bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐D‐206‐06: Task‐Specific Optimization of Scintillator Thickness for CMOS‐Detector Based Cone‐Beam Breast CT
Authors: Vedantham S , Shrestha S , Shi L , Vijayaraghavan G , Karellas A 
Published: July 2016

Purpose:To optimize the cesium iodide (CsI:Tl) scintillator thickness in a complimentary metal‐oxide semiconductor (CMOS)‐based detector for use in dedicated cone‐beam breast CT.Methods:The imaging task considered was the detection of a microcalcification cluster comprising six 220µm diameter calcium carbonate spheres, arranged in the form of a regular pentagon with 2 mm spacing on its sides and a central calcification, similar to that in ACR‐recommended mammography accreditation phantom, at a mean glandular dose of 4.5 mGy. Generalized parallel‐cascades based linear systems analysis was used to determine Fourier‐domain image quality metrics in reconstructed object space, from which the detectability index inclusive of anatomical noise was determined for a non‐prewhitening numerical observer. For 300 projections over 2π, magnification‐associated focal‐spot blur, Monte Carlo derived x‐ray scatter, K‐fluorescent emission and reabsorption within CsI:Tl, CsI:Tl quantum efficiency and optical blur, fiberoptic plate transmission efficiency and blur, CMOS quantum efficiency, pixel aperture function and additive noise, and filtered back‐projection to isotropic 105µm voxel pitch with bilinear interpolation were modeled. Imaging geometry of a clinical prototype breast CT system, a 60 kV Cu/Al filtered x‐ray spectrum from 0.3 mm focal spot incident on a 14 cm diameter semi‐ellipsoidal breast were used to determine the detectability index for 300–600 µm thick (75µm increments) CsI:Tl. The CsI:Tl thickness that maximized the detectability index was considered optimal.Results:The limiting resolution (10% modulation transfer function, MTF) progressively decreased with increasing CsI:Tl thickness. The zero‐frequency detective quantum efficiency, DQE(0), in projection space increased with increasing CsI:Tl thickness. The maximum detectability index was achieved with 525µm thick CsI:Tl scintillator. Reduced MTF at mid‐to‐high frequencies for 600µm thick CsI:Tl lowered the detectability index than 525µm CsI:Tl.Conclusion:For the x‐ray spectrum and imaging conditions considered, a 525µm thick CsI:Tl scintillator integrated with the CMOS detector is optimal for detecting microcalcification cluster.Funding support: Supported in part by NIH R01 CA195512. The contents are solely the responsibility of the authors and do not reflect the official views of the NIH or the NCI. Disclosures: SV, GV and AK ‐ Research collaboration, Koning Corp., West Henrietta, NY.
SU‐D‐209‐02: Percent Depth Dose Curves for Fluoroscopic X‐Ray Beam Qualities Incorporating Copper Filtration
Authors: Wunderle K , Godley A , Shen Z , Rakowski J , Dong F 
Published: July 2016

Purpose:The purpose of this investigation was to quantify percent depth dose (PDD) curves for fluoroscopic x‐ray beam qualities incorporating added copper filtration.Methods:A PTW (Freiburg, Germany) MP3 water tank was used with a Standard Imaging (Middleton, WI) Exradin Model 11 Spokas Chamber to measure PDD curves for 60, 80, 100 and 120 kVp x‐ray beams with copper filtration ranging from 0.0–0.9 mm at 22cm and 42cm fields of view from 0 to 150 mm of water. A free‐in‐air monitor chamber was used to normalize the water tank data to fluctuations in output from the fluoroscope. The measurements were acquired on a Siemens (Erlangen, Germany) Artis ZeeGo fluoroscope. The fluoroscope was inverted from the typical orientation providing an x‐ray beam originating from above the water tank. The water tank was positioned so that the water level was located at 60cm from the focal spot; which also represents the focal spot to interventional reference plane distance for that fluoroscope.Results:PDDs for 60, 80, 100, and 120 kVp with 0 mm of copper filtration compared well to previously published data by Fetterly et al. [Med Phys, 28, 205 (2001)] for those beam qualities given differences in fluoroscopes, geometric orientation, type of ionization chamber, and the water tank used for data collection. PDDs for 60, 80, 100, and 120 kVp with copper filtration were obtained and are presented, which have not been previously investigated and published.Conclusion:The equipment and processes used to acquire the reported data were sound and compared well with previously published data for PDDs without copper filtration. PDD data for the fluoroscopic x‐ray beams incorporating copper filtration can be used as reference data for estimating organ or soft tissue dose at depth involving similar beam qualities or for comparison with mathematical models.
SU‐D‐209‐03: Radiation Dose Reduction Using Real‐Time Image Processing in Interventional Radiology
Authors: Kanal K , Moirano J , Zamora D , Stewart B 
Published: July 2016

Purpose:To characterize changes in radiation dose after introducing a new real‐time image processing technology in interventional radiology systems.Methods:Interventional radiology (IR) procedures are increasingly complex, at times requiring substantial time and radiation dose. The risk of inducing tissue reactions as well as long‐term stochastic effects such as radiation‐induced cancer is not trivial. To reduce this risk, IR systems are increasingly equipped with dose reduction technologies.Recently, ClarityIQ (Philips Healthcare) technology was installed in our existing neuroradiology IR (NIR) and vascular IR (VIR) suites respectively. ClarityIQ includes real‐time image processing that reduces noise/artifacts, enhances images, and sharpens edges while also reducing radiation dose rates. We reviewed 412 NIR (175 pre‐ and 237 post‐ClarityIQ) procedures and 329 VIR (156 preand 173 post‐ClarityIQ) procedures performed at our institution pre‐ and post‐ClarityIQ implementation. NIR procedures were primarily classified as interventional or diagnostic. VIR procedures included drain port, drain placement, tube change, mesenteric, and implanted venous procedures. Air Kerma (AK in units of mGy) was documented for all the cases using a commercial radiation exposure management system.Results:When considering all NIR procedures, median AK decreased from 1194 mGy to 561 mGy. When considering all VIR procedures, median AK decreased from 49 to 14 mGy. Both NIR and VIR exhibited a decrease in AK exceeding 50% after ClarityIQ implementation, a statistically significant (p<0.05) difference. Of the 5 most common VIR procedures, all median AK values decreased, but significance (p<0.05) was only reached in venous access (N=53), angio mesenteric (N=41), and drain placement procedures (N=31).Conclusion:ClarityIQ can reduce dose significantly for both NIR and VIR procedures. Image quality was not assessed in conjunction with the dose reduction.
SU‐D‐207B‐05: Robust Intra‐Tumor Partitioning to Identify High‐Risk Subregions for Prognosis in Lung Cancer
Authors: Wu J , Gensheimer M , Dong X , Rubin D , Napel S , Diehn M , Loo B , Li R 
Published: July 2016

Purpose:To develop an intra‐tumor partitioning framework for identifying high‐risk subregions from 18F‐fluorodeoxyglucose positron emission tomography (FDG‐PET) and CT imaging, and to test whether tumor burden associated with the high‐risk subregions is prognostic of outcomes in lung cancer.Methods:In this institutional review board‐approved retrospective study, we analyzed the pre‐treatment FDG‐PET and CT scans of 44 lung cancer patients treated with radiotherapy. A novel, intra‐tumor partitioning method was developed based on a two‐stage clustering process: first at patient‐level, each tumor was over‐segmented into many superpixels by k‐means clustering of integrated PET and CT images; next, tumor subregions were identified by merging previously defined superpixels via population‐level hierarchical clustering. The volume associated with each of the subregions was evaluated using Kaplan‐Meier analysis regarding its prognostic capability in predicting overall survival (OS) and out‐of‐field progression (OFP).Results:Three spatially distinct subregions were identified within each tumor, which were highly robust to uncertainty in PET/CT co‐registration. Among these, the volume of the most metabolically active and metabolically heterogeneous solid component of the tumor was predictive of OS and OFP on the entire cohort, with a concordance index or CI = 0.66–0.67. When restricting the analysis to patients with stage III disease (n = 32), the same subregion achieved an even higher CI = 0.75 (HR = 3.93, logrank p = 0.002) for predicting OS, and a CI = 0.76 (HR = 4.84, logrank p = 0.002) for predicting OFP. In comparison, conventional imaging markers including tumor volume, SUVmax and MTV50 were not predictive of OS or OFP, with CI mostly below 0.60 (p < 0.001).Conclusion:We propose a robust intra‐tumor partitioning method to identify clinically relevant, high‐risk subregions in lung cancer. We envision that this approach will be applicable to identifying useful imaging biomarkers in many cancer types.
SU‐F‐SPS‐02: Accuracy of the Small Field Dosimetry Using the Monte Carlo and Sequential Dose Calculation Algorithms of Multiplan Treatment Planning System Within and Beyond Heterogeneous Media for Cyberknife M6 Unit
Authors: Serin E. , Codel G. , Mabhouti H. , Cebe M. , Sanli E. , Pacaci P. , Kucuk N. , Kucukmorkoc E. , Doyuran M. , Canoglu D. , Altinok A. , Acar H. , Caglar Ozkok H. 
Published: July 2016

Purpose:In small field geometries, the electronic equilibrium can be lost, making it challenging for the dose‐calculation algorithm to accurately predict the dose, especially in the presence of tissue heterogeneities. In this study, dosimetric accuracy of Monte Carlo (MC) advanced dose calculation and sequential algorithms of Multiplan treatment planning system were investigated for small radiation fields incident on homogeneous and heterogeneous geometries.Methods:Small open fields of fixed cones of Cyberknife M6 unit 100 to 500 mm2 were used for this study. The fields were incident on in house phantom containing lung, air, and bone inhomogeneities and also homogeneous phantom. Using the same film batch, the net OD to dose calibration curve was obtained using CK with the 60 mm fixed cone by delivering 0‐ 800 cGy. Films were scanned 48 hours after irradiation using an Epson 1000XL flatbed scanner. The dosimetric accuracy of MC and sequential algorithms in the presence of the inhomogeneities was compared against EBT3 film dosimetryResults:Open field tests in a homogeneous phantom showed good agreement between two algorithms and film measurement For MC algorithm, the minimum gamma analysis passing rates between measured and calculated dose distributions were 99.7% and 98.3% for homogeneous and inhomogeneous fields in the case of lung and bone respectively. For sequential algorithm, the minimum gamma analysis passing rates were 98.9% and 92.5% for for homogeneous and inhomogeneous fields respectively for used all cone sizes. In the case of the air heterogeneity, the differences were larger for both calculation algorithms. Overall, when compared to measurement, the MC had better agreement than sequential algorithm.Conclusion:The Monte Carlo calculation algorithm in the Multiplan treatment planning system is an improvement over the existing sequential algorithm. Dose discrepancies were observed for in the presence of air inhomogeneities.
SU‐F‐SPS‐04: Dosimetric Evaluation of the Dose Calculation Accuracy of Different Algorithms for Two Different Treatment Techniques During Whole Breast Irradiation
Authors: Pacaci P , Cebe M , Mabhouti H , Codel G , Serin E , Sanli E , Kucukmorkoc E , Doyuran M , Kucuk N , Canoglu D , Altinok A , Acar H , Caglar Ozkok H 
Published: July 2016

Purpose:In this study, dosimetric comparison of field in field (FIF) and intensity modulated radiation therapy (IMRT) techniques used for treatment of whole breast radiotherapy (WBRT) were made. The dosimetric accuracy of treatment planning system (TPS) for Anisotropic Analytical Algorithm (AAA) and Acuros XB (AXB) algorithms in predicting PTV and OAR doses was also investigated.Methods:Two different treatment planning techniques of left‐sided breast cancer were generated for rando phantom. FIF and IMRT plans were compared for doses in PTV and OAR volumes including ipsilateral lung, heart, left ascending coronary artery, contralateral lung and the contralateral breast. PTV and OARs doses and homogeneity and conformality indexes were compared between two techniques. The accuracy of TPS dose calculation algorithms was tested by comparing PTV and OAR doses measured by thermoluminescent dosimetry with the dose calculated by the TPS using AAA and AXB for both techniques.Results:IMRT plans had better conformality and homogeneity indexes than FIF technique and it spared OARs better than FIF. While both algorithms overestimated PTV doses they underestimated all OAR doses. For IMRT plan, PTV doses, overestimation up to 2.5 % was seen with AAA algorithm but it decreased to 1.8 % when AXB algorithm was used. Based on the results of the anthropomorphic measurements for OAR doses, underestimation greater than 7 % is possible by the AAA. The results from the AXB are much better than the AAA algorithm. However, underestimations of 4.8 % were found in some of the points even for AXB. For FIF plan, similar trend was seen for PTV and OARs doses in both algorithm.Conclusion:When using the Eclipse TPS for breast cancer, AXB the should be used instead of the AAA algorithm, bearing in mind that the AXB may still underestimate all OAR doses.
SU‐F‐SPS‐06: Implementation of a Back‐Projection Algorithm for 2D in Vivo Dosimetry with An EPID System
Authors: Hernandez Reyes B , Rodriguez Perez E , Sosa Aquino M 
Published: July 2016

Purpose:To implement a back‐projection algorithm for 2D dose reconstructions for in vivo dosimetry in radiation therapy using an Electronic Portal Imaging Device (EPID) based on amorphous silicon.Methods:An EPID system was used to calculate dose‐response function, pixel sensitivity map, exponential scatter kernels and beam hardenig correction for the back‐projection algorithm. All measurements were done with a 6 MV beam. A 2D dose reconstruction for an irradiated water phantom (30×30×30 cm3) was done to verify the algorithm implementation. Gamma index evaluation between the 2D reconstructed dose and the calculated with a treatment planning system (TPS) was done.Results:A linear fit was found for the dose‐response function. The pixel sensitivity map has a radial symmetry and was calculated with a profile of the pixel sensitivity variation. The parameters for the scatter kernels were determined only for a 6 MV beam. The primary dose was estimated applying the scatter kernel within EPID and scatter kernel within the patient. The beam hardening coefficient is σBH= 3.788×10−4 cm2 and the effective linear attenuation coefficient is µAC= 0.06084 cm−1. The 95% of points evaluated had γ values not longer than the unity, with gamma criteria of ΔD = 3% and Δd = 3 mm, and within the 50% isodose surface.Conclusion:The use of EPID systems proved to be a fast tool for in vivo dosimetry, but the implementation is more complex that the elaborated for pre‐treatment dose verification, therefore, a simplest method must be investigated. The accuracy of this method should be improved modifying the algorithm in order to compare lower isodose curves.
SU‐F‐SPS‐07: Magnetic Resonance Spectroscopy Findings in Early‐Phase Psychosis
Authors: Wright A. , Ma R. , Hummer T. , Francis M. , Mehdiyoun N. , Dydak U. , Breier A. 
Published: July 2016

Purpose:Schizophrenia is a psychiatric disorder characterized by disordered thoughts, abnormal social behaviors, flat affect, and auditory or visual hallucinations. The current study aims to investigate alterations in brain metabolism in patients near the onset of psychosis (early‐phase psychosis, EPP), to characterize abnormalities during the early stages of schizophrenia. To this end, we used magnetic resonance imaging (MRI) and spectroscopy (MRS) to measure metabolite levels and subsequently monitor the effect of treatment with N‐acetylcysteine (NAC).Methods:Here we report on the cross‐sectional comparison at the baseline scan between 13 healthy controls (mean age = 21.5 yrs) and 28 EPP patients (mean age = 23.9 yrs), within three years of psychotic illness onset. Metabolite levels of glutamine + glutamate (Glx), N‐acetylaspartate (NAA), creatine (Cre), and myo‐inositol (mI) were measured on a Siemens 3T whole‐body scanner with MRS voxels placed in the frontal lobe (size = 2×2×2 cm3; TE = 30ms; TA = 4min). Metabolite levels were quantified using LCModel V6.2‐0R, scaled to the internal water signal, and reported in institutional units (i.u.). Comparison of NAA, Cre and Glx levels between the two groups was performed using two‐tailed unpaired t‐tests.Results:A significant decrease of Glx concentration in FEP patients was found (patients: 4.1±1.4 i.u.; controls: 5.2 ± 0.2 i.u.; p=0.04). No significant differences were found at baseline in Cre nor NAA concentrations.Conclusion:Significant decreases in Glx were observed in the frontal lobe of the FEP patients. This decrease supports prior research on schizophrenia in similar cortical regions. The alteration in frontal Glx levels may be involved in the behavioral and cognitive abnormalities. Future steps include investigating the effect of NAC vs. placebo treatment on reversing this decrease in Glx in EPP patients over a 12‐month period.This project is supported by the Stanley Medical Research Institute.
SU‐F‐SPS‐08: Measuring the Interaction Of DDR Cell Receptors and Extracellular Matrix Collagen in Prostate Cells
Authors: Dong J , Sarkar A , Suhail A , Fridman R , Hoffmann P 
Published: July 2016

Purpose:Discoidin domain receptors (DDR) have recently been recognized as important players in cancer progression. DDRs are cell receptors that interact with collagen, an extracellular matrix (ECM) protein. However the detailed mechanism of their interaction is unclear. Here we attempted to examine their interaction in terms of structural (surface topography), mechanical (rupture force), and kinetic (binding probability) information on the single molecular scale with the use of atomic force microscopy (AFM).Methods:The Quantitative Nano‐mechanical property Mapping (QNM) mode of AFM allowed to assess the cells in liquid growth media at their optimal physiological while being viable. Human benign prostate hyperplasia (BPH‐1) cell line was genetically regulated to suppress DDR expression (DDR‐ cells) and was compared with naturally DDR expressing cells (DDR+).Results:Binding force measurements (n = 1000) were obtained before and after the two groups were treated with fibronectin (FN), an integrin‐inhibiting antibody to block the binding of integrin. The quantification indicates that cells containing DDR bind with collagen at a most probable force of 80.3–83.0 ±7.6 pN. The probability of them binding is 0.167 when other interactions (mainly due to integrin‐collagen binding) are minimized.Conclusion:Together with further force measurements at different pulling speeds will determine dissociation rate, binding distance and activation barrier. These parameters in benign cells provides some groundwork in understanding DDR's behavior in various cell microenvironments such as in malignant tumor cells.Funding supported by Richard Barber Interdisciplinary Research Program of Wayne State University
SU‐F‐SPS‐09: Parallel MC Kernel Calculations for VMAT Plan Improvement
Authors: Chamberlain S , French S , Nazareth D 
Published: July 2016

Purpose:Adding kernels (small perturbations in leaf positions) to the existing apertures of VMAT control points may improve plan quality. We investigate the calculation of kernel doses using a parallelized Monte Carlo (MC) method.Methods:A clinical prostate VMAT DICOM plan was exported from Eclipse. An arbitrary control point and leaf were chosen, and a modified MLC file was created, corresponding to the leaf position offset by 0.5cm. The additional dose produced by this 0.5 cm × 0.5 cm kernel was calculated using the DOSXYZnrc component module of BEAMnrc. A range of particle history counts were run (varying from 3 × 106 to 3 × 107); each job was split among 1, 10, or 100 parallel processes. A particle count of 3 × 106 was established as the lower range because it provided the minimal accuracy level.Results:As expected, an increase in particle counts linearly increases run time. For the lowest particle count, the time varied from 30 hours for the single‐processor run, to 0.30 hours for the 100‐processor run.Conclusion:Parallel processing of MC calculations in the EGS framework significantly decreases time necessary for each kernel dose calculation. Particle counts lower than 1 × 106 have too large of an error to output accurate dose for a Monte Carlo kernel calculation. Future work will investigate increasing the number of parallel processes and optimizing run times for multiple kernel calculations.
SU‐F‐SPS‐10: The Dosimetric Comparison of GammaKnife and Cyberknife Treatment Plans for Brain SRS Treatment
Authors: Sanli E , Mabhouti H , Cebe M , Codel G , Pacaci P , Serin E , Kucuk N , Kucukmorkoc E , Doyuran M , Canoglu D , Altinok A , Acar H , Caglar Ozkok H 
Published: July 2016

Purpose:Brain stereotactic radiosurgery (SRS) involves the use of precisely directed, single session radiation to create a desired radiobiologic response within the brain target with acceptable minimal effects on surrounding structures or tissues. In this study, the dosimetric comparison of GammaKnife perfection and Cyberknife M6 treatment plans were made.Methods:Treatment plannings were done for GammaKnife perfection unit using Gammaplan treatment planning system (TPS) on the CT scan of head and neck randophantom simulating the treatment of sterotactic treatments for one brain metastasis. The dose distribution were calculated using TMR 10 algorithm. The treatment planning for the same target were also done for Cyberknife M6 machine using Multiplan (TPS) with Monte Carlo algorithm. Using the same film batch, the net OD to dose calibration curve was obtained using both machine by delivering 0‐ 800 cGy. Films were scanned 48 hours after irradiation using an Epson 1000XL flatbed scanner. Dose distribution were measured using EBT3 film dosimeter. The measured and calculated doses were compared.Results:The dose distribution in the target and 2 cm beyond the target edge were calculated on TPSs and measured using EBT3 film. For cyberknife treatment plans, the gamma analysis passing rates between measured and calculated dose distributions were 99.2% and 96.7% for target and peripheral region of target respectively. For gammaknife treatment plans, the gamma analysis passing rates were 98.9% and 93.2% for target and peripheral region of target respectively.Conclusion:The study shows that dosimetrically comparable plans are achievable with Cyberknife and GammaKnife. Although TMR 10 algorithm predicts the target dose