bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐T‐782: Using Light Output From Doped Plastic Scintillators to Resolve the Linear Energy Transfer Spectrum of Clinical Electron Beams
Authors: Nusrat H , Pang G , Ahmad S , Keller B , Sarfehnia A 
Published: June 2015

Purpose:This research seeks to develop a portable, clinically‐suitable linear energy transfer (LET) detector. In radiotherapy, absorbed dose is commonly used to measure the amount of delivered radiation, though, it is not a good indicator of actual biological damage. LET is the energy absorbed per unit length by a medium along charged particle's pathway; studies have shown that LET correlates well with relative biological effectiveness (RBE).Methods:According to Birks’ law, light output of plastic scintillators is stopping‐power dependent. This dependency can be varied through doping by various high‐Z elements. By measuring light output signals of differently doped plastic scintillators (represented by column vector S, where each row corresponds to different scintillator material), the fluence of charged particles of a given LET (represented by column vector Φ, where each row corresponds to different LET bins) can be unfolded by S=R*Φ where R is system response matrix (each row represents a different scintillator, each column corresponds to different electron LET). Monte Carlo (MC) GEANT4.10.1 was used to evaluate ideal detector response of BC408 scintillating material doped with various concentrations of several high Z dopants. Measurements were performed to validate MC.Results:Signal for 1%‐lead doped BC408 and the non‐doped scintillator was measured experimentally by guiding light emitted by the scintillator (via in‐house made taper, fiber system) to a PMT and then an electrometer. Simulations of 1%Pb‐doped scintillator to non‐doped scintillator revealed 9.3% reduction in light output for 6 MeV electrons which compared well (within uncertainty) with measurements showing 10% reduction (6MeV electrons).Conclusion:Measurements were used to validate MC simulation of light output from doped scintillators. The doping of scintillators is a viable technique to induce LET dependence. Our goal is to use this effect to resolve the LET spectrum of an incident beam.
SU‐E‐T‐785: Using Systems Engineering to Design HDR Skin Treatment Operation for Small Lesions to Enhance Patient Safety
Authors: Saw C , Baikadi M , Peters C , Brereton H 
Published: June 2015

Purpose:Using systems engineering to design HDR skin treatment operation for small lesions using shielded applicators to enhance patient safety.Methods:Systems engineering is an interdisciplinary field that offers formal methodologies to study, design, implement, and manage complex engineering systems as a whole over their life‐cycles. The methodologies deal with human work‐processes, coordination of different team, optimization, and risk management. The V‐model of systems engineering emphasize two streams, the specification and the testing streams. The specification stream consists of user requirements, functional requirements, and design specifications while the testing on installation, operational, and performance specifications. In implementing system engineering to this project, the user and functional requirements are (a) HDR unit parameters be downloaded from the treatment planning system, (b) dwell times and positions be generated by treatment planning system, (c) source decay be computer calculated, (d) a double‐check system of treatment parameters to comply with the NRC regulation. These requirements are intended to reduce human intervention to improve patient safety.Results:A formal investigation indicated that the user requirements can be satisfied. The treatment operation consists of using the treatment planning system to generate a pseudo plan that is adjusted for different shielded applicators to compute the dwell times. The dwell positions, channel numbers, and the dwell times are verified by the medical physicist and downloaded into the HDR unit. The decayed source strength is transferred to a spreadsheet that computes the dwell times based on the type of applicators and prescribed dose used. Prior to treatment, the source strength, dwell times, dwell positions, and channel numbers are double‐checked by the radiation oncologist. No dosimetric parameters are manually calculated.Conclusion:Systems engineering provides methodologies to effectively design the HDR treatment operation that minimize human intervention and improve patient safety.
SU‐E‐T‐786: Utility of Gold Wires to Optimize Intensity Modulation Capacity of a Novel Directional Modulated Brachytherapy Tandem Applicator for Image Guided Cervical Cancer Brachytherapy
Authors: Han D , Safigholi H , Soliman A , Scanderbeg D , Liu Z , Song W 
Published: June 2015

Purpose:To evaluate the impact of using gold wires to differentially fill various channels on plan quality compared with conventional T&R applicator, inside a novel directional modulated brachytherapy (DMBT) tandem applicator for cervical cancer brachytherapy.Materials and Methods:The novel DMBT tandem applicator has a 5.4‐mm diameter MR‐compatible tungsten alloy enclosed in a 0.3‐mm thick plastic tubing that wraps around the tandem. To modulate the radiation intensity, 6 symmetric peripheral holes of 1.3‐mm diameter are grooved along the tungsten alloy rod. These grooved holes are differentially filled with gold wires to generate various degrees of directional beams. For example, three different fill patterns of 1) all void, 2) all filled except the hole containing the 192‐Ir source, and 3) two adjacent holes to the 192‐Ir source filled were Monte Carlo simulated. The resulting 3D dose distributions were imported into an in‐house‐coded inverse optimization planning system to generate HDR brachytherapy clinical plans for 19 patient cases. All plans generated were normalized to the same D90 as the clinical plans and D2cc doses of OARs were evaluated. Prescription ranged between 15 and 17.5Gy.Results:In general, the plans in case 1) resulted in the highest D2cc doses for the OARs with 11.65±2.30Gy, 7.47±3.05Gy, and 9.84±2.48Gy for bladder, rectum, and sigmoid, respectively, although the differences were small. For the case 2), D2cc doses were 11.61±2.29Gy, 7.41±3.07Gy, and 9.75±2.45Gy, respectively. And, for the case 3), D2cc doses were 11.60±2.28Gy, 7.41±3.05Gy, and 9.74±2.45Gy, respectively. Difference between 1) and 2) cases were small with the average D2cc difference of <0.64%. Difference between 1) and 3) cases were even smaller with the average D2cc difference of <0.1%.Conclusions:There is a minimal clinical benefit by differentially filling grooved holes in the novel DMBT tandem applicator for image guided cervical cancer brachytherapy.
SU‐E‐T‐789: Validation of 3DVH Accuracy On Quantifying Delivery Errors Based On Clinical Relevant DVH Metrics
Authors: Ma T , Kumaraswamy L 
Published: June 2015

Purpose:Detection of treatment delivery errors is important in radiation therapy. However, accurate quantification of delivery errors is also of great importance. This study aims to evaluate the 3DVH software's ability to accurately quantify delivery errors.Methods:Three VMAT plans (prostate, H&N and brain) were randomly chosen for this study. First, we evaluated whether delivery errors could be detected by gamma evaluation. Conventional per‐beam IMRT QA was performed with the ArcCHECK diode detector for the original plans and for the following modified plans: (1) induced dose difference error up to ±4.0% and (2) control point (CP) deletion (3 to 10 CPs were deleted) (3) gantry angle shift error (3 degree uniformly shift). 2D and 3D gamma evaluation were performed for all plans through SNC Patient and 3DVH, respectively. Subsequently, we investigated the accuracy of 3DVH analysis for all cases. This part evaluated, using the Eclipse TPS plans as standard, whether 3DVH accurately can model the changes in clinically relevant metrics caused by the delivery errors.Results:2D evaluation seemed to be more sensitive to delivery errors. The average differences between ECLIPSE predicted and 3DVH results for each pair of specific DVH constraints were within 2% for all three types of error‐induced treatment plans, illustrating the fact that 3DVH is fairly accurate in quantifying the delivery errors. Another interesting observation was that even though the gamma pass rates for the error plans are high, the DVHs showed significant differences between original plan and error‐induced plans in both Eclipse and 3DVH analysis.Conclusion:The 3DVH software is shown to accurately quantify the error in delivered dose based on clinically relevant DVH metrics, where a conventional gamma based pre‐treatment QA might not necessarily detect.
SU‐E‐T‐793: Validation of COMPASS 3D Dosimetry as Pre Treatment Verification with Commercial TPS Algorithms
Authors: Vikraman S , Manigandan D , Ramu M , Karrthick Kp , Rajesh T , Senniandavar V , Sambasivaselli R , Maragathaveni S , Dhivya N , Muthukumaran M , Tejinder K 
Published: June 2015

Purpose:The purpose of this study was to validate the advent of COMPASS 3D dosimetry as a routine pre treatment verification tool with commercially available CMS Monaco and Oncentra Masterplan planning system.Methods:Twenty esophagus patients were selected for this study. All these patients underwent radical VMAT treatment in Elekta Linac and plans were generated in Monaco v5.0 with MonteCarlo(MC) dose calculation algorithm. COMPASS 3D dosimetry comprises an advanced dose calculation algorithm of collapsed cone convolution(CCC). To validate CCC algorithm in COMPASS, The DICOM RT Plans generated using Monaco MC algorithm were transferred to Oncentra Masterplan v4.3 TPS. Only final dose calculations were performed using CCC algorithm with out optimization in Masterplan planning system. It is proven that MC algorithm is an accurate algorithm and obvious that there will be a difference with MC and CCC algorithms. Hence CCC in COMPASS should be validated with other commercially available CCC algorithm. To use the CCC as pretreatment verification tool with reference to MC generated treatment plans, CCC in OMP and CCC in COMPASS were validated using dose volume based indices such as D98, D95 for target volumes and OAR doses.Results:The point doses for open beams were observed <1% with reference to Monaco MC algorithms. Comparisons of CCC(OMP) Vs CCC(COMPASS) showed a mean difference of 1.82%±1.12SD and 1.65%±0.67SD for D98 and D95 respectively for Target coverage. Maximum point dose of −2.15%±0.60SD difference was observed in target volume. The mean lung dose of −2.68%±1.67SD was noticed between OMP and COMPASS. The maximum point doses for spinal cord were −1.82%±0.287SD.Conclusion:In this study, the accuracy of CCC algorithm in COMPASS 3D dosimetry was validated by compared with CCC algorithm in OMP TPS. Dose calculation in COMPASS is feasible within < 2% in comparison with commercially available TPS algorithms.
SU‐E‐T‐795: Validations of Dose Calculation Accuracy of Acuros BV in High‐Dose‐Rate (HDR) Brachytherapy with a Shielded Cylinder Applicator Using Monte Carlo Simulation
Authors: Li Y , Tian Z , Hrycushko B , Jiang S , Jia X 
Published: June 2015

Purpose:Acuros BV has become available to perform accurate dose calculations in high‐dose‐rate (HDR) brachytherapy with phantom heterogeneity considered by solving the Boltzmann transport equation. In this work, we performed validation studies regarding the dose calculation accuracy of Acuros BV in cases with a shielded cylinder applicator using Monte Carlo (MC) simulations.Methods:Fifteen cases were considered in our studies, covering five different diameters of the applicator and three different shielding degrees. For each case, a digital phantom was created in Varian BrachyVision with the cylinder applicator inserted in the middle of a large water phantom. A treatment plan with eight dwell positions was generated for these fifteen cases. Dose calculations were performed with Acuros BV. We then generated a voxelized phantom of the same geometry, and the materials were modeled according to the vendor's specifications. MC dose calculations were then performed using our in‐house developed fast MC dose engine for HDR brachytherapy (gBMC) on a GPU platform, which is able to simulate both photon transport and electron transport in a voxelized geometry. A phase‐space file for the Ir‐192 HDR source was used as a source model for MC simulations.Results:Satisfactory agreements between the dose distributions calculated by Acuros BV and those calculated by gBMC were observed in all cases. Quantitatively, we computed point‐wise dose difference within the region that receives a dose higher than 10% of the reference dose, defined to be the dose at 5mm outward away from the applicator surface. The mean dose difference was ∼0.45%–0.51% and the 95‐percentile maximum difference was ∼1.24%–1.47%.Conclusion:Acuros BV is able to accurately perform dose calculations in HDR brachytherapy with a shielded cylinder applicator.
SU‐E‐T‐799: Verification of a Simultaneous Treatment of Multiple Brain Metastases Using VMAT Technique by a Composite Alanine‐Gel Dosimeter Phantom
Authors: Pavoni J , Neves W , Silveira M , Ramos P , Haddad C , Filho O Baffa 
Published: June 2015

Purpose:This work presents an end‐to‐end test using a Gel‐Alanine phantom to validate the three‐dimensional (3D) dose distribution (DD) delivered by a single isocenter VMAT technique on the simultaneous treatment of multiple brain metastases.Methods:Three cylindrical phantons containing MAGIC‐f gel dosimeter were used to measure the 3D DD of a VMAT treatment, the first two were filled with the gel dosimeter (Gel 1 and 2) and the third one was filled with gel and 12 alanine dosimeters distributed along it (Gel 3). Gels 1 and 3 were irradiated and gel 2 was used to map the magnetic resonance image (MRI) scanner field inomogeneities. A CT scan of gel 3 was used for the VMAT treatment planning and 5 alanine pellets were chosen as lesions, around them a PTV was grown and different dose prescriptions were assigned for each one, varying from 5 to 9Gy. Before treatment, the plan was approved in a QA based on an ionization chamber absolute dose measurement, a radiochromic film planar dose measurement and a portal dosimetry per field verification; and also the phantons positioning were verified by ExacTrac 6D correction and OBI kV Cone Beam CT. The gels were irradiated, the MRIs were acquired 24 hours after irradiation and finally, the alanine dosimeters were analysed in a X‐band Electron Spin Resonance spectrometer.Results:The association of the two detectors enabled the 3D dose evaluation by gel and punctually inside target volumes by alanine. In the gamma analyses (3%/3mm) comparing the 5 PTVs’ central images DD with TPS expected DD more than 95% of the points were approved. The alanine absolute dose measurements were in agreement with TPS by less than 5%.Conclusion:The gel‐alanine phantom enabled the dosimetric validation of multiple brain metastases treatment using VMAT, being an almost ideal tool for this application.This work is partially supported by FAPESP.
SU‐E‐T‐802: Verification of Implanted Cardiac Pacemaker Doses in Intensity‐Modulated Radiation Therapy: Dose Prediction Accuracy and Reduction Effect of a Lead Sheet
Authors: Lee J , Chung J 
Published: June 2015

Purpose:To verify delivered doses on the implanted cardiac pacemaker, predicted doses with and without dose reduction method were verified using the MOSFET detectors in terms of beam delivery and dose calculation techniques in intensity‐modulated radiation therapy (IMRT).Methods:The pacemaker doses for a patient with a tongue cancer were predicted according to the beam delivery methods [step‐and‐shoot (SS) and sliding window (SW)], intensity levels for dose optimization, and dose calculation algorithms. Dosimetric effects on the pacemaker were calculated three dose engines: pencil‐beam convolution (PBC), analytical anisotropic algorithm (AAA), and Acuros‐XB. A lead shield of 2 mm thickness was designed for minimizing irradiated doses to the pacemaker. Dose variations affected by the heterogeneous material properties of the pacemaker and effectiveness of the lead shield were predicted by the Acuros‐XB. Dose prediction accuracy and the feasibility of the dose reduction strategy were verified based on the measured skin doses right above the pacemaker using mosfet detectors during the radiation treatment.Results:The Acuros‐XB showed underestimated skin doses and overestimated doses by the lead‐shield effect, even though the lower dose disagreement was observed. It led to improved dose prediction with higher intensity level of dose optimization in IMRT. The dedicated tertiary lead sheet effectively achieved reduction of pacemaker dose up to 60%.Conclusion:The current SS technique could deliver lower scattered doses than recommendation criteria, however, use of the lead sheet contributed to reduce scattered doses.Thin lead plate can be a useful tertiary shielder and it could not acuse malfunction or electrical damage of the implanted pacemaker in IMRT. It is required to estimate more accurate scattered doses of the patient with medical device to design proper dose reduction strategy.
SU‐E‐T‐808: Volumetric Modulated Arc Radiotherapy Vs. Intensity‐Modulated Radiotherapy for Early‐Stage Nasopharyngeal Carcinoma: A Dosimetric Study
Authors: Lu J‐Y , Huang B‐T , Zhang W‐Z 
Published: June 2015

Purpose:To compare volumetric modulated arc radiotherapy (VMAT) technique with fixed‐gantry intensity‐modulated radiotherapy (IMRT) technique for early‐stage nasopharyngeal carcinoma.Methods:CT datasets of ten patients with early‐stage nasopharyngeal carcinoma were included. Dual‐arc VMAT and nine‐field IMRT plans were generated for each case, and were then compared in terms of planning‐target‐volume (PTV) coverage, conformity index (CI) and homogeneity index (HI), as well as organ‐at‐risk (OAR) sparing, planning time, monitor units (MUs) and delivery time.Results:Compared with the IMRT plans, the VMAT plans provided comparable HI and CI of PTVnx (PTV of primary tumor of nasopharynx), superior CI and inferior HI of PTVnd (PTV of lymph nodes), as well as superior CI and comparable HI of PTV60 (high‐risk PTV). The VMAT plans provided better sparing of the spinal cord, oral cavity and normal tissue, but inferior sparing of the brainstem planning OAR volume (PRV), larynx and parotids, as well as comparable sparing of the spinal cord PRV, brainstem, lenses, optic nerves, optic chiasm. Moreover, the average planning time (181.6 ± 36.0 min) for the VMAT plans was 171% more than that of the IMRT plans (68.1 ± 7.6 min). The MUs of the VMAT plans (609 ± 43) were 70% lower than those of the IMRT plans (2071 ± 262), while the average delivery time (2.2 ± 0.1 min) was 66% less than that of the IMRT plans (6.6 ± 0.4 min).Conclusion:Compared with the IMRT technique, the VMAT technique can achieve similar or slightly superior target dose distribution, with no significant advantages on OAR sparing, and it can achieve significant reductions of MUs and delivery time.
SU‐E‐T‐809: Volumetric Modulated Arc Radiotherapy Vs. Intensity‐Modulated Radiotherapy for Locally Advanced Laryngeal Carcinoma: A Dosimetric Study
Authors: Lu J‐Y , Huang B‐T , Zhang W‐Z , Yan L‐J 
Published: June 2015

Purpose:To compare volumetric modulated arc radiotherapy (VMAT) technique with fixed‐gantry intensity‐modulated radiotherapy (IMRT) technique for locally advanced laryngeal carcinoma.Methods:CT datasets of eleven patients were included. Dual‐arc VMAT and 7‐field IMRT plans, which were created based on the Eclipse treatment planning system, were compared in terms of dose‐volume parameters, conformity index (CI) and homogeneity index (HI) of planning target volume (PTV), as well as organ‐at‐risk (OAR) sparing, planning time, monitor units (MUs) and delivery time.Results:Compared with the IMRT plans, the VMAT plans provided lower D2% and better CI/HI for the high‐risk PTV (PTV1), and provided better CI and comparable HI for the low‐risk PTV (PTV2). Concerning the OAR sparing, the VMAT plans demonstrated significantly lower Dmax of the spinal cord (planning OAR volume, PRV) and brainstem (PRV), as well as lower Dmean and V30Gy of the right parotid. No significant differences were observed between the two plans concerning the doses delivered to the thyroid, carotid, oral cavity and left parotid. Moreover, the VMAT planning (147 ± 18 min) consumed 213% more time than the IMRT planning (48 ± 10 min). The MUs of the VMAT plans (556 ± 52) were 64% less than those of the IMRT plans (1684 ± 409), and the average delivery time (2.1 ± 0.1 min) was 66% less than that of the IMRT plans (6.3 ± 0.7 min).Conclusion:Compared with the IMRT technique, the VMAT technique can achieve superior target dose distribution and better sparing of the spinal cord, brainstem and right parotid, with less MUs and less delivery time. It is recommended for the radiotherapy of locally advanced laryngeal carcinoma.
SU‐E‐T‐811: Volumetric Modulated Arc Therapy Vs. C‐IMRT for the Treatment of Upper Thoracic Esophageal Cancer
Authors: Zhang W , Wu L , Lu J , Chen C 
Published: June 2015

Purpose:To compare plans using volumetric‐modulated arc therapy (VMAT) with conventional sliding window intensity‐modulated radiation therapy (c‐IMRT) to treat upper thoracic esophageal cancer (EC).Methods:CT datasets of 11 patients with upper thoracic EC were identified. Four plans were generated for each patient: c‐IMRT with 5 fields (5F) and VMAT with a single arc (1A), two arcs (2A), or three arcs (3A). The prescribed doses were 64 Gy/32 F for the primary tumor (planning target volume 64, PTV64). The dose‐volume histogram data, the number of monitoring units (MUs) and the treatment time (TT) for the different plans were compared.Results:All of the plans generated similar dose distributions for PTVs and organs at risk (OARs), except that the 2A‐ and 3A‐VMAT plans yielded a significantly higher conformity index (CI) than the c‐IMRT plan. The CI of the PTV64 was improved by increasing the number of arcs in the VMAT plans. The maximum spinal cord dose and the planning risk volume of the spinal cord dose for the two techniques were similar. The 2A‐ and 3A‐VMAT plans yielded lower mean lung doses and heart V50 than the c‐IMRT. The V20 and V30 for the lungs in all of the VMAT plans were lower than those in the c‐IMRT plan, at the expense of increasing V5, V10 and V13. The VMAT plan resulted in significant reductions in MUs and TT.Conclusion:The 2A‐VMAT plan appeared to spare the lungs from moderate‐dose irradiation most effectively of all plans, at the expense of increasing the low‐dose irradiation volume, and also significantly reduced the number of required MUs and the TT. The CI of the PTVs and the OARs was improved by increasing the arc‐number from 1 to 2. however, no significant improvement was observed using the 3A‐VMAT, except for an increase in the TT.This work was sponsored by Shantou University Medical College Clinical Research Enhancement Initiative(NO.201424)