bluuebunny/crossref_metadata_2025_split huggingface dataset:
TU‐A‐19A‐01: Image Registration I: Deformable Image Registration, Contour Propagation and Dose Mapping: 101 and 201
Authors: Kessler M 
Published: July 2014

Deformable image registration, contour propagation and dose mapping have become common, possibly essential tools for modern image‐guided radiation therapy. Historically, these tools have been largely developed at academic medical centers and used in a rather limited and well controlled fashion. Today these tools are now available to the radiotherapy community at large, both as stand‐alone applications and as integrated components of both treatment planning and treatment delivery systems. Unfortunately, the details of how these tools work and their limitations are not generally documented or described by the vendors that provide them. Although “it looks right”, determining that unphysical deformations may have occurred is crucial. Because of this, understanding how and when to use, and not use these tools to support everyday clinical decisions is far from straight forward.The goal of this session will be to present both the theory (basic and advanced) and practical clinical use of deformable image registration, contour propagation and dose mapping. To the extent possible, the “secret sauce” that different vendor use to produce reasonable/acceptable results will be described. A detailed explanation of the possible sources of errors and actual examples of these will be presented. Knowing the underlying principles of the process and understanding the confounding factors will help the practicing medical physicist be better able to make decisions (about making decisions) using these tools available.Learning Objectives:

Understand the basic (101) and advanced (201) principles of deformable image registration, contour propagation and dose mapping data mapping.
Understand the sources and impact of errors in registration and data mapping and the methods for evaluating the performance of these tools.
Understand the clinical use and value of these tools, especially when used as a “black box”.
TU‐A‐18A‐01: Basic Principles of PET/CT, Calibration Methods and Contrast Recovery Across Multiple Cameras
Authors: Kappadath S , Nye J 
Published: July 2014

This continuing education session will discuss the physical principles of PET/CT imaging and characterization of contrast recovery using accreditation phantoms.A detailed overview will be given on the physical principles of PET including positron decay physics, 2D and 3D data acquisition, time‐of‐flight, scatter correction, CT attenuation correction, and image reconstruction. Instrument quality control and calibration procedures will be discussed. Technical challenges, common image artifacts and strategies to mitigate these issues will also be discussed.Data will be presented on acquisition techniques and reconstruction parameters affecting contrast recovery. The discussion will emphasize the minimization of reconstruction differences in quantification metrics such as SUV and contrast recovery coefficients for the NEMA and ACR clinical trial phantoms. Data from new and older generation scanners will be shown including comparison of contrast recovery measurements to their analytical solutions.The goal of this session is to update attendees on the quality control and calibration of PET/CT scanners, on methods to establish a common calibration for PET/CT scanners to control for instrument variance across multiple sites.Learning Objectives:

Review the physical principles of PET/CT, quality control and calibration
Gain further understanding on how to apply techniques for improving quantitative agreement across multiple cameras
Describe the differences between measured and expected contrast recovery for the NEMA and ACR PET phantoms
TU‐A‐18C‐01: ACR Accreditation Updates in CT, Ultrasound, Mammography and MRI
Authors: Price R , Berns E , Hangiandreou N , McNitt‐Gray M 
Published: July 2014

A goal of an imaging accreditation program is to ensure adequate image quality, verify appropriate staff qualifications, and to assure patient and personnel safety. Currently, more than 35,000 facilities in 10 modalities have been accredited by the American College of Radiology (ACR), making the ACR program one of the most prolific accreditation options in the U.S. In addition, the ACR is one of the accepted accreditations required by some state laws, CMS/MIPPA insurance and others. Familiarity with the ACR accreditation process is therefore essential to clinical diagnostic medical physicists. Maintaining sufficient knowledge of the ACR program must include keeping up‐to‐date as the various modality requirements are refined to better serve the goals of the program and to accommodate newer technologies and practices. This session consists of presentations from authorities in four ACR accreditation modality programs, including magnetic resonance imaging, mammography, ultrasound, and computed tomography. Each speaker will discuss the general components of the modality program and address any recent changes to the requirements.Learning Objectives:

To understand the requirements of the ACR MR accreditation program. The discussion will include accreditation of whole‐body general purpose magnets, dedicated extremity systems well as breast MRI accreditation. Anticipated updates to the ACR MRI Quality Control Manual will also be reviewed.
To understand the current ACR MAP Accreditation requirement and present the concepts and structure of the forthcoming ACR Digital Mammography QC Manual and Program.
To understand the new requirements of the ACR ultrasound accreditation program, and roles the physicist can play in annual equipment surveys and setting up and supervising the routine QC program.
To understand the requirements of the ACR CT accreditation program, including updates to the QC manual as well as updates through the FAQ process.
TU‐A‐16A‐01: Medical Physics Meets the Press: How to Talk to the Public Media
Authors: Opila S 
Published: July 2014

The session will introduce medical physicists to the basics of working with public media. The media landscape is constantly changing and medical physicists can serve an important role by offering their expertise on research, public health issues and more. This session is designed to provide participants with tips to work confidently with media in many different settings and effectively communicate key messages. Through this session, participants will gain an understanding of how the media works and news stories are developed, as well as how their role as medical physicists fits into the news cycle. Specific approaches to effectively communicating research to journalists will be covered, including the difference between interviews with trade reporters and interviews with general consumer news outlets. The art of working effectively with media starts with telling a good story and this session will provide participants with the tools to do that.Learning Objectives:

Understand how the media works and how news stories are developed.
Learn approaches to effectively communicate research to journalists.
Learn how to present information as a story appropriate for media consumption.
TU‐A‐BRE‐01: The Relative Biological Effectiveness of Proton Beams Relative to Photon Beams
Authors: Paganetti H , Stewart R , Carabe‐Fernandez A 
Published: July 2014

Proton therapy patients receive a 10% lower physical dose than the dose administered using photons, i.e. the proton relative biological effectiveness (RBE) is 1.1 in comparison to high‐energy photons. The use of a generic, spatially invariant RBE within tumor targets and normal tissue structures disregards a large body of evidence indicating that proton RBE tends to increase with increasing linear energy transfer (LET). Because the doseaveraged proton LET in the distal edge of a spread out Bragg peak (SOBP) is larger than the LET in the plateau region or proximal edge of a SOBP, the use of a spatially invariant RBE is not well justified from a mechanistic point of view. On the other hand, the available clinical data on local tumor control rates and early or late side effects do not provide strong evidence against the continued use of a constant and spatially invariant clinical RBE. The only potential downside to the ongoing use of a constant RBE of 1.1 seems to be that we are missing a potential opportunity to enhance the therapeutic ratio, i.e., design proton therapy treatments in ways that exploit, rather than mitigate, spatial variations in proton RBE. Speakers in this symposium will:1‐review the laboratory and clinical evidence for and against the continued use of a spatially invariant RBE of 1.1,2‐examine some of the putative mechanisms connecting spatial variations in particle LET to estimates of the proton RBE at the molecular, cellular and tissue levels3‐assess the possible clinical significance of incorporating models for spatial variations in proton RBE into treatment planning systems.4‐discuss treatment planning and delivery techniques that will exploit the spatial variations of RBE within proton beams.Learning Objectives:

To review laboratory and clinical evidence for and against the continued use of a constant RBE of 1.1
To understand major mechanisms connecting proton LET to RBE at the molecular, cellular and tissue levels.
To quantify the potential opportunities and potential pitfalls of neglecting spatial variations in proton RBE in treatment plans
To understand the minimum requirements required to design proton treatment plans that benefit from a spatially changing RBE and discuss some of the technological challenges they may require.
TU‐A‐BRD‐01: Outcomes of Hypofractionated Treatments – Initial Results of the WGSBRT
Authors: Li X , Lee P , Ohri N , Joiner M , Kong F , Jackson A 
Published: July 2014

Stereotactic Body Radiation Therapy (SBRT) has emerged in recent decades as a treatment paradigm that is becoming increasingly important in clinical practice. Clinical outcomes data are rapidly accumulating. Although published relations between outcomes and dose distributions are still sparse, the field has progressed to the point where evidence‐based normal tissue dose‐volume constraints, prescription strategies, and Tumor Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) models can be developed.The Working Group on SBRT (WGSBRT), under the Biological Effects Subcommittee of AAPM, is a group of physicists and physicians working in the area of SBRT. It is currently performing critical literature reviews to extract and synthesize usable data and to develop guidelines and models to aid with safe and effective treatment. The group is investigating clinically relevant findings from SBRT in six anatomical regions: Cranial, Head and Neck, Thoracic, Abdominal, Pelvic, and Spinal.In this session of AAPM 2014, interim results are presented on TCP for lung and liver, NTCP for thoracic organs, and radiobiological foundations:• Lung TCP: Detailed modeling of TCP data from 118 published studies on early stage lung SBRT investigates dose response and hypothesized mechanisms to explain the improved outcomes of SBRT. This is presented from the perspective of a physicist, a physician, and a radiobiologist.• Liver TCP: For primary and metastatic liver tumors, individual patient data were extracted from published reports to examine the effects of biologically effective dose on local control.• Thoracic NTCP: Clinically significant SBRT toxicity of lung, rib / chest wall and other structures are evaluated and compared among published clinical data, in terms of risk, risk factors, and safe practice.• Improving the clinical utility of published toxicity reports from SBRT and Hypofractionated treatments. What do we want, and how do we get it? Methods and problems of synthesizing data from published reports.Learning Objectives:

Common SBRT fractionation schemes and current evidence for efficacy.
Evidence for normal tissue tolerances in hypofractionated treatments.
Clinically relevant radiobiological effects at large fraction sizes.
TU‐A‐9A‐01: A Precise Deformable Image Registration System Using Feature‐Based Irregular Meshes
Authors: Cai Y , Zhong Z , Guo X , Gu X , Chiu T , Kearney V , Liu H , Jiang L , Chen S , Yordy J , Nedzi L , Mao W 
Published: July 2014

Purpose:To develop a deformable image registration system using irregular meshes generated based on image features. Finer meshes are generated at organ or tissue boundaries so that higher deformation resolution is achieved with limited number of control points.Methods:This deformable image registration system consists of two parts: a finite element modeling system and a GPU‐based registration system. The finite element modeling system is used to generate irregular meshes for the entire body or region of interest without segmentation. This system uses a Laplacian of Gaussion operator to extract features such as boundaries between organs and tissues. The placement of control points (vertices) of meshes is optimized based on feature intensities. The registration framework uses elastic energy as regularity and guarantees the final deformation vector field to be diffeomorphic. This system has been compared with registration algorithms based on regular meshes or voxels (Demons). The comparison is performed on XCAT digital phantom data and patient data.Results:Both XCAT male phantom and female phantom were used. Two respiratory phases were treated as floating and fix images for every phantom. Similarity measures were performed for image intensity and displacement vector field (DVF) for four sets of testing data with three types of deformation algorithms (irregular mesh, regular grid, and voxel). It clearly shows that the voxel‐based Demons algorithm leads to slightly better images. However, the DVF results show that mesh‐based algorithms behave much better. Compared with regular meshes, the irregular mesh we proposed leads to much faster convergence and converge to better results. The calculation is accelerated by GPU cards and a typical registration of patient data could be completed in about 1 minute.Conclusion:The feature‐based irregular meshing method provides a fast and accurate deformable image registration.This research is supported by CPRIT individual investigator award RP110329 and Varian research grant.
TU‐A‐9A‐10: Verification of Photoacoustic Computed Tomography Perfusion Imaging Using DCE‐CT
Authors: Roth A , Krutulis M , Verleker A , Stantz K 
Published: July 2014

Purpose:We propose to verify quantifiable perfusion information generated by a Photoacoustic Computed Tomography (PCT) scanner using Dynamic Contrast‐Enhanced CT (DCE‐CT), and to investigate physicsbased models of acoustic properties of tissue and photon transport to improve quantification. These corrections first necessitate a skin identifying algorithms to reduce speed‐of‐sound blurring and empirical photon correction methods.Methods:Xenograft mice (n=5) of breast cancer was imaged using DCE‐CT which was followed by DCE‐PCT. To obtain CT perfusion data, each mouse was i.v. injected (0.2mL Isovue @0.5mL/min) and subsequent radio‐opaque time curves fit to a 2‐compartmental model on a voxel‐wise basis. For DCE‐PCT, different concentrations of ICG (250, 125, and 62.5 micro‐Molar) were injected at the same rate, but also acquired at different sampling rates (3, 6, and 12 seconds). The time intensity curves from PCT were fit to a 1‐compartmental model on a voxel by voxel basis. The images were coregistered (Oncentra) based on the structural similarities of the tumor vasculature after which we compared both the contrastenhanced dynamics and the vascular physiology.Results:Moderate to high doses of ICG impact the washin phase of the PCT contrast due to photon losses as a function of depth. A semi‐automatic algorithm has been developed to identify the skin margin, and subsequent MC and empirical models of photon transport and variations in speed‐of‐sound are being evaluated.Conclusion:From our results we find that there is a need to apply photon and speed‐of‐sound corrections to our PCT data to improve the quantifiable image data at depth in the tumor for PCT. The dose and injection rate may help in reducing large systematic effects.Our project is partially funded by a NIH SBIR grant.
TU‐A‐9A‐11: Gold Nanoparticles Enhanced Diffuse Optical Tomography: A Proof of Concept Study
Authors: Yang Y , Dogan N 
Published: July 2014

Purpose:To investigate the feasibility and potential of gold nanoparticles (GNP) enhanced diffuse optical tomography (DOT) as a novel imaging strategy for tumor detection.Methods:Simulation was performed on a digital homogeneous cylindrical phantom of 30mm×30mm. Gold nanorods (GNR) with aspect ratio 3.9 and effective radius 21.86nm were used as contrast agent. The peak light absorption for these GNR occurs at 842nm within the near‐infrared region, with the absorption cross‐section of 1.97×10‐14m‐2 and scatter cross‐section of 1.07×10‐14m‐2. A 6mmdiameter sphere of GNR solution was positioned inside the tissue‐simulating phantom. Simulations were performed at the GNR concentration level of 1nM, 100pM and 10pM, respectively. The points representing laser sources and light detectors were around the phantom with 30o apart tangentially and 1mm apart axially for 9 rows. As one point being source, all the other points within the current row and nearby four rows become detectors. Hence there are 108 source points in total and 55 detector points corresponding to each source. Forward light transport at 842nm wavelength was run on a three‐dimensional mesh of 33186 nodes (∼0.5mm resolution) to acquire the light emission data. Reconstruction was performed on a coarse mesh of 19408 nodes (∼1mm resolution) with ∼20minutes on a 2.4GHz CPU and 8GB RAM computer.Results:The position of the GNR solution at 1nM, 100pM and 10pM concentration was reconstructed, respectively, with <1mm error. The GNR concentration was interpreted from the reconstructed absorption coefficient within the enhanced volume. The reconstructed maximum concentrations were 0.3nM, 120.0pM, and 5.3pM, respectively.Conclusion:To the best of our knowledge, this is the first time to apply GNP to enhance DOT. The simulation results showed the high sensitivity of GNP enhanced DOT, which is in pM concentration level, compared to the μM level for MRI agents and nM level for PET agents.
TU‐A‐12A‐01: Consistency of Lung Expansion and Contraction During Respiration: Implications for Quantitative Imaging
Authors: Patton T , Du K , Christensen G , Reinhardt J , Bayouth J 
Published: July 2014

Purpose:Four‐dimensional computed tomography (4DCT) can be used to evaluate longitudinal changes in pulmonary function. The sensitivity of such measurements to identify function change may be improved with reproducible breathing patterns. The purpose of this study was to determine if inhale was more consistent than exhale, i.e., lung expansion during inhalation compared to lung contraction during exhalation.Methods:Repeat 4DCT image data acquired within a short time interval from 8 patients. Using a tissue volume preserving deformable image registration algorithm, Jacobian ventilation maps in two scanning sessions were computed and compared on the same coordinate for reproducibility analysis. Equivalent lung volumes (ELV) were used for 5 subjects and equivalent title volumes (ETV) for the 3 subjects who experienced a baseline shift between scans. In addition, gamma pass rate was calculated from a modified gamma index evaluation between two ventilation maps, using acceptance criterions of 2mm distance‐to‐agreement and 5% ventilation difference. The gamma pass rates were then compared using paired t‐test to determine if there was a significant difference.Results:Inhalation was more reproducible than exhalation. In the 5 ELV subjects 78.5% of the lung voxels met the gamma criteria for expansion during inhalation when comparing the two scans, while significantly fewer (70.9% of the lung voxels) met the gamma criteria for contraction during exhalation (p = .027). In the 8 total subjects analyzed the average gamma pass rate for expansion during inhalation was 75.2% while for contraction during exhalation it was 70.3%; which trended towards significant (p = .064).Conclusion:This work implies inhalation is more reproducible than exhalation, when equivalent respiratory volumes are considered. The reason for this difference is unknown. Longitudinal investigation of pulmonary function change based on inhalation images appears appropriate for Jacobian‐based measure of lung tissue expansion.NIH Grant: R01 CA166703
TU‐A‐12A‐03: Monitoring Changes in Tumor Texture Features On Weekly CT and CBCT Scans of NSCLC Patients
Authors: Fave X , Zhang L , Yang J , Fried D , Balter P , Court L 
Published: July 2014

Purpose:To (1) track changes in CT texture features through time and (2) identify correlations between CT and CBCT texture feature values for NSCLC patients.Methods:Texture features were extracted from weekly CT and CBCT images of 30 NSCLC patients. The physician‐drawn GTV contours on the planning CT, during end of expiration phase (T50), were deformed to weekly CT images. The deformed contours were copied to rigidly registered average‐CT and CBCT images. These contours were imported to our in‐house texture feature analysis program, which performs a Laplacian of Gaussian spatial band‐pass filter at different scales followed by a calculation of the tumor uniformity. Three filter sizes were used (coarse, medium, and fine). (1) The normalized change in uniformity as a function of time was evaluated from the T50 images. (2) The uniformity values from the average‐CT and CBCT images were used to assess correlation.Results:(1) Texture features measured in T50 scans were shown to change over time for individual patients. As filter size increased, the range of measured normalized changes decreased from 103.6% (SD=22.8) to 25.2% (SD=7.9). (2) Texture features extracted from CT were shown to correlate with values in CBCT with R2 values of 0.79(coarse), 0.84(medium), and 0.84(fine). Correlation values increased for more coarse filters and lower lung tissue thresholds. The correlation was also dependent on removal of patients with metal artifacts, severe truncation of anatomy in CBCT images, or those with tumors smaller than 4.3cc. Seven patients were removed.Conclusions:We showed texture features vary for patients during their course of treatment and these changes can be monitored with CBCT images. Various studies have indicated CT texture features may correlate with patient prognosis. Therefore, our results could be used to observe changes in a patients prognosis and potentially adapt their treatment without any additional imaging studies.