bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐T‐488: Incorporating In‐House Treatment Planning Software Into Clinical Auto‐Planning Workflow
Authors: Lu W , Chen M , Tan J , Jiang S 
Published: June 2015

Purpose:To report the process of incorporating in‐house software tools into clinical workflow of auto‐planning with the objectives of achieving efficiency and quality plans.With multi‐year research and development, we built in‐house software suites of various GPU‐based components of a treatment planning system (TPS), which includes DICOM import/export, various deformable image registration (DIR) and contour generation algorithms, multiple dose calculators and optimizers, and plan generation with or without reference guidance. However, to meet clinical quality, we need to further test the robustness of the tools, streamline the processes, including the front and back end processes.Methods:We build an in‐house patient database management system and collect patient data of various delivery modalities, such as IMRT, VMAT, etc., and of various disease sites, such as head and neck, breast, lung, prostate, etc., to be used as repository for part of simulating the clinical workflow and subsequent testing.A unit‐testing tool was developed that any input parameter can be loaded from a configuration file for batch processing. Modular inputs and outputs were part of the design, and button clicking and human interaction can be bypassed.Results:The database with various delivery modalities and various disease sites allows the auto‐planning tools to test on variety of cases. The unit‐testing tools allow mass data processing and analysis. As testing showed, the whole auto‐planning process can be done in a couple of minutes without any human interaction.Conclusion:A database and unit‐testing tools are essential in incorporating the in‐house software into the clinical auto‐planning workflow and greatly facilitate the implementation by allowing component testing and mass data processing and analysis. Thus, desired functional behavior may be ensured, the impact of any code modification can be more easily identified, and any unintended alteration can be avoided.
SU‐E‐T‐489: Incorporating Skin Flash Into VMAT WBI: Impacts On Surface Dosimetry
Authors: Buele A Bejarano , Tanny S , Warrell G , Parsai E 
Published: June 2015

Purpose:Increased use of inverse planning limits the amount of skin flash in whole breast irradiation (WBI). Strategies to incorporate flash into inverse‐planned treatments involve overriding air to the density of water or tissue. This introduces uncertainties to the superficial dose distribution, potentially degrading the coverage at the skin‐bolus interface. We investigate the accuracy of various commonly used bolus materials to incorporate flash in VMAT WBI plans while minimizing the perturbation near the skin.Methods:We obtained a CT‐simulation of an anthropomorphic phantom with a breast attachment. Three VMAT plans were created with different boluses: 1 cm of 1 g/cm3 bolus (Superflab), 1 cm of 0.65 g/cm3 bolus (wet towels), and 1 cm of g/cm3 bolus with 2 dose levels accounting for the difference between bolus and tissue density. The PTV was extended into the bolus, outside the patient body contour to incorporate flash. OSLDs were used to obtain surface doses at the medial, lateral and tip sites of the breast. Each plan was irradiated four times using CBCT for positioning and dosimeter localization.Results:The average thickness of the wet‐towel bolus on delivery was 8 mm with a CBCT‐measured density of 0.6 g/cm3. OSLD measurements demonstrated good agreement with predicted doses from Pinnacle. Average deviations were −5.7%, −2.5%, and −2.6% for plans 1, 2, and 3, respectively. OSLDs placed at the medial and lateral portions of the breast showed the largest average deviations. The maximum recorded deviation from planned values was −8.6%. The largest dose fluctuations occurred near areas where the bolus failed to properly conform to the breast contour.Conclusion:Use of wet‐towel bolus improved dose delivery accuracy compared to standard Superflab bolus. Areas of poor bolus conformity adversely affected dose delivery. We recommend the use of wet‐towel bolus over Superflab bolus for VMAT WBI.
SU‐E‐T‐494: Influence of Proton Track‐Cell Nucleus Incidence Angle On Relative Biological Effectiveness
Authors: Pater P , Backstrom G , Enger S , Villegas F , Ahnesjo A , Seuntjens J , El Naqa I 
Published: June 2015

Purpose:To explain a Monte Carlo (MC) simulation artifact whereby differences in relative biological effectiveness (RBE) in the induction of initial double strand breaks are observed as a function of the proton track incidence angles in a geometric cell nucleus model. Secondly, to offer an alternative isotropic irradiation procedure to mitigate this effect.Methods:MC tracks of 1 MeV protons were generated in an event‐by‐event mode. They were overlaid on a cylindrical model of a cell nucleus containing 6×109 nucleotide base pairs. The tracks incidence angle θ with respect to the cell nucleus's axis was varied in 10 degrees intervals, each time generating one hundred fractions of ∼2 Gy. Strand breaks were scored in the modeled DNA sugar‐phosphate groups and further sub‐classified into single or double strand breaks (ssbs or dsbs). For each angle, an RBE for the induction of initial dsbs with reference to Co‐60 was calculated.Results:Our results show significant angular dependencies of RBE, with maximum values for incidence angles parallel to the nucleus central axis. Further examination shows that the higher cross‐sections for the creation of dsbs is due to the preferential alignment of tracks with geometrical sub‐parts of the cell nucleus model, especially the nucleosomes containing the sugar‐phosphate groups. To alleviate the impact of this simulation artifact, an average RBE was calculated with a procedure based on a weighted sampling of the angular data.Conclusion:This work demonstrates a possible numerical artifact in estimated RBE if the influence of the particle incidence angle is not correctly taken into account. A correction procedure is presented to better conform the simulations to real‐life experimental conditions.We would like to acknowledge support from the Fonds de recherche du Quebec Sante (FRQS), from the CREATE Medical Physics Research Training Network grant (number 432290) of NSERC, support from NSERC under grants RGPIN 397711‐11 and RGPIN‐2014‐06475 and support from the CIHR under grants MOP‐114910, MOP‐136774 and MOP‐102550.
SU‐E‐T‐504: Intensity‐Modulated Radiosurgery Treatments Derived by Optimizing Delivery of Sphere Packing Treatment Plans
Authors: Hermansen M , John T St. , Velasco B , Bova F 
Published: June 2015

PurposeTo minimize the number of monitor units required to deliver a sphere packing stereotactic radiosurgery (SRS) plan by eliminating overlaps of individual beam projections.MethodsAn algorithm was written in C++ to calculate SRS treatment doses using sphere packing. Three fixed beams were used to approximate each arc in a typical SRS treatment plan. For cases involving multiple isocenters, at each gantry and table angle position beams directed to individual spheres overlap to produce regions of high dose, resulting in intensity modulated beams. These high dose regions were dampened by post‐processing of the combined beam profile. The post‐process dampening involves removing the excess overlapping fluence from all but the highest contributing beam. The dampened beam profiles at each table and gantry angle position were then summed to produce the new total dose distribution.ResultsDelivery times for even the most complex multiple sphere plans can be reduced to consistent times of about 20 to 30 minutes. The total MUs required to deliver the plan can also be reduced by as much as 85% of the original plan's MUs.ConclusionRegions of high dose are removed. Dampening overlapping radiation fluence can produce the new beam profiles that have more uniform dose distributions using less MUs. This results in a treatment that requires significantly fewer intensity values than traditional IMRT or VAMT planning.
SU‐E‐T‐507: Internal Dosimetry in Nuclear Medicine Using GATE and XCAT Phantom: A Simulation Study
Authors: Fallahpoor M , Abbasi M , Sen A , Parach A , Kalantari F 
Published: June 2015

PurposeMonte Carlo simulations are routinely used for internal dosimetry studies. These studies are conducted with humanoid phantoms such as the XCAT phantom. In this abstract we present the absorbed doses for various pairs of source and target organs using three common radiotracers in nuclear medicine.MethodsThe GATE software package is used for the Monte Carlo simulations. A typical female XCAT phantom is used as the input. Three radiotracers 153Sm, 131I and 99mTc are studied. The Specific Absorbed Fraction (SAF) for gamma rays (99mTc, 153Sm and 131I) and Specific Fraction (SF) for beta particles (153Sm and 131I) are calculated for all 100 pairs of source target organs including brain, liver, lung, pancreas, kidney, adrenal, spleen, rib bone, bladder and ovaries.ResultsThe source organs themselves gain the highest absorbed dose as compared to other organs. The dose is found to be inversely proportional to distance from the source organ. In SAF results of 153Sm, when the source organ is lung, the rib bone, gain 0.0730 (Kg‐1) that is more than lung itself.ConclusionThe absorbed dose for various organs was studied in terms of SAF and SF. Such studies hold importance for future therapeutic procedures and optimization of induced radiotracer.
SU‐E‐T‐510: Interplay Between Spots Sizes, Spot / Line Spacing and Motion in Spot Scanning Proton Therapy
Authors: Lee TK 
Published: June 2015

PurposeIn proton beam configuration for spot scanning proton therapy (SSPT), one can define the spacing between spots and lines of scanning as a ratio of given spot size. If the spacing increases, the number of spots decreases which can potentially decrease scan time, and so can whole treatment time, and vice versa. However, if the spacing is too large, the uniformity of scanned field decreases. Also, the field uniformity can be affected by motion during SSPT beam delivery. In the present study, the interplay between spot/ line spacing and motion is investigated.MethodsWe used four Gaussian‐shape spot sizes with 0.5cm, 1.0cm, 1.5cm, and 2.0cm FWHM, three spot/line spacing that creates uniform field profile which are 1/3*FWHM, σ/3*FWHM and 2/3*FWHM, and three random motion amplitudes within, +/−0.3mm, +/−0.5mm, and +/−1.0mm. We planned with 2Gy uniform single layer of 10×10cm2 and 20×20cm2 fields. Then, mean dose within 80% area of given field size, contrubuting MU per each spot assuming 1cGy/MU calibration for all spot sizes, number of spots and uniformity were calculated.ResultsThe plans with spot/line spacing equal to or smaller than 2/3*FWHM without motion create ∼100% uniformity. However, it was found that the uniformity decreases with increased spacing, and it is more pronounced with smaller spot sizes, but is not affected by scanned field sizes.ConclusionIt was found that the motion during proton beam delivery can alter the dose uniformity and the amount of alteration changes with spot size which changes with energy and spot/line spacing. Currently, robust evaluation in TPS (e.g. Eclipse system) performs range uncertainty evaluation using isocenter shift and CT calibration error. Based on presented study, it is recommended to add interplay effect evaluation to robust evaluation process. For future study, the additional interplay between the energy layers and motion is expected to present volumetric effect.
SU‐E‐T‐516: Investigation of a Novel Radiochromic Radiation Reporting System Utilizing the Reduction of Ferric Ion
Authors: Lee H , Alqathami M , Wang J , Blencowe A , Ibbott G 
Published: June 2015

PurposeTo introduce and characterize a new “reverse‐Fricke” radiation reporting system utilizing the reduction of ferric ions (Fe3+) to ferrous ions (Fe2+).MethodsTwo formulations of the radiochromic reporting system, referred to as A and B, were prepared for investigation. Formulation‐A consisted of 14 mM 1,10‐phenanthroline, 42 mM ethanol, and 57 mM ammonium ferric oxalate in water. Formulation‐B consisted of 27 mM 1,10‐phenanthroline, 42 mM ethanol, and 28 mM ammonium ferric oxalate in water. Solutions were prepared immediately prior to irradiation with a Cobalt‐60 unit with radiation doses of 0, 1, 5, 10, 15, 20, and 25 Gy. The change in optical density over the visible range of 450–650 nm was measured using a spectrophotometer immediately after irradiation. The effective atomic numbers of the formulations were calculated using Mayneord's formula.ResultsIonizing radiation energy absorbed in the solutions causes the reduction of ferric ions (Fe3+) into ferrous ions (Fe2+), which then forms a 1:3 red colored complex with 1,10‐phenanthroline ([(C1 2H8N2)3Fe]2+) that can be measured spectrophotometrically. The absorbance spectra of the resulting complex displayed a peak maximum at 512 nm with a greater change in absorbance for Formulation‐B after receiving comparable radiation doses. The change in absorbance relative to dose exhibited a linear response up to 25 Gy for both Formulation‐A (R2 = 0.98) and Formulation‐B (R2 = 0.97). The novel formulations were also nearly water equivalent (Zeff = 7.42) with effective atomic numbers of 7.65 and 7.52 and mass densities within 0.2% of water.ConclusionBoth formulations displayed visible Fe2+ complex formation with 1,10‐phenanthroline after irradiation using a Cobalt‐60 source. The higher sensitivity measured for Formulation‐B is attributed to the increase in 1,10‐phenanthroline concentration and the increase in the 1,10‐phenanthroline to ammonium ferric oxalate ratio. Further investigation of this radiation reporting system in a 3D matrix material is encouraged.NSF GRFP Grant Award #LH‐102SPS
SU‐E‐T‐527: Is CTV‐Based Robust Optimized IMPT in Non‐Small‐Cell Lung Cancer Robust Against Respiratory Motion?
Authors: Anetai Y , Takegawa H , Inoue T , Mizuno H , Sumida I , Koizumi M , Ogawa K , van't Veld A , Korevaar E 
Published: June 2015

Purpose:To determine which proton planning technique on average‐CT is more vulnerable to respiratory motion induced density changes and interplay effect among (a) IMPT of CTV‐based minimax robust optimization with 5mm set‐up error considered, (b, c) IMPT/SFUD of 5mm‐expanded PTV optimization.Methods:Three planning techniques were optimized in Raystation with a prescription of 60/25 (Gy/fractions) and almost the same OAR constraints/objectives for each of 10 NSCLC patients. 4D dose without/with interplay effect was recalculated on eight 4D‐CT phases and accumulated after deforming the dose of each phase to a reference (exhalation phase). The change of D98% of each CTV caused by density changes and interplay was determined. In addition, evaluation of the DVH information vector (D99%, D98%, D95%, Dave, D50%, D2%, D1%) which compares the whole DVH by η score = (cosine similarity × Pearson correlation coefficient − 0.9) × 1000 quantified the degree of DVH change: score below 100 indicates changed DVH.Results:Three 3D plans of each technique satisfied our clinical goals. D98% shift mean±SD (Gy) due to density changes was largest in (c): −0.78±1.1 while (a): −0.11±0.65 and (b): − 0.59±0.93. Also the shift due to interplay effect most was (c): −.54±0.70 whereas (a): −0.25±0.93 and (b): −0.12±0.13. Moreover lowest η score caused by density change was also (c): 69, while (a) and (b) kept around 90. η score also indicated less effect of interplay than density changes. Note that generally the changed DVH were still acceptable clinically. Paired T‐tests showed a significantly smaller density change effect in (a) (p<0.05) than in (b) or (c) and no significant difference in interplay effect.Conclusion:CTV‐based robust optimized IMPT was more robust against respiratory motion induced density changes than PTV‐based IMPT and SFUD. The interplay effect was smaller than the effect of density changes and similar among the three techniques.The JSPS Core‐to‐Core Program (No. 23003), Japan Society for the Promotion of Science Grant‐in‐Aid for Scientific Research (No. 23390300), Grant‐in‐Aid for Young Scientists (B) (No. 21791194) and Grant‐in‐Aid for Cancer Research (H22‐3rd Term Cancer Control‐General‐043)
SU‐E‐T‐530: Knowledge‐Based Treatment Planning and Its Potential Role in the Transition Between Treatment Planning Systems
Authors: Masi K , Archer P , Hamstra D , Matuszak M 
Published: June 2015

Purpose:Commissioning a treatment planning system (TPS) involves many tasks, including making sure users have sufficient training and experience to create quality plans. We investigated the role that knowledge‐based planning (KBP) can play in aiding a clinic's transition to a new TPS.Methods:60 clinically treated prostate and prostate bed IMRT plans were exported from an in‐house TPS and used to create a KBP‐model in a newly introduced commercial TPS (Eclipse v13.5, Varian Medical Systems). To determine the benefit that KBP may have in a TPS transition, the model was tested on two groups. Group 1 consisted of the first 10 patients treated in the commercial TPS after the transition from the in‐house TPS, Group 2 consisted of 10 patients planned in the commercial TPS, but without the KBP model, after 8 months of clinical use. The KBP‐generated plan for each patient was compared to the clinically‐used plan in terms of quality and planning efficiency.Results:On average, the KBP‐generated plans provided better target coverage for group 1 than the clinical plans,and about equivalent coverage for group 2. The average absolute difference (KBP‐clinical) for D95 for the PTV was 0.48±0.49% and −0.11±0.48% for groups 1 and 2, respectively. For the OARs, the KBP‐generated plans produced lower doses for every normal tissue objective except the maximum dose to 0.1cc of rectum (0.50±0.27Gy and 0.22±0.17Gy for groups 1 and 2, respectively). The time needed for KBP‐generated plans ranged from 6– 15min compared to 30–150 and 15–60min for groups 1 and 2, respectively.Conclusion:Knowledge‐based planning is a promising tool to aid in transitions to new TPSs. Our study indicates that high‐quality treatment plans could have been generated in the new TPS more efficiently compared to not using KBP. Even after 8 months of clinical use, KBP still showed a quality and efficiency increase compared to manual planning.Partially supported by Varian Medical Systems
SU‐E‐T‐531: Large‐‐Scale DVH Quality Study: Correlated Aims Lead Relaxations
Authors: Nohadani O , Roy A , Das I 
Published: June 2015

Purpose:Intensity modulated radiation therapy plans are designed to optimally target a tumor while sparing surrounding tissue. Desired dose distributions are iteratively approached via inverse planning. This leads to tradeoffs between clinical objectives for the planning target volume (PTV), organs at risk, and normal tissues. Dose volume histogram (DVHs) related aims are followed that are either institutional or internationally recommended. We analyze common goals and identify potential reasons that often lead to tradeoffs.Methods:524 IMRT plans for various tumor sites were analyzed based on the main institutional DVH goal for PTV (D95) and the recommendations by ICRU‐83 (D2, D50, and D98). Robust statistical tools are developed and applied to ensure that the results are immune to data uncertainties. The probability of violation was measured for each of the DVH goals based on the frequency of not meeting recommended doses. Conditional probabilities for satisfying and/or violating DVH aims were computed to test the hypothesized pair‐wise relations between DVH aims. For example, for plans that satisfied D50, the probability of violating D98 was computed via P(D98 < 95% | 98% ≤ D50 ≤ 102%). The equality constraint D50 = 100% was relaxed to encompass the range [98,102]%.Results:A large majority of cases (88%) satisfied the institutional goal for PTV of D95 ≤ 95%. Similar consensus existed for D98. 51% of cases satisfied D2 ≥ 107%. However, only 18% of cases satisfied D50. The conditional probability showed correlations amongst the studied DVH goals. In fact, a negative correlation was revealed between D50 and D95 (and D98), suggesting that these competing goals cannot be satisfied concurrently.Conclusion:The majority of plans followed the institutional guidelines. The reason for their deviation from international recommendations seems to be that the latter goals are competing and cannot be satisfied concurrently in clinical practice.
SU‐E‐T‐534: Level of Residual Radioactivity of Activated Parts of a Decommissioned Cyclotron
Authors: Choi HHF , Leung TM , Chiu TL , Yang B , Wu PM , Cheung KY , Yu SK 
Published: June 2015

Purpose:CTI cyclotron RDS‐111 was used at the Hong Kong Sanatorium and Hospital (HKSH) to produce radiopharmaceuticals and radioactive tracers for diagnostic scans between 1999 and 2007. During the operation, some machine components became radioactive by activation. For the safety of staff, decommissioning took place in 2009, two years after the cyclotron had stopped operation. This study investigates the residual radioactivity and radionuclides found in different cyclotron components in 2014 in compliance with the local regulations in Hong Kong for transfer of radioactive waste.Methods:A representative sample of each part was counted using a high‐purity germanium detector (manufacturer: ORTECT) for at least four hours. GammaVision, a multichannel analyzer software, was used to identify the radionuclides found in the cyclotron components, as well as the associated activities. A standard library and a Mariscotti peak search algorithm were used to identify the present radionuclides. Only radionuclides with half‐life greater than 180 days were considered.Results:Among the components, the Havar target foil has the highest specific activity ((4.6±0.6)×102 Bq/g), with Co‐60 being the most prominent ((3.8±0.5)×102 Bq/g). The total activity of the target foil, however, is still low due to its small mass of 0.04 g. Radioisotopes Mn‐54 (46±6 Bq/g), Na‐22 (6.8±0.8 Bq/g), Co‐57 (7.3±0.9 Bq/g), and Fe‐59 (6.0±0.9 Bq/g) have also been detected in the target foil. The target window holder and the vacuum window register a specific activity of 88.3±0.6 Bq/g and 48.6±0.1 Bq/g, respectively. Other components, such as the collimator, the target tube, the valve body and the beamline, are also found with trace amounts of radionuclides.Conclusion:Even seven years after the cyclotron had stopped operation, some components still exhibited residual radioactivity from activation exceeding the IAEA clearance levels. Special consideration for radiological protection may need to be taken in the disposal of the cyclotron parts.