1. 51st AAPM Annual Meeting
    Mats Danielsson, PhD, Royal Institute of Technology, Stockholm, 10691, SWEDEN
    For more information about the American Association of Physicists in Medicine, visit aapm.org/

    AbstractID: 11927 Title: Photon Counting Detectors for Mammography
    Mammography is currently one of the most common x-ray imaging examinations. More than
    100 million women worldwide are screened every year and early detection of breast cancer
    through mammography has proven to be a key to significantly reduced mortality. The
    requirement on spatial resolution as well as contrast resolution is very high in order to detect
    and diagnose the cancer. Moreover, because of the large number of women going through this
    procedure and the fact that more than 99 % are healthy, it also becomes very important to
    minimize the radiation dose.
    Photon counting may be one way to meet the demands and mammography is the first
    modality in x-ray imaging to implement photon counting detectors. FDA approval is still
    pending but they are currently in routine clinical use in more than 15 countries. The photon
    counting enables a discrimination of all electronic noise and a more optimum use of the
    information in each x-ray. The absence of electronic noise is particularly important in low
    dose applications, in for example tomosynthesis a number of exposures from different angles
    are required and since the dose in each projection is just a fraction of the total dose for a
    mammogram the sensitivity to electronic noise will increase.
    Using the spectral information for each x-ray it is in principle possible to deduce the
    elemental composition of an object in the breast. This could for example be used to enhance
    microcalcifications relative to soft tissue and differentiate water from fat in cysts. Recently
    contrast mammography has attracted significant attention. In this application Iodine is used as
    a contrast media to visualize the vascular structure. As in breast MRI the cancer stand out
    because of the leaky vessels resulting from its angiogenesis. A photon counting detector gives
    a unique opportunity to image the Iodine through spectral imaging by adjusting one of the
    thresholds to its K-edge.
    Challenges for photon counting in mammography are high rates of x-rays, both to generate
    the required flux at the source and to handle the rates at the detector without pile-up. Even
    more difficult to handle are the charge sharing between detector pixels which, if not corrected
    for, will compromise the energy information.
    The current status of photon counting detectors in mammography will be described together
    with strategies to overcome the pit-falls. Also future possibilities with spectral imaging in
    mammography will be investigated and examples from ongoing clinical trials will be given.
    Learning objectives:
    1) Status of photon counting detectors in mammography
    2) Pit-falls and opportunities with photon counting detectors for mammography
    3) Future applications based on spectral detectors for mammography

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  2. 51st AAPM Annual Meeting
    Reuven Levinson, GE Healthcare, Haifa, ISRAEL
    For more information about the American Association of Physicists in Medicine, visit aapm.org/

    AbstractID: 11928 Title: Clinical CT Applications with Photon-Counting
    Detectors
    Photon-counting detectors are now being introduced in medical imaging systems. A
    major challenge for PC detectors is to enable high count rate operation required for
    medical imaging. High count rate operation is now available with state-of-the art
    pulse counting electronics. Pulse counting techniques can work together with directconversion
    sensors enabling additional cost and performance benefits versus indirectconversion
    sensors.
    PC detectors are easily configurable for multi-energy acquisitions, enabling dual and
    triple (k-edge) imaging techniques. The energy discrimination and binning by PC
    detectors competes well with the energy separation achieved with dual kVp imaging
    systems and provides unique performance capabilities for triple/k-edge imaging.
    PC detectors have been shown to have negligible levels on electronic noise. The low
    noise performance enables new scanning techniques and ultimately reduces the
    radiation dose the patient, an important consideration in the design of X-ray imaging
    systems.
    This lecture will provide an overview on the use of photon-counting detectors in dualenergy
    CT imaging and image quality on clinical CT applications.
    Learning objectives:
    1. Understand the operation of direct-conversion, photon-counting detectors
    2. Application of photon-counting detectors to multi-energy CT imaging
    3. Use of photon counting CT system in a clinical setting

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  3. 51st AAPM Annual Meeting
    Michael K. O'Connor, PhD, Mayo Clinic, Rochester, MN, 55905, US
    For more information about the American Association of Physicists in Medicine, visit aapm.org/

    AbstractID: 11931 Title: Molecular Imaging of the Breast
    Recent controversy over the efficacy of screening mammography highlights the need for more effective breast imaging techniques. While the
    sensitivity of mass breast cancer screening with mammography is in the range 60% - 90%, numerous studies have demonstrated that this
    sensitivity is reduced to less than 50% in radiographically dense breasts. Hence there is need for an alternative screening technique, particularly in
    women with radiographically dense breasts. A recent ACRIN trial shows that whole breast ultrasound had comparable performance to
    mammography. Breast MRI performs very well in this population, but high cost and variable specificity limit its application.
    Conventional scintimammography has a high overall sensitivity and specificity for the detection of breast cancer. However sensitivity drops to
    ~50% for the detection of breast lesions less than 15 mm in diameter, making it unsuitable as a diagnostic or screening tool. Molecular Breast
    Imaging (MBI) refers to a new technique that employs small field of view gamma cameras specifically designed for breast imaging. These
    cameras utilize either multi-crystal arrays of Sodium Iodide (NaI) or more recently, use semiconductor materials such as Cadmium-Zinc-
    Telluride (CZT). Using Tc-99m sestamibi as the primary radiopharmaceutical, MBI has been shown to have a high sensitivity (~90%) for the
    detection of breast lesions < 10 mm in diameter. Hence, MBI may be a valuable screening tool, particularly for women in whom the sensitivity
    of conventional mammography is reduced by the density of the breast parenchyma.
    This presentation will review the basic principles of molecular breast imaging, and present current clinical results. It will also present details of
    prototype systems currently under development and future plans for this technology.
    Learning Objectives:
    1. Understand the limitations of current imaging techniques of the breast, including mammography, ultrasound, MRI and scintimammography.
    2. Understand the basic concept of multi-crystal and semiconductor-based gamma cameras.
    3. Describe the relative advantages and disadvantages of scintimammography and molecular breast imaging.
    4. Understand the potential advantages/disadvantages and future applications for this technology in the detection and understanding of breast
    cancer.

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  4. 51st AAPM Annual Meeting
    Keith Paulsen Ph.D., Dartmouth Medical School, Hanover, NH, 03755-8000, US
    For more information about the American Association of Physicists in Medicine, visit aapm.org/


    AbstractID: 11932 Title: MR-Guided Near Infrared Spectral Tomography of the Breast
    Near-infrared (NIR) spectral tomography applies and records multiple wavelengths of light in the 700-850 nm range through a transceiving multifiber
    array in order to estimate absorption chromophores and scattering parameters within tissue. The technique provides important functional
    information associated with local concentrations of oxygenated and deoxygenated hemoglobin, oxygen saturation, and water and lipid fractions
    but on a centimeter spatial scale. In an effort to improve the spatial discrimination of these molecular characteristics of tissue, the technique has
    been combined with high resolution anatomical information obtained from MRI. Technical developments have lead to a simultaneous multimodality
    breast exam which combines the spectral NIR information with the data obtained during a dynamic contrast-enhanced breast MR study.
    Commercial and custom breast coils have been populated with a 16-channel fiber optical array and concomitant data acquisition module to
    explore the clinical potential of the approach. Clinical breast exams involving women with asymptomatic and symptomatic screening and
    diagnostic ammography along longitudinal studies of women with locally advance breast cancer receiving neoadjuvant chemotherapy have been
    performed. Results will be presented from anecdotal case reports as well as statistically valid findings from small clinical study designs and
    phantom experiments which indicate that the technique produces quantitative estimates of the NIR functional parameters at substantially
    improved spatial resolution relative to NIR spectral tomography when used in the breast alone.
    Learning Objectives:
    1. To learn the basic physical principles of NIR spectral tomography.
    2. To learn the basic clinical and physical characteristics of combined MR and NIR spectral tomography.
    3. To learn the latest clinical breast imaging results from the technology as developed by Dartmouth investigators.

    # vimeo.com/88174683 Uploaded 63 Plays 0 Comments
  5. 51st AAPM Annual Meeting
    Wei Zhao, PhD, SUNY Stony Brook, Stony Brook, NY, 11794-8460, US
    For more information about the American Association of Physicists in Medicine, visit aapm.org/

    AbstractID: 11930 Title: Recent Advances in Breast Tomosynthesis
    This presentation in the symposium is focused on the recent advances in digital breast
    tomosynthesis (DBT). DBT is a three-dimensional (3D) x-ray breast imaging technique.
    Several projection images of the breast are obtained from different angles, and image
    reconstruction is used to generate cross-sectional slices (with 1 mm thickness) that are
    parallel to the detector. Several DBT prototype systems have been developed by different
    manufacturers through modification of screening full-field digital mammography (FFDM)
    systems. The x-ray tube gantry typically rotates around the compressed breast with a
    limited angular range (15 to 60 degrees) and acquires a limited number of images (11 to
    49). In this presentation, an overview of the following aspects of DBT will be provided:

    1. Different approaches to system implementation of DBT, and their advantages and
    limitations;
    2. Comparison of different image reconstruction methods, including filtered back projection (FBP) and iterative reconstruction;
    3. Special considerations for DBT compared to conventional projection mammography: scattered radiation, x-ray spectrum and detector performance;
    4. Methods for the evaluation and optimization of DBT image quality;
    5. Clinical results of breast cancer detection using DBT and its comparison with projection mammography; 6. Combination of DBT with other 3D imaging methods for multi-modality breast imaging applications.

    # vimeo.com/88174685 Uploaded 83 Plays 0 Comments

2009 AAPM Annual Meeting

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