bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐T‐255: Optimized Supine Craniospinal Irradiation with Image‐Guided and Field Matched Beams
Authors: Jiang Z , Holupka E , Naughton J , Williams H , Galper S , Huang K 
Published: July 2014

Purpose:Conventional craniospinal irradiation (CSI) challenges include dose inhomogeneity at field junctions and position uncertainty due to the field divergence, particular for the two spinal fields. Here we outline a new supine CSI technique to address these difficulties.Methods:Patient was simulated in supine position. The cranial fields had isocenter at C2/C3 vertebral and were matched with 1st spinal field. Their inferior border was chosen to avoid the shoulder, as well as chin from the 1st spine field. Their collimator angles were dependent on asymmetry jaw setting of the 1st spinal field. With couch rotation, the spinal field gantry angles were adjusted to ensure, the inferior border of 1st and superior border of 2nd spinal fields were perpendicular to the table top. The radio‐opaque wire position for the spinal junction was located initially by the light field from an anterior setup beam, and was finalized by the portal imaging of the 1st spinal field. With reference to the spinal junction wire, the fields were matched by positioning the isocenter of the 2nd spinal field. A formula was derived to optimize supine CSI treatment planning, by utilizing the relationship among the Yjaw setting, the spinal field gantry angles, cranial field collimator angles, and the spinal field isocenters location. The plan was delivered with portal imaging alignment for the both cranial and spinal junctions.Results:Utilizing this technique with matching beams, and conventional technique such as feathering and forwarding planning, a homogenous dose distribution was achieved throughout the entire CSI treatment volume including the spinal junction. Placing the spinal junction wire visualized in both spinal portals, allows for precise determination and verification of the appropriate match line of the spine fields.Conclusion:This technique of optimization supine CSI achieved a homogenous dose distributions and patient localization accuracy with image‐guided and matched beams.
SU‐E‐T‐282: Remove Field‐Size Limitation Using the Combination of Collimator Rotation and Jaw Tracking with MLC Aperture
Authors: Shiu A , Chiu R , Cumming D , Chung E , Ragab O , Cui G 
Published: July 2014

Purpose:this study is to investigate the use of variable‐collimators and/or collimator‐rotation to overcome the field‐size limitation on TrueBeamSTX.Methods:The maximum static field‐size is 22‐ × 40‐cm for TrueBeamSTX and 40‐ × 40‐cm for Trilogy. Maximum displacement between adjacent leaf ends at a single carriage position is 15‐cm for TBSTX and 14‐cm for Trilogy. Our current practice for IMRT treatment at Trilogy is as follows, if MLC leaves travel more than 13.5 cm in the MLC traveling direction, the treatment fields will be split at isocenter to two groups of IMRT fields to cover the large tumors. However, TrueBeamSTX is not limited in this way because the jaws can track each segments of the MLC aperture. Radiation treatment plans for ten patients (different tumor sites) treated at Trilogy with one dimension of the field is greater than 22 cm and the other dimension is less than or equal to 22 cm. All the plans will be converted with jaws tracking each segment's MLC aperture. If necessary, the collimator rotation will also be applied for the planning. Comparison of the converted plans with the original clinical plans will be evaluated and based on the following criterion: (1) tumor coverage; (2) dose sparing to the critical structures; and (3) treatment time.Results:The tumor coverage is compatible between two plans. The dose of critical structures was evaluated in the cumulative DVH for spinal cord, parotids, and brainstem at V20 and V5. In all patients, the maximum reduction in V20 was never more than 5% and was typically less than 1%. In V5, the maximum reduction was 10% and 3% respectively. The significant difference can be found in using the variable collimator to shorten the treatment time.Conclusion:We conclude that we will use the variable‐collimator for all IMRT cases on TrueBeamSTX and as a potential backup machine for Trilogy.
SU‐E‐T‐301: Spectral Comparison of the Xoft and Zeiss 50 KVp X‐Ray Systems
Authors: Kelley L , Holt R , Rusch T 
Published: July 2014

Purpose:To compare x‐ray spectra of the 50 kVp Xoft Axxent™ and Zeiss INTRABEAM™ x‐ray sources after filtration by saline‐filled balloons applicators or spherical polymer applicators, respectively.Methods:Measurements were made for 3.5, 4.0 and 5.0 cm diameter applicators using an AmpTek model XR‐100T‐CdTe cadmium telluride spectrometer with 100 μm diameter collimating aperture and model PX4 digital pulse processor. Spectra were then corrected for escape processes using AmpTek XRF‐FP Escape software. Both Axxent and INTRABEAM sources were operated at 50 kV and 40 μA to eliminate pulse saturation. The balloon or spherical applicator was placed in a centering fixture in contact with the collimator cap. The distance through the collimator housing from the applicator surface to the spectrometer's beryllium entrance window was nominally 52mm. Approximately 500,000 counts were collected for each spectrum.Results:Measured spectra in all cases had a broad Bremsstrahlung continuum with subtle differences in characteristic low energy x‐rays lines from the different materials used for the anode thin films and substrates. After corrections for escape events average energies were calculated for spectra emerging from applicators. The average energies were 28.2 ±0.3 keV, 29.0±0.7 keV, and 31.7±0.9 keV for the 3.5, 4.0 and 5.0 cm diameter applicators, respectively. Differences in average energies ranged from 2.0 to 5.6% for these diameters. The mean energies of the spectra are more dependent on balloon size than on the delivery system used.Conclusion:Energy spectra at the surfaces of 3.5, 4.0 and 5.0 cm diameter applicators were measured for the Axxent and INTRABEAM x‐ray systems were using a Cd‐Te spectrometer. The average energies of the two x‐ray systems for comparable applicator sizes were within 5.6%, and as little as 0.6 keV difference for the smaller applicator size.Research sponsored by Xoft, a subsidiary of ICAD
SU‐E‐T‐305: Study of the Eclipse Electron Monte Carlo Algorithm for Patient Specific MU Calculations
Authors: Wang X , Qi S , Agazaryan N , DeMarco J 
Published: July 2014

Purpose:To evaluate the Eclipse electron Monte Carlo (eMC) algorithm based on patient specific monitor unit (MU) calculations, and to propose a new factor which quantitatively predicts the discrepancy of MUs between the eMC algorithm and hand calculations.Methods:Electron treatments were planned for 61 patients on Eclipse (Version 10.0) using the eMC algorithm for Varian TrueBeam linear accelerators. For each patient, the same treatment beam angle was kept for a point dose calculation at dmax performed with the reference condition, which used an open beam with a 15×15 cm2 size cone and 100 SSD. A patient specific correction factor (PCF) was obtained by getting the ratio between this point dose and the calibration dose, which is 1 cGy per MU delivered at dmax. The hand calculation results were corrected by the PCFs and compared with MUs from the treatment plans.Results:The MU from the treatment plans were in average (7.1±6.1)% higher than the hand calculations. The average MU difference between the corrected hand calculations and the eMC treatment plans was (0.07±3.48)%. A correlation coefficient of 0.8 was found between (1‐PCF) and the percentage difference between the treatment plan and hand calculations. Most outliers were treatment plans with small beam opening (< 4 cm) and low energy beams (6 and 9 MeV).Conclusion:For CT‐based patient treatment plans, the eMC algorithm tends to generate a larger MU than hand calculations. Caution should be taken for eMC patient plans with small field sizes and low energy beams. We hypothesize that the PCF ratio reflects the influence of patient surface curvature and tissue inhomogeneity to patient specific percent depth dose (PDD) curve and MU calculations in eMC algorithm.
SU‐E‐T‐323: The FLUKA Monte Carlo Code in Ion Beam Therapy
Authors: Rinaldi I ,   on behalf of the FLUKA collaboration
Published: July 2014

Purpose:Monte Carlo (MC) codes are increasingly used in the ion beam therapy community due to their detailed description of radiation transport and interaction with matter. The suitability of a MC code demands accurate and reliable physical models for the transport and the interaction of all components of the mixed radiation field. This contribution will address an overview of the recent developments in the FLUKA code oriented to its application in ion beam therapy.Methods:FLUKA is a general purpose MC code which allows the calculations of particle transport and interactions with matter, covering an extended range of applications. The user can manage the code through a graphic interface (FLAIR) developed using the Python programming language.Results:This contribution will present recent refinements in the description of the ionization processes and comparisons between FLUKA results and experimental data of ion beam therapy facilities. Moreover, several validations of the largely improved FLUKA nuclear models for imaging application to treatment monitoring will be shown. The complex calculation of prompt gamma ray emission compares favorably with experimental data and can be considered adequate for the intended applications. New features in the modeling of proton induced nuclear interactions also provide reliable cross section predictions for the production of radionuclides. Of great interest for the community are the developments introduced in FLAIR. The most recent efforts concern the capability of importing computed‐tomography images in order to build automatically patient geometries and the implementation of different types of existing positron‐emission‐tomography scanner devices for imaging applications.Conclusion:The FLUA code has been already chosen as reference MC code in many ion beam therapy centers, and is being continuously improved in order to match the needs of ion beam therapy applications.Parts of this work have been supported by the European FP7 project ENVISION (grant agreement no. 241851).
SU‐F‐BRF‐12: Investigating Dosimetric Effects of Inter‐Fraction Deformation in Lung Cancer Stereotactic Body Radiotherapy (SBRT)
Authors: Jia J , Tian Z , Gu X , Yan H , Jia X , Jiang S 
Published: July 2014

Purpose:We studied dosimetric effects of inter‐fraction deformation in lung stereotactic body radiotherapy (SBRT), in order to investigate the necessity of adaptive re‐planning for lung SBRT treatments.Methods:Six lung cancer patients with different treatment fractions were retrospectively investigated. All the patients were immobilized and localized with a stereotactic body frame and were treated under cone‐beam CT (CBCT) image guidance at each fraction. We calculated the actual delivered dose of the treatment plan using the up‐to‐date patient geometry of each fraction, and compared the dose with the intended plan dose to investigate the dosimetric effects of the inter‐fraction deformation. Deformable registration was carried out between the treatment planning CT and the CBCT of each fraction to obtain deformed planning CT for more accurate dose calculations of the delivered dose. The extent of the inter‐fraction deformation was also evaluated by calculating the dice similarity coefficient between the delineated structures on the planning CT and those on the deformed planning CT.Results:The average dice coefficients for PTV, spinal cord, esophagus were 0.87, 0.83 and 0.69, respectively. The volume of PTV covered by prescription dose was decreased by 23.78% on average for all fractions and all patients. For spinal cord and esophagus, the volumes covered by the constraint dose were increased by 4.57% and 3.83%. The maximum dose was also increased by 4.11% for spinal cord and 4.29% for esophagus.Conclusion:Due to inter‐fraction deformation, large deterioration was found in both PTV coverage and OAR sparing, which demonstrated the needs for adaptive re‐planning of lung SBRT cases to improve target coverage while reducing radiation dose to nearby normal tissues.
SU‐F‐18C‐01: Minimum Detectability Analysis for Comprehensive Sized Based Optimization of Image Quality and Radiation Dose Across CT Protocols
Authors: Smitherman C , Chen B , Samei E 
Published: July 2014

Purpose:This work involved a comprehensive modeling of task‐based performance of CT across a wide range of protocols. The approach was used for optimization and consistency of dose and image quality within a large multi‐vendor clinical facility.Methods:150 adult protocols from the Duke University Medical Center were grouped into sub‐protocols with similar acquisition characteristics. A size based image quality phantom (Duke Mercury Phantom) was imaged using these sub‐protocols for a range of clinically relevant doses on two CT manufacturer platforms (Siemens, GE). The images were analyzed to extract task‐based image quality metrics such as the Task Transfer Function (TTF), Noise Power Spectrum, and Az based on designer nodule task functions. The data were analyzed in terms of the detectability of a lesion size/contrast as a function of dose, patient size, and protocol. A graphical user interface (GUI) was developed to predict image quality and dose to achieve a minimum level of detectability.Results:Image quality trends with variations in dose, patient size, and lesion contrast/size were evaluated and calculated data behaved as predicted. The GUI proved effective to predict the Az values representing radiologist confidence for a targeted lesion, patient size, and dose. As an example, an abdomen pelvis exam for the GE scanner, with a task size/contrast of 5‐mm/50‐HU, and an Az of 0.9 requires a dose of 4.0, 8.9, and 16.9 mGy for patient diameters of 25, 30, and 35 cm, respectively. For a constant patient diameter of 30 cm, the minimum detected lesion size at those dose levels would be 8.4, 5, and 3.9 mm, respectively.Conclusion:The designed CT protocol optimization platform can be used to evaluate minimum detectability across dose levels and patient diameters. The method can be used to improve individual protocols as well as to improve protocol consistency across CT scanners.
SU‐F‐18C‐06: Prospective Patient Evaluation of Iterative Reconstruction in Radiation Oncology
Authors: Price R , Vance S , Cattaneo R , Schultz L , Elshaikh M , Chetty I , Glide‐Hurst C 
Published: July 2014

Purpose:This work incorporates iterative reconstruction (IR) into a dose reduction study to characterize image quality metrics, delineation, and dosimetric assessment, with the goal of reducing imaging dose in Radiation Oncology.Methods:Three‐dimensional noise power spectrum (NPS) analysis characterized noise magnitude/texture (120 kVp, 50–200 mAs, IR levels 1–6 yielding noise reduction of 0.89–0.55 compared to filtered backprojection (FBP)). Task‐specific Modulation Transfer Functions (MTFtask) were characterized across varied subject contrasts. A prospective dose reduction study (500 to 150 mAs) was conducted for 12 patients (43 inter‐fraction CTs) for high‐dose rate brachytherapy. Three physicians performed qualitative image assessment between full‐dose FBP (FD‐FBP, 500 mAs), low‐dose FBP (LD‐FBP, 150–250 mAs), and low‐dose IRL5‐6 (LD‐IR) scans for image noise, cuff/bladder interface detectability, spatial resolution, texture, and segmentation confidence. Comparisons between LD‐FBP and LD‐IR were conducted for the following metrics: delineation (bladder and rectum evaluated via overlap indices (OI) and Dice similarity coefficients (DSC)), noise, boundary changes, dose calculation, and digitally reconstructed radiographs (DRRs).Results:NPS showed ∼50% reduction in noise magnitude and ∼0.1 1/mm spatial frequency shift with IRL6. The largest MTFtask decrease between FBP and IR was 0.08 A.U. Qualitative patient image evaluation revealed LD‐IR was equivalent or slightly worse than FD‐FBP, and superior to LD‐FBP for all metrics except low contrast interface and texture. The largest CT number discrepancy from FBP occurred at a bone/tissue interface using IRL6 (−1.2 ± 4.9 HU (range: −17.6 – 12.5 HU)). No significant contour differences (OIs and DSCs = 0.85 – 0.95) and dose calculation discrepancy (<0.02%) were observed. DRRs preserved anatomical detail and demonstrated <2% difference in intensity between LD‐FBP and LD‐IRL6.Conclusion:While phantom analysis showed slight noise texture differences with IR, patient results revealed that image quality, contouring ability, and dosimetric parameters were not adversely affected, thus support integrating IR into treatment planning.Research supported in part by a grant from Philips HealthCare.
SU‐F‐18C‐07: Automated CT QC Program with Analytics, Archival, and Notification Capabilities
Authors: Winslow J , Christianson O , Samei E 
Published: July 2014

Purpose:Tracking metrics over time is a well‐established means of establishing a quality control program. The number of metrics followed and testing frequency is limited by available resources. Automating the image analysis and data archival of a QC program enables objective and efficient tracking of performance metrics. The purpose of this study was to develop such a QC method and to assess its utility at a large clinical facility.Methods:The QC program at our institution is based on the acquisition of daily water‐phantom scans, and biweekly ACR‐phantom scans for each CT system. We developed a QC program to analyze these data. The QC software operates on the images sent directly to our server. The relevant information from DICOM headers was extracted, data analyzed, and a database was populated. The measurements performed on the waterphantom included water CT‐number, uniformity, noise, and artifact. The measurements performed on the ACR‐phantom included the MTF, NPS, detectability, artifact, uniformity, CNR, and the CT‐numbers for water, polyethylene, bone, air, and acrylic. Email notifications and criteria limits were directly based upon ACR accreditation requirements and developing threshold values.Results:Across ten clinical CT scanners, the daily water CT‐number was −0.2+/−1.4 HU(mean+/‐standard deviation). The corresponding numbers for 10%MTF, uniformity, CNR squared normalized to CTDI, and detectability squared normalized to CTDI were 0.69+/−0.01 (1/mm), 0.93+/−0.29, 0.06+/−0.02 (1/mGy), and 3.3+/−0.7 (1/mGy), respectively. For all ACR‐phantom inserts, the largest standard deviation for any individual scanner was 1.9 HU. Artifact analysis triggers successfully identified problematic images.Conclusion:Automating image analysis allows one to frequently track meaningful metrics that would be impractical to follow otherwise. System inconsistencies are more likely to be identified and corrected earlier. Much tighter system specific criteria limits are possible.
SU‐F‐18C‐11: Diameter Dependency of the Radial Dose Distribution in a Long Polyethylene Cylinder
Authors: Bakalyar D , Feng W , McKenney S 
Published: July 2014

Purpose:The radial dose distribution in the central plane of a long cylinder following a long CT scan depends upon the diameter and composition of the cylinder. An understanding of this behavior is required for determining the spatial average of the dose in the central plane. Polyethylene, the material for construction of the TG200/ICRU phantom (30 cm in diameter) was used for this study. Size effects are germane to the principles incorporated in size specific dose estimates (SSDE); thus diameter dependency was explored as well.Method:ssuming a uniform cylinder and cylindrically symmetric conditions of irradiation, the dose distribution can be described using a radial function. This function must be an even function of the radial distance due to the conditions of symmetry. Two effects are accounted for: The direct beam makes its weakest contribution at the center while the contribution due to scatter is strongest at the center and drops off abruptly at the outer radius. An analytic function incorporating these features was fit to Monte Carlo results determined for infinite polyethylene cylinders of various diameters. A further feature of this function is that it is integrable.Results:Symmetry and continuity dictate a local extremum at the center which is a minimum for the larger sizes. The competing effects described above can Resultin an absolute maximum occurring between the center and outer edge of the cylinders. For the smallest cylinders, the maximum dose may occur at the center.Conclusion:An integrable, analytic function can be used to characterize the radial dependency of dose for cylindrical CT phantoms of various sizes. One use for this is to help determine average dose distribution over the central cylinder plane when equilibrium dose has been reached.
MO‐A‐18C‐01: Proton Therapy I: Basics of Proton Therapy
Authors: Arjomandy B , Sahoo N , Pankuch M 
Published: July 2014

The goal of this session is to introduce the audience to the physics, dosimetry and treatment planning procedures used in proton therapy. The course material covers the basic physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for scattered and scanning proton beams. It will include the requirements for dosimetry measurements and present the equipment needed for commissioning of proton beams for clinical use and quality assurance checks as well as methods used for proton beam calibration and dose verification of patient treatment fields. The session covers the treatment planning strategies for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. Challenges involved in the motion management in proton therapy will also be discussed.Learning Objectives:

Gain knowledge on physics, dosimetry, treatment planning and quality assurance for proton therapy.
Understand the uncertainties associated with proton therapy and currently used strategies for their mitigation in treatment planning.