bluuebunny/crossref_metadata_2025_split huggingface dataset:
WE‐C‐224A‐05: Patient Modeling and Organ Dose Calculations Using Monte Carlo Methods
Authors: Xu X G , Paganetti H 
Published: July 2006

The risk for a patient to develop secondary cancers from non‐target exposures can be assessed from the equivalent doses to various radiosensitive organs. To determine organ doses, a computational model or physical phantom that represents the whole patient anatomy must be used. Physical phantoms (such as the RANDO and ATOM phantoms) have tiny cavities on each of the tissue‐equivalent slices for inserting TL and MOSFET dosimeters. When beam is delivered according to a patient's treatment plan, the dosimeters are processed to provide organ dose information. The experimental procedures can be time‐consuming and expensive, especially when various patients and treatment plans are studies. Virtual patient models, on the other hand, can be combined with a Monte Carlo code to simulate the transport of radiation in the body. These models cover the entire body and typically contain a large number of defined organs. Coupled with a model of the accelerator, one can calculate detailed information about secondary dose distributions in the patient body. Whole‐body models are classified into three types: 1) Stylized models that are based on surface equations, 2) Tomographic models that are derived from medical images, and 3) Hybrid equation‐voxel models that describe organ boundaries using advanced primitives such as the NURBS for realtime deformation (4D simulations). To date, more than 20 tomographic models have been developed for radiation protection and nuclear medicine applications. An international consortium on computational human models (www.virtualphantoms.org) has been recently formed to promote research in this area. A team of researchers from Rensselaer, Vanderbilt, University of Florida, Massachusetts General Hospital and Johns Hopkins University is working on a project to standardize a library of age‐ and gender‐specific models.This lecture presents the current status of patient modeling and the application of various tools to study secondary doses from radiation treatment involving both photons and protons. Detailed information on the VIP‐Man model developed from the Visible Human Project is presented. Segmentation of more than 80 organs, including the red bone marrow, and the implementation of the VIP‐Man model into EGS, MCNP/X and GEANT4 are discussed. Finally, organ doses and effective doses for proton treatment plans using various adult and pediatric patient models are presented.Educational Objectives of this symposium are:1. Understanding new tools of Monte Carlo‐based patient and accelerator modeling for secondary dose studies.2. Understanding the effective dose data for various modalities.
WE‐C‐230C‐01: Ultrasound QC Workshop
Authors: Pfeiffer D , Lu Z , Miller H , Spaulding R , Moore W 
Published: July 2006

Quality control testing of ultrasound scanners is gaining importance as the use of diagnostic ultrasound become more quantitative in nature and the systems and probes more complex in design. As evidenced by the rise in popularity of the American College of Radiology's ultrasound accreditation program, the need for comprehensive quality control programs is clear. This workshop is designed to provide attendees an opportunity to learn the impact of scanners and probes on various aspects of image quality and to refresh their skills in ultrasound QA/QC testing. The essential physics of ultrasound imaging and instrumentation will be reviewed. QA/QC testing procedures required by accreditation programs and advisory organizations will be presented. The impact of scanner and probe deficiencies on both B‐mode and Doppler performance will be demonstrated. Tools for analyzing probes will also be demonstrated.Finally, a discussion of quality control of prostate brachytherapy ultrasound will be presented. In the second half of the workshop, attendees will be given the opportunity to use the various tools and phantoms in a hands‐on environment. Experienced instructors will be at the ultrasound scanners to guide the exercises.Two identical sessions will be conducted, one in the morning and the second in the afternoon.Educational Objectives:1. To learn the effect of parameter settings and probes on various aspects of ultrasound imaging.2. To observe the impact of system and probe deficiencies on ultrasound performance and image quality.3. To become acquainted with various ultrasound QC phantoms and test tools and learn their proper use.
WE‐E‐ValB‐04: Functional and Molecular Imaging for Radiotherapy Guidance
Authors: Xing L 
Published: July 2006

Radiation therapy is an image‐guided procedure whose success depends strongly on the image modality used for treatment planning and the level of integration of the available imaging information. Advancement in IMRT has provided an unprecedented means to produce highly conformable dose distribution while sparing sensitive structures, which calls for better imaging tools for tumor target definition and for the management of inter‐ and intra‐fractional organ motion. In this talk we will summarize recent advances in functional and molecular imaging techniques and discuss various issues related to the integration of the newly emerged imaging data into radiation therapy planning. It is anticipated that the new imaging modalities will play an important role in radiation oncology practice and make significant impact in cancer diagnosis, staging, treatment planning, and monitoring of therapeutic response. The potential impact of biologically conformal radiation therapy (BCRT) or biologically guided radiation therapy (BGRT) will be discussed. Finally, issues related to the quality assurance of functional and molecular imaging and BCRT will also be addressed.Educational Objectives:1. Introduce the concept of functional and molecular imaging.2. Illustrate the steps involved in integrating molecular imaging such as PET and MRSI into treatment planning process.3. Introduce PET/MRI/MRSI and CT image fusion techniques (including deformable image registration).4. Provide an overview on recent advances in PET/CT and MRSI, and update on the development of new PET tracers and data acquisition techniques.This work was supported in part by NCI 5R01 CA98523‐01.
WE‐E‐224A‐01: The Best of Both Worlds: Taking Advantage of Brachytherapy and External Beam Radiotherapy
Authors: Yamada Y 
Published: July 2006

Introduction. Brachytherapy and external beam radiation represent opposite ends of the inverse square dose fall off spectrum. Brachytherapy is well suited for the delivery of conformal localized high dose radiation. While external beam radiation is well suited for conformal local and regional treatment, it is able to treat larger volumes in comparison to brachytherapy. This paradigm fits well with the natural history of many malignancies to provide maximal tumor control probability while minimizing normal tissue complications.Methods and Materials. Two examples of combining brachytherapy and external beam radiation which illustrate the brachytherapy/external beam radiation therapy paradigm will be presented: The combination of high dose rate (HDR) brachytherapy and intensity modulated radiation (IMRT) for the definitive management of localized prostate cancer, and the use of a Yttrium 90 dural plaque in conjunction with image guided IMRT for vertebral body chordomas with significant epidural disease.Results: HDR prostate brachytherapy and IMRT provides a very high level of disease control with only minor toxicity for patients with localized prostate cancer. This is likely due to careful treatment planning to minimize dose to critical structures such as the rectum and urethra while delivering a very high biologic effective dose to tumor bearing tissue. Similarly, Yttrium 90 dural plaques are able to deliver a very high dose of radiation to the dural surface, while underlying spinal cord will receive less than 5% of the prescribed dose. This will allow for a extremely high dose of radiation to be given to the planning target volume and increase the tumor control probability. Conclusions: Both brachytherapy and IMRT have inherent physical advantages that can be utilized to improve the therapeutic ratio of radiation therapy. Particularly in the management of tumors where a dose‐control relationship exits situated near dose sensitive structures, this paradigm is especially important.
TH‐A‐330D‐01: PET ‐ Radiation Safety and Shielding Requirements
Authors: Anderson J 
Published: July 2006

PET/CT imaging is a relatively new imaging modality that has become standard‐of‐care for the diagnosis and staging of many medical conditions. This has led to the widespread construction of new PET/CT installations. The design of such facilities, involving aspects of both nuclear medicine and radiology practice, presents some novel problems to the medical physicist. The recently issued report of AAPM Task Group 108, “PET and PET/CT Shielding Requirements,” addresses these difficulties and provides the designer with basic information needed for this work. The information from the report as well as the workflow in PET/CT facilities, the nature of the studies that are performed, the way in which to estimate patient workloads, and the computational approaches to radiation shielding design for high‐energy photon emitters will be discussed. Specific examples for the design of PET/CT shielding will be given.Educational Objectives:1. To discuss the recently released report of AAPM Task Group 108 on PET and PET/CT Shielding Requirements and provide some specific examples of the methods described in that report.2. To provide an overall understanding of the workflow, exam procedures, patient workloads, and radiation safety practices at PET and PET/CT imaging facilities.3. To review the approaches and necessary data for calculating shielding requirements for PET isotopes.
TH‐A‐ValB‐01: ACR CT Accreditation
Authors: Pfeiffer D 
Published: July 2006

The American College of Radiology accreditation program for computed tomography, introduced in 2002, is quickly gaining in popularity. It has established minimum standards for dose and image quality. Since the inception of the program, the scanners themselves have continued to evolve in complexity and capability. Medical physicists are required by the program to perform an annual survey of each scanner and are increasingly called upon to provide assistance with dose/image quality analyses. Thus, the involvement of medical physicists in CT is necessarily increasing.To provide optimal support for facilities in the accreditation program, it is necessary that physicists be fully aware of the requirements of the program. To that end, the essentials of the program will be briefly reviewed, including personnel requirements. The quality control component of the program will be discussed, with special attention given to the annual medical physics survey. Technologist testing requirements will also be discussed.The medical physicist can have a positive impact on the phantom images submitted as part of the accreditation process, so the site scanning instructions will be reviewed in detail, with comments made regarding common pitfalls.With the national awareness of radiation doses in CT, this area is perhaps where the physicist can have the largest impact clinically. In this lecture, the ACR accreditation program dosimetry requirements will be presented, including a discussion of common pitfalls and corrective measures.The education objectives of this program are to become familiar with:1. the general requirements for the ACR CT accreditation program2. the role and responsibilities of the medical physicist3. the image quality and dose measurements required by the program4. how to calculate CTDIw, CTDIvol, Dose Length Product and Effective Dose.
TH‐A‐224C‐02: Daily Localization ‐4: US, Calypso and AlignRT
Authors: Balter J 
Published: July 2006

Two technologies have been recently applied to commercial product development for localization and monitoring of treatment. Electromagnetic tracking, quite mature in aerospace and surgical guidance, has evolved to development of implantable markers. Video‐based surface mapping systems have been applied to a product that rapidly extracts the anterior surface of a patient as an aid to localization and motion measurement.These new systems show dramatic promise as aids to initial setup. Precision on the order of 1–2 mm has been described for both technologies. These systems act as surrogates for tumor localization inferring that either a) the patient's skin or b) implanted fiducial locations can be correlated to tumor position. For the prostate, implanted fiducials have shown acceptable accuracy when properly placed. For surface imaging, targets near/at the surface (e.g. breast cancer) should work very well. For other body sites, investigations are ongoing.In addition to rapid setup, the monitoring capability of these systems presents a paradigm that has been extremely limited to date in treatment rooms. The ability to more directly infer target position to aid in gating and tracking, especially without the use of additional ionizing radiation to the patient, may have dramatic impact on targeting accuracy.This lecture will overview these technologies, and will discuss core measurements to establish accuracy and compatibility in the radiotherapy environment. Procedures for use will be outlined, as well as potential limitations of these systems.Educational Objectives:1. Understand the operating principles of electromagnetic and surface localization.2. Overview systems using these technologies.3. Understand critical issues for commissioning of such systems.
TH‐A‐230A‐01: Heterogeneity Corrections in the IMRT Era
Authors: Papanikolaou N 
Published: July 2006

Intensity modulated radiation therapy (IMRT) has revolutionized the treatment planning process. We are now able to produce treatment plans for complex target shapes that have remarkable dose conformity while respecting the tolerance doses to critical structures. Although the emphasis has been given in the implementation of faster, more efficient, and more comprehensive optimization algorithms to solve the inverse problem, little has been done in the dose calculation aspect of the planning process. The convolution/superposition algorithm is the most popular photon dose engine used in treatment planning, while the Monte Carlo algorithm although available, remains a futuristic option.In this presentation we will discuss the algorithms that have historically been used for treatment planning with photon beams with emphasis on the convolution and Monte Carlo based methodologies and their application in IMRT planning. Clinical examples will also be presented to demonstrate the use and outcome of dose calculations in homogeneous and heterogeneous media.Educational Objectives:1. Review of dose calculation algorithms for photon beams.2. Demonstrate the effect of dose algorithm selection in IMRT planning.
TH‐B‐330A‐01: Shielding Design Workshop: CT
Authors: Martin M 
Published: July 2006

The application of the structural shielding design techniques and goals as outlined in NCRP Report 147: Structural Shielding Design for Medical X‐ray Imaging Facilities (2004) will be the basis for this practical course. The wide variety of facilities installing CT imaging equipment requires the medical physicist to consider an array of radiation protection concerns for the installation of these units. To meet the challenge of maintaining construction costs to a minimum while providing adequate radiation shielding protection requires the physicist to utilize all available materials to reduce radiation exposure to surrounding personnel and the public. Estimating future workloads as well as considering current workloads for uses of CT scanners as the ability to perform many more scans more quickly can present challenges. Practical examples of implementing multi‐slice scanners with a variety of imaging purposes into facilities with a wide variety of existing shielding materials will be explored in this course.Educational Objectives:1. Understand the methods of structural shielding design to use for sing and multi‐scan CT scanners.2. Understand the radiation exposure limits for surrounding areas occupied by the public and occupational personnel.3. Understand methods to predict applicable workloads for various types of facilities and CT scanners.
TH‐B‐224A‐01: QA for Linacs and MLC Used for IMRT
Authors: Xia P 
Published: July 2006

Intensity‐modulated radiotherapy (IMRT) has become a part of our routine treatment for external beam radiotherapy. Most quality assurance procedures set for linear accelerators and multi‐leaf collimators (MLC) have been designed for conventional external beam radiotherapy. With IMRT, radiation portals are often irregular, small, off‐center, and abutting in the middle of the target volumes, which require specific IMRT QA for the linear accelerators and MLCs. Some of the QA issues are related to the specific IMRT delivery method, and the specific treatment planning system. This review course will discuss (1) the characteristics of three major MLC collimators and the specific QA related to the unique MLC design; (2) additional QA for linear accelerators pertinent to the small MU and small field sizes used in IMRT; (3) tools often used to perform these QA tasks; (4) specific QA issues for different IMRT delivery methods, step and shoot vs sliding window.Educational Objectives:1. Understand the characteristics of three major MLC systems.2. Understand different IMRT delivery methods and their specific QA issues.3. Understand effect of QA on the IMRT delivery accuracy.
TH‐C‐330D‐01: Introduction and Overview
Authors: Sprawls P 
Published: July 2006

Medical physics education, especially for radiologists and medical physicists, is faced with several significant challenges because of a variety of conditions including the rapid changes in diagnostic and therapy technology and methods that must be addressed, prevailing attitudes on physics education within the clinical practice, and the need for qualified faculty and educational resources.Effective and efficient medical physics education for the future will result from a general re‐engineering and adopting revised models of the educational process to clearly define the needs and desired outcomes of educational activities and then develop a variety of methods and resources that will use state‐of‐the‐art technology to enhance the performance of both the learners and learning facilitators/teachers.This symposium provides a forum for exploring several current activities and initiatives that are significant to the future of medical physics education.
TH‐C‐330D‐03: Web‐Based Education: Current and Future Resources and Applications
Authors: Frey G 
Published: July 2006

The course will present a review of web based educational materials for medical physicists. This material can be divided into a number of broad categories. These include: 1) Materials that are available to the physicist that can be used as part of a program for teaching radiology residents, radiation oncology residents, medical physics students and technologists; 2) Materials that can assist the physicists in self‐directed professional development and maintenance of certification; 3) Materials that are designed for use by students and physicists in developing areas; and 4) Materials that are designed to help physicists locate and use materials in the other categories.This lecture will review materials in the various categories to assist medical physicists with locating and using appropriate materials.Educational Objectives:1. The participant will become aware of educational materials that are available on the web.2. The participant will be able to locate appropriate materials for web based SDED.3. The participant will be aware of the many different professional areas in which web based materials exist.
TH‐C‐330A‐05: Analysis of the Point Spread Function of Isocentric Digital Tomosynthesis (DTS)
Authors: Blessing M , Godfrey D , Lohr F , Yin F 
Published: July 2006

Purpose: This project presents an analysis of the point spread function (PSF) of isocentric digital tomosynthesis (DTS). DTS is a limited angle 3‐ dimensional reconstruction from cone beam projections, with high resolution for excellent imaging of both bony anatomy and soft tissue. Its major application is on‐board imaging. The scans can be acquired during a single breath hold, thus eliminating respiratory motion artifacts without gating techniques. Method and Materials: The geometry of a linear accelerator (Clinac 21EX from Varian) equipped with a kV on‐board imager and CBCT capability was used. We simulated projection data sets of a single point source (PS) for different total scan angles from 26° to 58°. The PS was located along the horizontal axis through the isocenter from the kV x‐ray source to the detector (z‐axis). DTS reconstructions were generated from the simulated projections, using a standard Feldkamp technique. The full width at half maximum (FWHM) of the resulting PSF was computed along the z‐direction in stacks of DTS slices. Results: The PSF shows a bow‐tie shape in the z‐direction. The spread of the blurring function increases for larger scan angles. Furthermore, the FWHM decreases as both distance from the detector and the scan angle increase. FWHM values ranged from ∼2.5mm to ∼5mm near the kV source, and from ∼5mm to ∼11mm near the detector, as the scan angle was varied. For a typical 44∼ scan, the FWHM varied from ∼3mm when the PS was moved 20cm towards the source away from the isocenter, to ∼6mm when was moved 24cm towards the detector. Conclusion: The blurring effect of isocentric DTS is dependent on the total scan angle and the point of interest. These characteristics will provide guidance to imaging techniques using DTS for clinical applications.This project is partially supported by Varian Medical System.
TH‐C‐330A‐07: Noise and Nodule Detectability in Simulated Cone Beam CT Imaging
Authors: Tu S , Shaw C , Lai C , Chen L , Liu X , Meng Y , Altunbas M , Wang T 
Published: July 2006

Purpose: To evaluate and quantify the impact of various types of noise (quantum noise, photon scatter, flat panel detector blurring, and system noise) on the nodule detectability in simulated cone beam CT (CBCT) images by conducting the eight‐alternative forced choice (8‐AFC) observer performance experiment. Method and Materials: We used Radon transform formalism to mathematically model a 3D chest phantom with spherical nodules of various sizes. Quantum noise, photon scatter, detector blurring, and system noise were then simulated and added to the projection images individually. The projection images were reconstructed by using the Feldkamp algorithm and the final images were then used for the observer performance study. Other impact factors for the image quality (e.g., contrast variation, x‐ray dose, nodule size, number of projection images, cone beam angle etc.) were also incorporated into the reading study. Detection curves were then determined statistically from the 8‐AFC experimental data by using a maximum‐likelihood method. Nodule detectability was then quantified directly from the reading performance participated by 6 observers in the 8‐AFC tests. Results: Our preliminary data indicated that at the high x‐ray dose level, photon scatter had the highest impact on the simulated CBCT images; while at the low dose level, system noise had the biggest impact. At all tested dose levels, detector blurring had the lowest impact on the detectability. In consistent with the previous theoretical study, the nodule detectability can be improved by increasing the number of projection images. Conclusion: Our work indicated that using photon scatter correction techniques and reducing the system noise had the biggest potential to improve the CBCT image quality. We are currently investigating the impact of various scatter reduction algorithms and reconstruction methods on the CBCT image quality.Supported in part by a research grant EB00117 by the National Institute of Biomedical Imaging and Bioengineering.