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At least 19 recordsLinked to original sources
PubMed1976

Comparison of image quality obtained with optical and radiographic magnification techniques in fine-detail skeletal radiography: effect of object thickness.

High-resolution radiography may be done using either optical or radiographic magnification. In the former technique, industrial Type M film was used without screens and the image was viewed with 4-10X optical magnification. In the latter technique, RP film was used with Detail screens and 4X geometric magnification together with a microfocus x-ray tube having a nominal focal spot size of 50 mum. The imaging properties of both techniques were evaluated by means of H & D curves, modulation transfer functions, and Wiener spectra. It was found that for thin objects such as the hand, optical magnification provides better bone images than radiographic magnification; whereas for thicker parts such as the knee, radiographic magnification is superior.

Bone and Bones↗
PubMed1977

[Radiographic magnification technique with a high-speed rare-earth screen-film system (author's transl)].

The advantages of radiographic magnification technique - better detail recognition and improved contrast with an enlarged field of vision - should prove an important supplement to the properties of a high-speed rare-earth system - low-current intensity, low voltage, short exposure time and, consequently, lower irradiation dosage. Physical measurements of the Wiener spectral value, MTF and HD curve proved the superiority of the radiographic magnification technique in combination with a rare-earth screen-film system as compared with a conventional system (Dupont Par speed screen, RP films). Phantom radiographs confirmed these results. The clinical usefulness of this method was assessed with respect to the detection rate of gall-stones by means of oral cholecystography. Two out of 25 cases showed gallstones only following implementation of the radiographic magnification technique. This method seems to be particularly valuable in angiography. In 7 out of 18 abdominal angiograms and 4 out of 14 renal angiograms the number of visible vessel ramifications was greater with the magnification technique. In 5 cases valuable diagnostic information was revealed only by means of the magnification technique. Despite two-fold or 1.7-fold magnification, measurements of skin irradiation exposure showed a reduction of about half in comparison with conventional techniques. Reduced exposure to irradiation combined with improved detail resolution should ensure that this method receives an established place in routine radiodiagnosis.

Angiography↗
PubMed1977

Direct radiographic magnification for skeletal radiology. An assessment of image quality and clinical application.

Recent advances in technology have made radiographic magnification of the skeleton clinically feasible. A new electron gun micro-focal tube combined with new high-resolution recording systems were used to perform magnification radiography which was then compared with conventional contact radiography. Quantitative evaluation included measurements of speed, contrast, resolution, and noise. Qualitative evaluation included an analysis of 215 clinical cases in which both techniques were used. The superior image quality of direct radiographic magnification is confirmed and the clinical areas in which it proved most helpful are defined.

Arthritis↗
PubMed1975

[Optimal distances for direct radiographic magnification].

This paper deals with the theoretical basis for radiographic magnification. In particular, the relationship between focal size and optimal magnification for various systems is discussed. Maximal resolution was chosen as the criterion for best results. It has been shown that resolution (Lp-mm) can be improved by the reciprocal of the focal spot and for optimal magnification (see article) where f is focal spot size and AVBW is resolution of the imaging system.

Humans↗
PubMedDate not supplied

Optical versus radiographic magnification for fine-detail skeletal radiography.

Fine-detail radiographic techniques for peripheral skeletal imaging have gained wide clinical acceptance. In this study, the imaging properties and clinical applications of the optical magnification technique, which employs fine-grain industrial film and a large focal spot, are compared quantitatively and qualitatively with those of three slow screen-film techniques, namely, contact exposure with a large focal spot, 2 times radiographic magnification with a 0.3 mm focal spot, and 4 times radiographic magnification with a 50 mu focal spot. The modulation transfer functions (MTF's) of the recording systems and focal spots are obtained and film sensitometry performed. Clinical comparisons are made for patients with metabolic, arthritic, and neoplastic skeletal disorders. The results illustrate the superiority of the optical magnification technique over contact or 2 times magnification techniques using slow screen-film systems. If a microfocus tube is used, however, direct radiographic magnification may provide images comparable in resolution, noise and contrast to those made with the optical magnification technique, and at lower radiation exposure to the patient.

Arthritis, Rheumatoid↗
PubMed1977

Noise reduction by radiographic magnification.

Effective noise in the rare-earth system can be substantially reduced by use of radiographic magnification technique. The basic imaging properties of the rare-earth system (Alpha 8-XM) and the medium-speed system (Par-RP) were evaluated by the Wiener spectra, modulation transfer functions, and H&D curves. The visibility of radiographic details was determined with simple test objects. Results indicate that, as the magnification increases, the effective noise in the rare-earth system is reduced, and that the visibility of small structures can be improved.

Models, Anatomic↗
PubMed1975

[Reduction in radiation scatter during radiographic magnification techniques (author's transl)].

The reduction in scatter during magnification techniques is compared with the effect of grids. The results of extensive measurements concerning scatter and distance in a water phantom are shown in 24 diagrams. The various factors were altered as follows: distance 0-1.5 m., phantom thickness 0-27.5 cm., area 5 cm. x 5 cm. - 30 cm. x 30 cm. and kilovoltage 50-150 kv. The amount of scatter immediately behind the phantom is compared with that through a grid by observing image quality for given amounts of scatter. This "grid-equivalent" image quality can be used to determine the circumstances under which a magnification technique can be employed without using a grid.

Radiation Dosage↗
PubMed1978

Application of radiographic magnification technique with an ultra-high-speed rare-earth screen/film system to oral cholecystography.

2X magnification employing a 200-mu focal spot and an Alpha 8-XM screen/film system was applied to oral cholecystography and the results compared with those for the conventional contact technique with the Par-RP system. The basic imaging properties of the system, as well as phantom studies, indicated that the image quality obtained with magnification is comparable to or better than that for the conventional technique. In clinical studies on the detection of gallstones, the conventional technique revealed 5 true-positive and 17 true-negative cases and 1 false-positive and 2 false-negative cases, while the magnification technique provided 7 true-positive and 18 true-negative cases but no false cases. With the magnification technique the skin dose was reduced to approximately half that for the conventional contact technique.

Cholecystography↗
PubMed1978

[Role of direct radiographic magnification in the evaluation of various morphological changes].

Radiograms with direct enlargement of the image were performed by means of X-ray apparatus "PEIC" designed by the firm "Svetlana", Leningrad. The status of the hand bones was studied in persons with posttraumatic bone regeneration, as well as angioarchitectonics of organs in experimental animals. In radiograms with direct enlargement some details characterising the process of ageing in the hand bones are observed more distinctly than in routine radiograms. The investigators succeeded in obtaining age changes in the structure of spongy substance and of cortical layer of phalanxes. The apparatus "PEIC" presents new possibilities for vital investigation of bone ostructures in experimental and clinical work, as well as to examine preparations of organs and their histological sections.

Adult↗
PubMed1976

Minute mucosal patterns in gastric carcinoma. Magnification radiography of resected gastric specimens.

Magnification radiographs of 32 resected gastric specimens were used for analysis of minute gastric mucosal patterns according to the size and shape of the gastric areas and the appearances of the sulci between them. The mucosal patterns of 92 portions of stomachs were divided into 5 types and observed for correlation with their macroscopic appearances and histology. Destruction of the gastric areas and the sulci was predominant in the carcinomatous mucosa. However, among the patterns of noncarcinomatous mucosa, 18% of those with marked mucosal atrophy had abnormal mucosal patterns impossible to distinguish from carcinomatous mucosa.

Gastric Mucosa↗
PubMed1975

[Critical comment on enlargement techniques in diagnostic radiology (author's transl)].

Detail sharpness in radiographic magnification depends upon the properties of the focal spot, the screen and upon object motion. With direct magnification the finite size of the focal spot causes an increased penumbra. Uneven distribution of focal spot radiation leads to formation of false images. Radiographic magnification is rational when using a minute focal spot in combination with a poorly resolving (high speed) screen while the object remains stationary. Using high detail screens or non screen films there is no improved but possibly inferior resolution to non-magnified images, even though 0.1 mm x 0.1 mm foci are employed. Radiographic magnification performed with focal spots larger than 0.3 mm x 0.3 mm is not reasonable. Magnification procedures cause a considerable radiation exposure to the patient.

Bone and Bones↗
PubMed1977

Magnification film mammography: image quality and clinical studies.

Direct radiographic magnification (1.5 X) of the breast with a microfocus x-ray tube was compared with conventional contact mammography. Measurements of modulation transfer functions, Wiener spectra, scattered radiation, and dosimetry permitted quantitative comparisons of resolution, noise, contrast, and patient exposure. Images of surgical specimens of the breast, and the breasts of 125 patients, were qualitatively compared. Magnification images were superior (increased resolution, reduced noise) to conventional mammography images, at the expense of increased radiation dose. Clinical study revealed that the superior magnification image is useful in distinguishing malignant from benign breast disease, in selected cases.

Breast Neoplasms↗
PubMed1992

Fetal fracture healing in a lamb model.

A large animal model to assess fetal fracture repair and the ability to close excisional bony defects is presented. Incisional and excisional ulnar fractures were made in 14 midgestation fetal lambs, harvested at serial time points, and subjected to high-resolution low-kilovolt magnification radiographs, magnetic resonance imaging scans, and histologic analysis. Fetal fracture healing was characterized by early closure of excisional defects and rapid fracture healing with minimal or no soft-tissue inflammation or callus formation. Magnetic resonance imaging scans of the fractures revealed a characteristic pattern compatible with the histologic findings, namely, minimal inflammation in soft tissue adjacent to the fracture site. Histologic and magnification radiographic findings indicated that complete bony repair occurred within 21 days in incisional defects and within 40 days in excisional defects. In both cases, healed fetal bone resembled normal bone matrix. Excisional defects, including periosteum, of greater than three times the width of the bony cortex closed rapidly with virtually normal-appearing bony matrix and with minimal or no callus formation.

Animals↗
PubMed1979

Microfocal spot magnification mammography using xeroradiographic and screen-film recording systems.

Direct radiographic magnification (1.5X) of the breast, using a microfocal spot x-ray tube and either a xeroradiographic or screen-film recording system, produces images superior in quality (improved resolution, reduced noise) to conventional contact mammograms. Six hundred twenty-one patients had a single magnification mammogram in addition to conventional mammography; 216 subsequently underwent biopsy within one month of study. The additional magnification mammogram increased the diagnostic accuracy of the conventional examination in 40% of the pathologically proved cases, particularly among those for which conventional mammograms were interpreted as equivocal for malignancy. The superior image quality of magnification mammograms appears useful in distinguishing malignant from benign breast disease.

Adult↗
PubMed1979

Magnification mammography: a low-dose technique.

Image quality and radiation exposures of a mammographic technique using direct radiographic magnification at 2 X with a microfocal spot x-ray tube and a fast, double screen-film system were compared to those of conventional contact mammography with a rare-earth screen and molybdenum target tube. The results indicate that the magnification technique yields improved detection of microcalcifications and comparable visualization of soft-tissue details, with a large reduction in radiation exposure. This technique has demonstrated the feasibility of carrying out high-quality mammography with an entrance dose of 1.35 X 10(-3) Gy (135 mrad) for the average breast.

Female↗
PubMed1977

Application of longitudinal magnification effect to magnification stereoscopic angiography: a new method of cerebral angiography.

A new method of stereoscopic cerebral angiography has been developed which employs 2X radiographic magnification. In order to obtain the same depth perception in the object as with conventional contact stereoscopic angiography, one can made the x-ray exposures at two focal spot positions which are separated by only 1 inch (2.5 cm), whereas the contact technique requires a separation of 4 inches (10 cm). The smaller distance is possible because, with 2X magnification, the transverse detail in the object is magnified by a factor of two, but the longitudinal detail, which is related to the stereo effect, is magnified by a factor of four, due to the longitudinal magnification effect. The small focal spot separation results in advantages such as improved stereoscopic image detail, better image quality, and low radiation exposure to the patient.

Cerebral Angiography↗