 second order statistic features, extracted from the co‐occurrence matrices and 10 features extracted from the run‐length matrices over four directions (00,450,900,1350) and distances of (d=1,3,5,7,9) pixels). Stepwise multi‐linear regression analysis was utilized to avoid feature redundancy leading to a feature subset feeding a Support Vector Machine (SVM) classifier. SVM‐model evaluation was performed by means of the leave‐one‐out method.Results:Maximum classification accuracy (93.5%) in distinguishing healthy from chronic liver disease patients was obtained employing three textural features (Standard Deviation, Sum‐Variance, Contrast) that describe the elastogram's contrast, variability and complexity. Sensitivity and specificity values were 93.3% and 94.0% respectively.Conclusion:The proposed classification scheme can provide reproducibility and reliability of liver SWE application in clinical practice. It can also assist the interpretation of SWE measurements which is considered as a difficult task due to absence of guidelines in the literature and to decrease the time/cost of diagnosis and the need for patients to undergo invasive examination.This research has been co‐financed by the European Union (European Social Fund ESF) and Greek national funds through the Operational Program ’Education and Lifelong Learning’ of the National Strategic Reference Framework (NSRF) Research Funding Program: ARCHIMEDES III. Investing in knowledge society through the European Social Fund.
SU‐E‐U‐03: Noncontact Ultrasound Spectroscopy of Cortical Bone Phantoms: Reproducibility
Authors: Ganezer K , Bulman J , Halcrow P , Neeson I 
Published: June 2015

Purpose:In this study we update our studies presented in a talk in the ultrasound symposium in 2014 on the topic of noncontact ultrasound spectroscopy applied to cortical bone phantoms in which we found we found a high correlation between the BUA parameter and the Bone Mineral densities of the phantoms that was provided a linear regression with a r^₂as high as 0.96. The purpose of our current study was to have two separate ultrasound analyzers one at CSUDH in Carson California and a second analyzer at VN and associates in Elizabethtown, Ontario, Canada, in which the two analyzers only had minor differences in the transducers, pulse generators, and other hardware and software. Our goal was to compare the BUA parameters, speed of sound(SOS), attenuation, and spectra. We also considered changes in speed of sound, and attenuation taken 4 years ago with similar measurements made recently.Methods:We used Matlab shell files to compute SOS for 2 different methods, BUA, and attenuation for 15 or 16 phantoms that ranged in BMD from 150–1700 gm/m^3. Linear regressions were calculated for sets of two parameters. Some of the phantoms were scanned using a pixelized grid.Results:The two systems behaved similarly. There seemed to be only small changes in SOS with larger changes in BUA, that might be attributed to oxidation and loss of water.Conclusion:There was a high degree of reproducibility in most of our measurements
SU‐E‐I‐01: Iterative CBCT Reconstruction with a Feature‐Preserving Penalty
Authors: Lyu Q , Li B , Ma J , Wang J 
Published: June 2015

Purpose:Low‐dose CBCT is desired in various clinical applications. Iterative image reconstruction algorithms have shown advantages in suppressing noise in low‐dose CBCT. However, due to the smoothness constraint enforced during the reconstruction process, edges may be blurred and image features may lose in the reconstructed image. In this work, we proposed a new penalty design to preserve image features in the image reconstructed by iterative algorithms.Methods:Low‐dose CBCT is reconstructed by minimizing the penalized weighted least‐squares (PWLS) objective function. Binary Robust Independent Elementary Features (BRIEF) of the image were integrated into the penalty of PWLS. BRIEF is a general purpose point descriptor that can be used to identify important features of an image. In this work, BRIEF distance of two neighboring pixels was used to weigh the smoothing parameter in PWLS. For pixels of large BRIEF distance, weaker smooth constraint will be enforced. Image features will be better preserved through such a design. The performance of the PWLS algorithm with BRIEF penalty was evaluated by a CatPhan 600 phantom.Results:The image quality reconstructed by the proposed PWLS‐BRIEF algorithm is superior to that by the conventional PWLS method and the standard FDK method. At matched noise level, edges in PWLS‐BRIEF reconstructed image are better preserved.Conclusion:This study demonstrated that the proposed PWLS‐BRIEF algorithm has great potential on preserving image features in low‐dose CBCT.
SU‐E‐I‐02: Characterizing Low‐Contrast Resolution for Non‐Circular CBCT Trajectories
Authors: Davis A , Pearson E , Pan X , Pelizzari C 
Published: June 2015

Purpose:The use of non‐circular scanning trajectories with optimization‐basedreconstruction algorithms can be used in conjunction with non‐planaracquisition geometries for axial field‐of‐view (FOV) extension incone‐beam CT (CBCT). To evaluate the utility of these trajectories,quantitative image quality metrics should be evaluated. Low‐contrastresolution (LCR) and CT number accuracy are significant challenges forCBCT. With unprecedented axial coverage provided by thesetrajectories, measuring such metrics throughout the axial range iscritical. There are currently no phantoms designed to measurelow‐contrast resolution over such an extended volume.Methods:The CATPHAN (The Phantom Laboratory, Salem NY) is the current standardfor image quality evaluation. While providing several useful modulesfor different evaluation metrics, each module was designed to beevaluated in a single slice and not for comparison across axialpositions. To characterize the LCR and HU accuracy over an extendedaxial length, we have designed and built a phantom with evaluationmodules at multiple and adjustable axial positions.Results:The modules were made from a cast polyurethane resin. Holes rangingfrom 1/8 to 5/8 inch were added at a constant radius from the modulecenter into which rods of two different plastic materials were pressedto provide two nominal levels of contrast (1.0% and 0.5%). Largerholes were bored to accept various RMI plugs with known electrondensities for HU accuracy evaluation. The modules can be inserted intoan acrylic tube long enough to cover the entire axial FOV and theirpositions adjusted to desired evaluation points.Conclusion:This phantom allows us to measure the LCR and HU accuracy across theaxial coverage within a single acquisition. These metrics can be usedto characterize the impact different trajectories and reconstructionparameters have on clinically relevant image quality performancemetrics.Funding was provided in part by Varian Medical Systems and NIH R01 Grants Nos. CA158446, CA182264, EB018102, and EB000225. The contents of this poster are solely the responsibility of the authors and do not necessarily represent the official view of any of the supporting organizations.