bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐E‐T‐253: Open‐Source Automatic Software for Quantifying Biological Assays of Radiation Effects
Authors: Detappe A , Korideck H , Makrigiorgos G , Berbeco R 
Published: July 2014

Purpose:Clonogenic cell survival is a common assay for quantifying the effect of drugs and radiation. Manual counting of surviving colonies can take 30–90seconds per plate, a major limitation for large studies. Currently available automatic counting tools are not easily modified for radiation oncology research. Our goal is to provide an open‐source toolkit for precise, accurate and fast analysis of biological assays in radiation oncology.Methods:As an example analysis, we used HeLa cells incubated with gadolinium nanoparticles prior to irradiation. After treatment, the cells are grown for 14days to allow for colony formation. To analyze the colony growth, we capture images of each dish for archiving and automatic computer‐based analysis. A FujifilmX20 camera is placed at the top of a box setup, 20cm above the sample, which is backlit by a LED lamp placed at the bottom of the box. We use a Gaussian filter (width=1.3mm) and color threshold (19–255). The minimum size for a colony to be counted is 1mm. For this example, 20 dishes with a large range of colonies were analyzed. Each dish was counted 3 times manually by 3 different users and then compared to our counter.Results:Automatic counting of cell colonies takes an average of 7seconds, enabling the analysis process to be accelerated 4–12 times. The average precision of the automatic counter was 1.7%. The Student t‐test demonstrated the non‐significant differences between the two counting methods (p=0.64). The ICC demonstrated the reliability of each method with ICC>0.999 (automatic) and ICC=0.95 (manual).Conclusion:We developed an open‐source automatic toolkit for the analysis of biological assays in radiation oncology and demonstrated the accuracy, precision and effort savings for clonogenic cell survival quantification. This toolkit is currently being used in two laboratories for routine experimental analysis and will be made freely available on our departmental website.
SU‐E‐T‐270: Quality Control of Source Strength and Indexer Length in HDR Brachytherapy Using Sun Nuclear Mapcheck2
Authors: Morales J 
Published: July 2014

Purpose:The goal of this work was to evaluate Sun Nuclear MapCheck2 capability for quantitative determination of both HDR source strength and position. Predictive power of Mapcheck2 dose matrix, originated by a microSelectron_v2 source from 22mm distance, was investigated.Methods:A Mick MultiDoc phantom with the 1400mm indexer length mark aligned over MapCheck2 central detector plus two additional 5cm plastic slabs were used as a composite phantom. Dose readings were transformed by applying published source anisotropy corrections and experimentally established radial dose and relative sensitivity factors. Angular dependence was not considered. Only readings from diodes located 2cm around the central detector were evaluated. The reproducibility of a fit between transformed dose readings and the ratio of virtual source strength and the square of source‐detector distance was investigated. Four parameters were considered in the model: virtual source strength, lateral, longitudinal and vertical source positions. Final source strength calibration factor was calculated from the ratio of reference measurements and results from the fit.Results:Original lateral and longitudinal source position estimations had systematic errors of 0.39mm and 0.75mm. After subtracting these errors, both source positions were predicted with a standard deviation of 0.15mm. Results for vertical positions were reproducible with a standard deviation of 0.05mm. The difference between calculated and reference source strengths from 34 independent measurement setups had a standard deviation of 0.3%. The coefficient of determination for the linear regression between known indexer lengths and results from the fit in the range 1400mm ± 5mm was 0.985.Conclusions:ource strength can be estimated with MapCheck2 at appropriate accuracy levels for quality control. Verification of indexer length with present implementation is more accurate than visual alternatives. Results can be improved by designing a coupling catheter phantom and refining relative diode calibration. Diode angular dependence in MapCheck2 does not play significant role.
SU‐E‐T‐271: Quantitative Analysis of Correlations Between Patient Geometry and Dosimetric Variation for Prostate Cancer Cases Using PCA and Step‐Wise Regression
Authors: Song T , Folkerts M , Zhen H , Tian Z , Zhou L , Jia X , Jiang S , Gu X 
Published: July 2014

Purpose:To study the potential correlations between patient geometry information and corresponding plan dosimetric variation in terms of planning target volumes (PTVs) coverage and organs‐at‐risk (OARs) dose sparing for prostate cancer cases.Methods:We extracted dosimetric and geometrical data from twenty‐three clinically acceptable prostate treatment plans. Dosimetric data extracted from each patient was PTV dose‐volume historgram (DVH), and dose‐wall‐volume histograms (DWHs) for the bladder and rectum. Geometrical data extracted was the PTV volume, OAR volumes, and COP (closeness of OAR to PTV). COP is the weighted sum of the overlapping wall histogram (OWH). OWH is proposed to describe the complex spatial relationship between PTV and a hollow organ. Principal component analysis (PCA) was performed on the (inverted and downsampled) DVH and DWH data from all the patients. We then fit the patient geometry features to first 3 PCA scores using a step‐wise regression analysis. The fitting results in a mapping from plan geometry information to dosimetric features.Results:First 3 PCA modes were found corresponded to clinically relevant features, indicating a tradeoff between homogenous coverage of the PTV and higher OAR dose, higher average dose to the OARs and PTV, and bladder and rectum dose tradeoffs along the first, second and third principal component respectively. Step‐wise regression results show baldder surface volume and OAR COP more relevant to the 1st PCA modes score rather than other features with p‐value of 0.58 for bladder volume, 0.26 for bladder COP, 0.98 for rectum COP, and less than 0.025 for other features after t‐test.Conclusion:Quantitative correlations were established between patient geometry and corresponding plan dosimetric variation in terms of PTV coverage, trade‐offs between PTV coverage and OAR dose sparing and trade‐offs between different OAR dose sparing. Thus a new patient dosimetric variation tendency can be predicted and act as guidance for setting up planning goals.
SU‐E‐T‐274: Radiation Therapy with Very High‐Energy Electron (VHEE) Beams in the Presence of Metal Implants
Authors: Jensen C , Palma B , Qu B , Maxim P , Hardemark B , Hynning E , Loo B , Bazalova M 
Published: July 2014

Purpose:To evaluate the effect of metal implants on treatment plans for radiation therapy with very high‐energy electron (VHEE) beams.Methods:The DOSXYZnrc/BEAMnrc Monte Carlo (MC) codes were used to simulate 50–150MeV VHEE beam dose deposition and its effects on steel and titanium (Ti) heterogeneities in a water phantom. Heterogeneities of thicknesses ranging from 0.5cm to 2cm were placed at 10cm depth. MC was also used to calculate electron and photon spectra generated by the VHEE beams' interaction with metal heterogeneities. The original VMAT patient dose calculation was planned in Eclipse. Patient dose calculations with MC‐generated beamlets were planned using a Matlab GUI and research version of RayStation. VHEE MC treatment planning was performed on water‐only geometry and water with segmented prostheses (steel and Ti) geometries with 100MeV and 150MeV beams.Results:100MeV PDD 5cm behind steel/Ti heterogeneity was 51% less than in the water‐only phantom. For some cases, dose enhancement lateral to the borders of the phantom increased the dose by up to 22% in steel and 18% in Ti heterogeneities. The dose immediately behind steel heterogeneity decreased by an average of 6%, although for 150MeV, the steel heterogeneity created a 23% increase in dose directly behind it. The average dose immediately behind Ti heterogeneities increased 10%. The prostate VHEE plans resulted in mean dose decrease to the bowel (20%), bladder (7%), and the urethra (5%) compared to the 15MV VMAT plan. The average dose to the body with prosthetic implants was 5% higher than to the body without implants.Conclusion:Based on MC simulations, metallic implants introduce dose perturbations to VHEE beams from lateral scatter and backscatter. However, when performing clinical planning on a prostate case, the use of multiple beams and inverse planning still produces VHEE plans that are dosimetrically superior to photon VMAT plans.BW Loo and P Maxim received research support from RaySearch laboratories; B Hardemark and E Hynning are employees of RaySearch.
SU‐E‐T‐278: Realization of Dose Verification Tool for IMRT Plan Based On DPM
Authors: Cai Jinfeng , LIN Hui , Cao Ruifen , Dai Yumei , Pei Xi , Zhang Jun , Hu Liqin ,   FDS Team
Published: July 2014

Purpose:To build a Monte Carlo dose verification tool for IMRT Plan by implementing a irradiation source model into DPM code. Extend the ability of DPM to calculate any incident angles and irregular‐inhomogeneous fields.Methods:With the virtual source and the energy spectrum which unfolded from the accelerator measurement data,combined with optimized intensity maps to calculate the dose distribution of the irradiation irregular‐inhomogeneous field. The irradiation source model of accelerator was substituted by a grid‐based surface source. The contour and the intensity distribution of the surface source were optimized by ARTS (Accurate/Advanced Radiotherapy System) optimization module based on the tumor configuration. The weight of the emitter was decided by the grid intensity. The direction of the emitter was decided by the combination of the virtual source and the emitter emitting position. The photon energy spectrum unfolded from the accelerator measurement data was adjusted by compensating the contaminated electron source. For verification, measured data and realistic clinical IMRT plan were compared with DPM dose calculation.Results:The regular field was verified by comparing with the measured data. It was illustrated that the differences were acceptable (<2% inside the field, 2–3mm in the penumbra). The dose calculation of irregular field by DPM simulation was also compared with that of FSPB (Finite Size Pencil Beam) and the passing rate of gamma analysis was 95.1% for peripheral lung cancer. The regular field and the irregular rotational field were all within the range of permitting error. The computing time of regular fields were less than 2h, and the test of peripheral lung cancer was 160min. Through parallel processing, the adapted DPM could complete the calculation of IMRT plan within half an hour.Conclusion:The adapted parallelized DPM code with irradiation source model is faster than classic Monte Carlo codes. Its computational accuracy and speed satisfy the clinical requirement, and it is expectable to be a Monte Carlo dose verification tool for IMRT Plan.Strategic Priority Research Program of the China Academy of Science(XDA03040000); National Natural Science Foundation of China (81101132)
SU‐E‐T‐295: Simultaneous Beam Sampling and Aperture Shape Optimization for Station Parameter Optimized Radiation Therapy (SPORT)
Authors: Zarepisheh M , Ye Y , Boyd S , Li R , Xing L 
Published: July 2014

Purpose:Station Parameter Optimized Radiation Therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital LINACs, in which the station parameters of a delivery system, (such as aperture shape and weight, couch position/angle, gantry/collimator angle) are optimized altogether. SPORT promises to deliver unprecedented radiation dose distributions efficiently, yet there does not exist any optimization algorithm to implement it. The purpose of this work is to propose an optimization algorithm to simultaneously optimize the beam sampling and aperture shapes.Methods:We build a mathematical model whose variables are beam angles (including non‐coplanar and/or even nonisocentric beams) and aperture shapes. To solve the resulting large scale optimization problem, we devise an exact, convergent and fast optimization algorithm by integrating three advanced optimization techniques named column generation, gradient method, and pattern search. Column generation is used to find a good set of aperture shapes as an initial solution by adding apertures sequentially. Then we apply the gradient method to iteratively improve the current solution by reshaping the aperture shapes and updating the beam angles toward the gradient. Algorithm continues by pattern search method to explore the part of the search space that cannot be reached by the gradient method.Results:The proposed technique is applied to a series of patient cases and significantly improves the plan quality. In a head‐and‐neck case, for example, the left parotid gland mean‐dose, brainstem max‐dose, spinal cord max‐dose, and mandible mean‐dose are reduced by 10%, 7%, 24% and 12% respectively, compared to the conventional VMAT plan while maintaining the same PTV coverage.Conclusion:Combined use of column generation, gradient search and pattern search algorithms provide an effective way to optimize simultaneously the large collection of station parameters and significantly improves quality of resultant treatment plans as compared with conventional VMAT or IMRT treatments.
SU‐E‐T‐298: Small Field Total Scatter Factors Using a Commercial Scintillator Detector: Calibration Parameters Are Not Independent of Field Size
Authors: Jornet N , Carrasco de Fez P , Jordi O , Latorre‐Musoll A , Eudaldo T , Ruiz‐Martinez A , Ribas Morales M 
Published: July 2014

Purpose:To evaluate the accuracy in total scatter factor (Sc,p) determination for small fields using commercial plastic scintillator detector (PSD). The manufacturer's spectral discrimination method to subtract Cerenkov light from the signal is discussed.Methods:Sc,p for field sizes ranging from 0.5 to 10 cm were measured using PSD Exradin (Standard Imaging) connected to two channel electrometer measuring the signals in two different spectral regions to subtract the Cerenkov signal from the PSD signal. A Pinpoint ionisation chamber 31006 (PTW) and a non‐shielded semiconductor detector EFD (Scanditronix) were used for comparison. Measures were performed for a 6 MV X‐ray beam. The Sc,p are measured at 10 cm depth in water for a SSD=100 cm and normalized to a 10' 10 cm2 field size at the isocenter. All detectors were placed with their symmetry axis parallel to the beam axis.We followed the manufacturer's recommended calibration methodology to subtract the Cerenkov contribution to the signal as well as a modified method using smaller field sizes. The Sc,p calculated by using both calibration methodologies were compared.Results:Sc,p measured with the semiconductor and the PinPoint detectors agree, within 1.5%, for field sizes between 10' 10 and 1' 1 cm2. Sc,p measured with the PSD using the manufacturer's calibration methodology were systematically 4% higher than those measured with the semiconductor detector for field sizes smaller than 5' 5 cm2. By using a modified calibration methodology for smalls fields and keeping the manufacturer calibration methodology for fields larger than 5' 5cm2 field Sc,p matched semiconductor results within 2% field sizes larger than 1.5 cm.Conclusion:The calibration methodology proposed by the manufacturer is not appropriate for dose measurements in small fields. The calibration parameters are not independent of the incident radiation spectrum for this PSD. This work was partially financed by grant 2012 of Barcelona board of the AECC.
SU‐E‐T‐303: Spot Scanning Dose Delivery with Rapid Cycling Proton Beams From RCMS
Authors: Cheng C , Liu H , Lee S 
Published: July 2014

Purpose:A rapid cycling proton beam has several distinct characteristics superior to a slow extraction synchrotron: The beam energy and energy spread, beam intensity and spot size can be varied spot by spot. The feasibility of using a spot scanning beam from a rapidc‐ycling‐medical‐synchrotron (RCMS) at 10 Hz repetition frequency is investigated in this study for its application in proton therapy.Methods:The versatility of the beam is illustrated by two examples in water phantoms: (1) a cylindrical PTV irradiated by a single field and (2) a spherical PTV irradiated by two parallel opposed fields. A uniform dose distribution is to be delivered to the volumes. Geant4 Monte Carlo code is used to validate the dose distributions in each example.Results:Transverse algorithms are developed to produce uniform distributions in each transverseplane in the two examples with a cylindrical and a spherical PTV respectively. Longitudinally, different proton energies are used in successive transverse planes toproduce the SOBP required to cover the PTVs. In general, uniformity of dosedistribution within 3% is obtained for the cylinder and 3.5% for the sphere. The transversealgorithms requires only few hundred beam spots for each plane The algorithms may beapplied to larger volumes by increasing the intensity spot by spot for the same deliverytime of the same dose. The treatment time can be shorter than 1 minute for any fieldconfiguration and tumor shape.Conclusion:The unique beam characteristics of a spot scanning beam from a RCMS at 10 Hz repetitionfrequency are used to design transverse and longitudinal algorithms to produce uniformdistribution for any arbitrary shape and size of targets. The proposed spot scanning beam ismore versatile than existing spot scanning beams in proton therapy with better beamcontrol and lower neutron dose.This work is supported in part by grants from the US Department of Energy under contract; DE‐FG02‐12ER41800 and the National Science Foundation NSF PHY‐1205431.
SU‐E‐T‐312: Test of the Generalized Tumor Dose (gTD) Model with An Independent Lung Tumor Dataset
Authors: Fontanella A , Robinson C , Zuniga A , Apte A , Thorstad W , Bradley J , Deasy J 
Published: July 2014

Purpose:We previously developed a novel approach to tumor response modeling which was inspired by the gEUD model of tumor cell kill under inhomogeneous dose profiles. The model assumes that the cell‐kill law is valid, but further adds a parameter analogous to the generalized equivalent uniform dose model to test the independence of response of tumor subvolumes. The purpose of this study was to test the resulting generalized tumor dose (gTD) model on an independent lung cancer subset.Methods:Niemierko's gEUD model of cell kill introduces a generalization term describing interactions among tumor sub‐volumes under non‐uniform dose distributions. This parameter effectively applies weights to sub‐volumes based off of tumor type‐specific sensitivities to variance in dose. We combine the gEUD with the cell‐kill based cEUD to form the “generalized tumor dose” (gTD) model, which is given by gTD=‐α−1*ln(Vt/Vref)‐ (α*a)−1*ln(Σi=1:subvolsM#subvols−1 *e (‐α*a*di)). This model was previously applied to lung and H&N data. Here, we apply the model to an independent lung dataset (N= 36).Results:We found that the model does not perform well for large tumors (volume > 70 cc.) However,. However, for tumors smaller than this volume, the model was well‐correlated with local control, with a normalized log‐likelihood value (log‐likelihood divided by the number of cases) of −0.604.Conclusion:The presented model continues to predict tumor response in this dataset, for tumors less than 70 cc. To date, no other TCP model has been validated on clinical datasets for tumors with varying volumes and dose distributions. More tests are needed to further refine and validate the model.
SU‐E‐T‐313: The Accuracy of the Acuros XB Advanced Dose Calculation Algorithm for IMRT Dose Distributions in Head and Neck
Authors: Araki F , Onizuka R , Ohno T , Tomiyama Y , Hioki K 
Published: July 2014

Purpose:To investigate the accuracy of the Acuros XB version 11 (AXB11) advanced dose calculation algorithm by comparing with Monte Caro (MC) calculations. The comparisons were performed with dose distributions for a virtual inhomogeneity phantom and intensity‐modulated radiotherapy (IMRT) in head and neck.Methods:Recently, AXB based on Linear Boltzmann Transport Equation has been installed in the Eclipse treatment planning system (Varian Medical Oncology System, USA). The dose calculation accuracy of AXB11 was tested by the EGSnrc‐MC calculations. In additions, AXB version 10 (AXB10) and Analytical Anisotropic Algorithm (AAA) were also used. First the accuracy of an inhomogeneity correction for AXB and AAA algorithms was evaluated by comparing with MC‐calculated dose distributions for a virtual inhomogeneity phantom that includes water, bone, air, adipose, muscle, and aluminum. Next the IMRT dose distributions for head and neck were compared with the AXB and AAA algorithms and MC by means of dose volume histograms and three dimensional gamma analysis for each structure (CTV, OAR, etc.).Results:For dose distributions with the virtual inhomogeneity phantom, AXB was in good agreement with those of MC, except the dose in air region. The dose in air region decreased in order of MC<AXB11<AXB10. This may be caused by the difference of the electron cut‐off energy for algorithms, ie: 0.700 MeV for MC, 0.711 MeV for AXB11, and 1.011 MeV for AXB 10. Since the AAA algorithm is based on the dose kernel of water, the doses in regions for air, bone, and aluminum considerably became higher than those of AXB and MC. The pass rates of the gamma analysis for IMRT dose distributions in head and neck were similar to those of MC in order of AXB11<AXB10<AAA.Conclusion:The dose calculation accuracy of AXB11 was almost equivalent to the MC dose calculation.
SU‐E‐T‐318: The Effect of Patient Positioning Errors On Target Coverage and Cochlear Dose in Stereotactic Radiosurgery Treatment of Acoustic Neuromas
Authors: Dellamonica D. , Luo G. , Ding G. 
Published: July 2014

Purpose:Setup errors on the order of millimeters may cause under‐dosing of targets and significant changes in dose to critical structures especially when planning with tight margins in stereotactic radiosurgery. This study evaluates the effects of these types of patient positioning uncertainties on planning target volume (PTV) coverage and cochlear dose for stereotactic treatments of acoustic neuromas.Methods:Twelve acoustic neuroma patient treatment plans were retrospectively evaluated in Brainlab iPlan RT Dose 4.1.3. All treatment beams were shaped by HDMLC from a Varian TX machine. Seven patients had planning margins of 2mm, five had 1–1.5mm. Six treatment plans were created for each patient simulating a 1mm setup error in six possible directions: anterior‐posterior, lateral, and superiorinferior. The arcs and HDMLC shapes were kept the same for each plan. Change in PTV coverage and mean dose to the cochlea was evaluated for each plan.Results:The average change in PTV coverage for the 72 simulated plans was −1.7% (range: −5 to +1.1%). The largest average change in coverage was observed for shifts in the patient's superior direction (−2.9%). The change in mean cochlear dose was highly dependent upon the direction of the shift. Shifts in the anterior and superior direction resulted in an average increase in dose of 13.5 and 3.8%, respectively, while shifts in the posterior and inferior direction resulted in an average decrease in dose of 17.9 and 10.2%. The average change in dose to the cochlea was 13.9% (range: 1.4 to 48.6%). No difference was observed based on the size of the planning margin.Conclusion:This study indicates that if the positioning uncertainty is kept within 1mm the setup errors may not result in significant under‐dosing of the acoustic neuroma target volumes. However, the change in mean cochlear dose is highly dependent upon the direction of the shift.