bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐J‐31: Biodynamic Imaging of Cancer Tissue and Response to Chemotherapy
Authors: Nolte D , Turek J , Matei D , Childress M , An R , Merrill D 
Published: July 2014

Purpose:To measure intracellular motions inside three‐dimensional living cancer tissue samples to establish a novel set of biodynamic biomarkers that assess tissue proliferative activity and sensitivity or resistance to chemotherapy.Methods:Biodynamic imaging (BDI) uses digital holography with low‐coherence low‐intensity light illumination to construct 3D holograms from depths up to a millimeter deep inside cancer tissue models that include multicellular tumor spheroids and ex vivo cancer biopsies from canine non‐Hodgkins lymphoma and epithelial ovarian cancer (EOC) mouse explants. Intracellular motions modulate the holographic intensity with frequencies related to the Doppler effect caused by the motions of a wide variety of intracellular components. These motions are affected by applied therapeutic agents, and BDI produces unique fingerprints of the action of specific drugs on the motions in specific cell types. In this study, chemotherapeutic agents (doxorubicin for canine lymphoma and oxoplatin for ovarian) are applied to the living tissue models and monitored over 10 hours by BDI.Results:Multicellular spheroids and patient biopsies are categorized as either sensitive or insensitive to applied therapeutics depending on the intracellular Doppler signatures of chemotherapy response. For both lymphoma and EOC there is strong specificity to the two types of sensitivities, with sensitive cell lines and biopsies exhibiting a global cessation of proliferation and strong suppression of metabolic activity, while insensitive cell lines and biopsies show moderate activation of Doppler frequencies associated with membrane processes and possible membrane trafficking.Conclusion:This work supports the hypothesis that biodynamic biomarkers from three‐dimensional living tumor tissue, that includes tissue heterogeneity and measured within 24 hours of surgery, is predictive of near‐term patient response to therapy. Future work will correlate biodynamic biomarkers with progression free survival times.This work is supported by NIH 1R01EB016582 and NSF 1263753‐CBET. Nolte, Turek and An have a financial interest in Animated Dynamics, Inc. that will be licensing technology from Purdue University.
SU‐E‐J‐32: Calypso(R) and Laser‐Based Localization Systems Comparison for Left‐Sided Breast Cancer Patients Using Deep Inspiration Breath Hold
Authors: Robertson S , Kaurin D , Kim J , Fang L , Sweeney L , Holloway K , Tran A 
Published: July 2014

Purpose:Our institution uses a manual laser‐based system for primary localization and verification during radiation treatment of left‐sided breast cancer patients using deep inspiration breath hold (DIBH). This primary system was compared with sternum‐placed Calypso(R) beacons (Varian Medical Systems, CA). Only intact breast patients are considered for this analysis.Methods:During computed tomography (CT) simulation, patients have BB and Calypso(R) surface beacons positioned sternally and marked for free‐breathing and DIBH CTs. During dosimetry planning, BB longitudinal displacement between free breathing and DIBH CT determines laser mark (BH mark) location. Calypso(R) beacon locations from the DIBH CT are entered at the Tracking Station. During Linac simulation and treatment, patients inhale until the cross‐hair and/or lasers coincide with the BH Mark, which can be seen using our high quality cameras (Pelco, CA). Daily Calypso(R) displacement values (difference from the DIBH‐CT‐based plan) are recorded. The displacement mean and standard deviation was calculated for each patient (77 patients, 1845 sessions). An aggregate mean and standard deviation was calculated weighted by the number of patient fractions.Some patients were shifted based on MV ports. A second data set was calculated with Calypso(R) values corrected by these shifts.Results:Mean displacement values indicate agreement within 1±3mm, with improvement for shifted data (Table).Conclusion:Both unshifted and shifted data sets show the Calypso(R) system coincides with the laser system within 1±3mm, demonstrating either localization/verification system will Resultin similar clinical outcomes. Displacement value uncertainty unilaterally reduces when shifts are taken into account.
SU‐E‐J‐33: Cardiac Movement in Deep Inspiration Breath‐Hold for Left‐Breast Cancer Radiotherapy
Authors: Kim M , Lee S , Suh T 
Published: July 2014

Purpose:The present study was designed to investigate the displacement of heart using Deep Inspiration Breath Hold (DIBH) CT data compared to free‐breathing (FB) CT data and radiation exposure to heart.Methods:Treatment planning was performed on the computed tomography (CT) datasets of 20 patients who had received lumpectomy treatments. Heart, lung and both breasts were outlined. The prescribed dose was 50 Gy divided into 28 fractions. The dose distributions in all the plans were required to fulfill the International Commission on Radiation Units and Measurement specifications that include 100% coverage of the CTV with ≥ 95% of the prescribed dose and that the volume inside the CTV receiving > 107% of the prescribed dose should be minimized. Displacement of heart was measured by calculating the distance between center of heart and left breast. For the evaluation of radiation dose to heart, minimum, maximum and mean dose to heart were calculated.Results:The maximum and minimum left‐right (LR) displacements of heart were 8.9 mm and 3 mm, respectively. The heart moved > 4 mm in the LR direction in 17 of the 20 patients. The distances between the heart and left breast ranged from 8.02–17.68 mm (mean, 12.23 mm) and 7.85–12.98 mm (mean, 8.97 mm) with DIBH CT and FB CT, respectively. The maximum doses to the heart were 3115 cGy and 4652 cGy for the DIBH and FB CT dataset, respectively.Conclusion:The present study has demonstrated that the DIBH technique could help to reduce the risk of radiation dose‐induced cardiac toxicity by using movement of cardiac; away from radiation field. The DIBH technique could be used in an actual treatment room for a few minutes and could effectively reduce the cardiac dose when used with a sub‐device or image acquisition standard to maintain consistent respiratory motion.
SU‐E‐J‐35: Clinical Performance Evaluation of a Phase II Proton CT Scanner
Authors: Mandapaka A , Ghebremedhin A , Farley D , Giacometti V , Vence N , Bashkirov V , Plautz T , Zatserklyaniy A , Johnson R , Sadrozinski H , Patyal B , Schulte R 
Published: July 2014

Purpose:To develop the methodology to evaluate the clinical performance of a Phase II Proton CT scannerMethods:Range errors on the order of 3%‐5% constitute a major uncertainty in current charged particle treatment planning based on Hounsfield Unit (HU)‐relative stopping power (RSP) calibration curves. Within our proton CT collaboration, we previously developed and built a Phase I proton CT scanner that provided a sensitive area of 9 cm (axial) × 18 cm (in‐plane). This scanner served to get initial experience with this new treatment planning tool and to incorporate lessons learned into the next generation design. A Phase II scanner was recently completed and is now undergoing initial performance testing. It will increase the proton acquisition rate and provide a larger detection area of 9 cm x 36 cm. We are now designing a comprehensive evaluation program to test the image quality, imaging dose, and range uncertainty associated with this scanner. The testing will be performed along the lines of AAPM TG 66.Results:In our discussion of the evaluation protocol we identified the following priorities. The image quality of proton CT images, in particular spatial resolution and low‐density contrast discrimination, will be evaluated with the Catphan600 phantom. Initial testing showed that the Catphan uniformity phantom did not provide sufficient uniformity; it was thus replaced by a cylindrical water phantom. The imaging dose will be tested with a Catphan dose module, and compared to a typical cone beam CT dose for comparable image quality. Lastly, we developed a dedicated dosimetry range phantom based on the CIRS pediatric head phantom HN715.Conclusion:A formal evaluation of proton CT as a new tool for proton treatment planning is an important task. The availability of the new Phase II proton CT scanner will allow us to perform this task.This research is supported by the National Institute of Biomedical Imaging and Bioengineering of the NIH under award number R01EB013118. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH
SU‐E‐J‐38: Comparison of 6MV Photon Dose in a Perpendicular and Parallel Magnetic Field
Authors: Ghila A , Fallone B , Rathee S 
Published: July 2014

Purpose:Integrating a linac with an MRI system would allow for real time tumour tracking however the patient will be irradiated in the presence of a magnetic field. The present study experimentally investigates the magnetic field effects on entrance, exit, and interface dose for both transverse and parallel magnetic fields.Methods:Polystyrene was used to construct a set of phantoms for Gafchromic film measurements. One phantom had an adjustable air gap and four other phantoms had one surface at various angles. The linac‐MR prototype consisting of a biplanar permanent magnet coupled to a linac was used for the transverse magnetic field measurements. A couple of solenoid electromagnets, stacked on top of each other and irradiated along their bore, were used for the parallel field measurements.Results:All doses are relative to no magnetic field. The transverse magnetic field reduced the entrance dose for all surface angles by strongly deflecting the contaminant electrons. The exit dose in a transverse magnetic field was found to be significantly higher. The entrance dose with a parallel magnetic field present is higher due to the contaminant electrons being concentrated within the beam area. The air gap phantom measurements, done in a transverse magnetic field, show a significant increase of the dose at the proximal side of the air gap and a decrease at the distal side. The measurements, done in the parallel magnetic field, show the concentration of secondary electrons in the air gap.Conclusion:The radiation dose measurements of a 6MV beam in a parallel and transverse magnetic field presented here are currently being replicated using Monte Carlo simulations. This verified Monte Carlo system could provide the dose calculation basis for future linac‐MR systems.
SU‐E‐J‐39: Comparison of PTV Margins Determined by In‐Room Stereoscopic Image Guidance and by On‐Board Cone Beam Computed Tomography Technique for Brain Radiotherapy Patients
Authors: Ganesh T , Paul S , Munshi A , Sarkar B , Krishnankutty S , Sathya J , George S , Jassal K , Roy S , Mohanti B 
Published: July 2014

Purpose:Stereoscopic in room kV image guidance is a faster tool in daily monitoring of patient positioning. Our centre, for the first time in the world, has integrated such a solution from BrainLAB (ExacTrac) with Elekta's volumetric cone beam computed tomography (XVI). Using van Herk's formula, we compared the planning target volume (PTV) margins calculated by both these systems for patients treated with brain radiotherapy.Methods:For a total of 24 patients who received partial or whole brain radiotherapy, verification images were acquired for 524 treatment sessions by XVI and for 334 sessions by ExacTrac out of the total 547 sessions. Systematic and random errors were calculated in cranio‐caudal, lateral and antero‐posterior directions for both techniques. PTV margins were then determined using van Herk formula.Results:In the cranio‐caudal direction, systematic error, random error and the calculated PTV margin were found to be 0.13 cm, 0.12 cm and 0.41 cm with XVI and 0.14 cm, 0.13 cm and 0.44 cm with ExacTrac. The corresponding values in lateral direction were 0.13 cm 0.1 cm and 0.4 cm with XVI and 0.13 cm, 0.12 cm and 0.42 cm with ExacTrac imaging. The same parameters for antero‐posterior were for 0.1 cm, 0.11 cm and 0.34 cm with XVI and 0.13 cm, 0.16 cm and 0.43 cm with ExacTrac imaging. The margins estimated with the two imaging modalities were comparable within ± 1 mm limit.Conclusion:Verification of setup errors in the major axes by two independent imaging systems showed the results are comparable and within ± 1 mm. This implies that planar imaging based ExacTrac can yield equal accuracy in setup error determination as the time consuming volumetric imaging which is considered as the gold standard. Accordingly PTV margins estimated by this faster imaging technique can be confidently used in clinical setup.
SU‐E‐J‐40: Comparison of Two Head and Neck Immobilization Device Fabrication and Simulation Protocols: Effects On Setup Deviation and Intrafraction Motion During Treatment
Authors: Hosotani M , Lacey S M , Pafundi D H , Antolak J A , Foote R L , Herman M G , Garces Y I , Daniels T B , Brinkmann D H 
Published: July 2014

Purpose:To compare two protocols for head and neck immobilization device fabrication and simulation and their effect on daily setup deviation and intrafraction motion over the course of VMAT or static IMRT.Methods:Fifteen post‐surgical bilateral head and neck patients were immobilized with a custom‐fit dental mold attached to a 5–point thermoplastic mask and treated with VMAT or IMRT. After fabrication of the immobilization device, which included 5–10 minutes for mask hardening, the patient either was scanned immediately without any positioning adjustments (N = 10), or got off of the simulation table for approximately 1 minute and was repositioned in treatment position prior to scanning (N = 5). Patients were localized using kV orthogonal imaging matching to overall bony anatomy for 30–35 fractions. Translational setup deviations were determined retrospectively by matching pre‐ and post‐treatment kV orthogonal images to reference DRRs using bony anatomy near isocenter (typically C4) as well as gold fiducial markers embedded in the dental mold. Intrafraction motion was determined based on comparison of pre‐treatment kV orthogonal images with post‐treatment kV orthogonal images for each fraction. Margins were calculated using the pre‐ and posttreatment setup deviation data of each patient cohort.Results:Treatment position repositioning prior to simulation scanning decreased the patient group mean intrafraction motion near the dental mold (P < 0.02) and near isocenter (P < 0.04), but did not statistically significantly change the group mean setup uncertainty.Conclusion:Repositioning of the patient in treatment position prior to simulation reduced intrafraction motion, but did not affect patient setup uncertainty during head and neck treatment. These results indicate that on average repositioning the patient in treatment position decreases patient intrafraction motion over the course of treatment for post‐surgical bilateral head and neck patients immobilized with dental molds attached to a thermoplastic mask.
SU‐E‐J‐42: Customized Deformable Image Registration Using Open‐Source Software SlicerRT
Authors: Gaitan J Cifuentes , Kirby N , Lasso A , Chin L , Pinter C , Pignol J , Fichtinger G , Pouliot J 
Published: July 2014

Purpose:SlicerRT is a flexible platform that allows the user to incorporate the necessary images registration and processing tools to improve clinical workflow. This work validates the accuracy and the versatility of the deformable image registration algorithm of the free open‐source software SlicerRT using a deformable physical pelvic phantom versus available commercial image fusion algorithms.Methods:Optical camera images of nonradiopaque markers implanted in an anatomical pelvic phantom were used to measure the ground‐truth deformation and evaluate the theoretical deformations for several DIR algorithms. To perform the registration, full and empty bladder computed tomography (CT) images of the phantom were obtained and used as fixed and moving images, respectively. The DIR module, found in SlicerRT, used a B‐spline deformable image registration with multiple optimization parameters that allowed customization of the registration including a regularization term that controlled the amount of local voxel displacement. The virtual deformation field at the center of the phantom was obtained and compared to the experimental ground‐truth values. The parameters of SlicerRT were then varied to improve spatial accuracy. To quantify image similarity, the mean absolute difference (MAD) parameter using Hounsfield units was calculated. In addition, the Dice coefficient of the contoured rectum was evaluated to validate the strength of the algorithm to transfer anatomical contours.Results:Overall, SlicerRT achieved one of the lowest MAD values across the algorithm spectrum, but slightly smaller mean spatial errors in comparison to MIM software (MIM). On the other hand, SlicerRT created higher mean spatial errors than Velocity Medical Solutions (VEL), although obtaining an improvement on the DICE to 0.91. The large spatial errors were attributed to the poor contrast in the prostate bladder interface of the phantom.Conclusion:Based phantom validation, SlicerRT is capable of achieving comparable DIR accuracy to commercial programs such as MIM and VEL.
SU‐E‐J‐46: Development of a Compton Camera Prototype for Online Range Verification of Laser‐Accelerated Proton Beams
Authors: Thirolf PG , Aldawood S , Boehmer M , Bortfeldt J , Castelhano I , Gernhaeuser R , v.d. Kolff H , Lang C , Maier L , Schaart DR , Parodi K 
Published: July 2014

Purpose:Development of a photon detection system designed for online range verification of laser‐accelerated proton beams via prompt‐gamma imaging of nuclear reactions.Methods:We develop a Compton camera for the position‐sensitive detection of prompt photons emitted from nuclear reactions between the proton beam and biological samples. The detector is designed to be capable to reconstruct the photon source origin not only from the Compton scattering kinematics of the primary photon, but also to allow for tracking of the Compton‐scattered electrons.Results:Simulation studies resulted in the design of the Compton camera based on a LaBr3(Ce) scintillation crystal acting as absorber, preceded by a stacked array of 6 double‐sided silicon strip detectors as scatterers. From the design simulations, an angular resolution of ≤ 2° and an image reconstruction efficiency of 10−3 −10−5 (at 2–6 MeV) can be expected. The LaBr3 crystal has been characterized with calibration sources, resulting in a time resolution of 273 ps (FWHM) and an energy resolution of about 3.8% (FWHM). Using a collimated (1 mm diameter) 137Cs calibration source, the light distribution was measured for each of 64 pixels (6×6 mm2). Data were also taken with 0.5 mm collimation and 0.5 mm step size to generate a reference library of light distributions that allows for reconstructing the interaction position of the initial photon using a k‐nearest neighbor (k‐NN) algorithm developed by the Delft group.Conclusion:The Compton‐camera approach for prompt‐gamma detection offers promising perspectives for ion beam range verification. A Compton camera prototype is presently being developed and characterized in Garching. Furthermore, an arrangement of, e.g., 4 camera modules could even be used in a ‘gamma‐PET’ mode to detect delayed annihilation radiation from positron emitters in the irradiation interrupts (with improved performance in the presence of an additional third (prompt) photon (as in 10C and 14O).This work was supported by the DFG Cluster of Excellence MAP (Munich‐Centre for Advanced Photonics)
SU‐E‐J‐49: Distal Edge Activity Fall Off Of Proton Therapy Beams
Authors: Elmekawy A , Butuceanu C , Zhu L , Ewell L 
Published: July 2014

Purpose:To characterize and quantify the distal edge activity fall off, created in a phantom by a proton therapy beamMethod and Materials:A 30×30×10cm polymethylmethacrylate phantom was irradiated with a proton therapy beam using different ranges and beams. The irradiation volume is approximated by a right circular cylinder of diameter 7.6cm and varying lengths. After irradiation, the phantom was scanned via a Philips Gemini Big Bore™ PET‐CT for isotope activation. Varian Eclipse™ treatment planning system as well as ImageJ™ were used to analyze the resulting PET and CT scans. The region of activity within the phantom was longitudinally measured as a function of PET slice number. Dose estimations were made via Monte Carlo (GATE) simulation.Results:For both the spread out Bragg peak (SOBP) and the mono‐energetic pristine Bragg peak proton beams, the proximal activation rise was steep: average slope −0.735 (average intensity/slice number) ± 0.091 (standard deviation) for the pristine beams and −1.149 ± 0.117 for the SOBP beams. In contrast, the distal fall offs were dissimilar. The distal fall off in activity for the pristine beams was fit well by a linear curve: R2 (Pierson Product) was 0.9968, 0.9955 and 0.9909 for the 13.5, 17.0 and 21.0cm range beams respectively. The good fit allows for a slope comparison between the different ranges. The slope varied as a function of range from 1.021 for the 13.5cm beam to 0.8407 (average intensity/slice number) for the 21.0cm beam. This dependence can be characterized: −0.0234(average intensity/slice number/cm range). For the SOBP beams, the slopes were significantly less and were also less linear: average slope 0.2628 ± 0.0474, average R2=0.9236.Conclusion:The distal activation fall off edge for pristine proton beams was linear and steep. The corresponding quantities for SOBP beams were shallower and less linear.Philips has provided support for this work.
SU‐E‐J‐50: Does a Breathing Surrogate From a Point On the Abdominal Skin Represent the Organ Motion in Thorax for Phase‐Based 4D CT Sorting?
Authors: Lin M , D' Souza W , Lasio G , Lu W , Prado K , Feigenberg S , Yi B 
Published: July 2014

Purpose:This work aims (1) to determine the validity of the current practice of the phase‐based 4DCT sorting (abdomen signal) for thorax scans; (2) to assess the potential benefit of utilizing the 3D surface breathing surrogate of chest area for phase‐based 4DCT sorting.Methods:Dynamic 3D surface images over the chest and abdomen were acquired using 3D‐suface‐camera‐system (VisionRT Ltd., London, UK) for a total of 10 patients. The vertical motions of five regions‐of‐interest (ROIs): abdomen, mid‐sternum, lower‐, middle‐, and upper‐ ipsilateral‐chest were tracked. Based on our previous work, the main source of motion artifact is the variation‐of‐phase‐differences (VPD) between the breathing surrogate and the organ motion during scanning. Thus, we utilize VPD as a quantitative index of the variation of the resulting 4DCT images. The average VPD over a 60 second time‐period was calculated for each of the abdomen and ROI combination. A simulation study with a wire phantom was designed to demonstrate the resulting 4DCT images.Results:Simulation showed significant image distortion or motion artifacts when VPD is larger than 5% of breathing period. The average VPDs of individual ROIs of each patient indicates that 75%, 59% and 22% cases have VPD larger than 5%, 10% and 15% of period each cycle between the selected ROI and the abdominal motions patterns, respectively (10.1±6.0 %, minimum 1.0% to maximum 23.9 %). Overall, patients with less 3‐second breathing‐period present VPD larger than 10%. The correlations between the abdomen and individual chest ROIs motions as well as the motions among chest ROIs are highly case‐dependent.Conclusion:Abdominal motion does not represent the chest motions for some of the patients. This results in motion artifacts in the phase‐based 4DCT. Utilizing the surface surrogate of the chest region can potentially improve phase‐based 4DCT sorting for thorax 4DCT scan, especially for fast breathing patients.