bluuebunny/crossref_metadata_2025_split huggingface dataset:
TU‐H‐202‐01: Introduction to CT Ventilation Imaging: Principles, Validation and Clinical Translation
Authors: Yamamoto T. 
Published: July 2016

CT ventilation imaging is an exciting functional imaging modality that combines four‐dimensional computed tomography (4DCT) and deformable image registration (DIR) to provide exquisite ventilation maps of the lung. CT ventilation imaging can be used for:

Functional avoidance in thoracic radiation therapy,
Imaging longitudinal changes in regional lung function for treatment assessment and adaptation,
Image‐assisted diagnosis of non‐oncologic respiratory diseases.CT ventilation imaging uses CT, a predominantly anatomic imaging modality, and through imaging processing creates functional images. CT ventilation imaging provides functional images that are higher resolution, faster and cheaper to perform than the clinical standard, SPECT. Indeed the number of CT ventilation abstracts presented at the AAPM meeting has been doubling every two years. With the world's‐first clinical trial of CT ventilation functional image‐guided radiation therapy now underway, the first dedicated scientific symposium will educate and stimulate AAPM members from both radiology and radiation oncology.This symposium will compare the foundations of CT ventilation imaging with competing MRI, PET and SPECT ventilation imaging methods, and details the first clinical trial of CT ventilation imaging for functional avoidance in lung cancer radiation therapy. The spatial‐temporal nature of pulmonary ventilation, response maps to radiation and the design of predictive models will be presented. Validation efforts and challenges will also be discussed, from clinical outcome correlations in single time point and longitudinal studies, to cross‐modality image comparisons in the first multi‐institutional CT ventilation imaging challenge.The panel will discuss the future role of CT ventilation imaging, and what level of physiologic validation is needed for applications in radiation oncology and beyond.

Learning Objectives:
Learn the principles of CT ventilation imaging and how ventilation images are acquired with MRI, PET and SPECT
Understand the methods used to benchmark CT ventilation and the correlations between CT ventilation imaging and clinical outcomes
Recognize the clinical applications of CT ventilation imaging in radiation oncology and beyondAustralian NHMRC Fellowship. Australian NSW Cancer Institute Fellowship.; Y. Vinogradskiy, The authors acknowledge NIH R01CA200817 grant and Stat of Colorado grant.; T. Yamamoto, This study was supported in part by the American Cancer Society and the Dean of the University of California Davis School of Medicine (ACS IRG‐95‐125‐13). Philips Radiation Oncology Systems loaned us a research version of the Pinnacle3 treatment planning system.; J. Bayouth, Funding support from NCIR01 CA166703; J. Kipritidis, This work has been supported by a Cancer Institute NSW Early Career Fellowship and an NHMRC Australia Fellowship.No commercial funding was received for this work.
TU‐H‐207A‐08: Estimating Radiation Dose From Low‐Dose Lung Cancer Screening CT Exams Using Tube Current Modulation
Authors: Hardy A , Bostani M , McMillan K , Zankl M , Cagnon C , McNitt‐Gray M 
Published: July 2016

Purpose:The purpose of this work is to estimate effective and lung doses from a low‐dose lung cancer screening CT protocol using Tube Current Modulation (TCM) across patient models of different sizes.Methods:Monte Carlo simulation methods were used to estimate effective and lung doses from a low‐dose lung cancer screening protocol for a 64‐slice CT (Sensation 64, Siemens Healthcare) that used TCM. Scanning parameters were from the AAPM protocols. Ten GSF voxelized patient models were used and had all radiosensitive organs identified to facilitate estimating both organ and effective doses. Predicted TCM schemes for each patient model were generated using a validated method wherein tissue attenuation characteristics and scanner limitations were used to determine the TCM output as a function of table position and source angle. The water equivalent diameter (WED) was determined by estimating the attenuation at the center of the scan volume for each patient model. Monte Carlo simulations were performed using the unique TCM scheme for each patient model. Lung doses were tallied and effective doses were estimated using ICRP 103 tissue weighting factors. Effective and lung dose values were normalized by scanspecific 32 cm CTDIvol values based upon the average tube current across the entire simulated scan. Absolute and normalized doses were reported as a function of WED for each patient.Results:For all ten patients modeled, the effective dose using TCM protocols was below 1.5 mSv. Smaller sized patient models experienced lower absolute doses compared to larger sized patients. Normalized effective and lung doses showed some dependence on patient size (R2 = 0.77 and 0.78, respectively).Conclusion:Effective doses for a low‐dose lung screening protocol using TCM were below 1.5 mSv for all patient models used in this study.Institutional research agreement, Siemens Healthcare; Past recipient, research grant support, Siemens Healthcare; Consultant, Toshiba America Medical Systems; Consultant, Samsung Electronics
TU‐H‐206‐02: Novel Linearly‐Filled Derenzo PET Phantom Design
Authors: Graves S , Cox B , Farhoud M , Valdovinos H , Jeffery J , Eliceiri K , Barnhart T , Nickles R 
Published: July 2016

Purpose:To design a linearly‐filled Derenzo positron emission tomography (PET) phantom, eliminating the extraneous radioisotope volumes in a conventional reservoir‐type design. This activity reduction combined with the elimination of bubbles in smaller phantom channels would significantly reduce personnel dose, radioisotope cost, and would improve image quality by reducing out‐of‐slice activity scatter.Methods:A computer‐aided design (CAD) was created of a modular Derenzo phantom consisting of three phantom layers with gaskets between the layers. The central piece contains the active pattern volume and channels connecting adjacent rods in a serpentine pattern. The two end‐pieces contained an inlet and an outlet for filling purposes. Phantom prototypes were 3D printed on a Viper Si2 stereolithography machine. The two gaskets were fabricated from silicon sheets using a PLS 6.75 laser cutter. Phantoms were held together by pass‐through glass‐filled nylon bolts and nuts. Phantoms were filled with 52Mn, 64Cu, 74Br, and 124I for testing, and were imaged on a Siemens Inveon MicroPET scanner.Results:Four phantom prototypes were constructed using male Leur Lock fittings for inlet/outlet ports. 3D printed layers were sanded to ensure proper coupling to the silicon gaskets. The filling volume for each prototype was approximately 2.4 mL. The filling process was found to be rapid, leak‐tight, and with minimal back‐pressure. PET images were reconstructed by OSEM3D, and axial slices along the phantom pattern length were averaged to provide final images. Image distortion was isotope dependent with 52Mn and 64Cu having the least distortion and 124I having the most distortion.Conclusion:These results indicate that the linearlyfilled Derenzo design improves on conventional reservoir‐type designs by eliminating potential bubbles in small channels and by reducing activity level, radioisotope volume, radioisotope cost, personnel dose, filling time, and out‐of‐slice activity scatterThe method described in this abstract has been filed as a patent application to the US Patent and Trade Office by the Wisconsin Alumni Research Foundation (WARF).
TU‐H‐206‐05: Investigating the Resistance of GS‐BSSFP to Motion Artifacts
Authors: Hoff M , Andre J , Xiang Q 
Published: July 2016

Purpose:In addition to correcting magnetic field inhomogeneity‐induced banding artifacts in balanced steady state free precession (bSSFP) MRI, preliminary in vivo studies indicate that the geometric solution (GS) also mitigates motion artifacts. The purpose here is to investigate the source of motion artifact correction through simulations, to further ascertain GS‐bSSFP's clinical potential.Methods:Four bSSFP MR images with Δθ = 0°, 90°, 180°, and 270° respective phase cycling and TE/TR = 4.2/2.1ms were 1) acquired in vivo with a 3D axially‐oriented sequence on a Philips Ingenia 3T MRI scanner using a flip angle α = 30°, and 180/180/120 matrix size and 1.0/1.0/1.0mm voxel size along frequency/phase/slice directions, and 2) simulated using α = 80°, parameters varied across the field‐of‐view (T1 relaxation = 200–>3000ms, T2 relaxation = 40‐>3000ms, and field inhomogeneity θ = −π−>+π), and added zero‐mean Gaussian noise. The GS (the cross‐point of lines/spokes connecting alternating phase cycles in the complex plane) and complex sum (CS) were computed pixel‐by‐pixel. Simulated data noise was reoriented in each associated spoke's frame of reference in order to derive the noise radiality. Plots were then generated of GS and CS error and deviation as a function of the noise radiality in the original data.Results:In vivo data indicates that the GS mitigates motion artifacts relative to the CS in the foramen magnum region. Simulated data indicates that the GS has less error in size and deviation than the CS, and this discrepancy grows as noise radiality increases.Conclusion:The GS shows more accuracy than the CS in all tests executed, especially as phasecycled image noise radiality increases. This implies that noise‐like image artifacts such as those caused by motion and flow are suppressed by the GS, inspiring clinical applications of GS‐bSSFP given its additional elimination of banding artifacts.
TU‐H‐206‐09: Acceptance Testing of Ultrasound Systems for Shear Wave Elastography Measurements
Authors: Long Z , Tradup D , Song P , Stekel S , Chen S , Hangiandreou N 
Published: July 2016

Purpose:Acceptance testing of shear wave elastography on ten ultrasound systems is reported. Furthermore, variations in testing procedures related to coupling medium, number of operators, and phantom homogeneity were investigated.Methods:Shear wave speed measurements were made on ten systems (GE LOGIQ E9 XDclear 2.0 ultrasound scanner with C1‐6 and 9L transducers). Measurements were acquired using the CIRS Model 039 shear wave liver fibrosis phantoms (“soft” and “hard” phantoms, with stiffness of ∼3.5 and 45 kPa, respectively) at two depths (3 and 7 cm for C1‐6; 1 and 4 cm for 9L), by two operators. Each measurement was repeated for five times without specifying the transducer location on the phantom. 45 ppm salt water (as recommended by QIBA) was used for coupling. Furthermore, phantom homogeneity was investigated by comparing C1‐6 measurements made at five positions marked on each phantom. Three operators acquired C1‐6 measurements on one scanner, and one repeated the measurements after a week. US gel was compared with salt water as a coupling medium.Results:Averaged shear wave speed using the ten C1‐6 and 9L transducers are summarized in Table 1. The greatest maximum deviation of an individual measurement from the group mean (Table 2) was 5.4% of the mean and 2.3 times the standard deviation among all groups. Salt water and US coupling gel showed no significant difference. Velocities from the five measurement locations had a maximum deviation of 5.9% or less. The maximum inhomogeneity averaged over the two phantoms and all measurement locations was 2.6%. Inter‐ and intra‐operator coefficients of variation were all ≤ 2.2%.Conclusion:The measurement variations were considered to be reasonable, and all equipment was accepted. The use of salt water versus gel for acoustic coupling, single versus multiple phantom measurement locations, or single versus multiple operators would not cause significant differences in acceptance test results.Pengfei Song and Shigao Chen receive royalties from GE Medical Systems for the shear wave elastography technology.
TU‐H‐CAMPUS‐JeP1‐01: Characterization of a Parameterized Image Similarity Cost Function for Automated Patient and Site Specific DIR Accuracy Optimizations
Authors: Neylon J , Min Y , Hasse K , Low D , Santhanam A 
Published: July 2016

Purpose:Clinical deformable image registration (DIR) accuracy is difficult to quantify, making validation and verification manual and time consuming. It has also been seen that DIR accuracy can be improved by patient and site specific optimization. We previously investigated a cost function to parameterize image similarity metrics (ISMs) and provide a quantifiable comparison of DIR performance. In this abstract, we characterize and optimize the cost function response (CFR) and correlation to target registration error (TRE) in a dense registration parameter space.Methods:A validated head‐and‐neck biomechanical model was used to induce clinical deformations in patient kVCT data (source), outputting known ground truth deformation vector fields (DVFs) and simulated CTs of deformed anatomy (target). The source and target were registered repeatedly using an in‐house optical flow DIR, systematically sampling the registration parameter space, and producing TREs and data volumes deformed according to the DIR DVF (warp). Normalized mutual information (NMI) was chosen as the test ISM. The cost function variables (CFV) were also systematically sampled to characterize their effect on the CFR. Sub‐volume analysis was performed on the data, defined by structures of interest in the head‐and‐neck region.Results:Strong inverse correlation was observed between the TRE and CFR when the data was subdivided around specific structures like the PTV, parotids, and mandible, reaching values of −0.95. The CFR slope changed by an order of magnitude by manipulating the CFV. Response and correlation were improved by adjusting on a structure specific basis. The CFR achieved a predominantly convex response, which should facilitate its use as an energy term in an optimization scheme.Conclusions:Replacing the time consuming, manually placed landmark assessment methodology is necessary for patient and site specific registration optimization to be clinically feasible. The proposed cost function is a promising alternative for fast, fully automated DIR performance quantification.
TU‐H‐CAMPUS‐IeP2‐02: Four‐Dimensional Coronary Artery Visualization Based On Image Propagation
Authors: Liu B , Liang B , Xu X , Guo B , Wei R , Xu S , Zhou F , Wu Q 
Published: July 2016

Purpose:4D visualization of coronary artery using X‐ray angiograms rotationally acquired on C‐arm has many valuable applications, like dynamic roadmapping. In this work we propose and validate a method to visualize 4D artery based on 3D coronary image propagation.Methods:After sorting the angiograms into different cardiac phases using nearest‐neighbor ECG gating, a high quality 3D coronary image was reconstructed at one phase using a motion‐compensated iterative reconstruction method. Then the reconstructed image was propagated to other cardiac phases by registering it to the angiograms of each phase (stage I registration). A third‐order B‐spline was used to model the vessel motion and the parameters were solved by maximizing the normalized correlation (NC) between the projections of the 3D image and the angiograms under the constraints of motion smoothness and volume preserving. Because the angiograms corresponding to one phase contain residual vessel motion and the registration method could only match the mean vessel morphology, morphological mismatch still existed between the propagated image and each angiogram. To obtain accurate vessel morphology according to each angiogram, we further registered the propagated image to each angiogram using the aforementioned registration method (stage II registration).Results:The proposed method was evaluated on angiograms simulated using 4D XCAT phantom. The reconstructed image at end‐diastolic phase (phase 0%) was consecutively propagated to end‐systolic phase (phase 40%) every 5%. After stage I registration, the mean distance between the propagated and ground truth vessel centerlines was decreased from 2.2±1.2 to 0.6±0.2 mm. The mean centerline distance was further decreased to 0.5±0.2 mm after the stage II registration.Conclusion:A 4D coronary artery visualization method based on image propagation was proposed. The experimental results show that accurate 4D morphology of coronary artery could be obtained using this method.This work was supported by the National Natural Science Foundation of China (61171005).
TU‐H‐CAMPUS‐IeP2‐05: Breast and Soft Tissue‐Equivalent 3D Printed Phantoms for Imaging and Dosimetry
Authors: Hintenlang D , Terracino B 
Published: July 2016

Purpose:The study has the goal to demonstrate that breast and soft tissue‐equivalent phantoms for dosimetry applications in the diagnostic energy range can be fabricated using common 3D printing methods.Methods:3D printing provides the opportunity to rapidly prototype uniquely designed objects from a variety of materials. Common 3D printers are usually limited to printing objects based on thermoplastic materials such as PLA, or ABS. The most commonly available plastic is PLA, which has a density significantly greater than soft tissue. We utilized a popular 3D printer to demonstrate that tissue specific phantom materials can be generated through the careful selection of 3D printing parameters. A series of stepwedges were designed and printed using a Makerbot Replicator2 3D printing system. The print file provides custom adjustment of the infill density, orientation and position of the object on the printer stage, selection of infill patterns, and other control parameters. The x‐ray attenuation and uniformity of fabricated phantoms were evaluated and compared to common tissue‐equivalent phantom materials, acrylic and BR12. X‐ray exposure measurements were made using narrow beam geometry on a clinical mammography unit at 28 kVp on the series of phantoms. The 3D printed phantoms were imaged at 28 kVp to visualize the internal structure and uniformity in different planes of the phantoms.Results:By utilizing specific in‐fill density and patterns we are able to produce a phantom closely matching the attenuation characteristics of BR12 at 28 kVp. The in‐fill patterns used are heterogeneous, so a judicious selection of fill pattern and the orientation of the fill pattern must be made in order to obtain homogenous attenuation along the intended direction of beam propagation.Conclusions:By careful manipulation of the printing parameters, breast and soft tissue‐equivalent phantoms appropriate for use at imaging energies can be fabricated using 3D printing techniques.
TU‐H‐CAMPUS‐JeP2‐03: Machine‐Learning‐Based Delineation Framework of GTV Regions of Solid and Ground Glass Opacity Lung Tumors at Datasets of Planning CT and PET/CT Images
Authors: Ikushima K , Arimura H , Jin Z , Yabuuchi H , Kuwazuru J , Shioyama Y , Sasaki T , Honda H , Sasaki M 
Published: July 2016

Purpose:In radiation treatment planning, delineation of gross tumor volume (GTV) is very important, because the GTVs affect the accuracies of radiation therapy procedure. To assist radiation oncologists in the delineation of GTV regions while treatment planning for lung cancer, we have proposed a machine‐learning‐based delineation framework of GTV regions of solid and ground glass opacity (GGO) lung tumors following by optimum contour selection (OCS) method.Methods:Our basic idea was to feed voxel‐based image features around GTV contours determined by radiation oncologists into a machine learning classifier in the training step, after which the classifier produced the degree of GTV for each voxel in the testing step. Ten data sets of planning CT and PET/CT images were selected for this study. The support vector machine (SVM), which learned voxel‐based features which include voxel value and magnitudes of image gradient vector that obtained from each voxel in the planning CT and PET/CT images, extracted initial GTV regions. The final GTV regions were determined using the OCS method that was able to select a global optimum object contour based on multiple active delineations with a level set method around the GTV. To evaluate the results of proposed framework for ten cases (solid:6, GGO:4), we used the three‐dimensional Dice similarity coefficient (DSC), which denoted the degree of region similarity between the GTVs delineated by radiation oncologists and the proposed framework.Results:The proposed method achieved an average three‐dimensional DSC of 0.81 for ten lung cancer patients, while a standardized uptake value‐based method segmented GTV regions with the DSC of 0.43. The average DSCs for solid and GGO were 0.84 and 0.76, respectively, obtained by the proposed framework.Conclusion:The proposed framework with the support vector machine may be useful for assisting radiation oncologists in delineating solid and GGO lung tumors.
TU‐H‐CAMPUS‐JeP2‐04: Deriving Delivered Doses to Assess the Viability of 2.5 Mm Margins in Head and Neck SBRT
Authors: Lin S , Shang Q , Pirozzi S , Godley A 
Published: July 2016

Purpose:To calculate the delivered dose for head and neck SBRT patients using pre‐treatment images. This delivered dose was then used to determine the viability of 2.5 mm margins.Methods:Daily cone beam CTs (CBCTs) were collected for 20 patients along with a planning CT, planned dose, and planning structures. The day 1 CBCT was aligned to the planning CT using the treatment shifts (six degrees of freedom) and then the dose and contours were transferred to the CBCT. The day 1 CBCT becomes the reference image for days 2–5. The day 2–5 CBCTs were also aligned to the planning CT using the treatment shifts given and the dose transferred. The day 2–5 CBCTs were then deformably registered to the day 1 CBCT. The doses delivered on days 2–5 were then deformed to the day 1 CBCT where they could be accumulated. This was achieved with MIM 6.5.1 (MIM Software, Cleveland OH). The accumulated doses for the 20 patients were evaluated against the planned doses using the initial planning criteria as points of comparison.Results:The delivered CTV dose conformed to the planned 98.6% coverage, with an average decrease of 2.6% between planned and delivered coverage. This implies the 2.5 mm margin was sufficient. Larger CTVs correlated to smaller differences between planned and delivered coverage. Delivered dose to critical structures including the spinal cord, mandible, brain, brainstem, and larynx was acceptable, with differences between planned and delivered max dose <5% on average. Similarly for the parotid glands, globes, cochlear, optic nerve, lens, and submandibular glands, differences between planned and delivered doses were generally <5%.Conclusion:The 2.5 mm margin provided acceptable CTV coverage, adequately accounting for setup errors. Organ at risk sparing was also satisfactory. Small tumor volumes (<20 cc) may require a larger margin to treat effectively.