bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐T‐113: An Unified Imaging and Robotic Couch Quality Assurance Procedure and Automation Software
Authors: Schreibmann E , Elder E 
Published: June 2015

Purpose:To introduce a quality assurance (QA) procedure for the robotic 6DoF couches integrates the couch and imaging components QA procedures into a simple workflow.Method:Current QA procedure for the imaging systems is to carefully align a phantom at isocenter and measure in images acquired using the on‐board imaging (OBI) system if the phantom appears aligned with the isocenter. For the robotic couches a complementary procedure offsets a phantom from to measure the couch's ability to reposition the phantom at isocenter. We propose a two‐in –one procedure that starts with a phantom displaced with random positions and orientation and asks the imaging system to align it back at isocenter. Accuracy is measured by comparing the repositioned phantom againts the treatment field. A software module was also implemented to analyze, quantify and report the results.Results:The procedure has been implemented clinically using a SRS calibration phantom (VisionRT, London, UK) and the automated software version that is able to detect errors of less than 0.1 mm or 0.1 degrees. The software detects the markers locations with a combination of contouring and intensity filters to compute the shifts/rotations needed to reposition the phantom to it's ideal location using a interactive closest point algorithm to match markers segmentations as extracted from imaging with a mesh representation of their expected location according to the phantom specifications. Once the shifts are send to the couch for repositioning, the procedure is repeated to measure the residual error in imaging to measure robotic couch repositioning accuracy and the phantom location against the graticule is verified.Conclusions:A simplified QA procedure and the associated software are presented to streamline the quality assurance of imaging and 6D couch components into a single, easy‐to‐use procedure.
SU‐E‐T‐114: Analysis of MLC Errors On Gamma Pass Rates for Patient‐Specific and Conventional Phantoms
Authors: Sterling D , Ehler E 
Published: June 2015

Purpose:To evaluate whether a 3D patient‐specific phantom is better able to detect known MLC errors in a clinically delivered treatment plan than conventional phantoms. 3D printing may make fabrication of such phantoms feasible.Methods:Two types of MLC errors were introduced into a clinically delivered, non‐coplanar IMRT, partial brain treatment plan. First, uniformly distributed random errors of up to 3mm, 2mm, and 1mm were introduced into the MLC positions for each field. Second, systematic MLC‐bank position errors of 5mm, 3.5mm, and 2mm due to simulated effects of gantry and MLC sag were introduced. The original plan was recalculated with these errors on the original CT dataset as well as cylindrical and planar IMRT QA phantoms. The original dataset was considered to be a perfect 3D patient‐specific phantom. The phantoms were considered to be ideal 3D dosimetry systems with no resolution limitations.Results:Passing rates for Gamma Index (3%/3mm and no dose threshold) were calculated on the 3D phantom, cylindrical phantom, and both on a composite and field‐by‐field basis for the planar phantom. Pass rates for 5mm systematic and 3mm random error were 86.0%, 89.6%, 98% and 98.3% respectively. For 3.5mm systematic and 2mm random error the pass rates were 94.7%, 96.2%, 99.2% and 99.2% respectively. For 2mm systematic error with 1mm random error the pass rates were 99.9%, 100%, 100% and 100% respectively.Conclusion:A 3D phantom with the patient anatomy is able to discern errors, both severe and subtle, that are not seen using conventional phantoms. Therefore, 3D phantoms may be beneficial for commissioning new treatment machines and modalities, patient‐specific QA and end‐to‐end testing.
SU‐E‐T‐116: Analysis of Patient Specific VMAT QA Passing Rates with Delta4 for Matched Machines
Authors: Keller J , Hardin M , Giaddui T , Kremmel E , Peng C , Doyle L , Yu Y , Harrison A 
Published: June 2015

Purpose:To test whether unified vendor specified beam conformance for matched machines implies volumetric modulated arc radiotherapy(VMAT) delivery consistency.Methods:Twenty‐two identical patient QA plans, eleven 6MV and eleven 15MV, were delivered to the Delta⁴(Scandidos, Uppsala, Sweden) on two Varian TrueBEAM matched machines. Sixteen patient QA plans, nine 6 MV and seven 10 MV, were delivered to Delta⁴ on two Elekta Agility matched machines. The percent dose deviation(%DDev), distance‐to‐agreement(DTA), and the gamma analysis(γ) were collected for all plans and the differences in measurements were tabulated between matched machines. A paired t‐test analysis of the data with an alpha of 0.05 determines statistical significance. Power(P) was calculated to detect a difference of 5%; all data except Elekta %DDev sets were strong with above a 0.85 power.Results:The average differences for Varian machines (%DDev, DTA, and γ) are 6.4%, 1.6% and 2.7% for 6MV, respectively, and 8.0%, 0.6%, and 2.5% for 15MV. The average differences for matched Elekta machines (%DDev, DTA, and γ) are 10.2%, 0.6% and 0.9% for 6 MV, respectively, and 7.0%, 1.9%, and 2.8% for 10MV.A paired t‐test shows for Varian the %DDev difference is significant for 6MV and 15MV(p‐value6MV=0.019, P6MV=0.96; p‐value15MV=0.0003, P15MV=0.86). Differences in DTA are insignificant for both 6MV and 15MV(p‐value6MV=0.063, P6MV=1; p‐value15MV=0.907, P15MV=1). Varian differences in gamma are significant for both energies(p‐value6MV=0.025, P6MV=0.99; p‐value15MV=0.013, P15MV=1). A paired t‐test shows for Elekta the difference in %DDev is significant for 6MV but not 10MV(p‐value6MV=0.00065, P6MV=0.68; p‐value10MV=0.262, P10MV=0.39). Differences in DTA are statistically insignificant(p‐value6MV=0.803, P6MV = 1; p‐value10MV=0.269, P10MV=1). Elekta differences in gamma are significant for 10MV only(p‐value6MV=0.094, P6MV=1; p‐value10MV=0.011, P10MV=1).Conclusion:These results show vendor specified beam conformance across machines does not ensure equivalent patient specific QA pass rates. Gamma differences are statistically significant in three of the four comparisons for two pairs of vendor matched machines.
SU‐E‐T‐121: Analyzing the Broadening Effect On the Bragg Peak Due to Heterogeneous Geometries and Implementing User‐Routines in the Monte‐Carlo Code FLUKA in Order to Reduce Computation Time
Authors: Baumann K , Weber U , Simeonov Y , Zink K 
Published: June 2015

Purpose:Aim of this study was to analyze the modulating, broadening effect on the Bragg Peak due to heterogeneous geometries like multi‐wire chambers in the beam path of a particle therapy beam line. The effect was described by a mathematical model which was implemented in the Monte‐Carlo code FLUKA via user‐routines, in order to reduce the computation time for the simulations.Methods:The depth dose curve of 80 MeV/u C12‐ions in a water phantom was calculated using the Monte‐Carlo code FLUKA (reference curve). The modulating effect on this dose distribution behind eleven mesh‐like foils (periodicity ∼80 microns) occurring in a typical set of multi‐wire and dose chambers was mathematically described by optimizing a normal distribution so that the reverence curve convoluted with this distribution equals the modulated dose curve. This distribution describes a displacement in water and was transferred in a probability distribution of the thickness of the eleven foils using the water equivalent thickness of the foil's material. From this distribution the distribution of the thickness of one foil was determined inversely. In FLUKA the heterogeneous foils were replaced by homogeneous foils and a user‐routine was programmed that varies the thickness of the homogeneous foils for each simulated particle using this distribution.Results:Using the mathematical model and user‐routine in FLUKA the broadening effect could be reproduced exactly when replacing the heterogeneous foils by homogeneous ones. The computation time was reduced by 90 percent.Conclusion:In this study the broadening effect on the Bragg Peak due to heterogeneous structures was analyzed, described by a mathematical model and implemented in FLUKA via user‐routines. Applying these routines the computing time was reduced by 90 percent. The developed tool can be used for any heterogeneous structure in the dimensions of microns to millimeters, in principle even for organic materials like lung tissue.
SU‐E‐T‐126: Application of PIPSpro and EPID for Quality Assurance of Medical Accelerators
Authors: Lin Z , Peng X , Lu J 
Published: June 2015

Purpose:The purpose is to study applying PIPSpro and EPID for routine quality assurance of medical accelerators.Methods:(1) The coincidence of Light field and radiation field: Placed the FC‐2 phantom on the treatment couch at the 100cm SSD. Using jaw set 10×10 cm2 or 15×15 cm2 field. Verified that the light field aligns with the engraved squares on the phantom. Placed the Crosshair Marker phantom on the top of the FC‐2 phantom with the cross‐hair and spherical marker aligned to the center of the light field. Acquired images with EPID and the images should be exported preferably in DICOM format. Analyzed Follow the recommended procedures in the radiation light field module of PIPSpro software.(2)MLC QA:Set up the MLC phantom on the treatment couch at isocenter. Positioned the EPID imager at the highest possible position without colliding with either the couch or the phantom. Created and delivered four different patterns for testing the MLC leaf position, leaf width, multi‐port and leaf transmission. (3)Radiation isocenter test: Included the isocenter of collimator rotation, gantry rotation and couch rotation. Set the jaws of the collimator to create a thin field as 0.4cm × 20cm.Irradiated film or EPID using an equidistant 15° spacing angles with rotating collimator, gantry and couch respectively.Results:We analyzed imagers from EPID and film with PIPSPro software. As a Result, we acquired the specifications of medical accelerators quickly. In the meantime, the results were saved to database for trending and future analysis.Conclusion:Quality assurance of medical accelerator is very important. We used PIPSpro and EPID for routine detection, not only improved our efficiency, but also saved the cost. It is an good method.
SU‐E‐T‐127: Application of TG‐119 for Evaluation of Proton Spot Scanning Based Planning and Treatment Delivery
Authors: Saini J , Cao N , Bowen S , Bloch C , Wong T 
Published: June 2015

Purpose:The clinical test cases presented in AAPM TG‐119 are used to evaluate the accuracy of treatment planning and delivery through spot scanning proton beams.Methods:An IBA spot scanning delivery system has been commissioned to be used with the RayStation treatment planning system. Various test cases provided in TG‐119 were used for planning and delivery verification. The CT dataset and structures as provided by TG‐119 were imported into a mock patient. The plans were optimized using the multi field optimization (MFO) to achieve the desired goals. The planner was given the flexibility to achieve the given dose‐volume goals by creating appropriate objectives and constraints. Beams were delivered to a phantom and measurements were performed at multiple depths using the MatrixxPT detector array. The analyses were performed on beam by beam basis and quantified using the gamma index. A tolerance of 3%/3 mm in 2D was used for gamma index analysis along with dose threshold of 10%.Results:The clinical goals for targets and critical structures were met or improved for all cases except the C‐Shape target with difficult constraints. The minimum gamma index using the 3%/3mm as a criterion is 93.3% for one of the planes measured for C‐Shape target. Using 2%/2mm as a criterion, the minimum gamma index drops to 70%. Only Prostate target has all the planes above >90% pass using the 2%/2mm criterion.Conclusion:The overall accuracy of the treatment planning and delivery is deemed clinically acceptable. The test cases with highly modulated beams can have steep gradients in the dose profiles that can reduce the gamma index pass rate. Gamma analysis based on 3D data may be needed for routine use of 2%/2mm criterion. In addition, improvements in modelling of spot profiles in dose engine may be required for further improving the gamma index pass rate.
SU‐E‐T‐128: Applying Failure Modes and Effects Analysis to a Risk‐Based Quality Management for Stereotactic Radiosurgery in Brazil
Authors: Teixeira F , de Almeida C , Huq M 
Published: June 2015

Purpose:The goal of the present work was to evaluate the process maps for stereotactic radiosurgery (SRS) treatment at three radiotherapy centers in Brazil and apply the FMEA technique to evaluate similarities and differences, if any, of the hazards and risks associated with these processes.Methods:A team, consisting of professionals from different disciplines and involved in the SRS treatment, was formed at each center. Each team was responsible for the development of the process map, and performance of FMEA and FTA. A facilitator knowledgeable in these techniques led the work at each center. The TG100 recommended scales were used for the evaluation of hazard and severity for each step for the major process “treatment planning”.Results:Hazard index given by the Risk Priority Number (RPN) is found to range from 4–270 for various processes and the severity (S) index is found to range from 1–10. The RPN values > 100 and severity value ≥ 7 were chosen to flag safety improvement interventions. Number of steps with RPN ≥100 were found to be 6, 59 and 45 for the three centers. The corresponding values for S ≥ 7 are 24, 21 and 25 respectively. The range of RPN and S values for each center belong to different process steps and failure modes.Conclusion:These results show that interventions to improve safety is different for each center and it is associated with the skill level of the professional team as well as the technology used to provide radiosurgery treatment. The present study will very likely be a model for implementation of risk‐based prospective quality management program for SRS treatment in Brazil where currently there are 28 radiotherapy centers performing SRS. A complete FMEA for SRS for these three radiotherapy centers is currently under development.
SU‐E‐T‐129: Are Knowledge‐Based Planning Dose Estimates Valid for Distensible Organs?
Authors: Lalonde R , Heron D , Readshaw A , Huq M 
Published: June 2015

Purpose:Knowledge‐based planning programs have become available to assist treatment planning in radiation therapy. Such programs can be used to generate estimated DVHs and planning constraints for organs at risk (OARs), based upon a model generated from previous plans. These estimates are based upon the planning CT scan. However, for distensible OARs like the bladder and rectum, daily variations in volume may make the dose estimates invalid. The purpose of this study is to determine whether knowledge‐based DVH dose estimates may be valid for distensible OARs.Methods:The Varian RapidPlan™ knowledge‐based planning module was used to generate OAR dose estimates and planning objectives for 10 prostate cases previously planned with VMAT, and final plans were calculated for each. Five weekly setup CBCT scans of each patient were then downloaded and contoured (assuming no change in size and shape of the target volume), and rectum and bladder DVHs were recalculated for each scan. Dose volumes were then compared at 75, 60,and 40 Gy for the bladder and rectum between the planning scan and the CBCTs.Results:Plan doses and estimates matched well at all dose points., Volumes of the rectum and bladder varied widely between planning CT and the CBCTs, ranging from 0.46 to 2.42 for the bladder and 0.71 to 2.18 for the rectum, causing relative dose volumes to vary between planning CT and CBCT, but absolute dose volumes were more consistent. The overall ratio of CBCT/plan dose volumes was 1.02 ±0.27 for rectum and 0.98 ±0.20 for bladder in these patients.Conclusion:Knowledge‐based planning dose volume estimates for distensible OARs are still valid, in absolute volume terms, between treatment planning scans and CBCT's taken during daily treatment. Further analysis of the data is being undertaken to determine how differences depend upon rectum and bladder filling state.This work has been supported by Varian Medical Systems.
SU‐E‐T‐130: Are Proton Gantries Needed? An Analysis of 4332 Patient Proton Gantry Treatment Plans From the Past 10 Years
Authors: Yan S , Lu H , Flanz J , Depauw N , Adams J , Gorissen BL , Wang Y , Daartz J , Bortfeld T 
Published: June 2015

Purpose:To ascertain the necessity of a proton gantry, as compared to the feasibility of using a horizontal fixed proton beam‐line for treatment with advanced technology.Methods:To calculate the percentage of patients that can be treated with a horizontal fixed beam‐line instead of a gantry, we analyze the distributions of beam orientations of our proton gantry patients treated over the past 10 years. We identify three horizontal fixed beam geometries (FIXED, BEND and MOVE) with the patient in lying and/or sitting positions. The FIXED geometry includes only table/chair rotations and translations. In BEND, the beam can be bent up/down for up to 20 degrees. MOVE allows for patient head/body angle adjustment. Based on the analysis, we select eight patients whose plan involves beams which are still challenging to achieve with a horizontal fixed beam. These beams are removed in the pencil beam scanning (PBS) plan optimized for the fixed beam‐line (PBS‐fix). We generate non‐coplanar PBS‐gantry plans for comparison, and perform a robustness analysis.Results:The percentage of patients with head‐and‐neck/brain tumors that can be treated with horizontal fixed beam is 44% in FIXED, 70% in 20‐degrees BEND, and 100% in 90‐degrees MOVE. For torso regions, 99% of the patients can be treated in 20‐degree BEND. The target coverage is more homogeneous with PBS‐fix plans compared to the clinical scattering treatment plans. The PBS‐fix plans reduce the mean dose to organs‐at‐risk by a factor of 1.1–28.5. PBS‐gantry plans are as good as PBS‐fix plans, sometimes marginally better.Conclusion:The majority of the beam orientations can be realized with a horizontal fixed beam‐line. Challenging non‐coplanar beams can be eliminated with PBS delivery. Clinical implementation of the proposed fixed beam‐line requires use of robotic patient positioning, further developments in immobilization, and image guidance. However, our results suggest that fixed beam‐lines can be as effective as gantries.
SU‐E‐T‐131: Artificial Neural Networks Applied to Overall Survival Prediction for Patients with Periampullary Carcinoma
Authors: Gong Y , Yu J , Yeung V , Palmer J , Yu Y , Lu B , Babinsky L , Burkhart R , Leiby B , Siow V , Lavu H , Rosato E , Winter J , Lewis N , Sama A , Mitchell E , Anne P , Hurwitz M , Yeo C , Bar‐Ad V , Xiao Y 
Published: June 2015

Purpose:Artificial neural networks (ANN) can be used to discover complex relations within datasets to help with medical decision making. This study aimed to develop an ANN method to predict two‐year overall survival of patients with peri‐ampullary cancer (PAC) following resection.Methods:Data were collected from 334 patients with PAC following resection treated in our institutional pancreatic tumor registry between 2006 and 2012. The dataset contains 14 variables including age, gender, T‐stage, tumor differentiation, positive‐lymph‐node ratio, positive resection margins, chemotherapy, radiation therapy, and tumor histology.After censoring for two‐year survival analysis, 309 patients were left, of which 44 patients (∼15%) were randomly selected to form testing set. The remaining 265 cases were randomly divided into training set (211 cases, ∼80% of 265) and validation set (54 cases, ∼20% of 265) for 20 times to build 20 ANN models. Each ANN has one hidden layer with 5 units. The 20 ANN models were ranked according to their concordance index (c‐index) of prediction on validation sets. To further improve prediction, the top 10% of ANN models were selected, and their outputs averaged for prediction on testing set.Results:By random division, 44 cases in testing set and the remaining 265 cases have approximately equal two‐year survival rates, 36.4% and 35.5% respectively. The 20 ANN models, which were trained and validated on the 265 cases, yielded mean c‐indexes as 0.59 and 0.63 on validation sets and the testing set, respectively. C‐index was 0.72 when the two best ANN models (top 10%) were used in prediction on testing set. The c‐index of Cox regression analysis was 0.63.Conclusion:ANN improved survival prediction for patients with PAC. More patient data and further analysis of additional factors may be needed for a more robust model, which will help guide physicians in providing optimal post‐operative care.This project was supported by PA CURE Grant.
SU‐E‐T‐133: Assessing IMRT Treatment Delivery Accuracy and Consistency On a Varian TrueBeam Using the SunNuclear PerFraction EPID Dosimetry Software
Authors: Dieterich S , Trestrail E , Holt R , Saini S , Pfeiffer I , Kent M , Hansen K 
Published: June 2015

Purpose:To assess if the TrueBeam HD120 collimator is delivering small IMRT fields accurately and consistently throughout the course of treatment using the SunNuclear PerFraction software.Methods:7‐field IMRT plans for 8 canine patients who passed IMRT QA using SunNuclear Mapcheck DQA were selected for this study. The animals were setup using CBCT image guidance. The EPID fluence maps were captured for each treatment field and each treatment fraction, with the first fraction EPID data serving as the baseline for comparison. The Sun Nuclear PerFraction Software was used to compare the EPID data for subsequent fractions using a Gamma (3%/3mm) pass rate of 90%. To simulate requirements for SRS, the data was reanalyzed using a Gamma (3%/1mm) pass rate of 90%. Low‐dose, low‐ and high gradient thresholds were used to focus the analysis on clinically relevant parts of the dose distribution.Results:Not all fractions could be analyzed, because during some of the treatment courses the DICOM tags in the EPID images intermittently change from CU to US (unspecified), which would indicate a temporary loss of EPID calibration. This technical issue is still being investigated. For the remaining fractions, the vast majority (7/8 of patients, 95% of fractions, and 96.6% of fields) are passing the less stringent Gamma criteria. The more stringent Gamma criteria caused a drop in pass rate (90 % of fractions, 84% of fields). For the patient with the lowest pass rate, wet towel bolus was used. Another patient with low pass rates experienced masseter muscle wasting.Conclusion:EPID dosimetry using the PerFraction software demonstrated that the majority of fields passed a Gamma (3%/3mm) for IMRT treatments delivered with a TrueBeam HD120 MLC. Pass rates dropped for a DTA of 1mm to model SRS tolerances. PerFraction pass rates can flag missing bolus or internal shields.Sanjeev Saini is an employee of Sun Nuclear Corporation. For this study, a pre‐release version of PerFRACTION 1.1 software from Sun Nuclear Corporation was used.