bluuebunny/crossref_metadata_2025_split huggingface dataset:
TU‐A‐BRCD‐01: Image Acquisition and Processing for Adaptive Radiotherapy
Authors: Kessler M , Siewerdsen J , Sonke J 
Published: June 2012

Adaptive radiotherapy involves acquisition and processing of image data from numerous devices at various time scales. In contrast to conventional radiotherapy which mainly involves unidirectional flow of image data in fairly large steps ‐ from the scanners to the planners to the treatment machines ‐ adaptive radiotherapy involves a bidirectional and iterative flow of image data.Acquisition and processing of multimodality imaging data for the initial planning step is now common place: x‐ray CT provides accurate geometric and density information; MR provides exquisite soft tissue contrast; and nuclear medicine imaging provides unique metabolic information. Data from these modalities are registered and integrated to help define the tumor volume(s) and surrounding healthy tissues. These modalities along with ultrasound and optical imaging can also provide 4D and time series image data to help model moment‐to‐moment physiologic motion and day‐to‐day functional and anatomic changes. Tracking these changes between and during treatment fractions is a key aspect of the adaptive radiotherapy process. Image processing steps required to support this tracking and adaptation of treatments include deformable image registration, contour propagation, and dose accumulation. The outputs of these steps are used to support decisions about maintaining or adapting the current treatment plan.This course will provide an overview of the different imaging devices used to support adaptive radiotherapy and highlight the benefits and challenges of each. The details of the various image processing tools used to extract, combine, and analyze the information from the various imaging data will also be presented. Finally, the effective use of these devices and tools for the adaptive radiotherapy process will be described and elucidated using several clinical examples.Learning Objectives:1. Understand the basic principles of image acquisition used in adaptive radiotherapy2. Understand the basic principles of image processing used in adaptive radiotherapy3. Understand how imaging and image processing are used in the adaptive radiotherapy process
WE‐A‐BRA‐02: First Commercial Hybrid MRI‐IMRT System
Authors: Mutic S 
Published: June 2012

The first commercially available MRI‐guided IMRT (MRIGRT) system (ViewRay, Cleveland, OH) has been installed at Washington University in St. Louis. This novel medical instrument combines magnetic resonance imaging and intensity modulated radiation therapy at a single isocenter for simultaneous use during therapy along with automated tissue tracking and beam control based on images of soft tissue acquired in real time rates of 2–4 FPS simultaneous to the delivery. The purpose of this presentation is to describe and evaluate the technical aspects of the instrument as well as its adaptive and image guided radiotherapy workflows. The ViewRay system consists of a 0.35‐T double‐doughnut MRI coupled with a gantry that houses three radiotherapy heads containing 15,000‐Ci Co‐60 sources (120° apart). IMRT delivery is enabled by 3 doubly‐focused MLCs that serve as the only collimators for each head, allowing a maximum field size of 27 cm2 at the 105‐cm isocenter. MRI imaging is used prior to and during delivery for patient setup evaluation, adaptive radiotherapy, and tissue tracking and beam control based on real time 2–4 FPS imaging (2 FPS in 3 parallel planes or 4 FPS in a single plane). The fast MR imaging coupled with fast autocontouring, image fusion that can transfer tissue densities (via contours through bulk density or from fused CT imaging), and dose calculation facilitate real time dose delivery evaluation, on couch reoptimization, and replanning when necessary. The instrument's multiframe per second MR imaging enables motion correlated delivery based on the actual target volumes rather than on surrogates. Following treatment, the image, contours, and control system data produce a record of the delivery that is automatically recorded and registered to the orginal plan for evaluation. All imaging and adaptive features are controlled by clinician directives at the planning stage and can be set as required, optional, or prohibited. The design and capabilities of the system create several novel concepts and promising capabilities in RT delivery from imaging and treatment to workflow and QA/QC. This presentation discusses the initial assessment of these features and their implementation and the early clinical experience with the system including validation of its capabilities.Learning Objectives:1. To describe technical design and capabilites of ViewRay system2. To describe adaptive and image guided RT workflow with this system3. To present initial validation assessment of the system
WE‐C‐211‐01: International Radiation Safety Standards and Systems
Authors: Rehani M 
Published: June 2012

International organizations play an important role in establishing roles, responsibilities and needs of medical physicists, be it for radiation protection or functional needs. The international Standards of safety (Basic Safety Standards‐BSS) steered by the IAEA and the European BSS provide requirements that may be mandatory directly or indirectly. In addition, International Commission on Radiological Protection (ICRP) provides principles of radiation protection. Both the IAEA and the EC have provided requirements for medical physicist to be in place, previously dominantly for radiotherapy and more recently for diagnostic radiology, nuclear medicine and other practices that utilize ionizing radiations. There are a number of new requirements in both BSS that are likely to be released in 2012–2013 but drafts are available. Besides requirements, international organizations provide means to meet requirements. These are training material and actions directed at both human resource development and development and enrichment of skills, capacity building through provision of equipment, publications and guidelines to promote rational and safer practice. A large number of IAEA and EC projects provide assistance towards the goals of organizations and there are many publications of IAEA, EC and ICRP that medical physicists should be aware of. Recent statement of the ICRP on tissue reaction lowering threshold and dose limit for lens of the eye and circulatory disease is of interest. EC has developed guideline on medical physics expert. The talk will review activities of IAEA, EC, and ICRP with focus on medical physicists and the impact in less resourced countries.Learning Objectives:1. To understand the system that has influence on countries outside US pertaining to activities of interest to medical physicists2. To become familiar with actions pertaining to medical physics experts and requirements on radiation protection3. To become familiar with new information from ICRP on thresholds and dose limits for tissue reaction4. To understand the potential role you can play in international activities
WE‐C‐213AB‐03: Preparing for Part II of the ABR Radiotherapy Physics Exam
Authors: Flynn R 
Published: June 2012

Attendees are taught an efficient organizational framework for Part II exam preparation that maximizes high‐yield active learning study activities and minimizes low‐yield study activities. This method is then combined with a productive group‐based study technique. The format and scope of the Part II ABR exam in radiotherapy physics is described, and the eligibility requirements are reviewed. High‐yield and low‐yield study activities are defined and examples are discussed in detail. A problem‐based strategy for limiting the scope of study material is described. A method for studying in groups by distributing delegable tasks among multiple group members and ensuring their completion is described.Learning Objectives:1. Understand the scope of material covered on Part II of the ABR radiotherapy physics exam and which references to study for the exam.2. Be able to design and execute an efficient study plan that enables an active learning approach.3. Learn to use group study techniques to enhance efficiency.
WE‐C‐213CD‐01: Decision Support for Radiation Therapy
Authors: Yin F 
Published: June 2012

Informatics in radiation therapy is less understood. Decision support for, or knowledge‐guided, radiation therapy, is a major component of informatics, where the data is mined, modeled and turned into computable knowledge. It is critically important for radiation therapy as it employs highly complex procedures, such as IMRT and IGRT, where radiation related normal tissue/organ damages and clinical outcomes require delicate balance. Decision support can be provided in passive, active, and cooperative modes. The passive mode focuses on improved presentation of available data and knowledge to minimize cognitive burden in decision making. The active mode applies machine learning algorithms, such as support vector machines, to generate decision suggestions based on existing knowledge. The cooperative mode allows users to interact with the decision support system to iteratively reach an optimal decision. Decision support for the execution of Clinical Practice Guidelines (CPG) is another important area in which significant improvement can be achieved by helping physicians following best clinical practices specified in the guidelines. In radiation therapy, significant data, algorithms, knowledge, and guidelines have been developed in the past two decades. Various modes of decision support systems have been proposed in recent years that incorporate different data, optimization algorithms, knowledge representations, and machine learning algorithms. In this session, we will first review concepts and systems of clinical decision support in general; followed by specific applications of decision support in radiation therapy. The basic principles of making decisions when the outcomes of any available actions are uncertain are discussed. Methods for applying these principles in medical environments are described. We will conclude our discussion with a number of state‐of‐the‐art techniques for decision support in radiation treatment planning and quality assurance.Learning Objectives:1. To discuss the need for decision support in health care and specifically in radiation therapy2. To review major concepts and approaches in clinical decision support systems3. To describe example systems for decision support in radiation therapy4. To present a number of new techniques for decision support in intensity modulated radiation treatment planning
WE‐G‐211‐03: Development of Ultrasound Imaging Equipment
Authors: Zagzebski J 
Published: June 2012

One of the earliest man‐made ultrasound images of the human body was produced by Dussik in 1941, when he attempted to image the brain using a through transmission technique. These early images were later judged to be artifacts related to sound wave transmission through skull bone. Pulse‐echo examination of the body started in the late 1940's following developments of sonar, radar, and ultrasound flaw detectors. Ludwig and colleagues measured speeds of sound in tissues, publishing the value 1540 m/s for many tissue paths, a figure still used today. Among the pioneering pulse‐ echo imaging teams in the USA were Wild and Reid who developed real time imaging of the breast in the early 1950's, and Howry and Bliss, who were able to generate detailed anatomical pictures of the neck by employing water bath scanners. Many other groups, including from Japan, Australia, and Europe were pursuing both A‐scope and B‐scope applications of ultrasound around this time. Notable achievements include work by Ian Donald in the UK, who in 1955 described a contact scanner and published B‐scope images depicting a variety of anatomical regions. The systems of Donald and of Wild are said to have inspired engineers from Howry's water bath team in Colorado to develop their own contact scanner, and in 1963 a new company, Physionics produced the first commercial, single element transducer “articulated arm” scanner. It provided bi‐stable B‐mode images on a storage oscilloscope, marking the beginning of widespread acceptance of this modality. Gradual instrument improvements include analog then digital scan converters for gray scale in the 70's, and both auxiliary and stand alone mechanical scanning real time probes. Phased array technology also emerged for cardiac imaging, as did linear arrays for obstetrics and abdominal imaging. Perhaps the most revolutionary instrument ever was produced in the early 1980's, the Acuson 128, introducing high image quality linear and phased array beamformed images for radiology applications and helping to conclude the brief era of manual scanners. As beamformers became digital devices in the 1990's, unprecedented image quality, diagnostic features, two dimensional arrays, and even system miniaturization evolved, bringing ultrasound imaging to its present state. The ultrasound field is still characterized by novel instruments emerging from the laboratories of clever scientists, addressing diagnostic and therapeutic needs not provided by present day technology.Learning Objectives:1. Describe features of the first commercially available ultrasound scanners.2. Identify the relationship between technological developments in radar and emergence of ultrasound as a modality3. Explain the significance of a high large channel count in beamforming4. Contrast echo acquisition and processing in a modern scanner with first generation devices.
WE‐G‐218‐02: The Measurement of Absorbed Dose to Active Intravenous Cardiac Devices in Patients Undergoing Radiotherapy
Authors: Reft C 
Published: June 2012

Radiotherapy departments are seeing an increasing number of patients presenting for treatment with active intravenous cardiac devices (AICDs). This is due to an increasing aging population and technology advances in these devices. The AAPM TG‐34 addressed the radiation effects in these devices and provided recommendations for patients with these devices undergoing radiotherapy. The current devices utilizing CMOS technology are more sensitive to radiation then the older bipolar devices. Therefore, it is important to estimate the dose to the device to ensure that the radiation does not adversely affect the performance of the device. This is particularly important for patients dependent on their accurate functioning. The dose to the device is generally from secondary radiation and is typically below 0.05 Gy with most of it coming from lower energy scatter radiation. Treatment planning systems can be used to estimate the dose to the device. However, these systems do not accurately calculate doses at distances more than 2–3 cm from the field edge. For these out–of–field dose measurements the dosimeter requires a high sensitivity and a relatively flat energy response. Thermoluminescent detectors and optically stimulated luminescent detectors satisfy these requirements and they are relatively unobtrusive. The newer formulations of radiochromic film with higher sensitivity can also be used. The detector should be place under 0.5 to 1.0 cm of bolus to minimize the contaminating head‐scatter electrons provide a more realistic measurement of the dose to the device.Learning Objectives:1. List the reasons for estimating the dose to the AICDs2. Provide a discussion on the various methods which include calculations and measurements to estimate the dose to the device as well as the uncertainties in these estimates.3. Identify detectors that satisfy the requirements for these in‐vivo out‐of‐field dose measurements as well as describe the appropriate correction factors to apply for accurate dose measurements.
TH‐A‐211‐02: Effects of Different Parameters on Deformable Image Registration
Authors: Kim J , Zhong H 
Published: June 2012

Deformable image registration algorithms generally consist of three components, similarity metric, transformation, and optimization. In addition to these components, the optimization also includes one or more regularization terms such as the smoothness of the underlying deformation or restrictions based on the physical properties of organs. It is also common for most of the algorithms to take a multi‐resolution approach to capture large initial deformations as well as to speed up the registration process. Understanding and proper choice of such parameters are critical to a successful registration. The effects of different choices of parameters will be presented using public domain algorithms as well as commercial software.Learning objectives:1. To understand the basic constituents of deformable image registration algorithms.2. To understand the consequences of the different parameter choices.
TH‐A‐218‐01: Managing Fat in MRI: A Technical Perspective
Authors: Ma J 
Published: June 2012

Water and fat are the two predominant sources of signal for in vivo MRI. Because fat is omnipresent in many parts of our body and because fat appears bright in many types of basic MR images, it is often essential to be able to successfully suppress the fat signal. Chemical shift selective saturation (CHESS) and short‐tau inversion recovery (STIR) are the two well‐known techniques for this purpose. Despite their widespread use and success, CHESS and STIR have fundamental limitations and as a consequence, poor fat suppression is one of the most frequently‐encountered image quality issues in clinical practice. Further, it is difficult to implement the CHESS or STIR‐based techniques for some emerging applications such as fast dynamic imaging. Another MRI technique for managing fat that has gained increasing clinical use only in the last few years was first published by Tom Dixon in 1984. The original idea of the so‐called Dixon techniques is to collect two images that have water and fat signals in‐phase and 180o out‐of‐phase, respectively. These two images can be added and subtracted to yield a “water‐only” image and a “fat‐only” image. Thus, the Dixon techniques have the potential for simultaneous fat suppression and fat quantification. Additionally, it was recognized and is now demonstrated that the Dixon techniques can be made highly insensitive to magnetic field inhomogeneity and highly SNR and scan time efficient. In this talk, I will provide an overview of some major development of the techniques for managing fat in MRI. I will focus particularly on the physical basis as well as the respective pros and cons of the different fat management techniques in MRI.Learning Objectives:1. Understand the physical basis and advantages and disadvantages of several major fat management techniques in MRI2. Understand some major issues and technical development of the Dixon techniques for water and fat imaging3. Understand some remaining challenges and future opportunities for fat imaging and applications by MRI
TH‐B‐218‐01: Iterative Reconstruction Methods in Computed Tomography
Authors: Stayman J 
Published: June 2012

Sophisticated iterative reconstruction methods for computed tomography have seen more widespread adoption with the availability of increased computational power and the desire for improved dose utilization. While improved image quality and dose reduction are possible with iterative approaches, there is a (sometimes confusing) diversity of algorithm choices. This presentation will introduce the basic concepts behind iterative reconstruction and statistical methods, including how such approaches are formed and illustrating different classes of reconstruction algorithm. Differences between iterative approaches and traditional reconstructions will be discussed ‐ both in terms of how data is processed as well as the differing image properties that arise from each type of algorithm. The lecture will highlight advantages and limitations of iterative reconstructions and provide listeners with a basic introduction of the inner workings of the iterative methodology.Learning Objectives:1. Understand the fundamentals of how iterative methods are formed and how to identify particular classes of iterative methods.2. Gain intuition into the flexibility of iterative methods and why these approaches can have an advantage over other techniques.3. Learn about the nature of iteratively reconstructed images and how images produced by these methods can have significantly different image properties from those produced by traditional analytic approaches.This talk may contain research sponsored by Siemens, Varian Medical Systems, and/or Carestream Health.
TH‐D‐BRCD‐02: TG‐51 Addendum ‐ Overview and Implementation
Authors: McEwen M 
Published: June 2012

This presentation will describe the new addendum to the AAPM's TG‐51 protocol covering photon beam reference dosimetry, which is in the final stages of review and will be published in 2012. The addendum does not hange either the formalism of TG‐51 or the standard reference conditions (i.e., 10 cm × 10 cm field at 1 m) but provides new chamber‐specific data together with detailed guidance on the relevant factors to take into account when following the TG‐51 protocol. The presentation will review the addendum in some detail with particular focus on: 1) Best practice recommendations to minimize errors and ensure consistent dosimetric reporting, including choice of chamber, experimental procedures, determination of correction factors, and application to FFF linacs.2) An in‐depth discussion of uncertainties with guidance on how the clinical physicist can affect the overall uncertainty in the determination of absorbed dose to waterLearning Objectives:1. Understand the scope of the TG‐51 addendum or photon beam dosimetry.2. Understand how the addendum should be implemented to achieve the highest level of accuracy.3. Understand how to construct an uncertainty budget for the determination of dose at the reference point and how the clinical user can influence the overall value of uncertainty.