bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐F‐T‐645: To Test Spatial Anddosimetric Accuracy of Small Cranial Target Irradiation Based On 1.5 T MRIscans Using Static Arcs with MLCDefined Fields
Authors: Brezovich I , Wu X , Popple R , Shen S , Cardan R , Bolding M , Fiveash J , Kraus J , Spencer S 
Published: July 2016

Purpose:To test spatial and dosimetric accuracy of small cranial target irradiation based on 1.5 T MRI scans using static arcs with MLC‐defined fieldsMethods:A plastic (PMMA) phantom simulating a small brain lesion was mounted on a GammaKnife headframe equipped with MRI localizer. The lesion was a 3 mm long, 3.175 mm diameter cylindrical cavity filled with MRI contrast. Radiochromic film passing through the cavity was marked with pin pricks at the cavity center. The cavity was contoured on an MRI image and fused with CT to simulate treatment of a lesion not visible on CT. The transfer of the target to CT involved registering the MRI contrast cannels of the localizer that were visible on both modalities. Treatments were planned to deliver 800 cGy to the cavity center using multiple static arcs with 5.0×2.4 mm MLC‐defined fields. The phantom was aligned on a STx accelerator by registering the conebeam CT with the planning CT. Films from coronal and sagittal planes were scanned and evaluated using ImageJ softwareResults:Geographic errors in treatment based on 1.5 T scans agreed within 0.33, −0.27 and 1.21 mm in the vertical, lateral and longitudinal dimensions, respectively. The doses delivered to the cavity center were 7.2% higher than planned. The dose distributions were similar to those of a GammaKnife.Conclusion:Radiation can be delivered with an accelerator at mm accuracy to small cranial targets based on 1.5 MRI scans fused to CTs using a standard GammaKnife headframe and MRI localizer. MLC‐defined static arcs produce isodose lines very similar to the GammaKnife.
SU‐F‐T‐651: Dosimetric Impact of Patient Setup Rotational Errors for Multi‐Staged Large AVM Gammaknife Radiosurgery
Authors: Ding C , Hrycushko B , Abdulrahman R , Whitworth L , Jiang S , Timmerman R 
Published: July 2016

Purpose:Multi‐staged large AVM (>10 cm3 or diameter > 3 cm) Gammaknife radiosurgery requires setting up the patient based on a pre‐treatment plan over several fractions. Residual rotational errors cannot be compensated by translational repositioning of the patient and may adversely impact the dose distribution on the total AVM target. This study evaluates the effect of residual rotational setup error.Methods:The total AVM target was contoured and split into several small sub‐targets. A Gammaknife plan was completed for the whole AVM target to meet the prescription goals. Shots were split and grouped according to the location of each sub‐target to be delivered in separate staged sup‐plans. Rotational errors of ±1‐5° about the three rotational axes along with 5mm random translational errors were used to simulate head frame setup errors on different treatment days. Software was developed to compensate for translational errors to bring the shots back to the position of the original plan. Dose distributions were compared between the original planned dose and that resulting from residual rotational errors.Results:The volume of the target having dose differences within 3% is decreased with larger residual rotational errors (98.28%, 84.22% and 68.08% for ±1°, ±3°, and ±5° rotation, respectively). The volume of the target with dose differences within 5% (99.89%, 94.86% and 83.01% for ±1°, ±3°, and ±5° rotation, respectively) indicate that rotation less than ±3° is acceptable for treatment.Conclusion:Dosimetric errors increase as rotational errors increase. The dosimetric impact was shown acceptable when rotational errors are less than 3°.
SU‐F‐T‐662: Feasibility Study of Fe3O4/TaOx Nano Particles as a Radiosensitizer for Radiation Therapy
Authors: Ahn S , Lee N , Shin S , Choi C , Han Y , Park H , Choi D , Lim D 
Published: July 2016

Purpose:To investigate the feasibility of using multifunctional Fe3O4/TaOx(core / shell) nano particles developed for CT and MRI contrast agent as dose enhancing radiosensitizers.Methods:Firstly, to verify the imaging detectability of Fe3O4/TaOx nano particles, in‐vivo tests were conducted. Approximately 600 mg/kg of 19 nm diameter Fe3O4/TaOx nano particles dispersed in phosphate buffered saline(PBS) were injected to ten nude Balb/c mice through the tail vein. Difference between pre‐ and post‐injection images was analyzed by computing the pixel histogram and correlation coefficient factor using MATLAB in the user defined ROI. Secondly, to quantify the potential therapeutic enhancement with nano materials, DER (Dose Enhancement Ratio) and number of SER (Secondary Electron Ratio) were computed using TOPAS(ver.2.0 P‐03) MC simulation.Results:In CT, MRI imaging, the aorta, the blood vessel, and the liver were clearly visualized after intravenous injection of Fe3O4/TaOx nano particles. There was large different between pre and post‐injection images of Histogram data and Coefficients of correlation factor in CT and MR are 0.006, 0.060, respectively. When 70 MeV protons were irradiated for a Gold, Tantalum, TaOx, Fe3O4/TaOx, Fe3O4 nano particle, DER was 2.59, 2.41, 1.68, 1.54 and 1.36 respectively. Similarly, SER increment was 2.31, 2.15, 1.56, 1.46, and 1.27 for Gold, Tantalum, TaOx, Fe3O4/TaOx, Fe3O4 nano particle, respectively.Conclusion:Fe3O4/TaOx nano particles have potential as a multifunctional agent which enhances the accuracy in cancer detection through visualization of developed tumor lesion and increases the therapeutic effect in proton therapy. The dose enhancement with Fe3O4/TaOx was estimated as half of the Gold. However, tumor targeting such as combined with magnetic field may overcome the low DER.This research was supported by the NRF funded by the Ministry of Science, ICT & Future Planning (2012M3A9B6055201 and 2012R1A1A2042414), Samsung Medical Center grant[GFO1130081]
SU‐F‐T‐665: Confocal Microscopy Imaging of Cell Cycle Distribution in Cells Treated with Pegylated Gold Nanoshells
Authors: Sadetaporn D , Flint D , McFadden C , Asaithamby A , Sawakuchi G 
Published: July 2016

Purpose:To use confocal microscopy to distinguish cells in different phases of the cell cycle before and after treatment with pegylated gold nanoshells (PEG‐AuNSs).Methods:Transfected fibrosarcoma cells (HT1080‐EYFP‐53BP1‐FUCCI) were cultured in T‐25 flasks and seeded in glass bottom dishes. These cells express the fluorescent probe AmCyan during the G2/S phases of the cell cycle, mCherry during the G1 phase, and EYFP tagged to the DNA repair protein 53BP1. After allowing cells 4 h to adhere to dishes, PEG‐AuNS (Nanospectra Biosciences, Houston, TX) at a concentration of 0.15 OD were administered. At time points of 8, 16 and 24 h following treatment, the PEG‐AuNS‐treated and control samples were washed with phosphate buffered saline (PBS) and fixed using 4% paraformaldehyde in PBS. Samples were imaged with an Olympus FV1200 confocal microscope using 473, 543, and 641 nm excitation lasers. We used band‐pass filters to select AmCyan and mCherry fluorescence. Reflection from the 641 nm laser was used to detect PEG‐AuNSs. Z‐stack images were analyzed to assess cell cycle distribution through fluorescent probe expression. Live cells were imaged after PEG‐AuNS treatment using a confocal microscope with a stage top CO2 incubator.Results:We were able to obtain high‐resolution images of cells with internalized AuNSs. We were also able to distinguish cells in different phases of the cell cycle.Conclusion:This work demonstrates a new assay to investigate the effect of AuNSs on the cell cycle phase in live cells. Future work will employ confocal microscopy and flow cytometry to focus on effects of AuNS treatment on cell cycle distribution.This research was supported by the Sister Institution Network Fund and the Center for Radiation Oncology Research at The University of Texas MD Anderson Cancer Center and Cancer Prevention and Research Institute of Texas. Gabriel Sawakuchi has research support from Elekta Inc.
SU‐F‐T‐669: Commissioning of An Electronic Brachytherapy System for Targeted Mouse Irradiation
Authors: Culberson W , Carchman E , Micka J 
Published: July 2016

Purpose:The aim of this study was to commission the Xoft Axxent™ electronic brachytherapy (eBT) source and 10 mm diameter surface applicator with NIST traceability for targeted irradiations of mouse anal carcinomas.Methods:The Xoft Axxent™ electronic brachytherapy (eBT) and 10 mm diameter surface applicator was chosen by the collaborating physician as a radiation delivery mechanism for mouse anal carcinomas. The target dose was 2 Gy at a depth of 3 mm in tissue to be delivered in a single fraction. To implement an accurate and reliable irradiation plan, the system was commissioned by first determining the eBT source output and corresponding dose rate at a depth of 3 mm in tissue. This was determined through parallel‐plate ion chamber measurements and published conversion factors. Well‐type ionization chamber measurements were used to determine a transfer coefficient, which correlates the measured dose rate at 3 mm to the NIST‐traceable quantity, air‐kerma rate at 50 cm in air, for eBT sources. By correlating these two quantities, daily monitoring in the well chamber becomes an accurate and efficient quality assurance technique. Once the dose‐rate was determined, a treatment recipe was developed and confirmed with chamber measurements to deliver the requested dose. Radiochromic film was used to verify the dose distribution across the field.Results:Dose rates at 3 mm depth in tissue were determined for two different Xoft Axxent™ sources and correlated with NIST‐traceable well‐type ionization chamber measurements. Unique transfer coefficients were determined for each source and the treatment recipe was validated by measurements. Film profiles showed a uniform dose distribution across the field.Conclusion:A Xoft Axxent™ eBT system was successfully commissioned for use in the irradiation of mouse rectal tumors. Dose rates in tissue were determined as well as other pertinent parameters to ensure accurate delivery of dose to the target region.
SU‐F‐T‐677: Synergistic Effect(s) of Clotrimazole On Radiation Cell Survival of A549 Lung Cancer Cells in Glucose Vs. Galactose Media
Authors: Boss G , Tambasco M , Garakani M 
Published: July 2016

Purpose:In order to determine the synergistic effect of clotrimazole on radiosensitivity of A549 lung cancer cells, and the effect of oxidative pathways on modulating radiosensitivity, we studied how these cells survived under varying amounts of radiation and clotrimazole as well ass when glucose was switched for galactose media.Methods:The glucose media was used to determine the presence of any synergistic effect of clotrimazole on radiation using values of radiation and clotrimazole concentrations, varying from 0 – 8 Gy and 0 – 20 µM, respectively. As a galactose diet is known to activate oxidative pathways, which do not rely on hexokinase II (HK2), all trials were repeated using galactose media to determine the extent that HK2 unbinding from the mitochondrial membrane plays a role in modulating the observed radiosensitivity. An apoptosis vs. necrosis assay was implemented to find out the modality by which cell death occurred. An intracellular lactate assay was performed to exhibit the extent of anaerobic glycolysis.Results:After running the primary experiments, it was found that in glucose media, the cancer cells showed higher cell kill when clotrimazole was added to the media, followed by the cells being irradiated.Conclusion:Given the preliminary results it is validated that under higher concentrations of clotrimazole, in glucose media, A549 lung cancer cells exhibit a lower amount of survival. While all results have not yet been gathered. We anticipate that in galactose media the A549 cells will exhibit this effect to a much smaller degree, if at all.
SU‐F‐T‐679: Monte Carlo Simulation On Surface Dose in Preclinical Irradiation Using Monoenergetic Photon Beams
Authors: Vuong A , Chow J 
Published: July 2016

Purpose:This study investigated the surface dose variation in preclinical irradiation using small animal, when monoenergetic photon beams with energy range from 50 keV to 1.25 MeV were used.Methods:Inhomogeneous, homogeneous and bone‐tissue homogeneous mouse phantom based on the same CT image set were used. The homogeneous and bone‐tissue homogeneous phantom were created with the relative electron density of all and only bone voxels of the mouse overridden to one, respectively. Monte Carlo simulation based on the EGSnrc‐based code was used to calculate the surface dose, when the phantoms were irradiated by a 360° photon arc with energies ranging from 50 keV to 1.25 MeV. The mean surface doses of the three phantoms were calculated. In addition, the surface doses from partial arcs, 45°–315°, 125°–225°, 45°–125° and 225°–315° covering the anterior, posterior, right lateral and left lateral region of the mouse were determined using different photon beam energies.Results:When the prescribed dose at the isocenter of the mouse was 2 Gy, the maximum mean surface doses, found at the 50‐keV photon beams, were 0.358 Gy, 0.363 Gy and 0.350 Gy for the inhomogeneous, homogeneous and bone‐tissue homogeneous mouse phantom, respectively. The mean surface dose of the mouse was found decreasing with an increase of the photon beam energy. For surface dose in different orientations, the lateral regions of the mouse were receiving lower dose than the anterior and posterior regions. This may be due to the increase of beam attenuation along the horizontal (left‐right) axis than the vertical (anterior‐posterior) in the mouse.Conclusion:It is concluded that consideration of phantom inhomogeneity in the dose calculation resulted in a lower mean surface dose of the mouse. The mean surface dose also decreased with an increase of photon beam energy in the kilovoltage range.
SU‐G‐BRA‐02: Development of a Learning Based Block Matching Algorithm for Ultrasound Tracking in Radiotherapy
Authors: Shepard A , Bednarz B 
Published: July 2016

Purpose:To develop an ultrasound learning‐based tracking algorithm with the potential to provide real‐time motion traces of anatomy‐based fiducials that may aid in the effective delivery of external beam radiation.Methods:The algorithm was developed in Matlab R2015a and consists of two main stages: reference frame selection, and localized block matching. Immediately following frame acquisition, a normalized cross‐correlation (NCC) similarity metric is used to determine a reference frame most similar to the current frame from a series of training set images that were acquired during a pretreatment scan. Segmented features in the reference frame provide the basis for the localized block matching to determine the feature locations in the current frame. The boundary points of the reference frame segmentation are used as the initial locations for the block matching and NCC is used to find the most similar block in the current frame. The best matched block locations in the current frame comprise the updated feature boundary. The algorithm was tested using five features from two sets of ultrasound patient data obtained from MICCAI 2014 CLUST. Due to the lack of a training set associated with the image sequences, the first 200 frames of the image sets were considered a valid training set for preliminary testing, and tracking was performed over the remaining frames.Results:Tracking of the five vessel features resulted in an average tracking error of 1.21 mm relative to predefined annotations. The average analysis rate was 15.7 FPS with analysis for one of the two patients reaching real‐time speeds. Computations were performed on an i5‐3230M at 2.60 GHz.Conclusion:Preliminary tests show tracking errors comparable with similar algorithms at close to real‐time speeds. Extension of the work onto a GPU platform has the potential to achieve real‐time performance, making tracking for therapy applications a feasible option.This work is partially funded by NIH grant R01CA190298
SU‐G‐BRA‐07: An Innovative Fiducial‐Less Tracking Method for Radiation Treatment of Abdominal Tumors by Diaphragm Disparity Analysis
Authors: Dick D , Wu X , Zhao W 
Published: July 2016

Purpose:To investigate the feasibility of tracking abdominal tumors without the use of gold fiducial markersMethods:In this simulation study, an abdominal 4DCT dataset, acquired previously and containing 8 phases of the breathing cycle, was used as the testing data. Two sets of DRR images (45 and 135 degrees) were generated for each phase. Three anatomical points along the lung‐diaphragm interface on each of the Digital Reconstructed Radiograph(DRR) images were identified by cross‐correlation. The gallbladder, which simulates the tumor, was contoured for each phase of the breathing cycle and the corresponding centroid values serve as the measured center of the tumor. A linear model was created to correlate the diaphragm's disparity of the three identified anatomical points with the center of the tumor. To verify the established linear model, we sequentially removed one phase of the data (i.e., 3 anatomical points and the corresponding tumor center) and created new linear models with the remaining 7 phases. Then we substituted the eliminated phase data (disparities of the 3 anatomical points) into the corresponding model to compare model‐generated tumor center and the measured tumor center.Results:The maximum difference between the modeled and the measured centroid values across the 8 phases were 0.72, 0.29 and 0.30 pixels in the x, y and z directions respectively, which yielded a maximum mean‐squared‐error value of 0.75 pixels. The outcomes of the verification process, by eliminating each phase, produced mean‐squared‐errors ranging from 0.41 to 1.28 pixels.Conclusion:Gold fiducial markers, requiring surgical procedures to be implanted, are conventionally used in radiation therapy. The present work shows the feasibility of a fiducial‐less tracking method for localizing abdominal tumors. Through developed diaphragm disparity analysis, the established linear model was verified with clinically accepted errors. The tracking method in real time under different radiation therapy platforms will be further investigated.
SU‐G‐BRA‐08: Diaphragm Motion Tracking Based On KV CBCT Projections with a Constrained Linear Regression Optimization
Authors: Wei J , Chao M 
Published: July 2016

Purpose:To develop a novel strategy to extract the respiratory motion of the thoracic diaphragm from kilovoltage cone beam computed tomography (CBCT) projections by a constrained linear regression optimization technique.Methods:A parabolic function was identified as the geometric model and was employed to fit the shape of the diaphragm on the CBCT projections. The search was initialized by five manually placed seeds on a pre‐selected projection image. Temporal redundancies, the enabling phenomenology in video compression and encoding techniques, inherent in the dynamic properties of the diaphragm motion together with the geometrical shape of the diaphragm boundary and the associated algebraic constraint that significantly reduced the searching space of viable parabolic parameters was integrated, which can be effectively optimized by a constrained linear regression approach on the subsequent projections. The innovative algebraic constraints stipulating the kinetic range of the motion and the spatial constraint preventing any unphysical deviations was able to obtain the optimal contour of the diaphragm with minimal initialization. The algorithm was assessed by a fluoroscopic movie acquired at anteriorposterior fixed direction and kilovoltage CBCT projection image sets from four lung and two liver patients. The automatic tracing by the proposed algorithm and manual tracking by a human operator were compared in both space and frequency domains.Results:The error between the estimated and manual detections for the fluoroscopic movie was 0.54mm with standard deviation (SD) of 0.45mm, while the average error for the CBCT projections was 0.79mm with SD of 0.64mm for all enrolled patients. The submillimeter accuracy outcome exhibits the promise of the proposed constrained linear regression approach to track the diaphragm motion on rotational projection images.Conclusion:The new algorithm will provide a potential solution to rendering diaphragm motion and ultimately improving tumor motion management for radiation therapy of cancer patients.
SU‐G‐BRA‐14: Dose in a Rigidly Moving Phantom with Jaw and MLC Compensation
Authors: Chao E , Lucas D 
Published: July 2016

Purpose:To validate dose calculation for a rigidly moving object with jaw motion and MLC shifts to compensate for the motion in a TomoTherapy™ treatment delivery.Methods:An off‐line version of the TomoTherapy dose calculator was extended to perform dose calculations for rigidly moving objects. A variety of motion traces were added to treatment delivery plans, along with corresponding jaw compensation and MLC shift compensation profiles. Jaw compensation profiles were calculated by shifting the jaws such that the center of the treatment beam moved by an amount equal to the motion in the longitudinal direction. Similarly, MLC compensation profiles were calculated by shifting the MLC leaves by an amount that most closely matched the motion in the transverse direction. The same jaw and MLC compensation profiles were used during simulated treatment deliveries on a TomoTherapy system, and film measurements were obtained in a rigidly moving phantom.Results:The off‐line TomoTherapy dose calculator accurately predicted dose profiles for a rigidly moving phantom along with jaw motion and MLC shifts to compensate for the motion. Calculations matched film measurements to within 2%/1 mm. Jaw and MLC compensation substantially reduced the discrepancy between the delivered dose distribution and the calculated dose with no motion. For axial motion, the compensated dose matched the no‐motion dose within 2%/1mm. For transverse motion, the dose matched within 2%/3mm (approximately half the width of an MLC leaf).Conclusion:The off‐line TomoTherapy dose calculator accurately computes dose delivered to a rigidly moving object, and accurately models the impact of moving the jaws and shifting the MLC leaf patterns to compensate for the motion. Jaw tracking and MLC leaf shifting can effectively compensate for the dosimetric impact of motion during a TomoTherapy treatment delivery.