During a radiation therapy treatment, many factors may influence the proper delivery of a calculated dose distribution. Some of these factors include misalignment of the treatment beam with respect to the patient, external or internal patient motion, or inaccurate positioning of beam-modifying devices.1 In order to quantify these geometric inaccuracies during treatment, a portal image is typica...

Foremost among the promising imaging performance characteristics of cone-beam CT using flat-panel imagers is the ability to form volumetric images with soft-tissue contrast visibility in combination with sub-millimeter 3-D spatial resolution. Each of these two essential characteristics is intimately related to the spatial-frequency-dependent signal and noise transfer characteristics of the imag...

Application of flat-panel imagers (FPIs) in cone-beam computed tomography (CBCT) offers a promising new modality for fully three-dimensional (3-D) x-ray imaging. Understanding the potential performance and fundamental limitations of such technology, however, requires knowledge of the noise characteristics of the 3-D imaging system. The noise performance of a prototype flat-panel cone-beam CT (F...

This panel highlights a selection of the most interesting and provocative papers from the 2002 New Security Paradigms Workshop. This workshop was held September 2002 the URL for more information is . The panel consists of authors of the selected papers, and the session is moderated by the workshop’s general chairs. We present selected papers focusing on exciting major theme...

This panel highlights a selection of the most interesting and provocative papers from the 2004 New Security Paradigms Workshop. This workshop was held September 2004 the URL for more information is . The panel consists of authors of the selected papers, and the session is moderated by the workshop’s general chairs. We present selected papers focusing on exciting major theme...

November 1998 2 medicamundi X-ray examinations of the skeleton are, after chest exposures, the most frequently performed type of radiological examination, representing about 30 % of the total. With a few exceptions, projection radiography forms the basis for the diagnosis of skeletal disorders and, in most cases, provides the information for the definitive diagnosis. In traumatology, rheumatolo...