bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐F‐T‐214: Re‐Thinking the Useful Clinical Beam Energy in Proton Therapy: An Opportunity for Cost Reduction
Authors: Bentefour El H , Lu H 
Published: July 2016

Purpose:We conducted a retrospective study of the useful clinical proton beam energy based on the beam range data of patients treated over the last 10 years at Massachusetts General Hospital Proton Therapy Center.Methods:Treatment field information were collected for all patients treated over the last 10 years (2005–2015) in the two gantry treatment rooms at MGH. The beam ranges for these fields were retrieved and categorized per treatment site. The 10 prostate patients that required the highest beam range (lateral fields) were selected. For these patients, anterior oblique beams (30–40 degrees) were simulated in a planning system to obtain the required beam ranges including the margins for potential range uncertainties.Results:There were a total of 4033 patients, treated with combined total of 23603 fields. All treatment indications were considered with the exception of ocular tumors generally treated in a fixed beam room. For all non‐prostate treatments (21811 fields), only 5 fields for 4 patients (1‐pancreas, 1‐lumbar chordoma, 2‐spine mets) required beam range greater than 25 cm. There were 446 prostate patients (1792 fields), with the required beam range from 22.3 to 29.0 cm; 386 of them had at least one of their lateral beam range greater than 25 cm. For the 10 prostate patients with highest lateral beam ranges (26 to 29 cm), their treatment with anterior oblique beams would drop the beam ranges below 25 cm (17.3 to 18.5 cm).Conclusion:if prostate patients are treated with anterior fields only, the useful maximum beam range is reduced to 25 cm. Thus a proton therapy system with maximum beam energy of 196 MeV is sufficient to treat all tumors sites with very rare exceptions (<0.1%). Designing such PT system would reduce the cost of proton therapy for hospitals and patients and increase the accessibility to the treatment.
SU‐F‐T‐231: Improving the Efficiency of a Radiotherapy Peer‐Review System for Quality Assurance
Authors: Hsu S , Basavatia A , Garg M , Kalnicki S , Tome W 
Published: July 2016

Purpose:To improve the efficiency of a radiotherapy peer‐review system using a commercially available software application for plan quality evaluation and documentation.Methods:A commercial application, FullAccess (Radialogica LLC, Version 1.4.4), was implemented in a Citrix platform for peer‐review process and patient documentation. This application can display images, isodose lines, and dose‐volume histograms and create plan reports for peer‐review process. Dose metrics in the report can also be benchmarked for plan quality evaluation. Site‐specific templates were generated based on departmental treatment planning policies and procedures for each disease site, which generally follow RTOG protocols as well as published prospective clinical trial data, including both conventional fractionation and hypo‐fractionation schema. Once a plan is ready for review, the planner exports the plan to FullAccess, applies the site‐specific template, and presents the report for plan review. The plan is still reviewed in the treatment planning system, as that is the legal record. Upon physician's approval of a plan, the plan is packaged for peer review with the plan report and dose metrics are saved to the database.Results:The reports show dose metrics of PTVs and critical organs for the plans and also indicate whether or not the metrics are within tolerance. Graphical results with green, yellow, and red lights are displayed of whether planning objectives have been met. In addition, benchmarking statistics are collected to see where the current plan falls compared to all historical plans on each metric. All physicians in peer review can easily verify constraints by these reports.Conclusion:We have demonstrated the improvement in a radiotherapy peer‐review system, which allows physicians to easily verify planning constraints for different disease sites and fractionation schema, allows for standardization in the clinic to ensure that departmental policies are maintained, and builds a comprehensive database for potential clinical outcome evaluation.
SU‐F‐T‐237: The Imaging and Radiation Oncology Core (IROC) Cooperatives Activities Supporting the NCI's National Clinical Trial Network
Authors: Followill D , Galvin J , Michalski J , Rosen M , FitzGerald T , Knopp M 
Published: July 2016

Purpose:The Imaging and Radiation Oncology Core (IROC) Cooperative has been active for the past two years supporting the National Clinical Trial Network and the details of that support are reported.Methods:There are six QA centers (Houston, Ohio, Philadelphia‐RT, Philadelphia‐DI, Rhode Island, St. Louis) providing an integrated RT and DI quality control program in support of the NCI's clinical trials. The QA Center's efforts are focused on assuring high quality data for clinical trials designed to improve the clinical outcomes for cancer patients worldwide. This program is administered through five core services: site qualification, trial design support, credentialing, data management, and case review.Results:IROC currently provides core support for 172 NCTN trials with RT, DI and RT/DI components. Many of these trials were legacy trial from the previous cooperative group program. IROC monitors nearly 1800 RT photon and 20 proton institutions. Over 28,000 beams outputs were monitored with 8% of the sites requiring repeat audits due to beam out of criteria. As part of credentialing, 950 QA phantoms have been irradiated, 515 imaging modalities evaluated and almost 4000 credentialing letters have been issued. In just year 2, 5290 RT and 4934 DI patient datasets were received (many using TRIAD) by IROC QA Centers to be prepared for review. During the past 2 years, a total of 6300 RT cases and 19,000 DI image sets were reviewed by IROC technical staff. To date, IROC has published 36 manuscripts.Conclusion:The QA services provided by IROC are numerous and are continually being evaluated for effectiveness, harmonized across all NCTN Groups and administered in an efficient and timely manner to enhance accurate and per protocol trial data submission. These efforts increase each NCTN Group's ability to derive meaningful outcomes from their clinical trials.This work was supported by DHHS NIH grant 5U24CA180803
SU‐F‐T‐257: Comparison Study of the Biological and Physical Optimization for Cervical Carcinoma
Authors: Feng Z , Tao C , Zhu J , Yu G , Qin S , Yin Y , Li D 
Published: July 2016

Purpose:In this study, IMRT optimization based on biological related models were applied in the clinic for cervical carcinoma cases and the results were compared with the traditional physical optimization. Methods: Twenty patients of advanced stage cervical carcinoma were selected in this study. The treatment plan was generated on each patient using both biological and physical optimized model respectively. Additionally, the biological optimization was based on two basic models for bladder and rectum: Poisson (adjustable parameters: alpha/beta, gamma, D50) and Lyman‐Kutcher‐Burman (adjustable parameters: m, n, D50). And then each optimized biological plan was compared with the corresponding physical plan. During this comparison, all biological and physical parameters, such as NTCP,TCP, target coverage and homogeneous index(HI), were evaluated by paired T‐test to verify IMRT plans quality.Results:The NTCP values by biological optimization were lower than the values from corresponding physical optimization. For the bladder and rectum, the detail of NTCP values are 0.144 and 0.178 with p=0.028 for bladder, and 0.108 and 0.186 with p= 7.97E‐5 for rectum respectively. The mean dose and V40 of bladder and rectum were comparable, and there was no significant difference between these two optimizations. For PTV, both optimized models achieved similar target coverage and homogeneous index (For example, D98=53.4 Gy and 54.6 Gy from biological optimization and physical optimization respectively with p=2.94E‐9), and there were no significant differences in the tumor control probability(TCP) values.Conclusion:IMRT optimization based on biological model did not decrease the plan quality, and could spare bladder and rectum with lower NTCP value much more compared with traditional physical optimization for cervical carcinoma. Our initial experiment demonstrated that the biological optimization could be a potential alternative method to the traditional physical one.We want to thank Dr. Lei Xing and Dr. Yong Yang in the Stanford University School of Medicine for this work. This work was jointly supported by NSFC (61471226), Natural Science Foundation for Distinguished Young Scholars of Shandong Province (JQ201516), and China Postdoctoral Science Foundation (2015T80739, 2014M551949).
SU‐F‐T‐261: Reconstruction of Initial Photon Fluence Based On EPID Images
Authors: Seliger T , Czarnecki D , Kussaether R , Maeder U , Engenhart‐Cabillic R , Poppe B , Zink K 
Published: July 2016

Purpose:Verifying an algorithm to reconstruct relative initial photon fluence for clinical use. Clinical EPID and CT images were acquired to reconstruct an external photon radiation treatment field. The reconstructed initial photon fluence could be used to verify the treatment or calculate the applied dose to the patient.Methods:The acquired EPID images were corrected for scatter caused by the patient and the EPID with an iterative reconstruction algorithm. The transmitted photon fluence behind the patient was calculated subsequently. Based on the transmitted fluence the initial photon fluence was calculated using a back‐projection algorithm which takes the patient geometry and its energy dependent linear attenuation into account. This attenuation was gained from the acquired cone‐beam CT or the planning CT by calculating a water‐equivalent radiological thickness for each irradiation direction. To verify the algorithm an inhomogeneous phantom consisting of three inhomogeneities was irradiated by a static 6 MV photon field and compared to a reference flood field image.Results:The mean deviation between the reconstructed relative photon fluence for the inhomogeneous phantom and the flood field EPID image was 3% rising up to 7% for off‐axis fluence. This was probably caused by the used clinical EPID calibration, which flattens the inhomogeneous fluence profile of the beam.Conclusion:In this clinical experiment the algorithm achieved good results in the center of the field while it showed high deviation of the lateral fluence. This could be reduced by optimizing the EPID calibration, considering the off‐axis differential energy response. In further progress this and other aspects of the EPID, eg. field size dependency, CT and dose calibration have to be studied to realize a clinical acceptable accuracy of 2%.
SU‐F‐T‐267: A Clarkson‐Based Independent Dose Verification for the Helical Tomotherapy
Authors: Nagata H , Hongo H , Kawai D , Takahashi R , Hashimoto H , Tachibana H 
Published: July 2016

Purpose:There have been few reports for independent dose verification for Tomotherapy. We evaluated the accuracy and the effectiveness of an independent dose verification system for the Tomotherapy.Methods:Simple MU Analysis (SMU, Triangle Product, Ishikawa, Japan) was used as the independent verification system and the system implemented a Clarkson‐based dose calculation algorithm using CT image dataset. For dose calculation in the SMU, the Tomotherapy machine‐specific dosimetric parameters (TMR, Scp, OAR and MLC transmission factor) were registered as the machine beam data. Dose calculation was performed after Tomotherapy sinogram from DICOM‐RT plan information was converted to the information for MU and MLC location at more segmented control points. The performance of the SMU was assessed by a point dose measurement in non‐IMRT and IMRT plans (simple target and mock prostate plans). Subsequently, 30 patients’ treatment plans for prostate were compared.Results:From the comparison, dose differences between the SMU and the measurement were within 3% for all cases in non‐IMRT plans. In the IMRT plan for the simple target, the differences (Average±1SD) were −0.70±1.10% (SMU vs. TPS), −0.40±0.10% (measurement vs. TPS) and −1.20±1.00% (measurement vs. SMU), respectively. For the mock prostate, the differences were −0.40±0.60% (SMU vs. TPS), −0.50±0.90% (measurement vs. TPS) and −0.90±0.60% (measurement vs. SMU), respectively. For patients’ plans, the difference was −0.50±2.10% (SMU vs. TPS).Conclusion:A Clarkson‐based independent dose verification for the Tomotherapy can be clinically available as a secondary check with the similar tolerance level of AAPM Task group 114.This research is partially supported by Japan Agency for Medical Research and Development (AMED)
SU‐F‐T‐274: Modified Dose Calibration Methods for IMRT QA
Authors: Luo W , Westlund S 
Published: July 2016

Purpose:To investigate IMRT QA uncertainties caused by dose calibration and modify widely used dose calibration procedures to improve IMRT QA accuracy and passing rate.Methods:IMRT QA dose measurement is calibrated using a calibration factor (CF) that is the ratio between measured value and expected value corresponding to the reference fields delivered on a phantom. Two IMRT QA phantoms were used for this study: a 30×30×30 cm3 solid water cube phantom (Cube), and the PTW Octavius phantom. CF was obtained by delivering 100 MUs to the phantoms with different reference fields ranging from 3×3 cm2 to 20×20 cm2. For Cube, CFs were obtained using the following beam arrangements: 2‐AP Field ‐ chamber at dmax, 2‐AP Field ‐ chamber at isocenter, 4‐beam box ‐ chamber at isocenter, and 8 equally spaced fields and chamber at isocenter. The same plans were delivered on Octavius and CFs were derived for the dose at the isocenter using the above beam arrangements. The Octavius plans were evaluated with PTW‐VeriSoft (Gamma criteria of 3%/3mm).Results:Four head and neck IMRT plans were included in this study. For point dose measurement with Cube, the CFs with 4‐Field gave the best agreement between measurement and calculation within 4% for large field plans. All the measurement results agreed within 2% for a small field plan. Compared with calibration field sizes, 5×5 to 15×15 were more accurate than other field sizes. For Octavius, 4‐Field calibration increased passing rate by up to 10% compared to AP calibration. Passing rate also increased by up to 4% with the increase of field size from 3×3 to 20×20.Conclusion:IMRT QA results are correlated with calibration methods used. The dose calibration using 4‐beam box with field sizes from 5×5 to 20×20 can improve IMRT QA accuracy and passing rate.
SU‐F‐T‐275: A Correlation Study On 3D Fluence‐Based QA and 2D Dose Measurement‐Based QA
Authors: Liu S , Mazur T , Li H , Green O , Sun B , Mutic S , Yang D 
Published: July 2016

Purpose:The aim of this paper was to demonstrate the feasibility and creditability of computing and verifying 3D fluencies to assure IMRT and VMAT treatment deliveries, by correlating the passing rates of the 3D fluence‐based QA (P(ά)) to the passing rates of 2D dose measurementbased QA (P(Dm)).Methods:3D volumetric primary fluencies are calculated by forward‐projecting the beam apertures and modulated by beam MU values at all gantry angles. We first introduce simulated machine parameter errors (MU, MLC positions, jaw, gantry and collimator) to the plan. Using passing rates of voxel intensity differences (P(Ir)) and 3D gamma analysis (P(γ)), calculated 3D fluencies, calculated 3D delivered dose, and measured 2D planar dose in phantom from the original plan are then compared with those from corresponding plans with errors, respectively. The correlations of these three groups of resultant passing rates, i.e. 3D fluence‐based QA (P(ά,Ir) and P(ά,γ)), calculated 3D dose (P(Dc,Ir) and P(Dc,γ)), and 2D dose measurement‐based QA (P(Dm,Ir) and P(Dm,γ)), will be investigated.Results:20 treatment plans with 5 different types of errors were tested. Spearman's correlations were found between P(ά,Ir) and P(Dc,Ir), and also between P(ά,γ) and P(Dc,γ), with averaged p‐value 0.037, 0.065, and averaged correlation coefficient ρ‐value 0.942, 0.871 respectively. Using Matrixx QA for IMRT plans, Spearman's correlations were also obtained between P(ά,Ir) and P(Dm,Ir) and also between P(ά,γ) and P(Dm,γ), with p‐value being 0.048, 0.071 and ρ‐value being 0.897, 0.779 respectively.Conclusion:The demonstrated correlations improve the creditability of using 3D fluence‐based QA for assuring treatment deliveries for IMRT/VMAT plans. Together with advantages of high detection sensitivity and better visualization of machine parameter errors, this study further demonstrates the accuracy and feasibility of 3D fluence based‐QA in pre‐treatment QA and daily QA.Research reported in this study is supported by the Agency for Healthcare Research and Quality (AHRQ) under award 1R01HS0222888. The senior author received research grants from ViewRay Inc. and Varian Medical System
SU‐F‐T‐281: Monte Carlo Investigation of Sources of Dosimetric Discrepancies with 2D Arrays
Authors: Afifi M , Deiab N , El‐Farrash A , Abd El‐Hafez A , Eldib A , Veltchev I , Ma C 
Published: July 2016

Purpose:Intensity modulated radiation therapy (IMRT) poses a number of challenges for properly measuring commissioning data and quality assurance (QA). Understanding the limitations and use of dosimeters to measure these dose distributions is critical to safe IMRT implementation. In this work, we used Monte Carlo simulations to investigate the possible sources of discrepancy between our measurement with 2D array system and our dose calculation using our treatment planning system (TPS).Material and Methods:MCBEAM and MCSIM Monte Carlo codes were used for treatment head simulation and phantom dose calculation. Accurate modeling of a 6MV beam from Varian trilogy machine was verified by comparing simulated and measured percentage depth doses and profiles. Dose distribution inside the 2D array was calculated using Monte Carlo simulations and our TPS. Then Cross profiles for different field sizes were compared with actual measurements for zero and 90° gantry angle setup. Through the analysis and comparison, we tried to determine the differences and quantify a possible angular calibration factor.Results:Minimum discrepancies was seen in the comparison between the simulated and the measured profiles for the zero gantry angles at all studied field sizes (4×4cm2, 10×10cm2, 15×15cm2, and 20×20cm2). Discrepancies between our measurements and calculations increased dramatically for the cross beam profiles at the 90° gantry angle. This could ascribe mainly to the different attenuation caused by the layer of electronics at the base behind the ion chambers in the 2D array. The degree of attenuation will vary depending on the angle of beam incidence. Correction factors were implemented to correct the errors.Conclusion:Monte Carlo modeling of the 2D arrays and the derivation of angular dependence correction factors will allow for improved accuracy of the device for IMRT QA.
SU‐F‐T‐288: Impact of Trajectory Log Files for Clarkson‐Based Independent Dose Verification of IMRT and VMAT
Authors: Takahashi R , Kamima T , Tachibana H 
Published: July 2016

Purpose:To investigate the effect of the trajectory files from linear accelerator for Clarkson‐based independent dose verification in IMRT and VMAT plans.Methods:A CT‐based independent dose verification software (Simple MU Analysis: SMU, Triangle Products, Japan) with a Clarksonbased algorithm was modified to calculate dose using the trajectory log files. Eclipse with the three techniques of step and shoot (SS), sliding window (SW) and Rapid Arc (RA) was used as treatment planning system (TPS). In this study, clinically approved IMRT and VMAT plans for prostate and head and neck (HN) at two institutions were retrospectively analyzed to assess the dose deviation between DICOM‐RT plan (PL) and trajectory log file (TJ). An additional analysis was performed to evaluate MLC error detection capability of SMU when the trajectory log files was modified by adding systematic errors (0.2, 0.5, 1.0 mm) and random errors (5, 10, 30 mm) to actual MLC position.Results:The dose deviations for prostate and HN in the two sites were 0.0% and 0.0% in SS, 0.1±0.0%, 0.1±0.1% in SW and 0.6±0.5%, 0.7±0.9% in RA, respectively. The MLC error detection capability shows the plans for HN IMRT were the most sensitive and 0.2 mm of systematic error affected 0.7% dose deviation on average. Effect of the MLC random error did not affect dose error.Conclusion:The use of trajectory log files including actual information of MLC location, gantry angle, etc should be more effective for an independent verification. The tolerance level for the secondary check using the trajectory file may be similar to that of the verification using DICOM‐RT plan file. From the view of the resolution of MLC positional error detection, the secondary check could detect the MLC position error corresponding to the treatment sites and techniques.This research is partially supported by Japan Agency for Medical Research and Development (AMED)
SU‐F‐T‐289: MLC Fluence Sonogram Based Delivery Quality Assurance for Bilateral Breast Irradiation
Authors: Thiyagarajan Rajesh , Karrthick KP , Kataria Tejinder , Arunai N , Raj Nambi , Mahendran Ramu , Selvan Tamil , Duraikannu Palani 
Published: July 2016

Purpose:Performing DQA for Bilateral (B‐L) breast tomotherapy is a challenging task due to the limitation of any commercially available detector array or film. Aim of this study is to perform DQA for B‐L breast tomotherapy plan using MLC fluence sinogram.Methods:Treatment plan was generated on Tomotherapy system for B‐L breast tumour. B‐L breast targets were given 50.4 Gy prescribed over 28 fractions. Plan is generated with 6 MV photon beam & pitch was set to 0.3. As the width of the total target is 39 cm (left & right) length is 20 cm. DQA plan delivered without any phantom on the mega voltage computed tomography (MCVT) detector system. The pulses recorded by MVCT system were exported to the delivery analysis software (Tomotherapy Inc.) for reconstruction. The detector signals are reconstructed to a sonogram and converted to MLC fluence sonogram. The MLC fluence sinogram compared with the planned fluence sinogram. Also point dose measured with cheese phantom and ionization chamber to verify the absolute dose componentResults:Planned fluence sinogram and reconstructed MLC fluence sinogram were compared using Gamma metric. MLC positional difference and intensity of the beamlet were used as parameters to evaluate gamma. 3 mm positional difference and 3% beamlet intensity difference were used set for gamma calculation. A total of 26784 non‐zero beamlets were included in the analysis out of which 161 beamlets had gamma more than 1. The gamma passing rate found to be 99.4%. Point dose measurements were within 1.3% of the calculated dose.Conclusion:MLC fluence sinogram based delivery quality assurance performed for bilateral breast irradiation. This would be a suitable alternate for large volume targets like bilateral breast, Total body irradiation etc. However conventional method of DQA should be used to validate this method periodically.