bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐F‐J‐178: A Computer Simulation Model Observer for Task‐Based Image Quality Assessment in Radiation Therapy
Authors: Dolly S , Yu L , Mutic S , Anastasio M , Li H 
Published: July 2016

Purpose:Traditionally, image quality in radiation therapy is assessed subjectively or by utilizing physically‐based metrics. Some model observers exist for task‐based medical image quality assessment, but almost exclusively for diagnostic imaging tasks. As opposed to disease diagnosis, the task for image observers in radiation therapy is to utilize the available images to design and deliver a radiation dose which maximizes patient disease control while minimizing normal tissue damage. The purpose of this study was to design and implement a new computer simulation model observer to enable task‐based image quality assessment in radiation therapy.Methods:A modular computer simulation framework was developed to resemble the radiotherapy observer by simulating an end‐to‐end radiation therapy treatment. Given images and the ground‐truth organ boundaries from a numerical phantom as inputs, the framework simulates an external beam radiation therapy treatment and quantifies patient treatment outcomes using the previously defined therapeutic operating characteristic (TOC) curve. As a preliminary demonstration, TOC curves were calculated for various CT acquisition and reconstruction parameters, with the goal of assessing and optimizing simulation CT image quality for radiation therapy. Sources of randomness and bias within the system were analyzed.Results:The relationship between CT imaging dose and patient treatment outcome was objectively quantified in terms of a singular value, the area under the TOC (AUTOC) curve. The AUTOC decreases more rapidly for low‐dose imaging protocols. AUTOC variation introduced by the dose optimization algorithm was approximately 0.02%, at the 95% confidence interval.Conclusion:A model observer has been developed and implemented to assess image quality based on radiation therapy treatment efficacy. It enables objective determination of appropriate imaging parameter values (e.g. imaging dose). Framework flexibility allows for incorporation of additional modules to include any aspect of the treatment process, and therefore has great potential for both assessment and optimization within radiation therapy.
SU‐F‐J‐179: Commissioning Dosimetric Data of a New 2.5 Megavoltage Imaging Beam from a TrueBeam Linear
Authors: Ding G 
Published: July 2016

Purpose:Recently a new 2.5 megavoltage imaging beam has become available in a TrueBeam linear accelerator for image guidance. There is limited information available related to the beam characteristics. Commissioning dosimetric data of the new imaging is necessary for configuration of the beam in a treatment planning system in order to calculate imaging doses to patients resulting from this new imaging beam. The purpose of this study is to provide measured commissioning data recommended for a beam configuration in a treatment planning system.Methods:A recently installed TrueBeam linear accelerator is equipped with a new low energy photon beam with a nominal energy of 2.5 MV which provides better image quality in addition to other therapeutic megavoltage beams. Dosimetric characteristics of the 2.5 MV are measured for commissioning. An ionization chamber was used to measure dosimetric data including depth‐dose curves and dose profiles at different depths for field sizes ranging from 5×5 cm2 to 40×40 cm2.Results:Although the new 2.5 MV beam is a flattening‐filter‐free (FFF) beam, its dose profiles are much flatter compared to a 6 MV FFF beam. The dose decrease at 20 cm away from the central axis is less than 30% for a 40×40 cm2 field. This moderately lower dose at off‐axis distances benefits the imaging quality. The values of percentage depth‐dose (PDD) curves are 53% and 63% for 10×10 cm2 and 40×40 cm2 fields respectively. The measured beam output is 0.85 cGy/MU for a reference field size at depth 5 cm obtained according to the AAPM TG‐51 protocol.Conclusion:This systematically measured commissioning data is useful for configuring the new imaging beam in a treatment planning system for patient imaging dose calculations resulting from the application of this 2.5 MV beam which is commonly set as a default in imaging procedures.
SU‐F‐J‐180: A Reference Data Set for Testing Two Dimension Registration Algorithms
Authors: Dankwa A , Castillo E , Guerrero T 
Published: July 2016

Purpose:To create and characterize a reference data set for testing image registration algorithms that transform portal image (PI) to digitally reconstructed radiograph (DRR).Methods:Anterior‐posterior (AP) and Lateral (LAT) projection and DRR image pairs from nine cases representing four different anatomical sites (head and neck, thoracic, abdominal, and pelvis) were selected for this study. Five experts will perform manual registration by placing landmarks points (LMPs) on the DRR and finding their corresponding points on the PI using computer assisted manual point selection tool (CAMPST), a custom‐made MATLAB software tool developed in house. The landmark selection process will be repeated on both the PI and the DRR in order to characterize inter‐ and ‐intra observer variations associated with the point selection process. Inter and an intra observer variation in LMPs was done using Bland‐Altman (B&A) analysis and one‐way analysis of variance. We set our limit such that the absolute value of the mean difference between the readings should not exceed 3mm. Later on in this project we will test different two dimension (2D) image registration algorithms and quantify the uncertainty associated with their registration.Results:Using one‐way analysis of variance (ANOVA) there was no variations within the readers. When Bland‐Altman analysis was used the variation within the readers was acceptable. The variation was higher in the PI compared to the DRR.ConclusionThe variation seen for the PI is because although the PI has a much better spatial resolution the poor resolution on the DRR makes it difficult to locate the actual corresponding anatomical feature on the PI. We hope this becomes more evident when all the readers complete the point selection. The reason for quantifying inter‐ and ‐intra observer variation tells us to what degree of accuracy a manual registration can be done.Research supported by William Beaumont Hospital Research Start Up Fund.
SU‐F‐J‐184: Proton Computed Tomography Using 1D Silicon Diode Array
Authors: Wang P , Cammin J , Bisello F , Solberg T , McDonough J , Zhu T , Menichelli D , Teo B 
Published: July 2016

Purpose:Proton radiography and proton computed tomography (PCT) can be used to measure proton stopping power directly. However, practical and cost effective proton imaging detectors are not widely available. In this study, the authors investigated the feasibility of proton imaging using a silicon diode array.Methods:A one‐dimensional silicon‐diode detector array (1DSDA) was aligned with the central axis (CAX) of the proton beam. Polymethyl methacrylate (PMMA) slabs were used to find the correspondence between the water equivalent thickness (WET) and 1DSDA channel number. 2D proton radiographs (PR) were obtained by translation and rotation of a phantom relative to CAX while the proton nozzle and 1DSDA were kept stationary. A PCT image of one slice of the phantom was reconstructed using filtered backprojection.Results:PR and PCT images of the PMMA cube were successfully acquired using the 1DSDA. The WET of the phantom was measured using PR data with an accuracy of 4.2% or better. Structures down to 1 mm in size could be resolved. Reconstruction of a PCT image showed very good agreement with simulation. Limitations in spatial resolution are attributed to limited spatial sampling, beam collimation, and proton scatter.Conclusion:The results demonstrate the feasibility of using silicon diode arrays for proton imaging. Such a device can potentially offer fast image acquisition, high spatial and energy resolution for PR and PCT.
SU‐F‐J‐190: Time Resolved Range Measurement System Using Scintillator and CCD Camera for the Slow Beam Extraction
Authors: Saotome N , Furukawa T , Mizushima K , Takeshita E , Hara Y , Saraya Y , Tansho R , Shirai T , Noda K 
Published: July 2016

Purpose:To investigate the time structure of the range, we have verified the rang shift due to the betatron tune shift with several synchrotron parameters.Methods:A cylindrical plastic scintillator block and a CCD camera were installed on the black box. Using image processing, the range was determined the 80 percent of distal dose of the depth light distribution. The root mean square error of the range measurement using the scintillator and CCD system is about 0.2 mm. Range measurement was performed at interval of 170 msec. The chromaticity of the synchrotron was changed in the range of plus or minus 1% from reference chromaticity in this study. All of the particle inside the synchrotron ring were extracted with the output beam intensity 1.8×108 and 5.0×107 particle per sec.Results:The time strictures of the range were changed by changing of the chromaticity. The reproducibility of the measurement was sufficient to observe the time structures of the range. The range shift was depending on the number of the residual particle inside the synchrotron ring.Conclusion:In slow beam extraction for scanned carbon‐ion therapy, the range shift is undesirable because it causes the dose uncertainty in the target. We introduced the time‐resolved range measurement using scintillator and CCD system. The scintillator and CCD system have enabled to verify the range shift with sufficient spatial resolution and reproducibility.
SU‐F‐J‐195: On the Performance of Four Dual Energy CT Formalisms for Extracting Proton Stopping Powers
Authors: Baer E , Lalonde A , Royle G , Bouchard H 
Published: July 2016

Purpose:Dual energy CT can predict stopping power ratios (SPR) for ion therapy treatment planning. Several approaches have been proposed recently, however accuracy and practicability in a clinical workflow are unaddressed. The aim of this work is to provide a fair comparison of available approaches in a human‐like phantom to find the optimal method for tissue characterization in a clinical situation.Methods:The SPR determination accuracy is investigated using simulated DECT images. A virtual human‐like phantom is created containing 14 different standard human tissues. SECT (120 kV) and DECT images (100 kV and 140 kV Sn) are simulated using the software ImaSim. The single energy CT (SECT) stoichiometric calibration method and four recently published calibration‐based DECT methods are implemented and used to predict the SPRs from simulated images. The difference between SPR predictions and theoretical SPR are compared pixelwize. Mean, standard deviation and skewness of the SPR difference distributions are used as measures for bias, dispersion and symmetry.Results:The average SPR differences and standard deviations are (0.22 ± 1.27)% for SECT, and A) (−0.26 ± 1.30)%, B) (0.08 ± 1.12)%, C) (0.06 ± 1.15)% and D) (−0.05 ± 1.05)% for the four DECT methods. While SPR prediction using SECT is showing a systematic error on SPR, the DECT methods B, C and D are unbiased. The skewness of the SECT distribution is 0.57%, and A) −0.19%, B) −0.56%, C) −0.29% and D) −0.07% for DECT methods respectively.Conclusion:The here presented DECT methods B, C and D outperform the commonly used SECT stoichiometric calibration. These methods predict SPR accurately without a bias and within ± 1.2% (68th percentile). This indicates that DECT potentially improves accuracy of range predictions in proton therapy. A validation of these findings using clinical CT images of real tissues is necessary.
SU‐F‐J‐197: A Novel Intra‐Beam Range Detection and Adaptation Strategy for Particle Therapy
Authors: Chen M , Jiang S , Shao Y , Lu W 
Published: July 2016

Purpose:In‐vivo range detection/verification is crucial in particle therapy for effective and safe delivery. The state‐of‐art techniques are not sufficient for in‐vivo on‐line range verification due to conflicts among patient dose, signal statistics and imaging time. We propose a novel intra‐beam range detection and adaptation strategy for particle therapy.Methods:This strategy uses the planned mid‐range spots as probing beams without adding extra radiation to patients. Such choice of probing beams ensures the Bragg peaks to remain inside the tumor even with significant range variation from the plan. It offers sufficient signal statistics for in‐beam positron emission tomography (PET) due to high positron activity of therapeutic dose. The probing beam signal can be acquired and reconstructed using in‐beam PET that allows for delineation of the Bragg peaks and detection of range shift with ease of detection enabled by single‐layered spots. If the detected range shift is within a pre‐defined tolerance, the remaining spots will be delivered as the original plan. Otherwise, a fast re‐optimization using range‐shifted beamlets and accounting for the probing beam dose is applied to consider the tradeoffs posed by the online anatomy. Simulated planning and delivery studies were used to demonstrate the effectiveness of the proposed techniques.Results:Simulations with online range variations due to shifts of various foreign objects into the beam path showed successful delineation of the Bragg peaks as a result of delivering probing beams. Without on‐line delivery adaptation, dose distribution was significantly distorted. In contrast, delivery adaptation incorporating detected range shift recovered well the planned dose.Conclusion:The proposed intra‐beam range detection and adaptation utilizing the planned mid‐range spots as probing beams, which illuminate the beam range with strong and accurate PET signals, is a safe, practical, yet effective approach to address range uncertainty issues in particle therapy.
SU‐F‐J‐200: An Improved Method for Event Selection in Compton Camera Imaging for Particle Therapy
Authors: Mackin D , Beddar S , Polf J , Peterson S , Draeger E 
Published: July 2016

Purpose:The uncertainty in the beam range in particle therapy limits the conformality of the dose distributions. Compton scatter cameras (CC), which measure the prompt gamma rays produced by nuclear interactions in the patient tissue, can reduce this uncertainty by producing 3D images confirming the particle beam range and dose delivery. However, the high intensity and short time windows of the particle beams limit the number of gammas detected. We attempt to address this problem by developing a method for filtering gamma ray scattering events from the background by applying the known gamma ray spectrum.Methods:We used a 4 stage Compton camera to record in list mode the energy deposition and scatter positions of gammas from a Co‐60 source. Each CC stage contained a 4×4 array of CdZnTe crystal. To produce images, we used a back‐projection algorithm and four filteringMethods:basic, energy windowing, delta energy (ΔE), or delta scattering angle (Δθ). Basic filtering requires events to be physically consistent. Energy windowing requires event energy to fall within a defined range. ΔE filtering selects events with the minimum difference between the measured and a known gamma energy (1.17 and 1.33 MeV for Co‐60). Δθ filtering selects events with the minimum difference between the measured scattering angle and the angle corresponding to a known gamma energy.Results:Energy window filtering reduced the FWHM from 197.8 mm for basic filtering to 78.3 mm. ΔE and Δθ filtering achieved the best results, FWHMs of 64.3 and 55.6 mm, respectively. In general, Δθ filtering selected events with scattering angles < 40°, while ΔE filtering selected events with angles > 60°.Conclusion:Filtering CC events improved the quality and resolution of the corresponding images. ΔE and Δθ filtering produced similar results but each favored different events.
SU‐F‐J‐202: Secondary Radiation Measurements for Charged Particle Therapy Monitoring: Fragmentation of Therapeutic He, C and O Ion Beams Impinging On a PMMA Target
Authors: Rucinski A , Battistoni G , Collamati F , Collini F , De Lucia E , Faccini R , Frallicciardi P , Mancini‐Terracciano C , Marafini M , Muraro S , Paramatti R , Patera V , Piersanti L , Pinci D , Russomando A , Sarti A , Sciubba A , Camillocci E Solfaroli , Toppi M , Traini G , Voena C 
Published: July 2016

Purpose:In Charged Particle Therapy (CPT), besides protons, there has been recently a growing interest in 4He, 12C and 16O beams. The secondary radiation produced in the interaction of those beams with a patient could be potentially used for on‐line monitoring of range uncertainties in order to fully exploit the advantages of those light ions resulting from increased Radio Biological Effectiveness, reduced multiple scattering and Oxygen Enhancement Ratio. The study and precise characterization of secondary radiation (beta+, prompt gamma, charged fragments) is the cornerstone of any R&D activity aiming for online monitoring development and purpose of the analysis presented here.Methods:We present the measurements of the secondary radiation generated by He, C and O beams impinging on a beam stopping PMMA target. The data has been collected at the Heidelberg Ionbeam Therapy center (HIT), where several millions of collisions were recorded at different energies, relevant for therapeutical applications.Results:The experimental setup, as well as the analysis strategies will be reviewed. The detected particle fluxes as a function of the primary beam energy and the emission angle with respect to the beam direction will be presented and compared to the results of other available measurements. In addition, the energy spectra and emission shapes of charged secondary particles will be shown and discussed in the context of the primary beam range monitoring technique that is being developed by the ARPG collaboration, within the INSIDE project funded by the Italian research ministry. The implications for dose monitoring applications will be discussed, in the context of the current (or planned) state‐of‐ the‐art detector solutions.Conclusion:The characterization of the radiation produced by 12C, 4He and 16O beams fully supports the feasibility of on‐line range monitoring in the clinical practice of CPT by means of secondary particles detection.
SU‐F‐J‐203: Retrospective Assessment of Delivered Proton Dose in Prostate Cancer Patients Based On Daily In‐Room CT Imaging
Authors: Stuetzer K , Paessler T , Valentini C , Exner F , Thiele J , Hoelscher T , Krause M , Richter C 
Published: July 2016

Purpose:Retrospective calculation of the delivered proton dose in prostate cancer patients based on a unique dataset of daily CT images.Methods:Inter‐fractional motion in prostate cancer patients treated at our proton facility is counteracted by water‐filled endorectal ballon and bladder filling protocol. Typical plans (XiO, Elekta Instruments AB, Stockholm) for 74 Gy(RBE) sequential boost treatment in 37 fractions include two series of opposing lateral double‐scattered proton beams covering the respective iCTV. Stability of fiducial markers and anatomy were checked in 12 patients by daily scheduled in‐room control CT (cCT) after immobilization and positioning according to bony anatomy utilizing orthogonal X‐ray. In RayStation 4.6 (RaySearch Laboritories AB, Stockholm), all cCTs are delineated retrospectively and the treatment plans were recalculated on the planning CT and the registered cCTs. All fraction doses were accumulated on the planning CT after deformable registration. Parameters of delivered dose to iCTV (D98%>95%, D2%<107%), bladder (V75Gy<15%, V70Gy<25%, V65Gy<30%), rectum (V70Gy<10%, V50Gy<40%) and femoral heads (V50Gy<5%) are compared to those in the treatment plan. Intra‐therapy variation is represented in DVH bands.Results:No alarming differences were observed between planned and retrospectively accumulated dose: iCTV constraints were met, except for one patient (D98%=94.6% in non‐boosted iCTV). Considered bladder and femoral head values were below the limits. Rectum V70Gy was slightly exceeded (<11.3%) in two patients. First intra‐therapy variability analysis in 4 patients showed no timedependent parameter drift, revealed strongest variability for bladder dose. In some fractions, iCTV coverage (D98%) and rectum V70Gy was missed.Conclusion:Double scattered proton plans are accurately delivered to prostate cancer patients due to fractionation effects and the applied precise positioning and immobilization protocols. As a result of rare interventions after daily 3D imaging of the first 12 patients, in‐room CT frequency for prostate cancer patients was reduced. The presented study supports this decision.The authors acknowledge the German Federal Ministry for Education and Research for funding the High Precision Radiotherapy Group at the OncoRay ‐ National Center for Radiation Research in Oncology (BMBF‐ 03Z1N51).
SU‐F‐J‐204: Carbon Digitally Reconstructed Radiography (CDRR): A GPU Based Tool for Fast and Versatile Carbonimaging Simulation
Authors: Dias M F , Seco J , Baroni G , Riboldi M 
Published: July 2016

Purpose:Research in carbon imaging has been growing over the past years, as a way to increase treatment accuracy and patient positioning in carbon therapy. The purpose of this tool is to allow a fast and flexible way to generate CDRR data without the need to use Monte Carlo (MC) simulations. It can also be used to predict future clinically measured data.Methods:A python interface has been developed, which uses information from CT or 4DCT and thetreatment calibration curve to compute the Water Equivalent Path Length (WEPL) of carbon ions. A GPU based ray tracing algorithm computes the WEPL of each individual carbon traveling through the CT voxels. A multiple peak detection method to estimate high contrast margin positioning has been implemented (described elsewhere). MC simulations have been used to simulate carbons depth dose curves in order to simulate the response of a range detector.Results:The tool allows the upload of CT or 4DCT images. The user has the possibility to selectphase/slice of interested as well as position, angle…). The WEPL is represented as a range detector which can be used to assess range dilution and multiple peak detection effects. The tool also provides knowledge of the minimum energy that should be considered for imaging purposes. The multiple peak detection method has been used in a lung tumor case, showing an accuracy of 1mm in determine the exact interface position.Conclusion:The tool offers an easy and fast way to simulate carbon imaging data. It can be used for educational and for clinical purposes, allowing the user to test beam energies and angles before real acquisition. An analysis add‐on is being developed, where the used will have the opportunity to select different reconstruction methods and detector types (range or energy).Fundacao para a Ciencia e a Tecnologia (FCT), PhD Grant number SFRH/BD/85749/2012