Med Phys
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MRI is rapidly growing as a tool for image-guided procedures in the breast such as needle localizations, biopsy, and cryotherapy. The ability of MRI to resolve small (<1 cm) lesions allows earlier detection and diagnosis than with ultrasound. Most MR-guidance methods perform a two-dimensional compression of the breast that distorts tissue anatomy and limits medial access. ⋯ Target lesions were 3-4 mm in diameter for 47% (13/28), 5-6 mm in diameter for 32% (9/28), and over 6 mm in diameter for 21% (6/28) of the trials, respectively. The 3D bladder concept was shown to immobilize a deformable animal tissue phantom during needle insertion. It is concluded that the MR-guidance system accurately localizes small targets on the order of 3-4 mm in a breast phantom with 360 degrees rotational access.
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Separation of water from fat tissues in magnetic resonance imaging is important for many applications because signals from fat tissues often interfere with diagnoses that are usually based on water signal characteristics. Water and fat can be separated with images acquired at different echo time shifts. The three-point method solves for the unknown off-resonance frequency together with the water and fat densities. ⋯ The NSA is particularly poor for the symmetric (-theta, 0, theta) CS encoding when the water and fat signals are comparable. This anomaly with equal amounts of water and fat is analyzed in a more intuitive geometric illustration. Theoretical prediction of NSA matches well with simulation results at high signal-to-noise ratio (SNR), while deviation arises at low SNR, which suggests that Monte Carlo simulation may be more appropriate to accurately predict noise performance of the algorithm when SNR is low.
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The authors present a new computerized scheme to automatically detect lung nodules depicted on computed tomography (CT) images. The procedure is performed in the signed distance field of the CT images. To obtain an accurate signed distance field, CT images are first interpolated linearly along the axial direction to form an isotropic data set. ⋯ This preliminary study demonstrates the feasibility of applying a simple and robust geometric model using the signed distance field to identify suspicious lung nodules. In the authors' data set the sensitivity of this scheme is not affected by nodule size. In addition to potentially being a stand alone approach, the signed distance field based method can be easily implemented as an initial filtering step in other computer-aided detection schemes.
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The fifth Bioengineering and Image Research Opportunities Workshop (BIROW V) was held on January 18-19, 2008. As with previous BIROW meetings, the purpose of BIROW V was to identify and characterize research and engineering opportunities in biomedical engineering and imaging. The topic of this BIROW meeting was Imaging and Characterizing Structure and Function in Native and Engineered Tissues. Under this topic, four areas were explored in depth: (1) Heterogeneous single-cell measurements and their integration into tissue and organism models; (2) Functional, molecular and structural imaging of engineered tissue in vitro and in vivo; (3) New technologies for characterizing cells and tissues in situ; (4) Imaging for targeted cell, gene and drug delivery.
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The following article represents a view of the professional aspects and endeavors of the American Association of Physicists in Medicine (AAPM) through the eyes and experiences of the current Professional Council Chair, information gathered from previous Council chairs and AAPM documents. Over its 50 year history the AAPM has made numerous contributions to the profession and practice of medical physics, through leadership and collaboration. Throughout this period the association went through growing pains and struggled to define and establish the proper level of professional responsibilities and commitment. It is likely that as medicine changes and the profession continues to evolve, that the AAPM will continue to grow, struggle, and adapt to address the future direction of medical physics.