Advanced multiple beam equalization radiography (AMBER) combined with computed radiography. Preliminary evaluation.

The combined use of AMBER (Advanced Multiple Beam Equalization Radiography) and a digital storage phosphor (SP) radiography system was evaluated for chest radiography in a pilot study with 4 patients. Four image modes with different dose levels were compared: the SP in combination with an AMBER equalized exposure (SP/AMBER) and 3 nonequalized exposures with dose levels corresponding to the respective calculated AMBER lung dose (SP/lung field dose), the calculated AMBER mediastinal dose (SP/mediastinal dose) and the calculated AMBER average dose (SP/average dose). All image modes were matched for Hurter and Driffield characteristics and subjectively rated according to visibility of details. The improved signal-to-noise (S/N) ratio of SP/AMBER resulted in a better visualization of structures in the mediastinum and the basal lung where SP/lung field dose scored lowest. For the central lung no quality differences were seen between techniques. The compressed dynamic range of the SP/AMBER images was more easily displayed on the hard-copy film. The combination of AMBER with SP radiography promises to overcome the dynamic range limitations of digital displays while, at moderate doses, giving better S/N and image quality than standard SP technique.

[Mathematical investigations of the functional tooth axis]. / Mathematisch-experimentelle Untersuchungen zur funktionellen Zahnachse.

The functional tooth axis is--contrary of the anatomical tooth axis--defined as follows: The effect of force in its direction causes a maximum of desmodontal fibres being stressed on drawing. After measure of an upper caninus, an upper and a lower molar mathematical models of the teeth and the desmodont of force are calculated with a computer simulation. A variety of functional tooth axes which are not identical with the anatomical ones, result for each tooth. The possible functional axes yield a variety which signifies the biological tolerance. This tolerance causes that many individual forms of occlusion don't have any pathological effect on the desmodont.

Cerebral listeriosis in adults. Three cases report.

The Authors describe three autoptic cases of meningoencephalitis in adults due to an emerging pathogen, the Gram-positive bacillus Listeria monocytogenes. Only one of these was an immunosuppressed patient (recurrent carcinoma of the larynx and bladder papillomas), while no severe cause of debilitation was detected in the other two cases, excluding colonic diverticulosis in both. The post-mortem examination revealed leptomeningitis and encephalitis. Lympho-monocytic tissue reaction with perivascular cuffing was present in all the cases. The etiologic agent, L. monocytogenes, was identified by cultures from clinical or autoptic specimens.

[Significance of duodenogastric reflux in the pathogenesis of primary stomach cancer]. / Zur Bedeutung des duodenogastralen Refluxes in der Pathogenese des primären Magenkarzinoms.

Duodenogastric reflux has often been discussed as a causative factor in the pathogenesis of gastric carcinoma. The author's clinical examinations of 135 patients with primary cancer of the stomach revealed slight increase in duodenogastric reflux. Yet, apart from these findings, no correlations were found to exist between reflux incidence and tumour localisation nor between histological tumour type and tumour size.

Cardiac gating in intravenous DSA.

ECG-gating of a pulsed radiation exposure during end-diastole using digital subtraction angiography shows significantly better results in the examination of the aortic arch vessels and pulmonary arteries and may be expected to decrease the rate of false positive diagnosis of stenosis when examining renal arteries. Different types of misregistration artifacts due to a smear effect by integrating several television frames using non-gated DSA are described and schematically explained. Furthermore, a short description of the difficulties which may be encountered with ecg-gated DSA--mainly rapid changes of heart frequency--is given.

Digital subtraction angiography (DSA): new perspectives in angiography.

Digital subtraction angiography (DSA) has strongly influenced angiographic procedures. Because it is less invasive it has increased the total number of angiographies in all places where it was introduced. The paper gives an introduction to the procedure explaining the roles of "digital" and "subtraction" in DSA. It is written from a technical point of view. The examples are taken from and with the DVI system.

Digital subtraction angiography: fundamental noise characteristics.

Detectability of low-contrast objects (vessels) in subtraction imaging depends on the noise properties of the image. There is a structure imposed upon the quantum noise that is due to the attenuation of the subtracted background object; this structure is referred to as a "noise print." It is shown to be a function of the manner of presubtraction processing (linear or logarithmic) and the local thickness of the attenuator in the x-ray beam path. The influence of the noise print on the visibility of vessels in subtraction images is demonstrated.

[Roentgen pictures in the digital image]. / Röntgenbilder in digitaler Darstellung.

In addition to computed tomography which presents actually the most important processing and transfer procedure of digital X-ray images, application of real time addition and subtraction of X-ray images in a digital mode has found considerable interest. An estimation of the information contents of both digital and analog images is made in close relation to applications. As example of an image processing system on digital base a recently developed system for intravenous arteriography is described: the Philips-DVI.

[Format and image contents of x-ray picture (author's transl)]. / Format und Bildinhalt.

This article is essentially on the lines of the paper read at the German Congress of Radiologists ("Deutscher Röntgenkongress") at Münster. It deals with the visual interpretation of the contents of roentgenographic films of widely different origin. On going deeper into the subject, it was found that by examining the pictures for structural contents as far as the image permits, it becomes possible to obtain a survey of all the usually prepared x-ray photographs--a viewpoint which has so far been greatly neglected. Knowledge of the conditions of observation and of the prerequisites is promoted at the same time. The need for radiation protection is re-emphasized from a new angle.

[Technical requirements for taking radiograms of the temporomandibular joint]. / Apparative Voraussetzungen zur Anfertigung von Nativ-Aufnahmen der Kiefergelenke

The technical possibilities for taking roentgenograms of the temporo-mandibular joint according to Schüler's projection are analyzed. This study also includes intraoral x-ray sources. The latter is usable for temporo-mandibular joint radiograms to a very limited degree only.

[Simple tests to control a tomographic device (author's transl)]. / Einfache Prüfmethoden für ein Schichtgerät

Simple tests to prove the resolution sharpness and blurring of a tomographic system are described.