bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐T‐776: Use of Quality Metrics for a New Hypo‐Fractionated Pre‐Surgical Mesothelioma Protocol
Authors: Richardson S , Mehta V 
Published: June 2015

Purpose:The “SMART” (Surgery for Mesothelioma After Radiation Therapy) approach involves hypo‐fractionated radiotherapy of the lung pleura to 25Gy over 5 days followed by surgical resection within 7. Early clinical results suggest that this approach is very promising, but also logistically challenging due to the multidisciplinary involvement. Due to the compressed schedule, high dose, and shortened planning time, the delivery of the planned doses were monitored for safety with quality metric software.Methods:Hypo‐fractionated IMRT treatment plans were developed for all patients and exported to Quality Reports™ software. Plan quality metrics or PQMs™ were created to calculate an objective scoring function for each plan. This allows for an objective assessment of the quality of the plan and a benchmark for plan improvement for subsequent patients. The priorities of various components were incorporated based on similar hypo‐fractionated protocols such as lung SBRT treatments.Results:Five patients have been treated at our institution using this approach. The plans were developed, QA performed, and ready within 5 days of simulation. Plan Quality metrics utilized in scoring included doses to OAR and target coverage. All patients tolerated treatment well and proceeded to surgery as scheduled. Reported toxicity included grade 1 nausea (n=1), grade 1 esophagitis (n=1), grade 2 fatigue (n=3). One patient had recurrent fluid accumulation following surgery. No patients experienced any pulmonary toxicity prior to surgery.Conclusion:An accelerated course of pre‐operative high dose radiation for mesothelioma is an innovative and promising new protocol. Without historical data, one must proceed cautiously and monitor the data carefully. The development of quality metrics and scoring functions for these treatments allows us to benchmark our plans and monitor improvement. If subsequent toxicities occur, these will be easy to investigate and incorporate into the metrics. This will improve the safe delivery of large doses for these patients.
SU‐E‐T‐777: Use of Tennis Racket and Air Gap Between the Body and Carbon Fiber Couch for Skin Sparing in Radiation Therapy of Prone Breast
Authors: Lief E 
Published: June 2015

Purpose:To reduce the skin dose from the carbon fiber couch scatter in radiation treatment of breast cancer in the prone position. If this issue is not addressed, the prone breast touching the solid carbon fiber couch can absorb significant dose to the skin and cause the skin reaction.Methods:1. Use of “tennis racket” instead of the solid couch. To check this hypothesis, we measured the dose at the depth of 5 mm in solid water phantom placed on the couch, using a Farmer chamber. A plan for a patient with 6MV beams, gantry angles of 113 and 286 degrees Varian scale was used. It was found that treatment with “tennis racket” instead of the solid carbon fiber couch reduces the surface dose by 5–7%, depending on the beam direction. 2. Use of the air gap between the couch and the body was analyzed using radiochromic film on the surface of the solid water phantom 10 cm thick. Initially the phantom was placed on the couch with the film sandwiched in between. Two fields at the angles of 135 and 315 degrees were used. The measurements were repeated for the air gap of 2 and 5 cm and 6 and 15 MV beams.Results:It was found that a 2‐cm gap decreased the surface dose by 3% for a 6 MV beam and by 5.5% for a 15 MV beam. A 5‐cm gap reduced the dose by 9% for 6 MV and 13.5% for 15 MV.Conclusion:Use of both methods (combined if possible) can significantly reduce the surface dose in radiation therapy of the prone breast and possible skin reaction. We plan to explore dependence of the dose reduction upon the angle of incidence.
SU‐E‐T‐779: Use of the Varian Eclipse Scripting API to Collect Volumetric Modulated Arc Therapy Plan Data
Authors: Janes L A , Anderson C J R , Matuszak M M , Roberts D A , Moran J M , Younge K C 
Published: June 2015

Purpose:We have introduced an automated script into the VMAT planning process to visualize and understand plan characteristics in comparison to past plans including number of arcs, arc weighting, and arc modulation.Methods:Varian's Eclipse Scripting Application Programming Interface (API) was used to create a script to compare new VMAT plans to past clinical VMAT plans, during and after the planning process. A graphical user interface was developed to display the results for straightforward analysis and interpretation. Analysis of previously treated plans from the past two years was used to design the data layout and organizational categories. In addition, a method was developed to automatically update the script as new plans are generated.Results:Plan data are represented in a histogram format, which is updateable with additional treatment plans by uploading a comma separated value file with the new patients’ information. The current script has the ability to display the number of arcs, the MU per arc and per control point, and the degree of modulation in each control point compared to all past VMAT plans. The user can filter the histogram by treatment site to easily compare the current plan to other plans of the same site, or to all sites. The histogram also contains the total number of plans being compared, the average value of the metric being examined, and the standard deviation of that metric. The script has been built with a modular framework such that additional plan metrics can be added as they are developed.Conclusions:The script interface provides easy to understand feedback on quality metrics of VMAT plans compared to other plans for the same body site. The script enables dosimetrists to ensure consistent plan quality, and assists physicists in checking plans prior to pre‐treatment quality assurance measurements.This project was supported in part by P01CA059827.
SU‐E‐T‐780: Use Robustness Optimization (RO) Method to Improve the Planning Efficiency for Pencil Beam Scanning Cranial Spinal Irradiation
Authors: Ding X , Traneus E , Zhang J , Lin H , Zhai H , Rosen L , Wu H 
Published: June 2015

Purpose:We evaluate the feasibility of using robustness optimization (RO) function to improve the planning efficiency of pencil beam scanning (PBS) craniospinal irradiation (CSI) with gradient matching technique.Methods:A CSI patient was planned with 2 lateral brain fields and 4 posterior fields to cover the entire spine to maximal field of 24 cm × 20 cm on a compact PBS gantry, ProteusONE. CSI plans were generated using traditional volumetric gradient dose optimization (VGDO) and robustness optimization (RO) method respectively. In traditional VGDO, besides the sectioned spine target volumes, gradient volume (GV) were generated as 4 equally spaced structures e.g. 80%, 60%, 40%, and 20% of prescription dose. In RO method, only sectioned spine target volumes with an overlap of 4cm were created. In the robustness optimization settings, 5mm uncertainty in superior and inferior direction was defined for auto gradient optimization. Dosimetric metrics of conformity number (CN), homogeneity index (HI), and maximal cord doses were compared in Raystation version 4.6.100.6.Results:In VGDO method, total 16 GV structures and five 100% dose level target structures were contoured compared to total 5 target structures in RO method which saves 30 min in contour. With the same PTV coverage (95% volume receive 30.6Gy prescription dose), maximum cord dose is 32.64Gy in VGDO and 31.94Gy in RO. HI is 1.03 and 1.04 for VGDO and RO respectively. CN is 0.93 and 0.94 for VGDO and RO respectively.Conclusions:The dosimetric comparison demonstrated both methods are equivalent in terms of plan quality. With robust optimization for CSI gradient matching, it efficiently reduces the amount of planning target contour structure by factor of 4 and thus improves the planning efficiency especially for 4 or more gradient junction area.
SU‐E‐T‐784: Using MLC Log Files for Daily IMRT Delivery Verification
Authors: Stathakis S , Defoor D , Linden P , Kirby N , Papanikolaou N 
Published: June 2015

Purpose:To verify daily intensity modulated radiation therapy (IMRT) treatments using multi‐leaf collimator (MLC) log files.Methods:The MLC log files from a NovalisTX Varian linear accelerator were used in this study. The MLC files were recorded daily for all patients undergoing IMRT or volumetric modulated arc therapy (VMAT). The first record of each patient was used as reference and all records for subsequent days were compared against the reference. An in house MATLAB software code was used for the comparisons. Each MLC log file was converted to a fluence map (FM) and a gamma index (γ) analysis was used for the evaluation of each daily delivery for every patient. The tolerance for the gamma index was set to 2% dose difference and 2mm distance to agreement while points with signal of 10% or lower of the maximum value were excluded from the comparisons.Results:The γ between each of the reference FMs and the consecutive daily fraction FMs had an average value of 99.1% (ranged from 98.2 to 100.0%). The FM images were reconstructed at various resolutions in order to study the effect of the resolution on the γ and at the same time reduce the time for processing the images. We found that the comparison of images with the highest resolution (768×1024) yielded on average a lower γ (99.1%) than the ones with low resolution (192×256) (γ 99.5%).Conclusion:We developed an in‐house software that allows us to monitor the quality of daily IMRT and VMAT treatment deliveries using information from the MLC log files of the linear accelerator. The information can be analyzed and evaluated as early as after the completion of each daily treatment. Such tool can be valuable to assess the effect of MLC positioning on plan quality, especially in the context of adaptive radiotherapy.
SU‐E‐T‐788: Validating the Use of Surfacing Mapping Tools for Motion and Irregular Breathing Pattern Monitoring On Lung SBRT Patients
Authors: Xie X , Cao D , Mehta V , Shepard D 
Published: June 2015

Validating the Use of Surfacing Mapping Tools for Monitoring Motion and Irregular Breathing Patterns for Lung SBRT PatientsPurpose:In this study, we have examined the utility of surface mapping in the treatment of lung SBRT patients. We examined the extent to which intra‐fraction patient motion and irregular breathing patterns impact the accuracy of treatment deliveries.Materials and Methods:The C‐RAD Catalyst, an optical surface mapping system was used to track the intra‐fractional isocenter motion of five lung SBRT patients treated with VMAT. A respiratory tracking tool was used to track the breathing pattern of these patients and to correlate the breathing pattern to the isocenter motion.Results:For 2 of the 5 patients the isocenter displacement exceeding the 5mm planning margin for a portion of the treatment delivery with the time outside of tolerance at 2.2%, and 2.5%.Conclusions:1) Breathing patterns may change between different fractions for the same patient; 2)Breathing patterns can change from the beginning to the end of the same fraction; 3) Not only amplitude, but also the baseline of breathing may change during an individual fraction; 4) We cannot predict which patients will have a stable isocenter in treatment even after the simulation study; and5)Real‐time motion monitoring with surface‐mapping tools and respiratory gating (free breathing or breath‐hold) may provide clinically valuable solution in motion management for lung SBRT patients.The research is supported by funding from Elekta.
SU‐E‐T‐792: Validation of a Secondary TPS for IROC‐H Recalculation of Anthropomorphic Phantoms
Authors: Kerns J , Howell R , Followill D , Melancon A , Stingo F , Kry S 
Published: June 2015

Purpose:To validate a secondary treatment planning system (sTPS) for use by the Imaging & Radiation Oncology Core‐Houston (IROC‐H). The TPS will recalculate phantom irradiations submitted by institutions to IROC‐H and compare plan results of the institution to the sTPS.Methods:In‐field dosimetric data was collected by IROC‐H for numerous linacs at 6, 10, 15, and 18 MV. The data was aggregated and used to define reference linac classes; each class was then modeled in the sTPS (Mobius3D) by matching the in‐field characteristics. Fields used to collect IROC‐H data were recreated and recalculated using Mobius3D. The same dosimetric points were measured in the recalculation and compared to the initial collection data. Additionally, a 6MV Monte Carlo beam configuration was used to compare penumbrae in the Mobius3D models. Finally, a handful of IROC‐H head and neck phantoms were recalculated using Mobius3D.Results:Recalculation and quantification of differences between reference data and Mobius3D values resulted in a relative matching score of 12.45 (0 is a perfect match) for the default 6MV Mobius3D beam configuration. By adjusting beam configuration options, iterations resulted in scores of 8.45, 6.32, and 3.52, showing that customization could have a dramatic effect on beam configuration. After in‐field optimization, penumbra was compared between Monte Carlo and Mobius3D for the reference fields. For open jaw fields, FWHM field widths and penumbra widths were different by <0.6 and <1mm respectively; for MLC open fields the penumbra widths were up to 1.5mm different. Phantom recalculations showed good agreement, having an average of 0.6% error per beam.Conclusion:A secondary TPS has been validated for simple irradiation geometries using reference data collected by IROC‐H. The beam was customized to the reference data iteratively and resulted in a good match. This system can provide independent recalculation of phantom plans based on independent reference data.
SU‐E‐T‐797: Variations of Cardiac Dose at Different Respiratory Status in CyberKnife M6â„¢ Treatment Plans for Accelerated Partial Breast Irradiation (APBI)
Authors: Long S , Shang C , Evans G , Leventouri T 
Published: June 2015

Purpose:Cyberknife robotic assisted radiation delivery has become a choice for accelerated breast RT, while a slightly increased cardiac dose has been reported. The dose dynamics throughout the respiration cycle has scarcely been explored. This study was designed to investigate the dose changes at each respiratory phase or status during respiration cycle.Methods:Six patients with 4DCT studies and six patients with a pair of free‐breathing and deep breath‐hold CT sets were used for dosimetry comparisons. 4DCT sets were obtained by Siemens™ CT and its respiratory gating system, comprising of 8 phases. Standard APBI plan at 340 cGy was done per fraction per NSABP B‐39/RTOG 0413 and modulated with Cyberknife M6™ on MultiPlan™5.1.2. For the purpose of this study, the tumor volume was outlined in the media‐lower quadrant of the left breast.Results:Except for D5cc in plans with 4DCT, cardiac doses are significantly different between respiratory phases in well inhaled breathing phases, and more significantly in plans with BH CT. Mean cardiac doses in 100% inhalation phase were often found to be 5–15% (p< 0.02) less than those in other phases.Conclusion:Although ineligible cardiac doses are noted in APBI plans using 4D free‐breathing CT and instantaneous free breathing CT series, a reduction in cardiac dose was seen for the well‐inhaled phases. This provides practical guidance for cardiac dose reduction applicable with CK M6 APBR.
SU‐E‐T‐798: Verification of 3DVH Dose Distribution Before Clinical Implementation for Patient‐Specific IMRT QA
Authors: McFadden D 
Published: June 2015

Purpose:In recent years patient‐specific IMRT QA has transitioned from film and chamber measurements to beam‐by‐beam 2D array measurements. 3DVH takes this transition a step further by estimating the 3D dose distribution delivered using 2D per beam diode array measurements. In this study, the 3D dose distribution generated by 3DVH is compared to film and chamber measurements. In addition, the accuracy ROI volume and error detection is investigated.Methods:Composite film and ion chamber measurements in a solid water phantom were performed for 9 IMRT PINNACLE patient plans for 4 treatment sites. The film and chamber measurements were compared to the dose distribution predicted by 3DVH using MAPCHECK2 per beam measurements. The absolute point dose measurement (CAX) was extracted from the predicted 3DVH and PINNACLE dose distribution and was compared by taking the ratio of measured to predicted doses. The dose distribution measured with film was compared to the distribution in the corresponding plane (AX, SAG, COR) extracted from predicted dose distribution by 3DVH and PINNACLE using a 2D gamma analysis. Gamma analysis was performed with 2% dose, 2 mm DTA, 20% threshold, and global normalization. In addition, the percent difference between 3DVH and PINNACLE ROI volumes was calculated.Results:The average ratio of the measured point dose vs the 3DVH predicted dose was 1.017 (σ=0.011). The average gamma passing rate for measured vs 3DVH dose distributions was 95.1% (σ=2.53%). The average percent difference of 3DVH vs PINNACLE ROI volume was 2.29% (σ=2.5%).Conclusion:The dose distributions predicted by 3DVH using MAPCHECK2 measurements are the same as the distributions that would have been obtained using film and chamber. The ROI volumes used in 3DVH are not an exact match to those in PINNACLE; the effect requires more investigation. The accuracy of error detection by 3DVH is currently being investigated.
SU‐E‐T‐804: Verification of the BJR‐25 Method of KQ Determination for CyberKnife Absolute Dosimetry
Authors: Gersh J , Willett B 
Published: June 2015

Purpose:Absolute calibration of the CyberKnife is performed using a 6cm‐diameter cone defined at 80cm SAD. Since kQ is defined using PDD values determined using 10×10 cm fields at 100cm SSD, the PDD must be corrected in order to correctly apply the quality conversion factor. The accepted method is based on equivalent field‐size conversions of PDD values using BJR25. Using the new InCise MLC system, the CK is capable of generating a rectangular field equivalent to 10×10 cm square field. In this study, a comparison is made between kQ values determined using the traditional BJR25 method and the MLC method introduced herein.Methods:First, kQ(BJR) is determined: a PDD is acquired using a 6cm circular field at 100cm SSD, its field size converted to an equivalent square, and PDD converted to a 10×10cm field using the appropriate BJR25 table. Maintaining a consistent setup, the collimator is changed, and the MLC method is used. Finally, kQ is determined using PDDs acquired with a 9.71×10.31cm at 100cm SSD. This field is produced by setting the field to a size of 7.77×8.25cm (since it is defined at 80cm SAD). An exact 10×10cm field since field size is relegated to increments of its leaf width (0.25cm). This comparison is made using an Exradin A1SL, IBA CC08, IBA CC13, and an Exradin A19. For each detector and collimator type, the beam injector was adjusted to give 5 different beam qualities; representing a range of clinical systems.Results:Averaging across all beam qualities, kQ(MLC) differed from kQ(BJR) by less than 0.15%. The difference between the values increased with detector volume.Conclusion:For CK users with standard cone collimators, the BJR25 method has been verified. For CK users the MLC system, a technique is described to determine kQ.Primary author is the President/Owner of Spectrum Medical Physics, LLC, a company which maintains contracts with Siemens Healthcare and Standard Imaging, Inc.
SU‐E‐T‐805: Verification of the Simplified Monte Carlo Method for Simulation in An Inhomogeneous Phantom
Authors: Mizutani S , Takada Y , Kohno R , Hotta K , Akimoto T 
Published: June 2015

Purpose:A simplified Monte Carlo (SMC) method has been developed to obtain fast and accurate dose calculation in heterogeneous tissues to improve the accuracy of dose calculation. We have applied the SMC method to calculation of dose kernels for the pencil beam scanning. While the SMC method tracks individual primary protons in medium, it simplifies the dose calculation by using a measured depth‐dose distribution instead of considering nuclear reactions and tracking secondary particles. To verify the accuracy of SMC calculation, we compared a dose‐calculation Result using the SMC method with that using the Full Monte Carlo (FMC) method in an inhomogeneous phantom.Methods:As a model of the inhomogeneous media, we considered a phantom complied of a rectangular acrylic block of size 150*300*200 mm 3 immersed in water within a virtual container with a size of 300*300*400 mm3.Results:We found excellent agreement of overall dose distributions between the SMC and FMC methods. As for the laterally integrated depth‐dose distributions, slight difference was found in front of the second Bragg‐Peak between the two algorithms. While it took 25717.0 s on 2.7 GHz Intel Core i7 for the FMC method to complete the calculation, it took 15.4 s for the SMC method to complete it. The SMC method can calculate the dose distribution approximately 1675 times faster than the FMC method.Conclusion:The dose distribution obtained by SMC method agreed well that obtained by the FMC method in a simple inhomogeneous phantom. In contrast, calculation time by the SMC method has been reduced by three orders in magnitude compared with the FMC method.
SU‐E‐T‐810: Volumetric Modulated Arc Therapy and Conventional Intensity‐Modulated Radiotherapy for Non‐Small‐Cell Lung Cancer with Simultaneously Integrated Boost Radiation Therapy: A Planning Comparison Study
Authors: Liu T , Chen J , Zhang G , Sun T 
Published: June 2015

Purpose:To compare and analyze the characteristics of intensity‐modulated arc therapy(IMAT) versus fixed‐gantry intensity‐modulated radiotherapy(IMRT) in treatment of non‐small‐cell lung cancer.Methods:Twelve patients treated in our radiotherapy center were selected for this study. The patient subsequently underwent 4D‐CT simulation.Margins of 5mm and 10mm were added to the ITV to generate the CTV and PTV respectively. Three treatment plans (IMRT,one single arc (RA1),double arcs (RA2))were generated with Eclipse ver.8.6 planning systems. Using a dose level of 75Gy in 15fractions to the ITV,60Gy in 15fractions to the CTV and 45Gy in 15fractions to the PTV respectively. The target and normol tissue volumes were compared,as were the dosimetry parameters.Results:There were no significant differences in CI of ITV,PTV,HI of ITV,CTV and PTV, V5,V10,V15,V20,V25,V30,V45,V50 of total‐lung and mean lung dose (all p>0.05). However, the differences were significant in terms of CI of CTV,V5 of B‐P (all p<0.05). On the MU, IMRT=1540MU,RA1=1006 MU and RA2=1096 MU. (F=12.00,P=0.000).On the treatment time, IMRT= 13.5min,RA1= 1.5min,and RA2=2.5 min (F= 30.11,P=0.000 ).Conclusion:IMAT is equal to IMRT in dosimetril evaluation. Due to much less Mu and delivery time,IMAT is an ideal technique in treating patients by reduceing the uncomfortable influnce which could effect the treatment.