bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐T‐234: Daily Quality Assurance for a Six Degrees of Freedom Couch Using a Novel Phantom
Authors: Woods K , Woollard J , Ayan A , Sandu A , Sommerfeld J , Laurel A , Gupta N 
Published: June 2015

Purpose:To test the accuracy and reproducibility of both translational and rotational movements for a couch with six degrees of freedom (6DoF) using a novel phantom designMethods:An end‐to‐end test was carried out using two different phantoms. A 6 cm3 cube with a central fiducial BB (WL‐QA Sun Nuclear) and a custom fabricated rectangular prism (31 cm × 8 cm × 8 cm), placed on a baseplate with known angular offsets for pitch, roll and yaw with a central fiducial BB and unique surface structures for registration purposes, were used. The end‐to‐end test included an initial CT simulation for a reference study, setup to an offset mark on each phantom, registration of the reference CT to the acquired cone‐beam CT, and final Winston‐Lutz delivery at four cardinal gantry angles. Results for both translational and rotational movements were recorded and compared for both phantoms.Results:Translational and rotational measurements were performed with a PerfectPitch (Varian) couch for 10 trials for both phantoms. Distinct translational shifts were [−5.372±0.384mm, −10.183±0.137mm, 14.028±0.155mm] for the cube and [7.520±0.159mm, −9.117±0.101mm, 16.273±0.115mm] for the prototype phantom for lateral, longitudinal, and vertical shifts, respectively. Distinct rotational adjustments were [1.121±0.102o, −1.067±0.235o, −2.662±0.380o] for the cube and [2.534±0.059o, 1.994±0.025o, 2.094±0.076o] for the prototype for pitch, roll, and yaw, respectively. Winston‐Lutz test results performed after 6DoF couch correction from each cardinal gantry angle ranged from 0.26–0.72mm for the cube and 0.55–0.86mm for the prototype.Conclusion:The prototype phantom is more precise for both translational and rotational adjustments compared to a commercial phantom. The design of the prototype phantom allows for a more discernible visual confirmation of correct translational and rotational adjustments with the prototype phantom. Winston‐Lutz results are more accurate for the commercial phantom but are still within tolerance for the prototype phantom.
SU‐E‐T‐235: Data Mining for Evaluating Treatment Performances Over a Large Quantity of Data to Monitor and Improve SBRT Workflow
Authors: Feng W , Chu A , Wuu C , Nguyen K 
Published: June 2015

Purpose:To quality assure a large quantity of retrospective treatment cases for treatment performances by randomly sampling is inefficient. Here we provide a method to efficiently monitor and investigate the QA of SBRT workflow over Mosaiq.Methods:The code developed with Microsoft SQL Server Management Studio 2008R2 and VBA was used for retrieving and sorting data from Mosaiq (version 2.3–2.6 during 2012–2015). SBRT patients were filtered by fractional dose over 350cGy and total fraction number less than 6, which SBRT prescriptions were defined. The quality assurance on the SBRT workflow was focused on the treatment deliveries such as patient positioning setup, CBCT indicated offsets and couch shifted corrections. The treatment delivery were done by Varian Truebeam systems and the record/verify by Mosaiq.Results:Total 82 SBRT patients corresponding to 103 courses and 854 CBCT images were found by the retrieval query. Most centers record daily pre‐treatment (Pre‐Tx: before treatment shift) image‐guided shifts along treatment course for inter‐fraction motion record, and it is useful to also verify it with post‐treatment imaging (Post‐Tx: after treatment CBCT verification) to verify intra‐fraction motion. Analyzing the details of daily recorded shifts can reveals the information of patient‐setup and staff's record/verify behaviors. 3 examples were provided as solid evidences and on‐going rectification for preventing future mistakes.Conclusions:The report gave feasible examples for inspector to verify a large amount of data during site investigation. This program can also be extended to a scheduled data mining with software to periodical analyze the timely records in Mosaiq, for example, a various control charts for different QA purposes. As the current trend of automation in radiation therapy field, the data mining would be a necessary tool in the future, just as the automatic plan quality evaluation has been under development in Eclipse.
SU‐E‐T‐241: Design and Implement of An Information Management System for Radiation Workers in a Hospital
Authors: Wu Q , Wu M 
Published: June 2015

Purpose:To meet the special needs of Medical Administration Division, an information management system for radiation workers in a hospital(IMSRWH) has been developed.Methods:There are about 200 radiation workers in 20 departments, such as department of radiology, department of radiation oncology, department of nuclear medicine, and so on. An IMSRWH server was used to run a database and web service of Apache+PHP+MySQL. The IMSRWH web service could be accessed with Internet Explorer(IE) to input, search, count, and print the radiation workers’ data. Every worker's data information includes the following tables: registration, personal dose monitoring records, personnel certificate, training certificate, personnel license, medical examination, etc, and each table includes more optional detail information.Results:In the past year, the IMSRWH has been successfully developed and implemented in the hospital. According to the needs, the user rights are divided into: the system administrator, office manager, department manager and radiation worker. The different users have the different interfaces, and the appropriate authority permissions mean corresponding operations. The administrator and office manager could manage all personnel information, department manager could manage the staff information of his department, and the workers could view or modify their own information. Because information updates, involving hundreds of each entry and modification are complicated, each table information of all workers can be batch import from or export to a Microsoft Excel CSV format file, to update all together. However, it has only Chinese version now.Conclusion:It was demonstrated to be user‐friendly and was proven to significantly improve the efficiency of the hospital management. Since it is an in‐house developed system, more functions can be added or modified to further enhance its potentials in research and clinical practice.
SU‐E‐T‐248: Determining Output Factor of Irregular Electron Cutouts at Extended SSD
Authors: Alkhatib H , Gebreamlak W , Tedeschi D , Mihailidis D 
Published: June 2015

Purpose:To calculate the output factor (OPF) of any irregularly shaped electron beam at extended SSDMethods:Using Cerrobend block, circular cutouts with diameter ranging from 2.0cm to the maximum possible size for 15×15 applicator of Varian 2100C and 14×14 applicator of ELEKTA Synergy LINACs were prepared. In addition, two irregular cutouts were made. For each cutout, percentage depth dose (PDD) at standard SSD and point doses at different SSD were measured in water using Scanditronix diodes and PTW 0.125 cm3 ion‐chambers, respectively. In addition, the distance at which electron fluence along the central axis becomes independent of cutout size was determined using EDR2 films. On each LINAC, electron beam energies of 6, 9, 12, and 15/20 MeV were used.Results:Using the open applicator as the reference field, the lateral buildup ratio (LBR) for each circular cutout as a function of depth was calculated. From the LBR value and radius of the cutout, the corresponding lateral spread parameter (σR(z)) was determined. Taking the cutout side dependence of σR(z)) into account, PDD of the irregular cutouts at the standard SSD were calculated. From the point dose measurement at different SSDs, the effective SSD of each cutout was calculated. Taking the calculated PDD of the irregular cutout and effective SSD (SSDeff) of the circular cutout into account, OPFs of the irregular cutout at extended SSD values were calculated. Finally, the calculated output factors were compared with the measured values.Conclusion:In this research, the improved LBR method has been generalized to calculate output factor of irregular cutouts at extended SSD. In a clinically useful region, the percentage difference between the measured and the calculated output factors of the irregular cutouts was within 2%. Similar results were obtained for all available electron energies of both Varian 2100C and ELEKTA Synergy machines.
SU‐E‐T‐250: Determining VMAT Machine Limitations of An Elekta Linear Accelerator with Agility MLC for Accurate Modeling in RayStation and Robust Delivery
Authors: Yang K , Yu Z , Chen H , Mourtada F 
Published: June 2015

Purpose:To implement VMAT in RayStation with the Elekta Synergy linac with the new Agility MLC, and to utilize the same vendor softwares to determine the optimum Elekta VMAT machine parameters in RayStation for accurate modeling and robust delivery.Methods:iCOMCat is utilized to create various beam patterns with user defined dose rate, gantry, MLC and jaw speed for each control point. The accuracy and stability of the output and beam profile are qualified for each isolated functional component of VMAT delivery using ion chamber and Profiler2 with isocentric mounting fixture. Service graphing on linac console is used to verify the mechanical motion accuracy. The determined optimum Elekta VMAT machine parameters were configured in RayStation v4.5.1. To evaluate the system overall performance, TG‐119 test cases and nine retrospective VMAT patients were planned on RayStation, and validated using both ArcCHECK (with plug and ion chamber) and MapCHECK2.Results:Machine output and profile varies <0.3% when only variable is dose rate (35MU/min‐600MU/min). <0.9% output and <0.3% profile variation are observed with additional gantry motion (0.53deg/s–5.8deg/s both directions). The output and profile variation are still <1% with additional slow leaf motion (<1.5cm/s both direction). However, the profile becomes less symmetric, and >1.5% output and 7% profile deviation is seen with >2.5cm/s leaf motion. All clinical cases achieved comparable plan quality as treated IMRT plans. The gamma passing rate is 99.5±0.5% on ArcCheck (<3% iso center dose deviation) and 99.1±0.8% on MapCheck2 using 3%/3mm gamma (10% lower threshold). Mechanical motion accuracy in all VMAT deliveries is <1°/1mm.Conclusion:Accurate RayStation modeling and robust VMAT delivery is achievable on Elekta Agility for <2.5cm/s leaf motion and full range of dose rate and gantry speed determined by the same vendor softwares. Our TG‐119 and patient results have provided us with the confidence to use VMAT clinically.
SU‐E‐T‐251: Developing a Daily Proton Beam Monitoring System
Authors: Yeo I , Ghebremedhin A , Patyal B 
Published: June 2015

Purpose:To develop a daily monitoring system for proton beam output check and beam uniformity check.Methods:Designed for continuously irradiated photon and electron beams with a field size of 20 cm × 20 cm, the daily output checker (Sun Nuclear, Inc.) is not suitable for monitoring proton beams with inter‐pulse beam‐off and a field size smaller than 14–16 cm in diameter. To allow such proton beam monitoring, the following tests were performed. 1. Absolute dose and array calibrations which accept continuous irradiation only, were performed using photon beams. 2. Five ion chambers within the central area of 8 cm × 8 cm were utilized to check constancy of output at the center of beam modulation and at distal edge and to check beam symmetry and flatness. 3. To simplify our evaluation, the array calibration was manually modified, such that all five chambers report equal values in spite of their differences in build‐up thicknesses. 4. The chamber at the lower‐right corner is placed under a buildup thickness that can offer dose measurement at the distal edge. This buildup thickness was determined by proton beam range measurements, which established buildup thickness for beam output measurement at the central chamber and range measurement at the corner chamber. 5. The beam‐off delay which allows receipt of pulsed irradiation was activated and optimal delay times were determined for each proton beam at 149.6, 185.6, and 249.5 MeV.Results:The above system was tested by miss‐steering proton beams and altering phantom thickness by 1 mm at a time. The system reliably monitored the beam with: 3% tolerance for beam flatness, symmetry and output. The range difference of 0.5 mm could be detected at all energies by setting a tolerance of 20%.Conclusion:A quick daily proton beam monitoring system was feasible.
SU‐E‐T‐252: Developing a Pencil Beam Dose Calculation Algorithm for CyberKnife System
Authors: Liang B , Liu B , Zhou F , Xu S , Wu Q 
Published: June 2015

Purpose:Currently there are two dose calculation algorithms available in the Cyberknife planning system: ray‐tracing and Monte Carlo, which is either not accurate or time‐consuming for irregular field shaped by the MLC that was recently introduced. The purpose of this study is to develop a fast and accurate pencil beam dose calculation algorithm which can handle irregular field.Methods:A pencil beam dose calculation algorithm widely used in Linac system is modified. The algorithm models both primary (short range) and scatter (long range) components with a single input parameter: TPR20/10. The TPR20/20/10 value was first estimated to derive an initial set of pencil beam model parameters (PBMP). The agreement between predicted and measured TPRs for all cones were evaluated using the root mean square of the difference (RMSTPR), which was then minimized by adjusting PBMPs. PBMPs are further tuned to minimize OCR RMS (RMSocr) by focusing at the outfield region. Finally, an arbitrary intensity profile is optimized by minimizing RMSocr difference at infield region. To test model validity, the PBMPs were obtained by fitting to only a subset of cones (4) and applied to all cones (12) for evaluation.Results:With RMS values normalized to the dmax and all cones combined, the average RMSTPR at build‐up and descending region is 2.3% and 0.4%, respectively. The RMSocr at infield, penumbra and outfield region is 1.5%, 7.8% and 0.6%, respectively. Average DTA in penumbra region is 0.5mm. There is no trend found in TPR or OCR agreement among cones or depths.Conclusion:We have developed a pencil beam algorithm for Cyberknife system. The prediction agrees well with commissioning data. Only a subset of measurements is needed to derive the model. Further improvements are needed for TPR buildup region and OCR penumbra. Experimental validations on MLC shaped irregular field needs to be performed.This work was partially supported by the National Natural Science Foundation of China (61171005) and the China Scholarship Council (CSC).
SU‐E‐T‐253: Development of a GDPM Monte Carlo Based Quality Assurance Tool for Cyberknife
Authors: Webster M , Ouyang L , Folkerts M , Tian Z , Jia X , Jiang S , Gu X 
Published: June 2015

Purpose:To develop a 3D quality assurance (QA) tool for Cyberknife plans using a GPU‐based Monte Carlo dose calculation package, gDPM. The developed QA tool will be used as a secondary check for Cyberknife treatment planning software (TPS) reported dose distributions.Methods:Phase space files of the 5, 7.5, 10, 15, and 60 mm iris cones were downloaded from IAEA phase‐space database. From the 60mm iris cone phase space file, we were able to generate raw phase space files for all other cones using a particle rejection method. The particles in the raw phase space files were binned with respect to the radial position and energy for commissioning. During the commissioning process, gDPM calculated percent depth dose and off‐center ratios which were compared to those measured in the Blue Phantom. The off‐axis data was measured with an SAD setup at depths of 15, 50, 100, 200, and 300 mm. At the commissioning stage, an optimization problem was solved to adjust the binned particles weights to minimize the difference between the calculated and measured ones. Commissioning validations will be performed by measuring point dose data of patient specific plans delivered to water phantoms. With commissioned phase space files, 3D patient‐specific dose distributions will be calculated and compared against TPS reported dose.Results:Beyond the initial buildup region, the root mean square difference between the calculated and measured percent depth dose differences was less than 0.5%. The full‐width half‐max data from the off‐axis ratio calculations was found to be within 0.1 mm of the measured data.Conclusion:Our current work showed excellent agreement between the gDPM calculated dose and the measured data for all cone sizes and types for the Cyberknife system. Implementation of a fast and accurate QA tool for patient specific plans will be feasible with this tool.
SU‐E‐T‐318: Dosimetric Evaluation of ArcCHECK and 3DVH System Using Customized Polymer Gel Dosimeter
Authors: Ono K , Fujimoto S , Hayashi S , Miyazawa M , Akagi Y , Hirokawa Y 
Published: June 2015

Purpose:ArcCHECK and 3DVH system (Sun Nuclear) can reconstruct the three‐dimensional (3D) dose distribution and provide the DVH analysis in a patient. The aim of this study was to evaluate dosimetric accuracy of this system using customized polymer gel dosimeter, and also Gafchromic EBT3 films.Methods:Polyacrylamide‐based gel contained magnesium chloride as a sensitizer (iPAGAT) was used in this study. Volumetric‐modulated arc therapy (VMAT) plan was performed for the C‐shape structure by the Eclipse treatment planning system (Varian) and used to irradiate the ArcCHECK by the Novalis Tx linear accelerator (Varian/BrainLAB). The cubic phantom filled with iPAGAT and EBT3 films placed in three orthogonal planes (axial, sagittal, and coronal) inserted into the I'mRT Phantom (IBA Dosimetry) simulated a patient were irradiated with the same VMAT plan. The measurement‐guided 3D dose distribution was reconstructed using 3DVH software from the measured data of the ArcCHECK. The 3D dose distribution in iPAGAT was read out by Signa 1.5 T MRI system (GE), and 2D dose distribution on EBT3 was read out by color scanner (Epson). The comparison of all the dose distributions was performed with dose profiles and gamma index analysis in orthogonal planes using in‐house developed software.Results:A good agreement was observed by overlaying the dose profiles of 3DVH, EBT3, and iPAGAT. The mean pass rates by gamma index analysis with 3%/3 mm criteria in orthogonal planes were 94.3% (3DVH vs EBT3), 91.1% (3DVH vs iPAGAT), and 96.4% (iPAGAT vs EBT3), respectively.Conclusion:3D dose distribution reconstructed by ArcCHECK and 3DVH system was estimated accurately in a patient. However, slightly differences were observed between 3DVH and iPAGAT because of MRI noise, therefore further study is required to improve the accuracy of MRI based polymer gel dosimetry for the DVH analysis.
SU‐E‐T‐326: Dosimetric Impact of Beam Energies and Jaw Tracking On Intracranial Tumors Using RapidArc
Authors: Hossain S , Keeling V , Ali I , Ahmad S , Algan O 
Published: June 2015

Purpose:To determine the dosimetric impact of jaw tracking and beam energies on dose conformity and normal‐brain‐tissue doses for intracranial tumors using VMAT (RapidArc).Methods:Seven patients with 1–2 and three patients with 4–6 intracranial tumors were planned using RapidArc for Varian TrueBeam STx machine with beam energies 6MV‐FFF (Flattening‐Filter‐Free), 8MV, 10MV, and 10MV‐FFF. The prescription dose ranged from 14–23Gy. Between 2 and 8 arcs were used with the following geometries: 2 full coplanar arcs and the non‐coplanar half arcs. Plans were optimized (jaw tracking ON) with a high priority to Normal‐Tissue‐Objective and normal‐brain‐tissue. Plans were calculated on 1mm grid size using AAA algorithm and then normalized so that 99% of each target volume received the prescription dose. Plans for the 6MV‐FFF were also optimized without jaw tracking (No‐JT) for comparison. Plan quality was assessed by target coverage using Paddick Conformity Index (PCI), sparing of normal‐brain‐tissue through analysis of V4Gy, V8Gy and V12Gy, and integral dose.Results:The average PCI ± standard deviation was 0.76±0.21 and 0.76±0.22 for 6MV‐FFF and 10 MV‐FFF, respectively. The average ratio in normal brain tissue volume (reported as follows V4,V8,V12) were (1.12±0.07,1.12±0.07,1.14±0.04), (1.12±0.08,1.12±0.09,1.13±0.06), (1.19±0.10,1.18±0.10,1.20±0.04), and (1.04±0.03,1.03±0.03,1.03±0.04) for 8MV/6MV‐FFF, 10MV‐FFF/6MV‐FFF, 10MV/6MV‐FFF, 6MV‐FFF No‐JT/6MV‐FFF, respectively. Statistically significant differences in normal‐brain‐tissue for V4, V8, and V12 were observed in all cases for the different energies (p‐values <0.05). V4 data shows significant differences in JT vs. No‐JT (p=0.04), however no difference was found for V8 and V12. Brain tissue sparing from best to worst occurred in this order 6MV‐FFF, 6MV‐FFF no‐JT, 10MV‐FFF, 8MV, and 10MV. The average ratio of integral brain dose was 1.05±0.04 (p=0.21), 1.04±0.05 (p=0.33), 1.09±0.06 (p=0.04), and 1.02±0.06 (p=0.61) for 8MV/6MV‐FFF, 10MV‐FFF/6MV‐FFF, 10MV/6MV‐FFF, and 6MV‐FFF No‐JT/6MV‐FFF, respectively.Conclusion:Normal brain tissue and integral dose improved using the lower energy and FFF beams, though plan conformity showed energy independence.
SU‐E‐T‐327: Dosimetric Impact of Beam Energy for Intrabeam Breast IORT with Different Residual Cancer Cell Distributions After Surgery
Authors: Schwid M , Zhang H 
Published: June 2015

Purpose:The purpose of this study was to evaluate the dosimetric impact of beam energy to the IORT treatment of residual cancer cells with different cancer cell distributions after breast‐conserving surgery.Methods:The three dimensional (3D) radiation doses of IORT using a 4‐cm spherical applicator at the energy of 40 keV and 50 keV were separately calculated at different depths of the postsurgical tumor bed. The modified linear quadratic model (MLQ) was used to estimate the radiobiological response of the tumor cells assuming different radio‐sensitivities and density distributions. The impact of radiation was evaluated for two types of breast cancer cell lines (α /β=10, and α /β =3.8) at 20 Gy dose prescribed at the applicator surface. Cancer cell distributions in the postsurgical tissue field were assumed to be a Gaussian with the standard deviations of 0.5, 1 and 2 mm respectively, namely the cancer cell infiltrations of 1.5, 3, and 6 mm respectively. The surface cancer cell percentage was assumed to be 0.01%, 0.1%, 1% and 10% separately. The equivalent uniform doses (EUD) for all the scenarios were calculated.Results:The EUDs were found to be dependent on the distributions of cancer cells, but independent of the cancer cell radio‐sensitivities and the density at the surface. EUDs of 50 keV are 1% larger than that of 40 keV. For a prescription dose of 20 Gy, EUDs of 50 keV beam are 17.52, 16.21 and 13.14 Gy respectively for 0.5, 1.0 and 2.0 mm of the standard deviation of cancer cell Gaussian distributions.Conclusion:The impact by selected energies of IORT beams is very minimal. When energy is changed from 50 keV to 40 keV, the EUDs are almost the same for the same cancer cell distribution. 40 keV can be safely used as an alternative of 50 keV beam in IORT.