bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐T‐336: Transition From Frame Based SRS to Frameless SRS Procedures: A Community Based Hospital Experience
Authors: Workie D , Hasson B , Geraghty C 
Published: July 2014

Purpose:The project intent is to transit from frame based SRS to frameless SRS procedure and workflow in a community hospital setting.Methods:The clinic has strong experience in a wide verity of frame based SRS procedures using Novalis 600N linac equipped with BrainLab Micro‐MLC and ExacTrac systems. The addition of new Novalis TX system has opened an opportunity to explore and implement frameless SRS treatment procedure. Phantom End to End studies were performed for this purpose. A calibrated Ionization Chamber was inserted into the phantom and the phantom was positioned on the CT scan couch and SRS immobilization mask was made. A CT scan of the Immobilized phantom was generated with the localization box in place. The CT scan was localized and the ionization Chamber active volume was contoured as a target on the IPlan planning system. A 5 Dynamic Conformal Arcs plan was generated on the Iplan planning system. The Phantom was positioned on the treatment Couch with the SRS Mask and frameless array system in place, and the initial target treatment ISO position was achieved. The chamber was then connected to an electrometer. The two Orthogonal KV images were taken and the final treatment position was achieved within 1mm and 1 degree using ExacTrac. The Five arcs were delivered and the electrometer reading was noted. In addition, RPC SRS head phantom study was performed following RPC procedure.Results:The average absolute dose delivered to the in‐house phantom target was in agreement within 1.5% of the planning dose. The RPC SRS phantom results were within the criteria set by RPC.Conclusion:This work gave the confidence to our clinic to move from invasive frame based to non invasive and efficient frameless SRS and SRT treatments. The clinic has now frameless SRS and SRT treatment procedures and workflow.
SU‐E‐T‐337: Treatment Planning Study of Craniospinal Irradiation with Spot Scanning Proton Therapy
Authors: Tasson A , Beltran C , Laack N , Childs S , Tryggestad E , Whitaker T 
Published: July 2014

Purpose:To develop a treatment planning technique that achieves optimal robustness against systematic position and range uncertainties, and interfield position errors for craniospinal irradiation (CSI) using spot scanning proton radiotherapy.Methods:Eighteen CSI patients who had previously been treated using photon radiation were used for this study. Eight patients were less than 10 years old. The prescription dose was 23.4Gy in 1.8Gy fractions. Two different field arrangement types were investigated: 1 posterior field per isocenter and 2 posterior oblique fields per isocenter. For each field type, two delivery configurations were used: 5cm bolus attached to the treatment table and a 4.5cm range shifter located inside the nozzle. The target for each plan was the whole brain and thecal sac. For children under the age of 10, all plan types were repeated with an additional dose of 21Gy prescribed to the vertebral bodies. Treatment fields were matched by stepping down the dose in 10% increments over 9cm. Robustness against 3% and 3mm uncertainties, as well as a 3mm inter‐field error was analyzed. Dose coverage of the target and critical structure sparing for each plan type will be considered. Ease of planning and treatment delivery was also considered for each plan type.Results:The mean dose volume histograms show that the bolus plan with posterior beams gave the best overall plan, and all proton plans were comparable to or better than the photon plans. The plan type that was the most robust against the imposed uncertainties was also the bolus plan with posterior beams. This is also the plan configuration that is the easiest to deliver and plan.Conclusion:The bolus plan with posterior beams achieved optimal robustness against systematic position and range uncertainties, as well as inter‐field position errors.
SU‐E‐T‐341: Use of Patient Geometry and Multiple Linear Regression to Predict Prescription Dose for Pleurectomy/decortication Cases in Malignant Pleural Mesothelioma
Authors: Dumane V , Yuan Y , Rimner A , Yorke E , Rosenzweig K 
Published: July 2014

Purpose:To identify patient geometric parameters that correlate with the prescription dose in the treatment of malignant pleural mesothelioma (MPM) so as to build a model that could assist in the prediction of the same apriori and this help in planning.Methods:Planning CT scans for ten right sided and ten left sided patients were examined to extract five parameters for each case, which involved ratio of the ipsilateral lung volume to the total lung volume (X1), volume of PTV overlap with ipsilateral lung to ipsilateral lung volume (X2), volume of the PTV overlap with ipsilateral lung to total lung volume (X3), volume of the PTV overlap with ipsilateral lung to PTV volume (X4) and ratio of contralateral lung volume to total lung volume (X5). Each patient for this study was planned with VMAT using 6 MV on Eclipse V11 to a prescription dose that kept the mean total lung dose just under 20 Gy. Correlation coefficients were obtained between the parameters and the dose prescribed. Those that significantly correlated were combined using multiple linear regression. The model built was tested on 9 new cases.Results:All geometric parameters investigated except X2 showed significant correlation with the prescription dose. The correlation coefficients were r = −0.5421 for X1 (p = 0.0135), r = −0.6891 for X3 (p = 0.0008), r = −0.6797 for X4 (p = 0.001) and r = 0.5421 for X5 (p = 0.0135). The predictive model D = 4192.2×1 – 3577.1×3 – 471.6×4 + 6253.4×5 had a higher correlation (r = 0.86, p = 1.0657e‐06) with dose. For 8 out of the 9 test cases, the predicted dose was either equal to or upto 1 fraction of the prescription dose.Conclusion:The multiple regression model developed here could serve as a guide for dose prescribed in treatment of MPM.
SU‐E‐T‐342: Use of Patient Geometry Measurements to Predict Dosimetric Gain with VMAT Over 3D for Chestwall and Regional Nodal Radiation
Authors: Dumane V , Hunt M , Steinberger E , Knoll M , Green S , Bakst R 
Published: July 2014

Purpose:To predict the dosimetric gain of VMAT over 3D for the treatment ofchestwall/IMN/supraclavicular nodes using geometric parameters acquired during simulationMethods:CT scans for 20 left and 20 right sided patients were retrospectively analyzed toobtain percent ipsilateral lung volume included in the PWT and supraclavicular fields, central lung depth (CLD), maximum lung depth (MLD), separation, chestwall concavity (defined here as the product of CLD and separation) and the maximum heart depth (MHD). VMAT, PWT and P/E plans were done for each case. The ipsilateral lung V20 Gy and mean, total lung V20 Gy and mean, heart V25 Gy and mean were noted for each plan. Correlation coefficients were obtained and linear regression models were built using data from the above training set of patients and then tested on 4 new patients.Results:The decrease in ipsilateral lung V20 Gy, total lung V20 Gy, ipsilateral lung mean and total lung mean with VMAT over PWT significantly (p<0.05) correlated with the percent volume of ipsilateral lung included in the PWT and supraclavicular fields with correlation coefficient values of r = 0.83, r = 0.77, r = 0.78 and r = 0.75 respectively. Significant correlations were also found between MHD and the decrease in heart V25 Gy and mean of r = 0.77 and r = 0.67 respectively. Dosimetric improvement with VMAT over P/E plans showed no correlation to any of the geometric parameters investigated in this study. The dosimetric gain predicted for the 4 test cases by the linear regression models given their respective percent ipsilateral lung volumes fell within the 95% confidence intervals around the best regression fit.Conclusion:The percent ipsilateral lung volume appears to be a strong predictor of the dosimetric gain on using VMAT over PWT apriori.
SU‐E‐T‐345: Validation of a Patient‐Specific Monte Carlo Targeted Radionuclide Therapy Dosimetry Platform
Authors: Besemer A , Bednarz B 
Published: July 2014

Purpose:There is a compelling need for personalized dosimetry in targeted radionuclide therapy given that conventional dose calculation methods fail to accurately predict dose response relationships. To address this need, we have developed a Geant4‐based Monte Carlo patient‐specific 3D dosimetry platform for TRT. This platform calculates patient‐specific dose distributions based on serial CT/PET or CT/SPECT images acquired after injection of the TRT agent. In this work, S‐values and specific absorbed fractions (SAFs) were calculated using this platform and benchmarked against reference values.Methods:S‐values for 1, 10, 100, and 1000g spherical tumors with uniform activity distributions of I‐124, I‐125, I‐131, F‐18, and Ra‐223 were calculated and compared to OLINDA/EXM reference values. SAFs for monoenergetic photons of 0.01, 0.1, and 1 MeV and S factors for monoenergetic electrons of 0.935 MeV were calculated for the liver, kidneys, lungs, pancreas, spleen, and adrenals in the Zubal Phantom and compared with previously published values. Sufficient particles were simulated to keep the voxel statistical uncertainty below 5%.Results:The calculated spherical S‐values agreed within a few percent of reference data from OLINDA/EXM for each radionuclide and sphere size. The comparison of photon SAFs and electron S‐values with previously published values showed good agreement with the previously published values. The S‐values and SAFs of the source organs agreed within 1%.Conclusion:Our platform has been benchmarked against reference values for a variety of radionuclides and over a wide range of energies and tumor sizes. Therefore, this platform could be used to provide accurate patientspecific dosimetry for use in radiopharmaceutical clinical trials.
SU‐E‐T‐486: Effect of the Normalized Prescription Isodose Line On Target Dose Deficiency in Lung SBRT Based On Monte Carlo Calculation
Authors: Zheng D , Zhang Q , Zhou S 
Published: July 2014

Purpose:To investigate the impact of normalized prescription isodose line on target dose deficiency calculated with Monte Carlo (MC) vs. pencil Beam (PB) in lung SBRT. RTOG guidelines recommend prescription lines between 60% and 90% for lung SBRT. How this affects the magnitude of MC‐calculated target dose deficiency has never been studied.Methods:Under an IRB‐approved protocol, four lung SBRT patients were replanned following RTOG0813 by a single physicist. For each patient, four alternative plans were generated based on PB calculation prescribing to 60–90% isodose lines, respectively. Each plan consisted of 360o coplanar dynamic conformal arcs with beam apertures manually optimized to achieve similar dose coverage and conformity for all plans of the same patient. Dose distribution was calculated with MC and compared to that with PB. PTV dose‐volume endpoints were compared, including Dmin, D5, Dmean, D95, and Dmax. PTV V100 coverage, conformity index (CI), and heterogeneity index (HI) were also evaluated.Results:For all 16 plans, median (range) PTV V100 and CI were 99.7% (97.5–100%) and 1.27 (1.20–1.41), respectively. As expected, lower prescription line resulted in higher target dose heterogeneity, yielding median (range) HI of 1.26 (1.05–1.51) for all plans. Comparing MC to PB, median (range) D95, Dmean, D5 PTV dose deficiency were 18.9% (11.2–23.2%), 15.6% (10.0–22.7%), and 9.4%(5.5–13.6%) of the prescription dose, respectively. The Dmean, D5, and Dmax deficiency was found to monotonically increase with decreasing prescription line from 90% to 60%, while the Dmin deficiency monotonically decreased. D95 deficiency exhibited more complex trend, reaching the largest deficiency at 80% for all patients.Conclusion:Dependence on prescription isodose line was found for MC‐calculated PTV dose deficiency of lung SBRT. When comparing reported MC dose deficiency values from different institutions, their individual selections of prescription line should be considered in addition to other factors affecting the deficiency magnitude.
SU‐E‐T‐487: Impact of Geometric Uncertainties in Accelerated Partial Breast Irradiation Using the Strut‐Adjusted Volume Implant (SAVI)
Authors: Akino Y , Slessinger E , Srivastava S , Das I 
Published: July 2014

Purpose:Single‐entry multi‐catheter devices have been developed for accelerated partial breast irradiation (APBI). Rotational and translational uncertainties are usually mitigated by quality assurance, however its actual dosimetric impact has not been addressed, which is presented here for SAVI applicator.Methods:Under Institutional Review Board exemption status, we retrospectively analyzed 48 APBI treatment plans using SAVI applicator. For quick calculation of dose‐volume histogram (DVH) considering geometric uncertainties, the coordinate of each voxel of critical organs after rotation or translation along the central catheter was calculated using an in‐house software instead of rotating or translating the entire dose distribution.Results:For most cases, the skin doses increased with rotation to both directions. At 10 degree of rotation, the increase of Dmax (percent prescribed dose) at 50% (median), 75%, 90%, and 100% (maximum) percentile were 0.3%, 1.7%, 5.6% and 25.0%, respectively. The increase of chest wall Dmax at 50%, 75%, 90%, and 100% percentile were 0.1%, 1.0%, 10.3% and 38.8%, respectively. The increase of skin Dmax of the patients with the distance between skin surface and lumpectomy cavity surface ≤16 mm was significantly larger than those with the distance >16 mm. Similarly, patients with the distance between lung and lumpectomy cavity surface ≤20 mm showed higher sensitivity of chest wall Dmax against rotation than patients with the distance <20 mm. Translation of the applicator showed larger impact on the skin dose than rotation, although the effects on chest wall was less than 2% even at 10 mm displacement. At 5 mm of translation, increase of skin Dmax at 50%, 75%, 90%, and 100% percentile were 2.3%, 8.0%, 15.3% and 77.7%, respectively.Conclusion:The impacts of the geometric uncertainties (rotation and translation) of SAVI applicator were investigated. The skin‐lumpectomy cavity and lung‐lumpectomy cavity distances showed significant relationship with skin and chest wall doses, respectively.
SU‐E‐T‐489: Plan Comparisons of Re‐Irradiation Treatment of Three Intensity Modulated Techniques
Authors: Lian J , Tang X , Liu R 
Published: July 2014

Purpose:There have been controversial reports on the comparison of dosimetric quality of TomoTherapy (Tomo), VMAT and IMRT. One of the main reasons is the sampled cases are often not dosimetrically challenging enough to test the limit of optimization/delivery modalities. We chose difficult re‐irradiation cases when certain organ at risk (OAR) requires extremely low dose to examine the ability of OAR sparing of three main intensity modulated techniques.Methods:Three previous treated patients with disease site on head and neck (HN), brain and lung are planned for reirradiation treatment. The Tomo planning used jaw 2.5cm and pitch 0.3. VMAT and IMRT were planned on Pinnacle for a Varian 21iX Linac with MLC leaf width 5mm. VMAT plan used 2 Arcs and IMRT plan had beams 11–13. The dosimetric endpoints and treatment time were compared for each technique of each patient.Results:Plans of three techniques cover PTV similarly. The HN case requires PTV dose 60Gy but to limit dose of cord which is 8mm away <12Gy. The cord dose of Tomo, VMAT and IMRT plan is 11.6Gy, 11.3Gy and 11.0Gy, respectively. The brain case has PTV prescription 50.4 Gy while requiring the dose of brainstem < 28Gy. Tomo, VMAT and IMRT plan generate brainstem dose 27.6Gy, 27.6Gy and 27.1Gy respectively. For the lung case, PTV was prescribed 42.5Gy but cord dose constraint was 22.5Gy. The cord dose is optimized to 22.3Gy, 20.8Gy and 21.4Gy by Tomo, VMAT and IMRT, respectively. The delivery time if normalized to Tomo is 47.0%/145.6% (VMAT/IMRT), 33.3%/106.3% and 74.1%/245.4% for HN, brain and lung case, respectively.Conclusion:Difficult re‐irradiation cases were used to test the limit of three intensity modulated techniques. Tomo, VMAT and IMRT show similar dosimetry while VMAT is the most efficient one and IMRT is the least.
SU‐E‐T‐493: Analysis of the Impact of Range and Setup Uncertainties On the Dose to Brain Stem and Whole Brain in the Passively Scattered Proton Therapy Plans
Authors: Sahoo N , Zhu X , Zhang X , Poenisch F , Li H , Wu R , Lii M , Umfleet W , Gillin M , Mahajan A , Grosshans D 
Published: July 2014

Purpose:To quantify the impact of range and setup uncertainties on various dosimetric indices that are used to assess normal tissue toxicities of patients receiving passive scattering proton beam therapy (PSPBT).Methods:Robust analysis of sample treatment plans of six brain cancer patients treated with PSPBT at our facility for whom the maximum brain stem dose exceeded 5800 CcGE were performed. The DVH of each plan was calculated in an Eclipse treatment planning system (TPS) version 11 applying ±3.5% range uncertainty and ±3 mm shift of the isocenter in x, y and z directions to account for setup uncertainties. Worst‐case dose indices for brain stem and whole brain were compared to their values in the nominal plan to determine the average change in their values. For the brain stem, maximum dose to 1 cc of volume, dose to 10%, 50%, 90% of volume (D10, D50, D90) and volume receiving 6000, 5400, 5000, 4500, 4000 CcGE (V60, V54, V50, V45, V40) were evaluated. For the whole brain, maximum dose to 1 cc of volume, and volume receiving 5400, 5000, 4500, 4000, 3000 CcGE (V54, V50, V45, V40 and V30) were assessed.Results:The average change in the values of these indices in the worst scenario cases from the nominal plan were as follows. Brain stem; Maximum dose to 1 cc of volume: 1.1%, D10: 1.4%, D50: 8.0%, D90:73.3%, V60:116.9%, V54:27.7%, V50: 21.2%, V45:16.2%, V40:13.6%,Whole brain; Maximum dose to 1 cc of volume: 0.3%, V54:11.4%, V50: 13.0%, V45:13.6%, V40:14.1%, V30:13.5%.Conclusion:Large to modest changes in the dosiemtric indices for brain stem and whole brain compared to nominal plan due to range and set up uncertainties were observed. Such potential changes should be taken into account while using any dosimetric parameters for outcome evaluation of patients receiving proton therapy.
SU‐E‐T‐500: Dose Escalation Strategy for Lung Cancer Patients Using a Biologically‐ Guided Target Definition
Authors: Shusharina N , Khan F , Choi N , Sharp G 
Published: July 2014

Purpose:Dose escalation strategy for lung cancer patients can lead to late symptoms such as pneumonitis and cardiac injury. We propose a strategy to increase radiation dose for improving local tumor control while simultaneously striving to minimize the injury of organs at risk (OAR). Our strategy is based on defining a small, biologically‐guided target volume for receiving additional radiation dose.Methods:106 patients with lung cancer treated with radiotherapy were selected for patients diagnosed with stage II and III disease. Previous research has shown that 50% of the maximum SUV threshold in FDG‐PET imaging is appropriate for delineation of the most aggressive part of a tumor. After PET‐ and CT‐derived targets were contoured, an IMRT treatment plan was designed to deliver 60 Gy to the GTV as delineated on a 4D CT (Plan 1). A second plan was designed with additional dose of 18 Gy to the PET‐derived volume (Plan 2). A composite plan was generated by the addition of Plan 1 and Plan 2.Results:Plan 1 was compared to the composite plan and increases in OAR dose were assessed. For seven patients on average, lung V5 was increased by 1.4% and V20 by 4.2% for ipsilateral lung and by 13.5% and 7% for contralateral lung. For total lung, V5 and V20 were increased by 4.5% and 4.8% respectively. Mean lung dose was increased by 9.7% for the total lung. The maximum dose to the spinal cord increased by 16% on average. For the heart, V20 increased by 4.2% and V40 by 5.2%.Conclusion:It seems feasible that an additional 18 Gy of radiation dose can be delivered to FDG PET‐derived subvolume of the CT‐based GTV of the primary tumor without significant increase in total dose to the critical organs such as lungs, spinal cord and heart.
SU‐E‐T‐502: Biometrically Accepted Patient Records
Authors: Basavatia A , Kalnicki S , Garg M , Fret J , Lukaj A , Yaparpalvi R , Hong L , Tome W 
Published: July 2014

Purpose:To implement a clinically useful palm vein pattern recognition biometric system to treat the correct treatment plan to the correct patient each and every time and to check‐in the patient into the department to access the correct medical record.Methods:A commercially available hand vein scanning system was paired to Aria and utilized an ADT interface from the hospital electronic health system. Integration at two points in Aria, version 11 MR2, first at the appointment tracker screen for the front desk medical record access and second at the queue screen on the 4D treatment console took place for patient daily time‐out. A test patient was utilized to check accuracy of identification as well as to check that no unintended interactions take place between the 4D treatment console and the hand vein scanning system. This system has been in clinical use since December 2013.Results:Since implementation, 445 patients have been enrolled into our biometric system. 95% of patients learn the correct methodology of hand placement on the scanner in the first try. We have had two instances of patient not found because of a bad initial scan. We simply erased the scanned metric and the patient enrolled again in those cases. The accuracy of the match is 100% for each patient, we have not had one patient misidentified. We can state this because we still use patient photo and date of birth as identifiers. A QA test patient is run monthly to check the integrity of the system.Conclusion:By utilizing palm vein scans along with the date of birth and patient photo, another means of patient identification now exits. This work indicates the successful implementation of technology in the area of patient safety by closing the gap of treating the wrong plan to a patient in radiation oncology.FOJP Service Corporation covered some of the costs of the hardware and software of the palm vein pattern recognition biometric system.