bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐T‐13: A Comparative Dosimetric Study On Radio‐Dynamic Therapy for Pelvic Cancer Treatment: Strategies for Bone Marrow Dose and Volume Reduction
Authors: Li C , Wang B , Dong Z , Ge W , Xu L , Ma C 
Published: June 2015

Purpose:Radio‐dynamic therapy (RDT) is a potentially effective modality for local and systemic cancer treatment. Using RDT, the administration of a radio‐sensitizer enhances the biological effect of high‐energy photons. Although the sensitizer uptake ratio of tumor to normal tissue is normally high, one cannot simply neglect its effect on critical structures. In this study, we aim to explore planning strategies to improve bone marrow sparing without compromising the plan quality for RDT treatment of pelvic cancers.Methods:Ten cervical and ten prostate cancer patients who previously received radiotherapy at our institution were selected for this study. For each patient, nine plans were created using the Varian Eclipse treatmentplanning‐system (TPS) with 3D‐CRT, IMRT, and VMAT delivery techniques containing various gantry angle combinations and optimization parameters (dose constraints to the bone marrow). To evaluate the plans for bone marrow sparing, the dose‐volume parameters V5, V10, V15, V20, V30, and V40 for bone marrow were examined. Effective doseenhancement factors for the sensitizer were used to weigh the dose‐volume histograms for various tissues from individual fractions.Results:The planning strategies had different impacts on bone marrow sparing for the cervical and prostate cases. For the cervical cases, provided the bone marrow constraints were properly set during optimization, the dose to bone marrow sparing was found to be comparable between different IMRT and VMAT plans regardless of the gantry angle selection. For the prostate cases, however, careful selection of gantry angles could dramatically improve the bone marrow sparing, although the dose distribution in bone marrow was clinically acceptable for all prostate plans that we created.Conclusion:For intensity‐modulated RDT planning for cervical cancer, planners should set bone marrow constraints properly to avoid any adverse damage, while for prostate cancer one can carefully select gantry angles to improve bone marrow sparing when necessary.
SU‐E‐T‐25: A Dosimetric Comparison of Three‐Dimension Conformal and Intensity‐Modulated Radiation Therapy in Esophageal Cancer
Authors: Gallardo N , Maneru F , Fuentemilla N , Olasolo J , Gracia M , Pellejero S , Bragado L , Lozares S , Miquelez S , Martin M 
Published: June 2015

Purpose:dosimetric comparison of 3DCRT and IMRT in 9 esophageal cancer. The aim of this paper is to know which of these two techniques is dosimetrically more favorable dosimetrically at both the CTV coverage and dose obtained in the relevant organs at risk, in this case, lungs and heart, as the spinal cord received in all cases below 45 Gy.Methods:we chose 9 patients from our center (CHN) with the same type of esophageal cancer and in which the prescribed dose was the same, 54 Gy. For these treatments we have used the same fields and the same angles (AP (0 °), OPD (225°–240°) and OPI (125°–135°)).All plans have been implemented using Eclipse (version 11.0) with AAA( Analytical Anisotropic Algorithm )(Version 11.0.31).Results:To analyze the coverage of the CTV, we have evaluated the D99% and found that the average dose received by 99% of CTV with IMRT is 53.8 ± 0.4 Gy (99.6% of the prescribed dose) and the mean value obtained with 3DCRT is 52.3 ± 0.6 Gy (96.8% of the prescribed dose).The last data analyzed was the D2% of PTV, a fact that gives us information on the maximum dose received by our PTV. D2% of the PTV for IMRT planning is 55.4 ± 0.4 Gy (102.6% of the prescribed dose) and with 3DCRT is 56.8 ± 0.7 Gy (105.2% of the prescribed dose).All parameters analyzed at risk organs (V30, V40, V45 and V50 for the case of heart and V5, V10, V15 and V20 for the case of the lungs) provide us irradiated volume percentages lower in IMRT than 3DCRT.Conclusion:IMRT provides a considerable improvement in the coverage of the CTV and the doses to organs at risk.
SU‐E‐T‐31: A Fast Finite Size Pencil Beam (FSPB) Convolution Algorithm for a New Co‐60 Arc Therapy Machine
Authors: Chibani O , Eldib A , Ma C 
Published: June 2015

Purpose:Present a fast Finite Size Pencil Beam (FSPB) convolution algorithm for a new Co‐60 arc therapy machine. The FSPB algorithm accounts for (i) strong angular divergence (short SAD), (ii) heterogeneity effect for primary attenuation, and (iii) source energy spectrum.Methods:The FSPB algorithm is based on a 0.5×0.5‐cm2 dose kernel calculated using the GEPTS (Gamma Electron and Positron Transport System) Monte Carlo code. The dose kernel is tabulated using a thin XYZ mesh (0.1 mm steps in lateral directions) for radius less than 1 cm and using an RZ mesh (with varying steps) for larger radial distance. To account for SSD effect, 11 dose kernels with SSDs varying between 30 cm to 80 cm are calculated. Maynord factor and “lateral stretching” are applied to account for differences between closest and actual SSD. Appropriate rotations and second order interpolation are used to calculate the dose from a given beamlet to a point.Results:Accuracy: Dose distributions in water with 80 cm SSD are calculated using the new FSPB convolution algorithm and full Monte Carlo simulation (gold standard). Figs 1–4 show excellent agreements between FSPB and Monte Carlo calculations for different field sizes and at different depths. The dose distribution for a prostate case is calculated using FSPB (Fig.5). Sixty conformal beams with rectum blocking are assumed. Figs 6–8 show the comparison with Monte Carlo simulation based on the same beam apertures. The excellent agreement demonstrates the accuracy of the new algorithm in handling SSD variation, oblique incidence, and scatter contribution.Speed: The FSPB convolution algorithm calculates 28 million dose points per second using a single 2.2‐GHz CPU. The present algorithm is seven times faster than a similar algorithm from Gu et al. (Phys. Med. Biol. 54, 2009, 6287–6297).Conclusion:A fast and accurate FSPB convolution algorithm was developed and benchmarked.
SU‐E‐T‐38: A Head to Head Comparison of Two Commercial Phantoms Used for SRS QA
Authors: Sarkar V , Huang L , Huang Y , Szegedi M , Rassiah‐Szegedi P , Zhao H , Salter B 
Published: June 2015

Purpose:To compare and contrast two commercial SRS QA phantoms.Methods:Both phantoms were evaluated in terms of their ease of setup as well as the time required to switch inserts for different tests. They were both used to evaluate the coincidence of the radiation and laser isocenters of a linear accelerator. End‐to‐end dosimetric tests were also performed using both ion chambers and films along two planes through the center of the phantoms. Since one phantom allows for multiple ion chamber orientations, a test was also performed to determine the effect of having the chamber oriented along the radiation beam axis’.Results:Changing inserts took 2 minutes on average for one phantom compared to 5 minutes for the other. The laser/radiation isocenter coincidence as determined from each phantom showed a maximum difference of 0.2mm. Ion chamber results were within 0.5% of the expected values when the chamber was perpendicular to the beams but measured a 3% underdose when the chamber was along the beam direction. Gamma (2%,2mm) pass rates of corresponding films were within 1% between phantoms.Conclusion:The results of the corresponding tests run on both phantoms were comparable, showing that the phantoms were equivalent for the subset of SRS QA tests run here. However, the under dose observed when the chamber was parallel to the beam direction suggests that this configuration should be avoided.
SU‐E‐T‐43: A Methodology for Quality Control of IMPT Treatment Plan Based On VMAT Plan
Authors: Jiang S , Yang Y , Liao L , Wang X , Li H , Zhu X , Zhang X 
Published: June 2015

Purpose:IMPT plan design is highly dependent on planner's experiences. VMAT plan design is relatively mature and can even be automated. The quality of IMPT plan designed by in‐experienced planner could be inferior to that of VMAT plan designed by experienced planner or automatic planning software. Here we introduce a method for designing IMPT plan based on VMAT plan to ensure the IMPT plan be superior to IMRT/VMAT plan for majority clinical scenario.Methods:To design a new IMPT plan, a VMAT plan is first generated either by experienced planner or by in‐house developed automatic planning system. An in‐house developed tool is used to generate the dose volume constrains for the IMPT plan as plan template to Eclipse TPS. The beam angles for IMPT plan are selected based on the preferred angles in the VMAT plan. IMPT plan is designed by importing the plan objectives generated from VMAT plan. Majority thoracic IMPT plans are designed using this plan approach in our center. In this work, a thoracic IMPT plan under RTOG 1308 protocol is selected to demonstrate the effectiveness and efficiency of this approach. The dosimetric indices of IMPT are compared with VMAT plan.Results:The PTV D95, lung V20, MLD, mean heart dose, esophagus D1, cord D1 are 70Gy, 31%, 17.8Gy, 25.5Gy, 73Gy, 45Gy for IMPT plan and 65.3Gy, 34%, 21.6Gy, 35Gy, 74Gy, 48Gy for VMAT plan. For majority cases, the high dose region of the normal tissue which is in proximity of PTV is comparable between IMPT and VMAT plan. The low dose region of the IMPT plan is significantly better than VMAT plan.Conclusion:Using the knowledge gained in VMAT plan design can help efficiently and effectively design high quality IMPT plan. The quality of IMPT plan can be controlled to ensure the superiority of IMPT plan compared to VMAT/IMRT plan.
SU‐E‐T‐45: A Modified Winston‐Lutz Test for Single Isocenter Multiple Targets SRS QA
Authors: Song C , Xue K , Li R , Xue T 
Published: June 2015

Purpose:When treating multiple targets with a single isocenter, the distances between some targets and the isocenter may be large. The gantry, couch and collimator angle errors, as well as the isocenter errors, are important for this kind of SRS treatment. We developed a Modified Winston‐Lutz (MWL) test to check the combined errors of the isocenter, the aforementioned angles, and MLC position and alignment.Methods:We use a phantom cube (VisionRt SRS QA phantom) containing 5 ceramic spheres with diameters of 7.5 mm. The maximum distance between two spheres is 8.0 cm, with the central sphere at the center of the phantom. The treatment machine is a TrueBeam STx with HD‐MLC. The spheres are contoured on CT images using the Varian Eclipse planning system. We generated eight fields with combinations of gantry angles of 0, 90, 180 and 270, couch angles of 0, 90 and 270, and collimator angles of 0, 45, 90, 270 and 315. The MLC apertures of four fields are fitted to spheres 1, 3 and 5 with 2 mm margins, and the other four fields are fitted to spheres 2 and 4. After CBCT alignment of the phantom, the eight fields are imaged with the MV port imager.Results:The MLC aperture off‐center errors of the central sphere and the maximum off‐center errors of the other four spheres are measured on the port images for each field. After eight tests, the errors of the central sphere on each field range from 0.0 mm to 0.6 mm. The maximum errors of the other spheres on each field range from 0.5 mm to 1.0 mm.Conclusion:We have developed an MWL test for single isocenter multiple target SRS treatments. On the TrueBeam, the errors of targets within 4 cm of the isocenter are 1 mm or less.
SU‐E‐T‐46: A Monte Carlo Investigation of Radiation Interactions with Gold Nanoparticles in Water for 6 MV, 85 KeV and 40 KeV Photon Beams
Authors: Flint D B , O'Brien D J , McFadden C H , Hallacy T M , Wolfe T , Krishnan S , Sawakuchi G O 
Published: June 2015

Purpose:To determine the effect of gold‐nanoparticles (AuNPs) on energy deposition in water for different irradiation conditions.Methods:TOPAS version B12 Monte Carlo code was used to simulate energy deposition in water from monoenergetic 40 keV and 85 keV photon beams and a 6 MV Varian Clinac photon beam (IAEA phase space file, 10x10 cm2, SSD 100 cm). For the 40 and 85 keV beams, monoenergetic 2x2 mm2 parallel beams were used to irradiate a 30x30x10 µm 3 water mini‐phantom located at 1.5 cm depth in a 30x30x50 cm3 water phantom. 5000 AuNPs of 50 nm diameter were randomly distributed inside the mini‐phantom. Energy deposition was scored in the mini‐phantom with the AuNPs’ material set to gold and then water. For the 6 MV beam, we created another phase space (PHSP) file on the surface of a 2 mm diameter sphere located at 1.5 cm depth in the water phantom. The PHSP file consisted of all particles entering the sphere including backscattered particles. Simulations were then performed using the new PHSP as the source with the mini‐phantom centered in a 2 mm diameter water sphere in vacuum. The g4em‐livermore reference list was used with “EMRangeMin/EMRangeMax = 100 eV/7 MeV” and “SetProductionCutLowerEdge = 990 eV” to create the new PHSP, and “SetProductionCutLowerEdge = 100 eV” for the mini‐phantom simulations. All other parameters were set as defaults (“finalRange = 100 µm”).Results:The addition of AuNPs resulted in an increase in the mini‐phantom energy deposition of (7.5 ± 8.7)%, (1.6 ± 8.2)%, and (−0.6 ± 1.1)% for 40 keV, 85 keV and 6 MV beams respectively.Conclusion:Enhanced energy deposition was seen at low photon energies, but decreased with increasing energy. No enhancement was observed for the 6 MV beam. Future work is required to decrease the statistical uncertainties in the simulations.This research is partially supported from institutional funds from the Center for Radiation Oncology Research, The University of Texas MD Anderson Cancer Center.
SU‐E‐T‐48: A Multi‐Institutional Study of Independent Dose Verification for Conventional, SRS and SBRT
Authors: Takahashi R , Tachibana H , Kamima T , Itano M , Yamazaki T , Ishibashi S , Higuchi Y , Shimizu H , Yamamoto T , Yamashita M , Baba H , Sugawara Y , Sato A , Nishiyama S , Kawai D , Miyaoka S 
Published: June 2015

Purpose:To show the results of a multi‐institutional study of the independent dose verification for conventional, Stereotactic radiosurgery and body radiotherapy (SRS and SBRT) plans based on the action level of AAPM TG‐114.Methods:This study was performed at 12 institutions in Japan. To eliminate the bias of independent dose verification program (Indp), all of the institutions used the same CT‐based independent dose verification software (Simple MU Analysis, Triangle Products, JP) with the Clarkson‐based algorithm. Eclipse (AAA, PBC), Pinnacle3 (Adaptive Convolve) and Xio (Superposition) were used as treatment planning system (TPS). The confidence limits (CL, Mean±2SD) for 18 sites (head, breast, lung, pelvis, etc.) were evaluated in comparison in dose between the TPS and the Indp.Results:A retrospective analysis of 6352 treatment fields was conducted. The CLs for conventional, SRS and SBRT were 1.0±3.7 %, 2.0±2.5 % and 6.2±4.4 %, respectively. In conventional plans, most of the sites showed within 5 % of TG‐114 action level. However, there were the systematic difference (4.0±4.0 % and 2.5±5.8 % for breast and lung, respectively). In SRS plans, our results showed good agreement compared to the action level. In SBRT plans, the discrepancy between the Indp was variable depending on dose calculation algorithms of TPS.Conclusion:The impact of dose calculation algorithms for the TPS and the Indp affects the action level. It is effective to set the site‐specific tolerances, especially for the site where inhomogeneous correction can affect dose distribution strongly.
SU‐E‐T‐54: A New Method for Optimizing Radiation Isocenter for Linac‐Based SRS
Authors: Hancock S , Hyer D , Nixon E 
Published: June 2015

Purpose:To develop a new method to minimize deviation of linac x‐ray beams from the centroid of the volumetric radiation isocenter for all combinations of gantry and table angle.Methods:A set of ball‐bearing (Winston‐Lutz) images was used to determine the gantry radiation isocenter as the midrange of deviation values. Deviations in the cross‐plane direction were minimized by calibration of MLC leaf position offset, and by adjusting beam position steering for each energy. Special attention was also paid to matching the absolute position of isocenter across all energies by adjusting position steering in the gun‐target axis. Displacement of table axis from the gantry isocenter, and recommended table axis adjustment for contemporary Elekta linacs, was also determined. Eight images were used to characterize the volumetric isocenter for the full range of gantry and table rotations available. Tabulation of deviation for each beam was used to test compliance with isocenter tolerance.Results:Four contemporary Elekta linacs were evaluated and the radius in the gun‐target axis of the radiation isocenter was 0.5 to 0.7 mm. After beam steering adjustment, the radius in the cross‐plane direction was typically 0.2 to 0.4 mm. Position matching between energies can be reduced to 0.28 mm. Maximum total deviation was 0.68 to 1.07 mm, depending primarily on the effect of systematic table axis wobble with rotation.Conclusion:This new method effectively facilitates minimization of deviation between beam center and target position. The test, which requires a few minutes to perform, can be easily incorporated into a routine machine QA program. A tighter radiation isocenter for contemporary Elekta linacs would require reducing the effect of gantry arm flex and/or table axis wobble that are the two main components of deviation from the designated isocenter point.
SU‐E‐T‐57: A Novel Method to Improve Dose Heterogeneity of Target and Organs at Risk Sparing in the Intensity‐Modulated Radiotherapy for Stage III Lung Cancer
Authors: Huang B‐T , Lu J‐Y 
Published: June 2015

Purpose:Intensity‐modulated radiotherapy (IMRT) treatment for lung cancer is difficult due to the heterogeneous dose distribution and excessive dose to the organs at risk (OARs). We introduce a simple method based on the base dose function (BDF) in Eclipse treatment planning system to overcome the difficulties.Methods:Thirteen patients suffered from stage III non‐small cell lung cancer (NSCLC) were enrolled in the study. Three kinds of approaches were applied to obtain clinically acceptable treatment plans: 1) conventionally optimizing method with hot and cold spots re‐optimization (CO); 2) target‐divided optimizing method (TDO) in which the optimization objective in the lung density of planning target volume (PTV) was set to 2 to 4 Gy higher than in the soft tissue density; 3) base dose function (BDF) in which the treatment plan was produced based on the original plan for re‐optimization. CO, TDO and BDF methods were then compared in terms of conformity index (CI), homogeneity index (HI), OARs sparing and monitor units (MUs). Additionally, delta4, portal dosimetry and IMSure were used to measure the dose delivering accuracy.Results:The BDF technique provided more superior CI and HI than the other two methods. Moreover, the new method also reduced the lung, esophagus, heart and spinal cord dose. However, the BDF plans needed extra 15% and 10% MUs than the CO and TDO methods. Dose verification results demonstrated good and comparable γ pass rates among the three methods.Conclusion:The proposed BDF method greatly improves the dose homogeneity and OARs sparing in the IMRT treatment for lung cancer.
SU‐E‐T‐63: A Preliminary Study of Gold Nanoparticles Enhanced Cone Beam Computed Tomography
Authors: Chen K , Sha H , Yang Y 
Published: June 2015

Purpose:Gold nanoparticles (GNPs) have potential of being used as a new‐generation contrast agent to enhance CT imaging of cancer. This feasibility study is to determine the GNP concentration required to provide sufficient image contrast in small animal cone beam CT (CBCT) imaging.Methods:The GNPs used are nanorods with 10nm diameter and 44nm length. A 50µl GNP colloid with an original GNP concentration of 3.6mg/ml was diluted to five different concentrations at 2.4, 2.1, 2.0, 1.9 and 1.8mg/ml, respectively. The GNP colloid was enclosed in a 150µl vial, and the GNP colloid vial was submerged in a water bottle for CBCT. CBCTs were acquired with x‐ray energy of 65kVp and tube current of 1.5mA. In addition, to evaluate the optimal x‐ray energy for GNP detection in CBCT, the GNP colloid of 1.8mg/ml was also imaged at x‐ray energy of 45kVp and 85kVp. Regions of interest were placed in axial CBCT slices contouring the GNP colloid volume and a same volume in the surrounding water to calculate the signal and contrast.Results:For the GNP colloid at concentrations of 3.6, 2.4, 2.1, 2.0, 1.9 and 1.8mg/ml, the image contrasts between GNP colloid and water were 68±4, 33±4, 23±3, 20±3, 13±4, and 10±3 HU, respectively. At 1.8mg/ml concentration level, the image contrasts were 16±3 and 7±4 HU, respectively, when the x‐ray energy was set at 45kVp and 85kVp.Conclusion:The minimal GNP concentration required on our small animal CBCT was estimated to be around 1.8mg/ml due to the fact that the minimum image contrast for adequate differentiation in CT is about 8 HU. CBCT at lower x‐ray energy, i.e. 45kVp, can provide better image contrast than at higher energies, i.e., 65kVp and 85kVp. A study of GNP enhanced CBCT for in vivo small animal imaging is ongoing efforts in our group.
SU‐E‐T‐65: A Prospective Trial of Open Face Masks for Head and Neck Radiotherapy
Authors: Wiant D , Squire S , Maurer J , Liu H , Hayes L , Sintay B 
Published: June 2015

Purpose:Open face head and neck masks allow for active patient monitoring during treatment and may reduced claustrophobia and anxiety compared to closed masks. The ability of open masks to limit intrafraction motion and to preserve the patient shape/position from simulation over protracted treatments should be considered.Methods:Thirty‐two head and neck patients were prospectively randomized to treatment in a closed mask or a novel open face mask. All patients received daily volumetric imaging. The daily images were automatically rigidly registered to the planning CT's offline using a commercial image processing tool. The shifts needed to optimize the registration, the mutual information coefficient (MI), and the Pearson correlation (PC) coefficients were recorded to evaluate shape preservation. The open group was set‐up and monitored with surface imaging at treatment. The real time surface imaging information was recorded to evaluate intrafraction motion.Results:Sixteen patients were included in each group. Evaluations were made over a total of 984 fractions. The mean MI and PC showed significantly higher shape preservation for the open group than for the closed group (p = 0). The mean rotations for the open group were smaller or < 0.15° larger versus the closed group. The mean intrafraction motion for the open group was 0.93 +/−0.99 mm (2 SD). The maximum single fraction displacement was 3.2 mm. Fourteen of 16 patients showed no significant correlation of motion with fraction number (p > 0.05).Conclusion:The open masks preserved shape as well as the closed masks, and they limited motion to < 2 mm for 95% of the treated fractions. These results are consistent over treatment courses of up to 35 fractions. The open mask is suitable for treatment with or without active monitoring.This work was partially supported by Qfix.