[en] Although field area and object thickness are important parameters in comparisons of techniques for optimal reduction of scattered radiation to the image, they are in practice seldom varied. The authors suggest that contrast degradation (CDF) and contrast improvement (CIF) factors be more frequently used and appropriately defined to make the dependence of CDF and CIF on field area (collimation) and object thickness (compression) explicit. Definitions are formulated and the results of experiments and Monte Carlo calculations (comprising effects of collimation, compression, air gap, antiscatter grid, detector thickness) cited to illustrate their usefulness. Currently used expressions for CIF (derived assuming monoenergetic radiation) lack a vector to account for the change in primary contrast caused by the antiscatter method when this affects the energy distribution of the transmitted primary photons (grids and compression) or the fractions of photon energy imparted to the detector (when comparing different detectors). Values of this factor are calculated for some cases. The appropriate choice of physical quantity to be used in the formulae for CDF and CIF is discussed. The energy imparted to the detector is advocated since this is directly related to the detector signals forming the image on, e.g. the x-ray film. (author)

[en] For many years routine operative cholangiography has involved the taking of two or three radiographs using a mobile radiography unit. Operative fluorocholangiography is an alternative procedure which utilizes a mobile image intensifier. With the addition of a videotape recorder it provides rapid and effective visualization of bile duct anatomy plus the advantages of a dynamic image and immediate replay facility. A technique for operative fluorocholangiography is described and discussed. 10 refs., 4 figs., 1 tab

[en] In this paper general guidance is offered in the area of facility preparation and planning for diagnostic medical imaging systems. Primary emphasis is given to aspects of project management and general facility requirements. A project management tool known as the critical path method is illustrated by its application to a general purpose radiographic/fluoroscopic suite

[en] In 1993, an undertable fluoroscopic system was retrofitted with a Fluorospot HC digital system at the radiological clinic of the Knappschaftskrankenhaus in Puettlingen, Germany. The experiences and possibilities resulting from this digital upgrade are related by the authors, whose narrative is also accompanied by examples of clinical images. The costs involved are also discussed in this article. (orig.)

[en] Purpose: This work involves the development of a new digital tomosynthesis technique into a clinical prototype imaging system for the three-dimensional visualization of patient anatomy. Material and Methods: The multiple projection algorithm (MPA) has been developed into a clinical prototype imaging system comprising a digital chain that is interfaced with an isocentric fluoroscopic unit to form an integrated DTS facility. Planes of varying orientations can be synthesized retrospectively on the basis of an acquired set of appropriate projection images extending over the whole volume of interest. Results and Conclusion: The system provides an image reconstruction and processing facility that can effectively augment fluoroscopic examinations. Reconstruction times of a few seconds per plane have been achieved. The region of interest can be approached by tracking through cross-sections with user-selected orientations. Anatomical planes of particular interest can be identified and their reconstructed images can be stored. The characteristics of the image presentation modality have the potential to extend the field of current digital tomosynthesis applications to new areas in radiology and other clinical domains. (orig.)

[en] Subject of this standard is a procedure for determination of the modulation transmission function (MTF). (orig./HP)

[en] The purpose of this paper is to describe some applications of MR fluoroscopy. These results were obtained using MR fluoroscopy system, which combines a General Electric 1.5T MR imager with the authors' custom-built reconstruction equipment. Many results derive from what is one of the more useful system features, the ability to modify scan-control parameters during imaging and to instantly see the results. Interactive MR imaging allows the operator to optimize scan-control parameters for the specific imaging situation

No abstract available

No abstract available

[en] A cross-sectional view is usually taken before the course of treatment and used in the planning stages. It is often assumed that the information remains valid throughout the treatment period, although in some cases this may be unjustified. Consideration should therefore be given to the determination of cross-sectional information at intervals throughout the treatment period so that changes in tumor size and position or in the patient's size and shape may be checked. For this purpose the cross-sectional imaging device must obviously demonstrate acceptable geometrical reproducibility. The determination of the entire cross-sectional view is often accomplished in two distinct stages. First, the position of the skin surface is determined. Second, the anatomic contents of the particular cross section are elucidated. Section I.B describes methods that give only the surface outlines, with no other information, and Secton I.C describes methods of obtaining internal anatomic information. Some of the latter methods also provide complementary surface outline information