PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “X-Ray Intensifying Screens”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed1979

The Nicholas Research Award for Radiographers 1977: anatomical and radiological registration in whole body computed tomography.

Accurate registration of a section 13 mm in depth in different patients or reregistration in the same patient during whole body computed tomography is a significant problem. The method described here attempts to overcome some of these difficulties. The feasibility of using the EMI Scanner X-ray tube and a pair of Kodak Lanex intensifying screens in a vacuum pack cassette has been examined. A registration system which as an accuracy to within 1 pixel has been described. This technique has its major application in the registration and recognition of the axial skeleton, on fixed bony structures. The registration of soft tissue structures, subject to greater physiological variation poses problems which are the subject of further investigation.

Bone and Bones↗
PubMedDate not supplied

Problems associated with simulated light sensitometry for low-crossover medical x-ray films.

Over the past ten years the evolution of medical x-ray films has been toward films with reduced intensifying-screen light crossover in order to reduce blur and obtain higher spatial resolution. For films with very low crossover, misleading and incorrect sensitometric data may be obtained for film contrast evaluation and processor control if a simulated light sensitometer with a single-sided, light-exposing device is used. Screen light exposures were made using an inverse square, intensity-scale sensitometer. Simulated light exposures were made using a widely used single-sided, simulated-light sensitometer commonly used for film processor quality control, and a new simulated-light sensitometer capable of producing either single- or double-sided sensitometric exposures. The films used included one single-emulsion film and three double-emulsion medical x-ray films with light-crossover values ranging from approximately 3% to 30%. Sensitometric data showed a significant distortion (bump) in the characteristic curve for the 3% light-crossover film exposed with the single-sided, simulated-light sensitometer.

Light↗
PubMed1979

[Examinations of rare-earth film-screen-systems for image detectors in mammography (author's transl)].

Intensifying screens based on Gd2 O2 S : Tb were analysed for x-ray exposure reduction and resolution using in mammorgraphy. The contrast of these screens coupled with a single emulsion film was tested and the density dominante was determined. A resolution grid on this density exposured shows the detail resolution and judge the quality profile of these new film-screen-combinations. To all factors was compared a non-screen industrial film for long time processing. The application of Gadolinium intensifying screens in mammography allowed an exposure reduction of 75% at the same image quality like a nonscreen industrial film.

Female↗
PubMed1979

[Modern urography].

An IVP optimum quality should be tailored to the particular needs of a given case and consequently most be supervised by the radiologist when it is being performed. The most meticulous technique is needed, the adequate amount of contrast medium should be used, compression of the ureters should be performed and under optimum conditions tomography during the nephrographic phase should be performed whenever the circumstances should require it. With only very few exceptions no significant differences between different contrast media exist. The use of medium speed high contrast x-ray films as well as the use of rare earth intensifiers screens avoid the need for extremely powerful generators that are very costly. Film processing is a critical step in obtaining a good study and should be automatic.

Contrast Media↗
PubMed1978

[New aspects concerning exposure factors during direct geometrical X-ray magnification (author's transl)].

The paper is concerned with the use of rare-earth intensifying screens in order to overcome some of the exposure problems during magnification techniques using very small focal spots. Theoretical experiments and tests with biological objects indicate that the use of high intensifying screens under these circumstances is acceptable and useful. A comparison has been carried out between the results of conventional techniques without magnification and magnification techniques using very small focal spots and rare-earth intensifying screens.

Film Dosimetry↗
PubMed1979

Application of magnification radiography to the biliary system.

Magnification radiography was applied for the diagnosis of the biliary tract diseases including cancer. Our X-ray unit was consisting of HITACHI DR-155-23 U-6M-55P and 0.1 mm focal-spot tube, FFD 80 cm giving a magnification of x2 with the conditions of 60 kVp, 20 mA, 0.8 sec. Intensifying screens such as Kyokko LH II (for a standard sized subject) or DuPont Q II (for an obese subject) were used in combination with Fuji RX films. We confirmed a high diagnostic value in revealing early lesions of this sytem. The skin dose test indicated that this technique was routinely applicable with safety for clinical use.

Biliary Tract↗
PubMed1979

Contact double-contrast cholangiography.

Recently operative cholangiography has become an essential step in biliary surgery. However, an usual technique in which x-ray film is set beneath the patient has its limitation in visualization of fine changes. The author devised a new technique to resolve this problem. A triangular mammography film designed for good positioning is vaccum-packed, coupled with an intensifying screen of the same size, and then is sterilized in advance. Barium solution mixed with Gascon drop (a defoaming agent) is used as contrast material. The duodenum and head of the pancreas are mobilized. Usual cholangiography is performed at first, introducing angiographic media through a catheter placed into the catheter placed into the common duct via the cystic duct. After this study a triangle film pack is set beneath the second part of the duodenum. Two to three milliliters of barium, 1 to 2 ml of Gascon, and 15 ml of air are pushed in; thus a contact double-contrast cholangiogram is obtained. This technique promises clear demonstration of the distal bile duct without risk, and even fine mucosal plicae may be discernible in the film.

Adult↗
PubMedDate not supplied

Noise characteristics of a microchannel plate x-ray image intensifier.

The noise performance of an experimental microchannel plate x-ray image intensifier has been evaluated. The intensifier, constructed for use with photons of energies between 20 and 150 keV, uses an MCP as the photon-to-electron converter. The influence of noise was determined by analysis of the optical-density fluctuations of a photograph of the viewing screen of the intensifier when the conversion layer was exposed to between 1 and 60 mR. Additionally, the contrast-detail performance of the experimental device was determined. The influence of both stochastic noise, due to quantum mottle and pulse-height variations, and structural noise, due to fluctuations in inherent gain from point to point, have been considered by using a model that adds these components.

Models, Theoretical↗
PubMed1992

Analogous filters for beam shaping in diagnostic radiology.

A computer simulation based on photon transport calculation was used to evaluate the properties of a wide variety of materials that could be used for the filtration of x-ray beams. A single filter was added to the inherent filtration. For comparison, the concept of analogous filters was introduced: two filters were considered analogous if both produced the same ratio of entrance exposure at the patient to the energy absorbed in the detector consisting of a pair of intensifying screens positioned immediately behind the water phantom. The efficiency, contrast and integral dose were calculated for filters of odd atomic numbers from 1 to 91 with a large number of different parameters (48,600 different combinations). They include essentially all major diagnostic radiology procedures, except mammography. Only extreme cases are presented here. No magic filter was found which would produce increased contrasts or a decreased integral dose, while maintaining efficiency close to that of aluminium. Filters of some atomic numbers produced increased contrast, but had negligible efficiency. Analogous filters of atomic numbers between 7 and 37 and also between 71 and 91, had almost identical properties but varied efficiencies. Unpredictable behaviour was obtained with filters of atomic numbers 38 to 70, where small changes in atomic number may produce large changes in all the properties due to the presence of K-edge discontinuities.

Computer Simulation↗
PubMedDate not supplied

Heuristic model for understanding x-ray film characteristics.

A simple, heuristic model of a photographic emulsion is described for the purpose of illustrating the fundamental physical processes and emulsion properties which determine the characteristics of an x-ray film (viz., the shape of the H - D curve, film gamma, and film speed). By means of this model, it is shown that the contrast multiplication afforded by an x-ray film (i.e., a film gamma greater than unity) is a direct result of the exponential attenuation of the viewing light by the developed film, and that film gamma is proportional to grain size, grain density, and emulsion thickness. The difference in the H - D curve that is observed when the same film is exposed to light from an intensifying screen or directly to x rays is also predicted by the model.

Models, Theoretical↗
PubMed1991

Development of a ceiling-suspended angiographic unit for interventional neuroradiology.

A new neuroangiographic unit was developed with a ceiling-suspended gantry, capable of rotation (110 degrees) and craniocaudal angulation (+/- 45 degrees) along the body axis. The gantry could also be rotated 225 degrees at the ceiling suspension axis and sidetracked away from the angiographic table in case of emergency. Two sets of a twin-focus X-ray tube and a 12-inch image intensifier (II) were mounted on the gantry in the isocentric and cross-firing positions. High resolution 1024 x 1024 matrix digital radiography was obtained with a speed of 30 frames/s, while conventional film-screen radiography was obtained at 4 films/s. Rapid film changers were installed and interchangeable with the IIs. The lateral II and X-ray tube could be positioned from either side of the patient. There was no angulated position of the lateral imaging system during angulated anteroposterior or Towne projection of the frontal imaging system. Automatic repositioning of the gantry was possible to the preset position. Stereoscopic, magnification and stereoscopic magnification radiography could be obtained easily in monoplane or biplane mode. Switching from fluoroscopy to radiography and vice versa was possible rapidly and easily. Neuroangiographic as well as interventional procedures were performed expeditiously with lower complication rates. Suspending the gantry from the ceiling made more space available on the floor for the anesthesiologists.

Angiography↗
PubMed1979

[Comparison of screens and screen-film-systems (author's transl)].

Important details are to be payed attention in comparison of different scrreens resp. screen-film-systems: 1. Physical characteristics of different groups of luminescent materials: f.i. calcium tung-state, rare-earths compounds, double halogenides. - 2. Different types of screens: highest details up to highest speed intensifying screens, have to be defined more specifically and differentiated against to each other too. - 3. Besides intensification, resolution has to be included into consideration since one of these dates alone does not allow any statement on the total function of a screen or a screen-film-system. - 4. The technical methodological conditions of apparatuses, object and its positioning have to be defined, f.i. X-ray quality, distances, grid, and in automatically controlled exposition, if necessary, position of ionization chamber as well as absorption of cassetts and screen. - 5. Considering these points gradation curves have to include the whole necessary or interesting diagnostic range. - 6. Due to functional correlation between intensification and resolution, the resolution has to be taken in consideration due to application; its interdependence of density and object (f.i. scattered radiation) is often not taken enough in consideration.

Humans↗
PubMed1978

[X-ray dose reduction in examination of infant's hip with image-intensifier-fluoroscopy-system (author's transl)].

An image intensifier--70mm camera--fluoroscopy system combined with a conventional X-ray tube is used for routine examination of the infant's hip. The high quality of 85% of these 70mm exposures makes immediate diagnostic interpretation possible. An even higher percentage can be achieved by most exact positioning of the patients. Apart from the radiation protection of the gonades, the X-ray skin dose of the primary beam is reduced by 90-95% compared with full size radiography using film screen combinations. This exposure technique can certainly be used not only for the examination of the infant's hip.

Fluoroscopy↗
PubMedDate not supplied

A digital-radiographic technique for in vitro tissue thickness measurement using iodine displacement.

A novel digital radiographic method has been developed for measuring the thickness of a tissue sample by iodine displacement. This simple, accurate method is useful both in medical research and in the comparison of pathological and clinical findings. Radiographic measurements of tissue samples in air suffer from the limitation that the quantity measured depends on the product of both thickness and radiographic attenuation coefficient. This technique allows one to obtain thickness measurements from a digital radiograph of a tissue sample suspended in a bath of radio-opaque contrast agent. The attenuation of the iodinated contrast agent is much higher than that of tissue or calcium. Thus the resulting image is determined largely by the contour of the surrounding bath, and is only slightly influenced by the composition of the tissue. This technique improves both the accuracy and precision of radiographic thickness determination. In this paper the iodine displacement technique is described and the accuracy and precision of thickness measurements in appropriate phantoms are quantified. This technique has been used with both image intensifier and screen-film based imaging systems to obtain thickness maps of calcified human aorta, with precision better than 4% and spatial resolution of 2.5 mm-1.

Aged↗
PubMed1992

Potential of digital flashing tomosynthesis for angiocardiographic evaluation.

A system for digital flashing tomosynthesis (DFTS) consists of four electrocardiogram-gated and simultaneously flashed x-ray tubes, a 14" image intensifier, a unit for digital subtraction angiography (DSA), a personal computer-hosted transputer network for three-dimensional (3D) reconstruction as well as for quantitative coronary angiography and ventriculography, a display unit and an individual digital archive. DFTS-tomoangiograms may be presented in single slice mode or as multiple slices of arbitrary thickness, using rotating and stereographic presentation of 3D images. DFTS represents a configuration for standardized digital angiocardiography with digital archiving and assures optimal reproducibility and safety. This angiographic configuration is feasible for both ambulatory angiography to allow high volume cardiovascular angiographic screening and for the quantitative assessment of natural progression or potential regression of coronary artery disease resulting from interventional or pharmacological therapy.

Angiocardiography↗