Med Phys
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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.
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Modulation of the activity of the subthalamic nucleus (STN) using deep brain stimulation (DBS) in patients with advanced Parkinson's disease is the most common procedure performed today by functional neurosurgeons. The STN contours cannot be entirely identified on common 1.5 T images; in particular, the ventromedial border of the STN often blends with the substantia nigra. 3 T magnetic resonance imaging (MRI) provides better resolution and can improve the identification of the STN borders. In this work, we have directly identified the STN using 3 T MR imaging to validate the accuracy of a computer-aided atlas-based procedure for automatic STN identification. ⋯ All indices indicated, on average, good agreement between manually and automatically identified structures; displacement of the centers of mass of the manually and automatically identified structures was less than or equal to 2.35 mm, and more than 80% of the manually identified volume was covered by the automatic localization, on average. Bland-Altman analysis indicated that the automatic STN identification was within the limits of agreement with the manual localization on 3 T MRIs. Automatic atlas-based STN localization provides an accurate and user-friendly tool and can enhance target identification when 1.5 T scanners with limited capability to identify the STN boundaries are used.
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Intensity modulated arc therapy (IMAT) is a rotational variant of Intensity modulated radiation therapy (IMRT) that is achieved by allowing the multileaf collimator (MLC) positions to vary as the gantry rotates around the patient. This work describes a method to generate an IMAT plan through the use of a fast ray tracing technique based on dosimetric and geometric information for setting initial MLC leaf positions prior to final IMAT optimization. ⋯ The use of a ray importance factor can generate initial IMAT arcs efficiently for further MLC leaf position optimization to obtain more favorable IMAT plan.