bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐T‐385: Evaluation of DVH Change for PTV Due to Patient Weight Loss in Prostate VMAT Using Gaussian Error Function
Authors: Viraganathan H , Jiang R , Chow J 
Published: June 2015

Purpose:We proposed a method to predict the change of dose‐volume histogram (DVH) for PTV due to patient weight loss in prostate volumetric modulated arc therapy (VMAT). This method is based on a pre‐calculated patient dataset and DVH curve fitting using the Gaussian error function (GEF).Methods:Pre‐calculated dose‐volume data from patients having weight loss in prostate VMAT was employed to predict the change of PTV coverage due to reduced depth in external contour. The effect of patient weight loss in treatment was described by a prostate dose‐volume factor (PDVF), which was evaluated by the prostate PTV. Along with the PDVF, the GEF was used to fit into the DVH curve for the PTV. To predict a new DVH due to weight loss, parameters from the GEF describing the shape of DVH curve were determined. Since the parameters were related to the PDVF as per the specific reduced depth, we could first predict the PDVF at a reduced depth based on the prostate size from the pre‐calculated dataset. Then parameters of the GEF could be determined from the PDVF to plot the new DVH for the PTV corresponding to the reduced depth.Results:A MATLAB program was built basing on the patient dataset with different prostate sizes. We input data of the prostate size and reduced depth of the patient into the program. The program then calculated the PDVF and DVH for the PTV considering the patient weight loss. The program was verified by different patient cases with various reduced depths.Conclusion:Our method can estimate the change of DVH for the PTV due to patient weight loss quickly without CT rescan and replan. This would help the radiation staff to predict the change of PTV coverage, when patient's external contour reduced in prostate VMAT.
SU‐E‐T‐386: Evaluation of EBT3 Film Response in Different Batches
Authors: Escarcia F , Herrera J , Garcia O 
Published: June 2015

Purpose:To investigate the uniformity of film response of EBT3 film of two different film batches. It has been reported that the response of the EBT film family is not homogenous between film batches. The later may have an impact in the dosimetry of small radiotherapy beams.Methods:A solid water phantom was used for dosimetric measurements. EBT3 film irradiation was performed with a 6 MV photon beam at 5 cm depth with a SAD of 100 cm. All irradiations were performed perpendicularly to the film plane covering the dose range 1 to 10 Gy. Three square field sizes were used to analyze the film response energy dependence: 10, 5 and 1 cm2. Two batches of film EBT3 were used #A03181302 (B1) and #03031403 (B2). Film read out was carrying out with an Epson Perfection V750‐Pro flatbed scanner in transmission mode with a spatial resolution of 72 dpi, with all post‐processing and colour management options turned off, using 48 bits RGB colour depth. The scans were analyzed with the red channel.Results:The results shown that there were differences between the film response for each batch. The differences between batches for 1 Gy were 2%, 6% and 12% for 10, 5 and 1 cm2 square field sizes, respectively. The differences found for 10 Gy were 13%, 14% and 13% for 10, 5 and 1 cm2 square field sizes, respectively. It can be observed that the dependence with field size dismissed for higher doses. The later may be due to film response saturation at 10 Gy.Conclusion:The EBT3 film ‐as its predecessors‐, it suffer for inter‐batch variability in the film response. Further research is required to assess the possible impact in small beam dosimetry.
SU‐E‐T‐389: Evaluation of Flattening‐Filter‐Free Arcs for Lung SBRT
Authors: Ouyang L , Lee H , Pompos A , Yan Y , Jiang S , Foster R 
Published: June 2015

Purpose:To evaluate dynamic conformal arc therapy (DCAT) and volumetric‐modulated arc therapy (VMAT) using flattening‐filter‐free (FFF) beams for treating non‐small cell lung cancer (NSCLC) with stereotactic body radiation therapy (SBRT).Methods:Five clinical patients, previously treated with SBRT using non‐coplanar 3D conformal radiation therapy (3DCRT), were selected and re‐planned with DCAT and VMAT with both FFF beam (6xFFF with a dose rate of 1200MU/min) and flattened beams (6x with 600 MU/min). All the arc plans were planned with one 360° arc and normalized to the same PTV coverage (100% prescription cover 95% PTV volume) for comparison. Treatment planning metrics such as R100%, R50%, D2cm and lung V20 were compared to the original plans. To evaluate the treatment efficiency differences, all the arc plans were delivered and plan delivery time was compared to that of the clinical treatment as recorded in Mosaiq.Results:All plans meet RTOG conformality constraints and normal tissue tolerances. Average R100% was similar for FFFDCAT (1.07±0.05), FFFVMAT (1.03±0.08) and flattened VMAT (fVMAT) (1.03±0.09) while flattened DCAT (fDCAT) (1.09±0.07) and 3DCRT (1.11±0.06) were significantly inferior (p<0.05, t test). FFFDCAT produced the best average intermediate dose conformality as indicated by R50% (3.86±0.44) and D2cm (43.7±5.3%) when compared to all the other techniques. Significant improvement (p<0.05) in lung V20 was also found with FFFDCAT (2.33±2.06%) when compared to FFFVMAT (2.48±2.03%), fVMAT (2.52±2.07%) and fDCAT (2.64±2.11%) and was slightly better than 3DCRT (2.43±2.04%), though not significant. The FFFDCAT delivery significantly improves the treatment efficiency with an average plan delivery time of 2.70±1.57 min (p<0.05), as compared to fDCAT (5.98±3.45min), fVMAT (6.51±2.94) and 3DCRT (25.14±5.67), but is not significantly better than the FFFVMAT (3.18±1.04).Conclusion:Combining FFF beams and DCAT provide promising improvements in NSCLC SBRT treatment in both plan quality and treatment efficiency and unlike VMAT, tumor coverage is not affected by MLC interplay effects.
SU‐E‐T‐393: Evaluation of Large Field IMRT Versus RapidArc Planning for Carcinoma Cervix with Para‐Aotic Node Irradiation
Authors: Raman S Kothanda , Girigesh Y , MISHRA M , Lalit K 
Published: June 2015

Purpose:The objective of this work is to evaluate and compare Large field IMRT and RapidArc planning for Carcinoma Cervix and Para‐aotic node irradiation.Methods:In this study, ten patients of Cervix with para‐aotic node have been selected with PTV length 35+2cm. All plans were generated in Eclipse TPS V10.0 with Dynamic IMRT and RapidArc technique using 6MV photon energy. In IMRT planning, 7 fields were chosen to get optimal plan and in RapidArc, double Full arc clockwise and counter clockwise were used for planning. All the plans were generated with single isocenter and calculated using AAA dose algorithm. For all the cases the prescribed dose to PTV was same and the plan acceptance criteria is; 95% of the PTV volume should receive 100% prescribed dose. The tolerance doses for the OAR's is also taken in to account. The evaluation criteria used for analysis are; 1) Homogeneity Index, 2) Conformity Index, 3) Mean Dose to OAR's, 4)Total monitor units delivered.Results:DVH analysis were performed for both IMRT and RapidArc planning. In both the plans, 95% of PTV volume receives prescribed dose and maximum dose are less than 107%. The conformity index are same in both the techniques. The mean Homogeneity index are 1.036 and 1.053 for IMRT and RapidArc plan. The mean (mean + SD) dose of bladder and rectum in IMRT is 44.2+1.55, 42.05+2.52 and RapidArc is 46.66+1.6, 44.2+2.75 respectively. There is no significant difference found in Right Femoral head, Left Femoral head and Kidney doses. It is found that total MU's are more in IMRT compared with RapidArc planning.Conclusion:In the case of cervix with Para‐arotic node single isocenter irradiation, IMRT planning in large‐field is better compared to RapidArc planning in terms of Homogeneity Index and mean dose of Bladder and Rectum.
SU‐E‐T‐394: Evaluation of Microwave Ablation Zone Variance Based On Reported Changes in Thermal and Electrical Properties of Tissues
Authors: Deshazer G , Prakash P , Hagmann M , Dupuy D , Merck D 
Published: June 2015

Purpose:Image‐guided percutaneous ablation is an, effective, inexpensive, and accessible treatment for liver, lung, and kidney cancers. However, its relatively high recurrence rate makes it more palliative. We hypothesize that higher rates are due in part to inadequate margin estimation, resulting from over‐simplified geometric planning. Better predictive planning is needed, however, this requires numerical model accounting for the physical characteristics of heterogeneous tissues around the target. Literature suggests that pathologies such as cirrhosis and malignant tissue have varying thermal and electrical properties when compared to normal tissue. The objective of this study is to employ a simulation based approach to determine the impact of heterogeneous tissue physical properties on treatment outcome.Methods:An electromagnetic‐thermal finite‐element model of the BSD Medical ST antenna was created. The antenna placed inside the center of a tumor that was immersed within liver tissue. The variance of ablation zone sizes with tissue physical properties was evaluated by assigning varying tissue dielectric and thermal properties to the tumor, consistent with data reported in the literature. 10–30 % variations in tissue effective electrical conductivity, and varying perfusion levels for tumor, normal, and cirrhotic liver (3–18 kg/m3/s) were considered. The CEM43 > 240 min threshold was used to estimate ablation zone extents.Results:Less than 4 mm variation in ablation zone extents was observed when considering 10–30 % differences in effective electrical conductivity between malignant and normal tissue. Perfusion variations showed the largest difference when compared to homogeneous simulation (∼ 4.5 mm − 1.0 cm).Conclusion:The results suggest that dielectric inhomogeneities have limited impact on predicted ablation zone extents. However, variances in tumor and normal liver tissue blood perfusion, within the range of clinically measured values reported in the literature, significantly affects predicted ablation zone volumes. Further research investigating the impact of other tissue properties is warranted.
SU‐E‐T‐405: Evaluation of the Raystation Electron Monte Carlo Algorithm for Varian Linear Accelerators
Authors: Sansourekidou P , Allen C 
Published: June 2015

Purpose:To evaluate the Raystation v4.51 Electron Monte Carlo algorithm for Varian Trilogy, IX and 2100 series linear accelerators and commission for clinical use.Methods:Seventy two water and forty air scans were acquired with a water tank in the form of profiles and depth doses, as requested by vendor. Data was imported into Rayphysics beam modeling module. Energy spectrum was modeled using seven parameters. Contamination photons were modeled using five parameters. Source phase space was modeled using six parameters. Calculations were performed in clinical version 4.51 and percent depth dose curves and profiles were extracted to be compared to water tank measurements. Sensitivity tests were performed for all parameters. Grid size and particle histories were evaluated per energy for statistical uncertainty performance.Results:Model accuracy for air profiles is poor in the shoulder and penumbra region. However, model accuracy for water scans is acceptable. All energies and cones are within 2%/2mm for 90% of the points evaluated. Source phase space parameters have a cumulative effect. To achieve distributions with satisfactory smoothness level a 0.1cm grid and 3,000,000 particle histories were used for commissioning calculations. Calculation time was approximately 3 hours per energy.Conclusion:Raystation electron Monte Carlo is acceptable for clinical use for the Varian accelerators listed. Results are inferior to Elekta Electron Monte Carlo modeling. Known issues were reported to Raysearch and will be resolved in upcoming releases. Auto‐modeling is limited to open cone depth dose curves and needs expansion.
SU‐E‐T‐406: Evaluation of the Stealth Chamber by IBA Under Large Field Conditions
Authors: Quino L Vazquez , Hernandez C Huerta , DeWeese M 
Published: June 2015

Purpose:To evaluate the performance of the stealth chamber by IBA under large field conditions.Methods:Measurement of PDDs and profiles for fields of 10×10, 15×15, 20×20 and 25×25 cm2 were acquired in a blue phantom2 scanning system for 6 and 15 MV beams in a Varian TrueBeam linear accelerator. The stealth chamber has a field size limit of 25×25 cm2. Measurements with two different detector set were performed. First a cc13 chamber as field and reference chamber was acquired. And with a cc13 chamber as field detector and the stealth chamber as the reference chamber. PDDs for the fields mentioned above were conducted and profiles with the same fields at depth of dmax, 5, 10 and 20 cm were acquired for comparison.Results:Examination of the PDDs and profile comparison with a criterion of 1% and 1 mm agreement was performed. Very good agreement between the cc13 and stealth chamber set was observed within the chosen criterion.Conclusion:This work indicates the comparable results obtained with the use of the stealth chamber and cc13 as the reference chamber in relative dosimetry measurements.
SU‐E‐T‐412: Evaluation of Tungsten‐Based Functional Paper for Attenuation Device in Intraoperative Radiotherapy for Breast Cancer
Authors: Kamomae T , Monzen H , Okudaira K , Miyake Y , Oguchi H , Komori M , Kawamura M , Itoh Y , Kikumori T , Naganawa S 
Published: June 2015

Purpose:Intraoperative radiotherapy (IORT) with an electron beam is one of the accelerated partial breast irradiation methods that have recently been used in early‐stage breast cancer. A protective acrylic resin‐copper disk is inserted between the breast tissue and the pectoralis muscle to minimize the dose received by the posterior structures. However, a problem with this protective disk is that the surgical incision must be larger than the field size because the disk is manufactured from stiff and unyielding materials. The purpose of this study was to assess the applicability of a new tungsten‐based functional paper (TFP) as an alternative to the existing protective disk in IORT.Methods:The newly introduced TFP (Toppan Printing Co., Ltd., Tokyo, JP) is anticipated to become a useful device that is lead‐free, light, flexible, and easily processed. The radiation shielding performance of TFP was verified by experimental measurements and Monte Carlo (MC) simulations using PHITS code. The doses transmitted through the protective disk or TFP were measured on a Mobetron mobile accelerator. The same geometries were then reproduced, and the dose distributions were simulated by the MC method.Results:The percentages of transmitted dose relative to the absence of the existing protective disk were lower than 2% in both the measurements and MC simulations. In the experimental measurements, the percentages of transmitted dose for a 9 MeV electron beam were 48.1, 2.3, and 0.6% with TFP thicknesses of 1.9, 3.7, and 7.4 mm, respectively. The percentages for a 12 MeV were 76.0, 49.3, 20.0, and 5.5% with TFP thicknesses of 1.9, 3.7, 7.4, and 14.8 mm, respectively. The results of the MC simulation showed a slight dose increase at the incident surface of the TFP caused by backscattered radiation.Conclusion:The results indicate that a small‐incision procedure may be possible by the use of TFP.
SU‐E‐T‐429: Feasibility Study On Three‐Dimensional GRID Therapy in Conventional Linacs
Authors: Yan Y , Meyer J , Timmerman R , Hrycushko B , Chen B , Saha D , Jiang S 
Published: June 2015

Purpose:Two‐dimensional GRID therapy, traditionally planned and delivered using a dedicated GRID block or MLC modulation, has shown clinical efficacy in treating bulky tumors. However, the large dose to normal tissues outside target can be limiting. We hypothesize that modulation in the third dimension will improve dose sparing of normal tissues, maximize the bystander effect within the target, and ultimately improve the therapy effectiveness. This study aims to investigate the feasibility of a three‐dimensional GRID technique using conventional LINACs to achieve a 3D lattice of high dose volumes within a target.Methods:Datasets of patient's having large tumor sizes were used to investigate the planning and delivering of 3D GRID using a Varian TrueBeam linac. Original patient contours of PTV are exported from a TPS to DICOManTX where 3D GRID targets are generated in programmable configurations. A structure of avoidance (SOA), i.e., PTV minus GRID targets, is also generated to facilitate inverse planning to achieve the desired pattern. The artificial structures were sent back to the TPS where an IMRT or VMAT plan is designed to deliver a desired high dose to GRID targets while minimizing the dose to the SOA as much as possible.Results:The programmable GRID target generator enables us to modify the target geometry to maximize the peak‐to‐valley ratio. Preliminary results show that plans based on spherical GRID targets achieve a higher peak‐to‐valley dose ratio compared with cylindrical targets. High dose spillage outside the target was eliminated. IMRT planning requires the number of beams to be larger than 16, while for VMAT the number of arcs should be at least 4 in order to achieve dosimetric goals.Conclusion:Planning and delivering 3D GRID therapy using conventional LINACs was shown to be feasible. More research and development are required before this new modality can be implemented clinically.
SU‐E‐T‐492: Influence of Clipping PTV in Build‐Up Region On IMRT Plan Quality and Deliverability
Authors: Sharma S , Manigandan D , Sahai P , Biswas A , Subramani V , Chander S , Julkha P , Rath G 
Published: June 2015

Purpose:To study the influence of clipping PTV from body contour on plan quality and deliverability in build‐up region for superficial target.Methods:Five previously treated patients of post‐operative carcinoma of parotid were re‐planned for IMRT (6MV X‐rays, sliding window technique, five fields and 60Gy/30 fractions) using eclipse treatment planning system (TPS) by keeping dose volume constraints and all other parameters constant, only PTV was clipped from body contour by 0mm, 1mm, 2mm and 3mm respectively. Planned fluence was transferred to previously scanned solid water phantom by placing I'matriXX array at 0.5cm depth (2mm slab+3mm inherent). Fluence was delivered by Varian CL2300C/D linac at 99.5cm source to detector distance. Measured fluence was compared with TPS dose plane using 2D gamma evaluation using 3%/3mm DTA criteria. Total MU (monitor unit) required to deliver a plan was also noted. For plan quality, PTV, maximum‐dose, minimum‐dose, coverage index (CI=PTV volume covered by prescription dose/PTV) and heterogeneity index HI=D5/D95 were analyzed using dose volume histogram (DVH).Results:The Result of gamma function analysis for I'matriXX and TPS were 97.63±1.79%, 97.48±0.99, 98.08±0.89% and 98.01±0.78% at 0.5cm build‐up depth for 0, 1, 2 and 3mm PTV clipping, respectively. I'matriXX measured dose was higher compared to TPS. Total MU required for delivering a plan were 552±61, 503±47, 436±24 and 407±22. Maximum‐dose to PTV was 6635.80±62.01cGy, 6635.80±40.60cGy, 6608.43±51.07cGy and 6564.20±28.51cGy. Similarly, minimum‐dose to PTV was 3306.23±458.56cGy, 3546.57±721.01cGy, 4591.43±298.81cGy and 4861.90±412.40cGy. CI was 0.9347±0.020, 0.9398±0.021, 0.9448±0.022 and 0.9481±0.021. Similarly, HI was 1.089±0.015, 1.084±0.014, 1.078±0.009 and 1.074±0.008 for 0, 1, 2 and 3mm PTV clipping, respectively.Conclusion:Gamma function analysis resulted in almost similar results. However, I'matriXX was overestimating the dose compared to TPS. MU required to deliver a plan decreases with increase in PTV clipping. CI, PTV minimum‐dose and plan homogeneity increases with increase in PTV clipping from skin.
SU‐E‐T‐500: Initial Implementation of GPU‐Based Particle Swarm Optimization for 4D IMRT Planning in Lung SBRT
Authors: Modiri A , Hagan A , Gu X , Sawant A 
Published: June 2015

Purpose4D‐IMRT planning, combined with dynamic MLC tracking delivery, utilizes the temporal dimension as an additional degree of freedom to achieve improved OAR‐sparing. The computational complexity for such optimization increases exponentially with increase in dimensionality. In order to accomplish this task in a clinically‐feasible time frame, we present an initial implementation of GPU‐based 4D‐IMRT planning based on particle swarm optimization (PSO).MethodsThe target and normal structures were manually contoured on ten phases of a 4DCT scan of a NSCLC patient with a 54cm3 right‐lower‐lobe tumor (1.5cm motion). Corresponding ten 3D‐IMRT plans were created in the Eclipse treatment planning system (Ver‐13.6). A vendor‐provided scripting interface was used to export 3D‐dose matrices corresponding to each control point (10 phases × 9 beams × 166 control points = 14,940), which served as input to PSO. The optimization task was to iteratively adjust the weights of each control point and scale the corresponding dose matrices. In order to handle the large amount of data in GPU memory, dose matrices were sparsified and placed in contiguous memory blocks with the 14,940 weight‐variables. PSO was implemented on CPU (dual‐Xeon, 3.1GHz) and GPU (dual‐K20 Tesla, 2496 cores, 3.52Tflops, each) platforms. NiftyReg, an open‐source deformable image registration package, was used to calculate the summed dose.ResultsThe 4D‐PSO plan yielded PTV coverage comparable to the clinical ITV‐based plan and significantly higher OAR‐sparing, as follows: lung Dmean=33%; lung V20=27%; spinal cord Dmax=26%; esophagus Dmax=42%; heart Dmax=0%; heart Dmean=47%. The GPU‐PSO processing time for 14940 variables and 7 PSO‐particles was 41% that of CPU‐PSO (199 vs. 488 minutes).ConclusionTruly 4D‐IMRT planning can yield significant OAR dose‐sparing while preserving PTV coverage. The corresponding optimization problem is large‐scale, non‐convex and computationally rigorous. Our initial results indicate that GPU‐based PSO with further software optimization can make such planning clinically feasible.This work was supported through funding from the National Institutes of Health and Varian Medical Systems.