bluuebunny/crossref_metadata_2025_split huggingface dataset:
TU‐C‐BRC‐02: Infrastructure to Integrate Imaging in Clinical Trials
Authors: Sullivan D 
Published: April 2010

Imaging biomarkers are increasingly used as primary or secondary endpoints in therapeutic trials. There are many academic units, professional organizations, industry groups and federal agencies addressing one or more components or issues associated with imaging biomarkers, and communication and coordination of efforts has been minimal. The RSNA has organized an Imaging Biomarkers Roundtable to establish ongoing communication among these organizations, and to develop a roadmap of activities and goals.Validation of imaging methods as biomarkers is complicated by the variability within and between patients, by the human observer component, by the variability across imaging devices from different manufacturers, and by the need to standardize methods across institutions and centers. To understand the errors and reduce them where possible, the Quantitative Imaging Biomarkers Alliance (QIBA) has been formed. These and other efforts are active and productive. Accomplishments and future plans will be discussed.Learning Objectives:1. Understand efforts to integrate imaging biomarkers in clinical trials.2. Understand efforts to improve the accuracy and precision of imaging biomarkers.
TU‐C‐303A‐06: Quiet Respiration Breathing Motion Model Parameters for Free‐Breathing Patients
Authors: Zhao T , Lu W , Bradley J , Parikh P , Hubenschmidt J , Low D 
Published: April 2010

Purpose: To determine the quiet respiration breathing motion model parameters for lung cancer and non‐lung cancer patients. Method and Materials: 49 free‐breathing patient 4DCT image data sets (25 scans, ciné mode) were collected with simultaneous quantitative spirometry. A cross‐correlation registration technique was employed to track the lung tissue motion between scans. The registration results were fed back to a lung‐motion model: , where x is the position of a piece of tissue located at reference position x0. α is a parameter which characterizes the motion due to local air filling (motion as a function of tidal volume) and β is the parameter that accounts for the motion due to the imbalance of dynamical stress distributions during inspiration and exhalation which cause lung motion hysteresis (motion as a function of airflow). The parameters α and β together provide a quantitative characterization of breathing motion that inherently includes the complex hysteresis interplay. The α and β distributions were examined for each patient to determine overall general patterns and intra‐patient pattern variations. Results: For 44 patients, the greatest value of |α| was observed in the inferior and posterior lungs. In three patients, |α| reached its maximum in the anterior lung, while for two patients; |α| was greatest in the lateral lung. The hysteresis motion β had greater variability, but for the majority of patients, |β| was largest in the lateral lungs. Conclusion: This is the first report of the 3‐dimensional breathing motion model parameter for a large cohort of patients. The overall α and β maps varied smoothly as expected. The majority of patients exhibited consistent α maps, and the β maps showed greater intra‐patient variability. The motion parameter intra‐patient variability will inform our need for custom radiation therapy motion models.This work supported in part by NIHR01CA096679 and NIHR01CA116712
WE‐B‐211A‐02: Development of Therapy Response Models Based Upon Functional MRI
Authors: Cao Y 
Published: April 2010

The potential clinical value of in vivo functional and physiological MR imaging for assessment of therapeutic response has been explored in recent years. Such imaging may provide early prediction for treatment outcomes including local tumor control as well as normal tissue complications with greater predictive power compared to conventional clinical assessment methods and related anatomic imaging. The advantage of early assessment is to allow for re‐optimizing individual patients' treatment plans, including decisions of total dose, modifying risks of critical normal tissue, and optimizing use of concomitant therapies. A response model, e.g., predicting tumor or normal tissue response to doses based upon functional imaging biomarkers, can aid in clinical decision‐making. The volumetric data presented in both image‐derived metrics as well as local dose appear to provide a significant wealth of information. Care must be taken, however, to understand the limits of input data from which the model is developed.This lecture will provide an overview on how to use functional imaging to develop a response model for individualized therapy. The limitations of these techniques will also be discussed.Learning Objectives:1. Understand functional imaging as a biomarker for therapy response;2. Understand influence of imaging parameters and image quality on quantitative metrics and uncertainty in the response model.3. Understand clinical applications and limitations.
WE‐B‐BRC‐01: Dosimetry Metrology for IMRT
Authors: Stern R , Moran J 
Published: April 2010

This session will present dosimetry tools and techniques for intensity modulated radiation therapy based on the AAPM Task Group 120 report. First, advantages and disadvantages of different detectors including ion chambers and 2D dosimetry systems will be discussed in the context of IMRT distributions. Second, considerations with respect to phantoms will be discussed. Next, the application of different dosimetric analysis tools will be presented. The final topic is the next generation of detectors for QA such as polymer gels.The educational objectives of this session are to provide information to:1. Determine the best detector for a given measurement scenario2. Assess the impact of phantom selection on the measurement3. Understand the benefits and limitations of different analysis tools for evaluating calculations and measurements of IMRT fields4. Learn about new dosimetry systems for IMRT measurements
WE‐C‐BRC‐08: A Method to Evaluate Region‐Specific Pulmonary Function Using 4D CT Images for Lung Cancer Patients Undergoing Radiation Therapy
Authors: Zhong H , Fragoso M , Patel S , Ajlouni M , Movsas B , Chetty I 
Published: April 2010

Purpose: Collateral radiation exposure to healthy lung tissue during radiation therapy can result in changes in structural and biomechanical properties of the lung. These changes may cause various clinical symptoms. The purpose of this study was to develop a functional imaging technique to assess the lung's region‐specific ventilation and pressure during or after radiation treatment.Method and Materials: With an in‐house developed finite element framework, a heterogeneous elastic model was developed for a lung patient and its Young's moduli were derived from a set of 4D CT images, acquired during radiation treatment. Each phase of the 4D dataset was registered, using deformable image registration (ITK demons algorithm) with the end‐inhale reference dataset. The resultant deformation matrix was used first to calculate the volumetric variation of each image voxel to generate a 3D ventilation image, and then to compute its corresponding transpulmonary pressure with the mechanical model. Results: Lung volumes on each phase of the acquired 4D dataset were compared with those derived from the deformed model, and were found to be within 1% of each other. The maximum ventilation occurs from phase 1 to phase 2, the earliest expiration phase. The average ventilation increased from 20.2% in phase 2 to 30.8% in phase 5 and their correspondent pressures increased from 1.57 Kpa to 2.25 Kpa. This result is generally consistent with published measurements. Conclusion: This study describes a theoretical approach to calculate the region‐specific ventilation and mechanical functions using deformable image registration. The method may be applied toward understanding how the mechanical properties of damaged lung differ from that of healthy lung tissue, and therefore it has potential applicability as a diagnostic indicator, as well as a tool for predicting radiation‐induced lung damages. Work is underway to correlate this approach with other traditional functional‐imaging modalities used to assess lung function.
WE‐E‐303A‐01: Image‐Guided Therapies: Advances in Imaging, Modeling, and New Applications
Authors: Siewerdsen J , Hawkes D , Keall P 
Published: April 2010

Recent advances in imaging technology, image modeling and registration, and advanced therapeutics offer the potential for precise, image‐guided therapies that will transform existing approaches to planning, intervention, adaptation, and monitoring of therapeutic response. Such therapies are marked by a dramatic increase in the application of image information from multiple modalities and demand accurate coregistration of morphological and functional information across a broad range of spatial and temporal scales. The scope of advanced therapeutic modalities enabled by such advances is broad, ranging from high‐precision image‐guided radiation therapy and surgery to minimally invasive target ablation, cell‐based therapies, and other forms of novel therapeutics. Moreover, the information acquired during the course of intervention will drive patterns of therapy delivery that are increasingly adaptive and patient‐specific. This symposium focuses on the scientific principles and recent advances in imaging, guidance, image modeling, registration, adaptation, and advanced therapy delivery techniques. Three speakers will present on topics central to such advancement: Dr. Siewerdsen will discuss principles of imaging performance, guidance, and the development and integration of new technologies for therapy guidance; Dr. Hawkes will address principles of rigid and deformable image registration, fusion, visualization, and augmented reality; finally, Dr. Keall will discuss the latest advances in imaging, adaptation, and novel treatment delivery techniques in image‐guided radiation therapy.Learning Objectives:1. Gain exposure to new developments in imaging technologies for image‐guided interventions.2. Understand challenges in rigid and deformable image registration, fusion, and visualization.3. Learn the latest advances in imaging, adaptation, and therapy delivery techniques in IGRT.
WE‐E‐210A‐03: 3D Carotid Ultrasound Imaging for Monitoring Carotid Atherosclerosis
Authors: Fenster A 
Published: April 2010

Atherosclerosis is characterized by the development of plaques in the arterial wall, ultimately leading to heart attacks and strokes. Quantitative measurements of the progression and regression of carotid plaque burden are important in monitoring patients and evaluating new treatment options. 3D carotid ultrasound (3D US) has the potential to be an effective method to monitor the progression of carotid artery plaques in symptomatic and asymptomatic patients. To meet this challenge, we developed a 3D carotid US system that allows detailed studies of plaques in 3D. Our software includes 3D reconstruction, viewing, and segmentation of carotid plaques, surface morphology analysis, and registration software to allow quantitative tracking of plaque changes. We used our system to examine the detailed relationship between the 3D US‐based measurement of plaque volume, the 3D scanning parameters, volume measurement variability, and plaque surface morphology. In this paper, we describe the acquisition and reconstruction of 3D carotid US images, and extended concepts used in intima‐media thickness (IMT) measurements based on 2D images to a metric we call the 3D vessel‐wall‐plus‐plaque thickness (3D VWT), which is obtained by computing the distance between the carotid wall and lumen surfaces on a point‐by‐point basis in a 3D image of the carotid arteries. The VWT measurements can be superimposed on the arterial wall to produce the 3D VWT map. Since changes in plaque thickness is important in monitoring patients who are at risk for stroke, we also compute the change of VWT by comparing the 3D VWT maps obtained at two different times. To facilitate the visualization and interpretation of the 3D VWT and 3D VWT‐Change maps, we developed a technique to flatten these maps in an area‐preserving manner.Learning Objectives:1. Understand the limitations of conventional carotid ultrasound imaging2. Understand the methods that can be used to overcome the limitations of the use of conventional ultrasound to monitor progression of carotid disease3. Understand the advantages of 3D ultrasound images to monitor progression of carotid disease
TH‐B‐213A‐01: Risks From Occupational Radiation Exposures
Authors: Berrington A 
Published: April 2010

Radiologists and radiologic technicians were among the earliest occupational groups to be exposed to ionizing radiation, and still constitute one of the largest groups of workers exposed to man‐made sources of radiation whilst at work. Studies of human populations exposed to acute, high doses of ionizing radiation have proved valuable in assessing the link between radiation and cancer and have been used to derive quantitative estimates of risk. However, the applicability of these estimates to the assessment of risks following fractionated or low level exposures remains uncertain. A number of epidemiologic studies have been conducted therefore to assess the potential risks from medical occupational exposure directly, including studies of radiologists in the UK, US and China and a cohort of radiologic technicians radiographers in the U.S.This lecture will provide an overview of these epidemiological studies and their findings, as well as a description of a new study of physicians that perform fluoroscopically guided procedures that we are currently running at the National Cancer Institute. The use of cancer risk projection models that we have developed to estimate potential lifetime cancer risk following specified exposure histories will also be described with examples.Learning Objectives:1. Understand the strengths and limitations of the epidemiologic studies of medical radiation workers2. Understand the strengths and limitations of risk projection models to estimate lifetime cancer risks from occupational radiation exposures
TH‐C‐BRD‐03: Kilovoltage Stereotactic Radiosurgery for Age Related Macula Degeneration: Assessment of Patient Effective Dose and Patient Specific Tissue Doses
Authors: Hanlon J , Lee C , Bolch W , Chell E , Gertner M , Hansen S 
Published: April 2010

Purpose: Age‐related macula degeneration (AMD) is a leading cause of vision loss in the United States. Radiation therapy was initially explored as a treatment option in the 1990's, but has since been abandoned in favor of intraocular drug injections. Interest continues for stereotactic radiosurgery (SRS), an option that provides a noninvasive treatment for the wet form of AMD. Method and Materials: Two adult heads, male and female, were computationally modeled with Rhinoceros 4.0 using CT slice segmentation scaled to ICRP Publication 89 reference values. The head phantoms were voxelized and a three‐beam photon treatment (100 kVp) was modeled using the MCNPX radiation transport code to evaluate tissue dose and effective dose. Treatment was also simulated using the reference heads with changeable optic nerve positions based on individual patient variability seen in a head CT scan review. Results: A cumulative dose of 24 Gy to the macula (8 Gy per beam) yielded an effective dose of 0.28 mSv. The maximum doses to the most extreme patient specific optic nerve positions were evaluated using Dose Volume Histograms and found to be below the thresholds for serious complications, as were other reference tissues. Conclusion: The results of this study show that SRS is a safe option considering effective dose and tissue toxicity for a reference individual. Patient specific models will be created from the CT review and treatment will be modeled using MCNPX to establish certainty that this is a safe treatment option for all individuals considering other patient specific variations in anatomy.This work was sponsored by Oraya Therapeutics.
TH‐C‐BRB‐02: Professional — SAM
Authors: Yester M 
Published: April 2010

Currently, a common initiative in many fields is quality improvement. This endeavor is especially prominent in the medical community with concerns on patient safety and reduction of medical errors. As part of its certification oversight, the American Board of Medical Specialties (ABMS) has made QI one of the four sections of its Maintenance of Certification (MOC) process. This is particularly relevant to those medical physicists with time limited ABR certificates or for other ABR Diplomates voluntarily enrolled in the MOC program. One of the key aspects of The ABR expectation for Practice Quality Improvement (PQI), Part IV of the ABR MOC program, is that Diplomates provide evidence of an ongoing program of improvement of practice either as an individual or within the system the individual is employed. For physicists, this may seem somewhat nebulous due to the many duties and responsibilities in the clinical realm. For diagnostic physicists, this may seem even more undefined, especially for consultants. As a beginning dialogue related to PQI, suggestions for projects appropriate for physicists are presented. Another method for fulfillment of the PQI section is participation in society based PQI programs. Such programs are under development within AAPM and details on a program for diagnostic imaging physicists is presented.Objectives: At the conclusion of the presentation, an individual will1. Gain knowledge of the basic aspects of PQI as pertain to physicists.2. Learn about examples of projects that would be acceptable for demonstration of PQI for physicists.3. Learn about the development of a society based program for PQI for diagnostic imaging physicists within the AAPM.
TH‐C‐BRC‐05: A CMOS‐Based Digital Imager Integrated with An Orthovoltage X‐Ray Therapy Unit for Guidance of Precise Small Animal Irradiation
Authors: Wang Z , Saito N , Podgorsak MB 
Published: April 2010

Purpose: Orthovoltage x‐ray units are commonly used in experimental irradiation of small animal models. However, the irradiation of targets that are deep‐seated within the animal is rather problematic without an image‐guidance system. This study was aimed at evaluating the use of a CMOS‐based portal‐imaging system to provide image‐guidance for small animal irradiation using an orthovoltage unit. Method and Materials: The imaging system consists of a CMOS‐based x‐ray sensor and a frame grabber connected to a PC. A fast frame rate (20 frame/sec, 50 ms/frame exposure, 96 m pixel size) was used to minimize image saturation due to the relatively high output of a typical therapeutic x‐ray unit (Phillips RT‐250). We first evaluated the imaging system with a contrast and resolution phantom. A pilot animal study with this system was then carried out for experimental thoracic irradiation of mice to induce pulmonary fibrosis. We used 75‐kVp beam for imaging, and 250‐kVp beam for the treatment, while keeping the same irradiation geometry setup. Based on image findings, radiation shields to protect the critical organs were custom‐made. Results: The 8‐mm diameter contrast discs in the testing phantom, with a minimum contrast of 0.9%, are all visible in the images. The spatial resolution based on bar‐pattern findings is at least 4.0 lp/mm. Mouse anatomical structures are clearly visible in the images. The portal images provided sufficient information for target localization and shield placement in the mice lung irradiation experiments. Conclusion: The CMOS‐based imaging system provides high quality images. It is convenient to use in comparison to the use of x‐ray films. We expect more accurate small animal irradiation results under the portal‐imaging guidance. Development of future applications of the imager may include multi‐directional imaging guidance and 3‐dimentional cone‐beam CT guidance for animal irradiation.(Acknowledgment: Rad‐icon Imaging Corp. graciously provided the Shod‐o‐box™ imager for evaluation.)
TH‐C‐BRC‐09: Commissioning of a 3D MicroCT‐Based Small Animal Radiotherapy System
Authors: Rodriguez M , Zhou H , Jogani R , Nelson G , Keall P , Graves E 
Published: April 2010

Purpose: We commissioned a novel microCT‐based kilovoltage 3D conformal radiotherapy system. A two‐stage, variable‐aperture collimator has been installed between the X‐ray source and the CT isocenter to confine the X‐ray beam, so that the system can be used for both imaging and treatment. Commissioning included alignment of the axes of the collimator and the X‐ray beam, measurement of the beam penumbra, measurement of the X‐ray beam dose rate in water, and measurement of the effective aperture size at isocenter. Method and Materials:
Images projected to gafchromic films placed at the isocenter and the microCT detector were analyzed by software developed for this commissioning, which provided quick and precise guidance for mechanical and control‐software adjustments. The penumbra was measured by fitting the beam profile to piece‐wise linear functions. The collimator‐beam alignment, the aperture ratio of the two stages, and the absolute aperture calibration were measured with known image pixel sizes. The attenuation was measured by comparing the signals in the shielded and the exposed areas in the images. Measurement of the dose rate in water was accomplished using solid water phantoms and film, calibrated using parallel ion chamber measurements. Results: The measured penumbra width was 0.5 mm, dictated primarily by the finite x‐ray source spot size. Alignment of the collimator and X‐ray beam alignment was achieved within 0.1 mm. The beam width precision was less than 0.05 mm, guaranteed by the stage‐aperture ratio and absolute beam‐width calibration. The measured attenuation was better than 99.85%. Conclusion: The 3D‐conformal‐animal‐radiation‐system commissioning has achieved the design goals that ensure the precise delivery of x‐ray beam to deep‐seated targets in experimental animals.The techniques developed for the commissioning also provided reliable methods for future system quality assurance.
TH‐C‐210A‐02: Principles of Perfusion Measurement with CT
Authors: Gould R 
Published: April 2010

CT has been used as a tool for determining blood perfusion to a diverse group of organ systems including the kidney, the lungs, the myocardium and the brain. Improvements in CT scanner design have improved and expanded capabilities for perfusion assessment, for example, faster scan times have enabled shorter sample duration and increased the number of samples that can be acquired per unit time. Greater x‐ray beam width in the Z‐axis and more rapid and controlled table movement have increased the coverage area. Gating techniques have reduced patient motion problems in some organs. However, perfusion studies remain challenging in many organs and in many patients. Artifacts, including beam hardening and streaking, and inherent limitations, including noise and partial volume effects, can limit the accuracy of measurements.In this talk, methods for CT perfusion measurements will be reviewed. Developments in CT that have improved perfusion measurements will be discussed and sources of error will be described.Learning Objectives:1. Understand the principles of perfusion measurement with CT2. Review the sources for error in perfusion measurements with CT