bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐T‐616: Plan Quality Assessment of Both Treatment Planning System Dose and Measurement‐Based 3D Reconstructed Dose in the Patient
Authors: Olch A 
Published: June 2015

Purpose:Systematic radiotherapy plan quality assessment promotes quality improvement. Software tools can perform this analysis by applying site‐specific structure dose metrics. The next step is to similarly evaluate the quality of the dose delivery. This study defines metrics for acceptable doses to targets and normal organs for a particular treatment site and scores each plan accordingly. The input can be the TPS or the measurement‐based 3D patient dose. From this analysis, one can determine whether the delivered dose distribution to the patient receives a score which is comparable to the TPS plan score, otherwise replanning may be indicated.Methods:Eleven neuroblastoma patient plans were exported from Eclipse to the Quality Reports program. A scoring algorithm defined a score for each normal and target structure based on dose‐volume parameters. Each plan was scored by this algorithm and the percentage of total possible points was obtained. Each plan also underwent IMRT QA measurements with a Mapcheck2 or ArcCheck. These measurements were input into the 3DVH program to compute the patient 3D dose distribution which was analyzed using the same scoring algorithm as the TPS plan.Results:The mean quality score for the TPS plans was 75.37% (std dev=14.15%) compared to 71.95% (std dev=13.45%) for the 3DVH dose distribution. For 3/11 plans, the 3DVH‐based quality score was higher than the TPS score, by between 0.5 to 8.4 percentage points. Eight/11 plans scores decreased based on IMRT QA measurements by 1.2 to 18.6 points.Conclusion:Software was used to determine the degree to which the plan quality score differed between the TPS and measurement‐based dose. Although the delivery score was generally in good agreement with the planned dose score, there were some that improved while there was one plan whose delivered dose quality was significantly less than planned. This methodology helps evaluate both planned and delivered dose quality.Sun Nuclear Corporation has provded a license for the software described.
SU‐E‐T‐619: Planning 131I Thyroid Treatments for Patients Requiring Hemodialysis
Authors: Stroud D 
Published: June 2015

Purpose:Treatment of 131I thyroid cancer patients who also require regular hemodialysis (HD) treatments requires consideration of the administered activity and the HD schedule. In this work the red bone marrow is considered the dose limiting organ and the treatment plan optimized the HD schedule with the amount of radioactivity administered.Methods:The ‘Safe’ dose was considered to be 2 Gy (200 rad) to the red bone marrow.1 131Iodine doses of 50 mCi to 100 mCi were modeled and found to require a range of HD schedules. In order to achieve the safe dose to the red marrow, more aggressive HD schedules are required. 100 mCi required an aggressive HD treatment of every 24 hours for at least one week to achieve the ‘safe’ dose and an exposure appropriate for release from the hospital. A more normal schedule of HD beginning at 18 hours then every 48 hours allowed for up to 60 mCi administered dose allowed for a safe dose and expected release after less than one week.2In addition room was equipped with video cameras cameras for monitoring the patient and their vital signs from an adjacent room during HD. In this way the dialysis nurses were able to monitor the patient closely from an adjoining room.Results:Two HD patients were administered adjusted doses of about 50 mCi. The medical and nursing staff were exposed to no more than 4 mR for the entire treatment. The residual Iodine in the patient appeared to be normal after 4 to 6 days when the patient was released.Conclusion:With careful treatment planning 131Iodine treatments can be performed safely for patients needing HD and treatments appear to be as effective as those for patients with normal renal function.
SU‐E‐T‐620: Planning and Dosimetry for Pulsed Low Dose Rate RT for Recurrent Lung, Spine, GYN and Head and Neck Cancers
Authors: Tong X , Luo F , Liu Y , Zhang W , Xu Q , Zhang T , Li J , Chen L , Ma C 
Published: June 2015

Purpose:Extensive in vitro and in vivo studies have shown that pulsed low dose rate (PLDR) radiotherapy has potential to provide significant local tumor control and to reduce normal tissue toxicities. This work investigated the planning and dosimetry of PLDR re‐irradiation for recurrent cancers.Methods:We analyzed the treatment plans and dosimetry for 13 recurrent patients who were treated with the PLDR technique in this study. All cases were planned with the 3DCRT technique with optimal beam angle selection. The treatment was performed on a Siemens accelerator using 6MV beams. The target volume ranged between 161 and 703cc. The previous RT dose was 40–60Gy while the re‐irradiation dose was 16–60Gy. The interval between previous RT and re‐irradiation was 13–336 months, and the follow‐up time was up to 27months. The total prescription dose was administered in 2Gy/day fractions with the daily dose delivered in 10 sub‐fractions (pulses) of 20cGy with a 3min interval between the pulses to achieve an effective dose rate of 6.7cGy/min.Results:The clinical outcome was analyzed based on the treatment plans. All pulses were kept with Dmax<40cGy. The PLDR treatments were effective (CR: 3 patients, PR: 10 patients). The acute and late toxicities were all acceptable (generally grade II or under). Two patients died three months after the PLDR re‐irradiation, one due to massive cerebral infarction and the other due to acute cardiac failure. All others survived more than 8 months. Five patients showed good conditions at the last follow‐up. Among them two recurrent lung cancer patients had survived 23 months and one nasopharyngeal cancer patient had survived 27 months.Conclusion:The PLDR technique was effective for the palliative treatment of head and neck, lung, spine and GYN cancers. Further phase II and III studies are warranted to quantify the efficacy of PLDR for recurrent cancers.
SU‐E‐T‐621: Planning Methodologies for Cancer of the Anal Canal: Comparing IMRT, Rapid Arc, and Pencil Beam Scanning Proton Beam
Authors: McGlade J , Kassaee A 
Published: June 2015

Purpose:To evaluate planning methods for anal canal cancer and compare the results of 9‐field Intensity Modulated Radiotherapy (IMRT), Volumetric Modulated Arc Therapy (Varian, RapidArc), and Proton Pencil Beam Scanning (PBS).Methods:We generated plans with IMRT, RapidArc (RA) and PBS for twenty patients for both initial phase including nodes and cone down phase of treatment using Eclipe (Varian). We evaluated the advantage of each technique for each phase. RA plans used 2 to 4 arcs and various collimator orientations. PBS used two posterior oblique fields. We evaluated the plans comparing dose volume histogram (DVH), locations of hot spots, and PTV dose conformity.Results:Due to complex shape of target, for RA plans, multiple arcs (>2) are required to achieve optimal PTV conformity. When the PTV exceeds 15 cm in the superior‐inferior direction, limitations of deliverability start to dominate. The PTV should be divided into a superior and an inferior structure. The optimization is performed with fixed jaws for each structure and collimator set to 90 degrees for the inferior PTV. Proton PBS plans show little advantage in small bowel sparing when treating the nodes. However, PBS plan reduces volumetric dose to the bladder at the cost of higher doses to the perineal skin. IMRT plans provide good target conformity, but they generate hot spots outside of the target volume.Conclusion:When using one planning technique for entire course of treatment, Multiple arc (>2) RA plans are better as compared to IMRT and PBS plans. When combining techniques, RA for the initial phase in combination with PBS for the cone down phase results in the most optimal plans.
SU‐E‐T‐622: Planning Technique for Passively‐Scattered Involved‐Node Proton Therapy of Mediastinal Lymphoma with Consideration of Cardiac Motion
Authors: Flampouri S , Li Z , Hoppe B 
Published: June 2015

Purpose:To develop a treatment planning method for passively‐scattered involved‐node proton therapy of mediastinal lymphoma robust to breathing and cardiac motions.Methods:Beam‐specific planning treatment volumes (bsPTV) are calculated for each proton field to incorporate pertinent uncertainties. Geometric margins are added laterally to each beam while margins for range uncertainty due to setup errors, breathing, and calibration curve uncertainties are added along each beam. The calculation of breathing motion and deformation effects on proton range includes all 4DCT phases. The anisotropic water equivalent margins are translated to distances on average 4DCT. Treatment plans are designed so each beam adequately covers the corresponding bsPTV. For targets close to the heart, cardiac motion effects on dosemaps are estimated by using a library of anonymous ECG‐gated cardiac CTs (cCT). The cCT, originally contrast‐enhanced, are partially overridden to allow meaningful proton dose calculations. Targets similar to the treatment targets are drawn on one or more cCT sets matching the anatomy of the patient. Plans based on the average cCT are calculated on individual phases, then deformed to the average and accumulated. When clinically significant dose discrepancies occur between planned and accumulated doses, the patient plan is modified to reduce the cardiac motion effects.Results:We found that bsPTVs as planning targets create dose distributions similar to the conventional proton planning distributions, while they are a valuable tool for visualization of the uncertainties. For large targets with variability in motion and depth, integral dose was reduced because of the anisotropic margins. In most cases, heart motion has a clinically insignificant effect on target coverage.Conclusion:A treatment planning method was developed and used for proton therapy of mediastinal lymphoma. The technique incorporates bsPTVs compensating for all common sources of uncertainties and estimation of the effects of cardiac motion not commonly performed.
SU‐E‐T‐624: Portal Dosimetry Commissioning of Multiple (6) Varian TrueBeam Linacs Equipped with PortalVision DMI MV Imager
Authors: Weldon M , DiCostanzo D , Grzetic S , Hessler J 
Published: June 2015

Purpose:To show that a single model for Portal Domisetry (PD) can be established for beam‐matched TrueBeam™ linacs that are equipped with the DMI imager (43×43cm effective area).Methods:Our department acquired 6 new TrueBeam™s, 4 “Slim” and 2 “Edge” models. The Slims were equipped with 6 and 10MV photons, and the Edges with 6MV. MLCs differed between the Slims and Edges (Millennium 120 vs HD‐MLC respectively). PD model was created from data acquired using a single linac (Slim). This includes maximum field size profile, as well as output factors and acquired measured fluence using the DMI imager. All identical linacs were beam‐matched, profiles were within 1% at maximum field size at a variety of depths. The profile correction file was generated from 40×40 profile acquired at 5cm depth, 95cm SSD, and was adjusted for deviation at the field edges and corners. The PD model and profile correction was applied to all six TrueBeam™s and imagers. A variety of jaw only and sliding window (SW) MLC test fields, as well as TG‐119 and clinical SW and VMAT plans were run on each linac to validate the model.Results:For 6X and 10X, field by field comparison using 3mm/3% absolute gamma criteria passed 90% or better for all cases. This was also true for composite comparisons of TG‐199 and clinical plans, matching our current department criteria.Conclusion:Using a single model per photon energy for PD for the TrueBeam™ equipped with a DMI imager can produce clinically acceptable results across multiple identical and matched linacs. It is also possible to use the same PD model despite different MLCs. This can save time during commissioning and software updates.
SU‐E‐T‐628: Predicted Risk of Post‐Irradiation Cerebral Necrosis in Pediatric Brain Cancer Patients: A Treatment Planning Comparison of Proton Vs. Photon Therapy
Authors: Freund D , Zhang R , Newhauser W , Sanders M 
Published: June 2015

Purpose:Post‐irradiation cerebral necrosis (PICN) is a severe late effect that can Result from brain cancers treatment using radiation therapy. The purpose of this study was to compare the treatment plans and predicted risk of PICN after volumetric modulated arc therapy (VMAT) to the risk after passively scattered proton therapy (PSPT) and intensity modulated proton therapy (IMPT) in a cohort of pediatric patients.Methods:Thirteen pediatric patients with varying age and sex were selected for this study. A clinical treatment volume (CTV) was constructed for 8 glioma patients and 5 ependymoma patients. Prescribed dose was 54 Gy over 30 fractions to the planning volume. Dosimetric endpoints were compared between VMAT and proton plans. The normal tissue complication probability (NTCP) following VMAT and proton therapy planning was also calculated using PICN as the biological endpoint. Sensitivity tests were performed to determine if predicted risk of PICN was sensitive to positional errors, proton range errors and selection of risk models.Results:Both PSPT and IMPT plans resulted in a significant increase in the maximum dose and reduction in the total brain volume irradiated to low doses compared with the VMAT plans. The average ratios of NTCP between PSPT and VMAT were 0.56 and 0.38 for glioma and ependymoma patients respectively and the average ratios of NTCP between IMPT and VMAT were 0.67 and 0.68 for glioma and ependymoma plans respectively. Sensitivity test revealed that predicted ratios of risk were insensitive to range and positional errors but varied with risk model selection.Conclusion:Both PSPT and IMPT plans resulted in a decrease in the predictive risk of necrosis for the pediatric plans studied in this work. Sensitivity analysis upheld the qualitative findings of the risk models used in this study, however more accurate models that take into account dose and volume are needed.
SU‐E‐T‐629: Prediction of the ViewRay Radiotherapy Treatment Time for Clinical Logistics
Authors: Liu S , Wooten H , Wu Y , Yang D 
Published: June 2015

Purpose:An algorithm is developed in our clinic, given a new treatment plan, to predict treatment delivery time for radiation therapy (RT) treatments of patients on ViewRay magnetic resonance‐image guided radiation therapy (MR‐IGRT) delivery system. This algorithm is necessary for managing patient treatment appointments, and is useful as an indicator to assess the treatment plan complexity.Methods:A patient's total treatment delivery time, not including time required for localization, may be described as the sum of four components: (1) the treatment initialization time; (2) the total beam‐on time; (3) the gantry rotation time; and (4) the multileaf collimator (MLC) motion time. Each of the four components is predicted separately. The total beam‐on time can be calculated using both the planned beam‐on time and the decay‐corrected delivery dose rate. To predict the remaining components, we quantitatively analyze the patient treatment delivery record files. The initialization time is demonstrated to be random since it depends on the final gantry angle and MLC leaf positions of the previous treatment. Based on modeling the relationships between the gantry rotation angles and the corresponding rotation time, and between the furthest MLC leaf moving distance and the corresponding MLC motion time, the total delivery time is predicted using linear regression.Results:The proposed algorithm has demonstrated the feasibility of predicting the ViewRay treatment delivery time for any treatment plan of any patient. The average prediction error is 0.89 minutes or 5.34%, and the maximal prediction error is 2.09 minutes or 13.87%.Conclusion:We have developed a treatment delivery time prediction algorithm based on the analysis of previous patients’ treatment delivery records. The accuracy of our prediction is sufficient for guiding and arranging patient treatment appointments on a daily basis. The predicted delivery time could also be used as an indicator to assess the treatment plan complexity.This work was supported by a research grant from Viewray Inc.
SU‐E‐T‐646: Quality Assurance of Truebeam Multi‐Leaf Collimator Using a MLC QA Phantom
Authors: Zhang J , Hong D , Lu J 
Published: June 2015

Purpose:To perform a routine quality assurance procedure for Truebeam multi‐leaf collimator (MLC) using MLC QA phantom, verify the stability and reliability of MLC during the treatment.Methods:MLC QA phantom is a specialized phantom for MLC quality assurance (QA), and contains five radio‐opaque spheres that are embedded in an “L” shape. The phantom was placed isocentrically on the Truebeam treatment couch for the tests. A quality assurance plan was setted up in the Eclipse v10.0, the fields that need to be delivered in order to acquire the necessary images, the MLC shapes can then be obtained by the images. The images acquired by the electronic portal imaging device (EPID), and imported into the PIPSpro software for the analysis. The tests were delivered twelve weeks (once a week) to verify consistency of the delivery, and the images are acquired in the same manner each time.Results:For the Leaf position test, the average position error was 0.23mm±0.02mm (range: 0.18mm∼0.25mm). The Leaf width was measured at the isocenter, the average error was 0.06mm±0.02mm (range: 0.02mm∼0.08mm) for the Leaf width test. Multi‐Port test showed the dynamic leaf shift error, the average error was 0.28mm±0.03mm (range: 0.2mm∼0.35mm). For the leaf transmission test, the average inter‐leaf leakage value was 1.0%±0.17% (range: 0.8%∼1.3%) and the average inter‐bank leakage value was 32.6%±2.1% (range: 30.2%∼36.1%).Conclusion:By the test of 12 weeks, the MLC system of the Truebeam is running in a good condition and the MLC system can be steadily and reliably carried out during the treatment. The MLC QA phantom is a useful test tool for the MLC QA.
SU‐E‐T‐648: Quality Assurance Using the RADPOS System for 4D Radiotherapy with CyberKnife
Authors: Marants R , Vandervoort E , Cygler J E 
Published: June 2015

Purpose:The CyberKnife robotic radiosurgery system uses Synchrony respiratory motion compensation, which requires independent performance verification. In this work, the RADPOS 4D dosimetry system's motion measurements are compared with internal fiducial position measurements. In addition, RADPOS measurements are compared with Synchrony's predictive correlation model, which is based on internal fiducial and external LED marker position measurements.Methods:A treatment plan was created for a lung insert containing fiducials, RADPOS detector, and Solid Water tumor phantom. Two Quasar Respiratory Motion Phantoms (Q1 and Q2) and two RADPOS detectors (R1 and R2) were used: Q1 simulated lung motion with a lung insert moving in the superior/inferior direction, while Q2 simulated chest motion with a chest platform moving in the anterior/posterior direction. Before treatment, R1 was secured inside of the tumor phantom within Q1, while LED markers and R2 were positioned on the chest platform of Q2. Two treatment delivery cases were studied: isocentric plan (I) and non‐isocentric patient plan (P). Four motion cases were studied: no motion (0), sinusoidal and in‐phase (1), sinusoidal and out‐of‐phase (2), patient waveform and out‐of‐phase (3). A coordinate alignment algorithm was implemented, allowing RADPOS and model position data to be compared within the fiducial coordinate system.Results:The standard deviation of the differences between RADPOS and fiducial position measurements was below 0.6 mm for all experimental cases. The standard deviation of the differences between RADPOS and model position data was 1.0, 1.5, and 1.6 mm along the primary direction of motion for case I1, I2, and P3, respectively.Conclusion:Our work demonstrates that RADPOS is a useful tool for independent quality assurance of CyberKnife treatment with Synchrony respiratory compensation. RADPOS and fiducial position measurement closely match, and RADPOS confirms the effectiveness of CyberKnife's Synchrony motion tracking.This work was supported by OCAIRO (Ontario Consortium for Adaptive Interventions in Radiation Oncology) grant.
SU‐E‐T‐650: Quantification and Modeling of the Dosimetric Impact of the IBEAM Evo Treatment Couchtop EP (Elekta) in VMAT
Authors: Zhang R , Bai W , Fleckenstein J 
Published: June 2015

Purpose:quantification and modelling of the dosimetric impact of the treatment couch in Monaco Treatment Planning System.Methods:The attenuation characteristics of couchtop EP was evaluated for two different photon acceleration potentials (6MV and 10MV) for a field size of (10×10) cm2. Phantom positions in A‐B direction: on the left half, in the center and on the right half of the couch. Dose measurements of couch attenuation were performed at gantry angles from 180° to 122°, using a 0.125cc semiflex ionization chamber isocentrically placed in the center of a homogeneous cylindric sliced RW3 phantom. Each experimental setup was first measured on the LINAC and then reproduced in the TPS. By adjusting the relative‐to‐water electron density (ED) values of the couch, the measured attenuation was replicated. The simulated results were evaluated by comparing the measurements and simulations.Results:Without the couch model included the maximum difference between measured and calculated dose was 5.5% (5.1%) and 6.6% (6.1%) for 2 mm and 5 mm voxel size, when the phantom was positioned on the left (center). The couch model was included in the TPS with a uniform ED of 0.18 or a 2 component model with a fiber ED= 0.6 and foam core ED= 0.1. After including the treatment couch, the mean dose attenuation was reduced from 2.8% without couch included to (0.0, 0.8, −0.2, 0.6)%. The 4 different values represent the 1 and 2 components model and 2 and 5 mm voxel grid size.Conclusion:For a uniform relative‐to‐water couch electron density of 0.18 a good agreement between measured and calculated dose distributions was obtained for all different energies, voxel grid spacings and gantry angles. Therefore, we conclude that the Monaco couch model accurately describes the dose perturbations due to the presence of the patient couch and should therefore be used during treatment planning.This project is supported by Technology Foundation for Selected Overseas Chinese Scholar, Ministry of Hebei Personnel of China