bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐T‐316: The Design of a Risk Index Method for 3D Patient Specific QA
Authors: Cho W , Xing L , Suh T , Wu H 
Published: July 2014

Purpose:To suggest a new guidance for the evaluation of 3D patient specific QA, a structure‐specific risk‐index (RI) method was designed and implemented.Methods:A new algorithm was designed to assign the score of Pass, Fail or Pass with Risk to all 3D voxels in each structure by improving a conventional Gamma Index (GI) algorithm, which implied the degree of the risk of under‐dose to the treatment target or over‐dose to the organ at risks (OAR). Structure‐specific distance to agreement (DTOA), dose difference and minimum checkable dose were applied to the GI algorithm, and additional parameters such as dose gradient factor and dose limit of structures were used to the RI method. Maximum passing rate (PR) and minimum PR were designed and calculated for each structure with the RI method. 3D doses were acquired from a spine SBRT plan by simulating the shift of beam iso‐center, and tested to show the feasibility of the suggested method.Results:When the iso‐center was shifted by 1 mm, 2 mm, and 3 mm, the PR of conventional GI method between shifted and non‐shifted 3D doses were 99.9%, 97.4%, and 89.7% for PTV, 99.8%, 84.8%, and 63.2% for spinal cord, and 100%, 99.5%, 91.7% for right lung. The minimum PRs from the RI method were 98.9%, 96.9%, and 89.5% for PTV, and 96.1%, 79.3%, 57.5% for spinal cord, and 92.5%, 92.0%, 84.4% for right lung, respectively. The maximum PRs from the RI method were equal or less than the PRs from the conventional GI evaluation.Conclusion:Designed 3D RI method showed more strict acceptance level than the conventional GI method, especially for OARs. The RI method is expected to give the degrees of risks in the delivered doses, as well as the degrees of agreements between calculated 3D doses and measured (or simulated) 3D doses.
SU‐E‐T‐319: The Effect of Slice Thickness On IMRT Planning
Authors: Srivastava S , Cheng C , Das I 
Published: July 2014

Purpose:The accuracy of volume estimated of a treatment planning system is investigated in this study. In addition, the effect of slice thickness on IMRT planning is also studied.Methods:The accuracy in volume determination was investigated using a water phantom containing various objects with known volumes ranging from 1–100cm3. The phantom was scanned with different slice thickness (1–10 mm). The CT data sets were sent to Eclipse TPS for contour delineation and volume calculation. The effect of slice thickness on IMRT planning was studied using a commercial phantom containing four different shaped objects. The phantom was scanned with different slice thickness (1–5 mm). IMRT plans were generated for the different CT datasets to calculate TCP, homogeneity (HI) and conformity indices (CI).Results:The variability of volumes with CT slice thickness was significant especially for small volume structures. The minimum and maximum error in the volume estimation is in the range of −2.3% to 92%. On the other hand, with increasing slice thickness, the PTV mean dose and TCP values decreases. Maximum variation of ∼5% was observed in mean dose and ∼2% in TCP with slice thickness change from 1–5 mm. The relative decrease in target volume receiving 95% of prescribed dose is ∼5% slice thickness change from 1–5 mm. HI increases up to 163% and CI decreases by 4% between 1–5 mm slice thickness change, producing highly inhomogeneous and least conformal plan.Conclusion:Accuracy of volume estimation is dependent on CT slice thickness and the contouring algorithm in a TPS. During TPS commissioning and for all clinical protocols, evaluation of volume should be included to provide the limit of accuracy in DVH calculation. A smaller slice thickness provides superior dosimetry with improved TCP values. Thus, the smallest possible slice thickness should be used for IMRT planning
SU‐E‐T‐320: The Effect of Survivin Perturbation On the Radiation Response of Breast Cancer Cell Lines
Authors: Smith D , Debeb B , Woodward W 
Published: July 2014

Purpose:Survivin is the smallest member of the inhibitor of apoptosis protein family and is well‐known for its universal over‐expression in human cancers. Due to its role in apoptosis and cellular proliferation, survivin is implicated in the radiation response in several cancer types, and antisurvivin treatments have had success as a radiation sensitizer in many preclinical cancer models. As no studies to date have reported survivin as a factor affecting radiation resistance in breast cancer models, we sought to evaluate the synergistic relationship between survivin function and irradiation in breast cancer cell lines.Methods:Information regarding survivin protein expression in breast cancer was retrieved from three public databases: Oncomine, Kaplan‐Meier Plotter, and GOBO. For the in vitro studies, survivin function was compromised by transducing a non‐functional mutant form (survivin‐DN) into two breast cancer cell lines, the estrogen receptor‐positive MCF7 and the triple‐negative, inflammatory SUM149. Cell growth was compared in the survivin‐DN and control populations with colony‐formation assays. To assess how survivin affects radiation response, clonogenic assays were performed by irradiating the cell lines up to 6 Gy.Results:From the public databases, survivin is more highly expressed in triple‐negative breast cancer compared to all other subtypes, and is prognostic of poor survival in all breast cancer patients. In MCF7, the survivin‐DN population had decreased colony‐formation potential; the opposite was true in SUM149. In the clonogenic assays, abrogation of survivin function radio‐protected MCF7 cells in monolayer and 3D growth conditions, while SUM149 survivin‐DN cells were radiosensitized in monolayer conditions.Conclusion:We observed synergy between survivin function and radiation, although the results between the two cell lines were disparate. Further investigation is required to identify the mechanism of this discrepancy, including evaluation of the potential role of estrogen receptor status, before proceeding with small‐animal experiments.
SU‐E‐T‐321: The Effects of a Dynamic Collimation System On Proton Pencil Beams to Improve Lateral Tissue Sparing in Spot Scanned Proton Therapy
Authors: Hill P , Wang D , Flynn R , Hyer D 
Published: July 2014

Purpose:To evaluate the lateral beam penumbra in pencil beam scanning proton therapy delivered using a dynamic collimator device capable of trimming a portion of the primary beam in close proximity to the patient.Methods:Monte Carlo simulations of pencil beams were performed using MCNPX. Each simulation transported a 125 MeV proton pencil beam through a range shifter, past acollimator, and into a water phantom. Two parameters were varied among the simulations, the source beam size (sigma in air from 3 to 9 mm), and the position of the edge of the collimator (placed from 0 to 30 mm from the central axis of the beam). Proton flux was tallied at the phantom surface to determine the effective beam sizefor all combinations of source beam size and collimator edge position.Results:Quantifying beam size at the phantom surface provides a useful measure tocompare performance among varying source beam sizes and collimation conditions. For arelatively large source beam size (9 mm) entering the range shifter, sigma at thesurface was found to be 10 mm without collimation versus 4 mm with collimation. Additionally, sigma at the surface achievable with collimation was found to be smallerthan for any uncollimated beam, even for very small source beam sizes. Finally, thelateral penumbra achievable with collimation was determined to be largely independentof the source beam size.Conclusion:Collimation can significantly reduce proton pencil beam lateral penumbra.Given the known dosimetric disadvantages resulting from large beam spot sizes,employing a dynamic collimation system can significantly improve lateral tissuesparing in spot‐scanned dose distributions.
SU‐E‐T‐322: The Evaluation of the Gafchromic EBT3 Film in Low Dose 6 MV X‐Ray Beams with Different Scanning Modes
Authors: Lee H , Kim D , Chung W , Sung J , Yoon M 
Published: July 2014

Purpose:We have evaluated the response of the Gafchromic EBT3 film in low dose for 6 MV x‐ray beams with two scanning modes, the reflection scanning mode and the transmission scanning mode.Methods:We irradiated the Gafcromic EBT3 film using a 60 degree enhanced dynamic wedge (EDW) with 6 MV x‐ray beams from Clinac iX Linear accelerator (Varian Medical Systems, Palo Alto, CA). The irradiated Gafchromic EBT3 film was scanned with different scanning modes, the reflection scanning mode and the transmission scanning mode. The scanned Gafchromic EBT3 film was analyzed with MATLAB.Results:When 7.2 cGy was irradiated to the Gafchromic EBT3 film, the uncertainty was 0.54 cGy with reflection scanning mode and was 0.88 cGy with transmission scanning mode. When 24 cGy was irradiated to the Gafchromic EBT3 film, the uncertainty was similar to the case of 7.2 cGy irradiation showing 0.51 cGy of uncertainty with reflection scanning mode and 0.87 cGy of uncertainty with transmission scanning mode. The result suggests that the reflection mode should be used in Gafchromic EBT3 film for low irradiation.Conclusion:The result suggests that the reflection mode should be used in Gafchromic EBT3 film for low irradiation.
SU‐E‐T‐325: The New Evaluation Method of the VMAT Plan Delivery Using Varian DynaLog Files and Modulation Complexity Score (MCS)
Authors: Tateoka K , Fujimomo K , Saitou Y , Nakazawa T , Abe T , Nakata A , Yano M , Hareyama M 
Published: July 2014

Purpose:The aim of the study is to evaluate the use of Varian DynaLog files to verify VMAT plans delivery and modulation complexity score (MCS) of VMAT.Methods:Delivery accuracy of machine performance was quantified by multileaf collimator (MLC) position errors, gantry angle errors and fluence delivery accuracy for volumetric modulated arc therapy (VMAT). The relationship between machine performance and plan complexity were also investigated using the modulation complexity score (MCS). Plan and Actual MLC positions, gantry angles and delivered fraction of monitor units were extracted from Varian DynaLog files. These factors were taken from the record and verify system of MLC control file. Planned and delivered beam data were compared to determine leaf position errors and gantry angle errors. Analysis was also performed on planned and actual fluence maps reconstructed from those of the DynaLog files. This analysis was performed for all treatment fractions of 5 prostate VMAT plans. The analysis of DynaLog files have been carried out by in‐house programming in Visual C++.Results:The root mean square of leaf position and gantry angle errors were about 0.12 and 0.15, respectively. The Gamma of planned and actual fluence maps at 3%/3 mm criterion was about 99.21. The gamma of the leaf position errors were not directly related to plan complexity as determined by the MCS. Therefore, the gamma of the gantry angle errors were directly related to plan complexity as determined by the MCS.Conclusion:This study shows Varian dynalog files for VMAT plan can be diagnosed delivery errors not possible with phantom based quality assurance. Furthermore, the MCS of VMAT plan can evaluate delivery accuracy for patients receiving of VMAT. Machine performance was found to be directly related to plan complexity but this is not the dominant determinant of delivery accuracy.
SU‐E‐T‐326: The Oxygen Saturation (SO2) and Breath‐Holding Time Variation Applied Active Breathing Control (ABC)
Authors: Gong G , Yin Y 
Published: July 2014

Purpose:To study the oxygen saturation (SO2) and breath‐holding time variation applied active breathing control (ABC) in radiotherapy of tumor.Methods:24 volunteers were involved in our trials, and they all did breath‐holding motion assisted by ELEKTA Active Breathing Coordinator 2.0 for 10 times respectively. And the patient monitor was used to observe the oxygen saturation (SO2) variation. The variation of SO2, and length of breath‐holding time and the time for recovering to the initial value of SO2 were recorded and analyzed.Results:(1) The volunteers were divided into two groups according to the SO2 variation in breath‐holding: A group, 14 cases whose SO2 reduction were more than 2% (initial value was 97% to 99%, while termination value was 91% to 96%); B group, 10 cases were less than 2% in breath‐holding without inhaling oxygen. (2) The interfraction breath holding time varied from 8 to 20s for A group compared to the first breath‐holding time, and for B group varied from 4 to 14s. (3) The breathing holding time of B group prolonged mean 8s, compared to A group. (4) The time for restoring to the initial value of SO2 was from 10s to 30s. And the breath‐holding time shortened obviously for patients whose SO2 did not recover to normal.Conclusion:It is very obvious that the SO2 reduction in breath‐holding associated with ABC for partial people. It is necessary to check the SO2 variation in breath training, and enough time should be given to recover SO2.
SU‐E‐T‐327: The Update of a XML Composing Tool for TrueBeam Developer Mode
Authors: Yan Y , Mao W , Jiang S 
Published: July 2014

Purpose:To introduce a major upgrade of a novel XML beam composing tool to scientists and engineers who strive to translate certain capabilities of TrueBeam Developer Mode to future clinical benefits of radiation therapy.Methods:TrueBeam Developer Mode provides the users with a test bed for unconventional plans utilizing certain unique features not accessible at the clinical mode. To access the full set of capabilities, a XML beam definition file accommodating all parameters including kV/MV imaging triggers in the plan can be locally loaded at this mode, however it is difficult and laborious to compose one in a text editor. In this study, a stand‐along interactive XML beam composing application, TrueBeam TeachMod, was developed on Windows platforms to assist users in making their unique plans in a WYSWYG manner. A conventional plan can be imported in a DICOM RT object as the start of the beam editing process in which trajectories of all axes of a TrueBeam machine can be modified to the intended values at any control point. TeachMod also includes libraries of predefined imaging and treatment procedures to further expedite the process.Results:The TeachMod application is a major of the TeachMod module within DICOManTX. It fully supports TrueBeam 2.0. Trajectories of all axes including all MLC leaves can be graphically rendered and edited as needed. The time for XML beam composing has been reduced to a negligible amount regardless the complexity of the plan. A good understanding of XML language and TrueBeam schema is not required though preferred.Conclusion:Creating XML beams manually in a text editor will be a lengthy error‐prone process for sophisticated plans. A XML beam composing tool is highly desirable for R&D activities. It will bridge the gap between scopes of TrueBeam capabilities and their clinical application potentials.
SU‐F‐BRF‐07: Impact of Different Patient Setup Strategies in Adaptive Radiation Therapy with Simultaneous Integrated Volume‐Adapted Boost of NSCLC
Authors: Balik S , Weiss E , Dogan N , fatyga m , Sleeman W , Wu Y , Hugo G 
Published: July 2014

Purpose:To evaluate the potential impact of several setup error correction strategies on a proposed image‐guided adaptive radiotherapy strategy for locally advanced lung cancer.Methods:Daily 4D cone‐beam CT and weekly 4D fan‐beam CT images were acquired from 9 lung cancer patients undergoing concurrent chemoradiation therapy. Initial planning CT was deformably registered to daily CBCT images to generate synthetic treatment courses. An adaptive radiation therapy course was simulated using the weekly CT images with replanning twice and a hypofractionated, simultaneous integrated boost to a total dose of 66 Gy to the original PTV and either a 66 Gy (no boost) or 82 Gy (boost) dose to the boost PTV (ITV + 3mm) in 33 fractions with IMRT or VMAT. Lymph nodes (LN) were not boosted (prescribed to 66 Gy in both plans). Synthetic images were rigidly, bony (BN) or tumor and carina (TC), registered to the corresponding plan CT, dose was computed on these from adaptive replans (PLAN) and deformably accumulated back to the original planning CT. Cumulative D98% of CTV of PT (ITV for 82Gy) and LN, and normal tissue dose changes were analyzed.Results:Two patients were removed from the study due to large registration errors. For the remaining 7 patients, D98% for CTV‐PT (ITV‐PT for 82 Gy) and CTV‐LN was within 1 Gy of PLAN for both 66 Gy and 82 Gy plans with both setup techniques. Overall, TC based setup provided better results, especially for LN coverage (p = 0.1 for 66Gy plan and p = 0.2 for 82 Gy plan, comparison of BN and TC), though not significant. Normal tissue dose constraints violated for some patients if constraint was barely achieved in PLAN.Conclusion:The hypofractionated adaptive strategy appears to be deliverable with soft tissue alignment for the evaluated margins and planning parameters.Research was supported by NIH P01CA116602
SU‐F‐BRF‐08: Conformal Mapping‐Based 3D Surface Matching and Registration
Authors: Song Y , Zeng W , Liu C , Gu X 
Published: July 2014

Purpose:Recently, non‐rigid 3D surface matching and registration has been used extensively in engineering and medicine. However, matching 3D surfaces undergoing non‐rigid deformation accurately is still a challenging mathematical problem. In this study, we present a novel algorithm to address this issue by introducing intrinsic symmetry to the registrationMethods:Our computational algorithm for symmetric conformal mapping is divided into three major steps: 1) Finding the symmetric plane; 2) Finding feature points; and 3) Performing cross registration. The key strategy is to preserve the symmetry during the conformal mapping, such that the image on the parameter domain is symmetric and the area distortion factor on the parameter image is also symmetric. Several novel algorithms were developed using different conformal geometric tools. One was based on solving Riemann‐Cauchy equation and the other one employed curvature flowResults:Our algorithm was implemented using generic C++ on Windows XP and used conjugate gradient search optimization for acceleration. The human face 3D surface images were acquired using a high speed 3D scanner based on the phase‐shifting method. The scanning speed was 30 frames/sec. The image resolution for each frame was 640 × 480. For 3D human face surfaces with different expressions, postures, and boundaries, our algorithms were able to produce consistent result on the texture pattern on the overlapping regionConclusion:We proposed a novel algorithm to improve the robustness of conformal geometric methods by incorporating the symmetric information into the mapping process. To objectively evaluate its performance, we compared it with most existing techniques. Experimental results indicated that our method outperformed all the others in terms of robustness. The technique has a great potential in real‐time patient monitoring and tracking in image‐guided radiation therapy
SU‐F‐BRF‐09: A Non‐Rigid Point Matching Method for Accurate Bladder Dose Summation in Cervical Cancer HDR Brachytherapy
Authors: Chen H , Zhen X , Zhong Z , Pompos A , Yan H , Zhou L , Jiang S , Gu X 
Published: July 2014

Purpose:To propose and validate a deformable point matching scheme for surface deformation to facilitate accurate bladder dose summation for fractionated HDR cervical cancer treatment.Method:A deformable point matching scheme based on the thin plate spline robust point matching (TPSRPM) algorithm is proposed for bladder surface registration. The surface of bladders segmented from fractional CT images is extracted and discretized with triangular surface mesh. Deformation between the two bladder surfaces are obtained by matching the two meshes' vertices via the TPS‐RPM algorithm, and the deformation vector fields (DVFs) characteristic of this deformation is estimated by B‐spline approximation. Numerically, the algorithm is quantitatively compared with the Demons algorithm using five clinical cervical cancer cases by several metrics: vertex‐to‐vertex distance (VVD), Hausdorff distance (HD), percent error (PE), and conformity index (CI). Experimentally, the algorithm is validated on a balloon phantom with 12 surface fiducial markers. The balloon is inflated with different amount of water, and the displacement of fiducial markers is benchmarked as ground truth to study TPS‐RPM calculated DVFs' accuracy.Results:In numerical evaluation, the mean VVD is 3.7(±2.0) mm after Demons, and 1.3(±0.9) mm after TPS‐RPM. The mean HD is 14.4 mm after Demons, and 5.3mm after TPS‐RPM. The mean PE is 101.7% after Demons and decreases to 18.7% after TPS‐RPM. The mean CI is 0.63 after Demons, and increases to 0.90 after TPS‐RPM. In the phantom study, the mean Euclidean distance of the fiducials is 7.4±3.0mm and 4.2±1.8mm after Demons and TPS‐RPM, respectively.Conclusions:The bladder wall deformation is more accurate using the feature‐based TPS‐RPM algorithm than the intensity‐based Demons algorithm, indicating that TPS‐RPM has the potential for accurate bladder dose deformation and dose summation for multi‐fractional cervical HDR brachytherapy.This work is supported in part by the National Natural ScienceFoundation of China (no 30970866 and no 81301940).
SU‐F‐BRF‐13: Investigating the Feasibility of Accurate Dose Measurement in a Deforming Radiochromic Dosimeter
Authors: Juang T , Adamovics J , Oldham M 
Published: July 2014

Purpose:Presage‐Def, a deformable radiochromic 3D dosimeter, has been previously shown to have potential for validating deformable image registration algorithms. This work extends this effort to investigate the feasibility of using Presage‐Def to validate dose‐accumulation algorithms in deforming structures.Methods:Two cylindrical Presage‐Def dosimeters (8cm diameter, 4.5cm length) were irradiated in a water‐bath with a simple 4‐field box treatment. Isocentric dose was 20Gy. One dosimeter served as control (no deformation) while the other was laterally compressed during irradiation by 21%. Both dosimeters were imaged before and after irradiation with a fast (∼10 minutes for 1mm isotropic resolution), broad beam, high resolution optical‐CT scanner. Measured dose distributions were compared to corresponding distributions calculated by a commissioned Eclipse planning system. Accuracy in the control was evaluated with 3D gamma (3%/3mm). The dose distribution calculated for the compressed dosimeter in the irradiation geometry cannot be directly compared via profiles or 3D gamma to the measured distribution, which deforms with release from compression. Thus, accuracy under deformation was determined by comparing integral dose within the high dose region of the deformed dosimeter distribution versus calculated dose. Dose profiles were used to study temporal stability of measured dose distributions.Results:Good dose agreement was demonstrated in the control with a 3D gamma passing rate of 96.6%. For the dosimeter irradiated under compression, the measured integral dose in the high dose region (518.0Gy*cm3) was within 6% of the Eclipse‐calculated integral dose (549.4Gy*cm3). Elevated signal was noted on the dosimeter edge in the direction of compression. Change in dosimeter signal over 1.5 hours was ≤2.7%, and the relative dose distribution remained stable over this period of time.Conclusion:Presage‐Def is promising as a 3D dosimeter capable of accurately measuring dose in a deforming structure, and warrants further study to quantify comprehensive accuracy at different levels of deformation.This work was supported by NIH R01CA100835.John Adamovics is the president of Heuris Inc., which commercializes PRESAGE.