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At least 811 records · Page 45Linked to original sources
PubMed2003

Dual focal-spot imaging for phase extraction in phase-contrast radiography.

The purpose of this study was to evaluate dual focal spot imaging as a method for extracting the phase component from a phase-contrast radiography image. All measurements were performed using a microfocus tungsten-target x-ray tube with an adjustable focal-spot size (0.01 mm to 0.045 mm). For each object, high-resolution digital radiographs were obtained with two different focal spot sizes to produce matched image pairs in which all other geometric variables as well as total exposure and tube kVp were held constant. For each image pair, a phase extraction was performed using pixel-wise division. The phase-extracted image resulted in an image similar to the standard image processing tool commonly referred to as "unsharp masking" but with the additional edge-enhancement produced by phase-contrast effects. The phase-extracted image illustrates the differences between the two images whose imaging parameters differ only in focal spot size. The resulting image shows effects from both phase contrast as well as geometric unsharpness. In weakly attenuating materials the phase-contrast effect predominates, while in strongly attenuating materials the phase effects are so small that they are not detectable. The phase-extracted image in the strongly attenuating object reflects differences in geometric unsharpness. The degree of phase extraction depends strongly on the size of the smallest focal spot used. This technique of dual-focal spot phase-contrast radiography provides a simple technique for phase-component (edge) extraction in phase-contrast radiography. In strongly attenuating materials the phase-component is overwhelmed by differences in geometric unsharpness. In these cases the technique provides a form of unsharp masking which also accentuates the edges. Thus, the two effects are complimentary and may be useful in the detection of small objects.

Algorithms↗
PubMed2005

Performance comparison of an active matrix flat panel imager, computed radiography system, and a screen-film system at four standard radiation qualities.

Four standard radiation qualities (from RQA 3 to RQA 9) were used to compare the imaging performance of a computed radiography (CR) system (general purpose and high resolution phosphor plates of a Kodak CR 9000 system), a selenium-based direct flat panel detector (Kodak Direct View DR 9000), and a conventional screen-film system (Kodak T-MAT L/RA film with a 3M Trimax Regular screen of speed 400) in conventional radiography. Reference exposure levels were chosen according to the manufacturer's recommendations to be representative of clinical practice (exposure index of 1700 for digital systems and a film optical density of 1.4). With the exception of the RQA 3 beam quality, the exposure levels needed to produce a mean digital signal of 1700 were higher than those needed to obtain a mean film optical density of 1.4. In spite of intense developments in the field of digital detectors, screen-film systems are still very efficient detectors for most of the beam qualities used in radiology. An important outcome of this study is the behavior of the detective quantum efficiency of the digital radiography (DR) system as a function of beam energy. The practice of users to increase beam energy when switching from a screen-film system to a CR system, in order to improve the compromise between patient dose and image quality, might not be appropriate when switching from screen-film to selenium-based DR systems.

Radiographic Image Enhancement↗
PubMed2006

Digital radiography. A comparison with modern conventional imaging.

The development of computed radiography over the past two decades has transformed radiological imaging. The radiology departments in the 21st century will look very different from those in the preceding period. In this review, the development of digital radiography is presented with a description of its various forms and a comparison with screen film radiography.

Costs and Cost Analysis↗
PubMed2001

Image quality and dose comparison among screen-film, computed, and CT scanned projection radiography: applications to CT urography.

PURPOSE: To evaluate image quality and dose for abdominal imaging techniques that could be used as part of a computed tomographic (CT) urographic examination: screen-film (S-F) radiography or computed radiography (CR), performed with moving and stationary grids, and CT scanned projection radiography (CT SPR). MATERIALS AND METHODS: An image quality phantom underwent imaging with moving and stationary grids with both a clinical S-F combination and CR plate. CT SPR was performed with six CT scanners at various milliampere second and kilovolt peak settings. Entrance skin exposure (ESE); spatial, contrast, and temporal resolutions; geometric accuracy; and artifacts were assessed. RESULTS: S-F or CR images, with either grid, provided image quality equivalent to that with the clinical standard, S-F with a moving grid. ESE values for both S-F and CR were 435 mR (112.2 microC/kg [1 mR = 0.258 microC/kg]) with a moving grid and 226 mR (58.3 microC/kg) with a stationary grid. All CT SPR images provided inferior spatial resolution compared with S-F or CR images. High-contrast objects generated substantial artifacts on CT SPR images. Compared with S-F, CR and CT SPR provided improved resolution of small low-contrast objects. The contrast between iodine and soft-tissue-mimicking structures on CT SPR images acquired at 80 kVp was twice that at 120 kVp. CT SPR images with acceptable noise levels required a midline ESE value of approximately 300 mR (77.4 microC/kg) at 80 kVp. CONCLUSION: S-F and CR provided better spatial resolution than did CT SPR. However, CT SPR provided improved low-contrast resolution compared with S-F, at exposures comparable to those used for S-F or CR.

Equipment Design↗
PubMed1991

Skull radiography in the evaluation of acute head trauma: a survey of current practice.

A survey was conducted to determine the extent to which skull radiography continues to be used for the evaluation of head trauma. Of 53 hospitals with emergency departments and computed tomography (CT) available full time, only 6% (n = 3) reported that skull radiographs were never a part of the evaluation of acute head injuries. At more than half of the institutions, skull radiographs were obtained always or often in cases of head trauma. High usage rates occurred at teaching and nonteaching institutions and were not related to the availability of CT or the size of the hospitals. CT was always employed in cases of severe head trauma, and skull radiography was frequently used in cases of minor injuries. Magnetic resonance imaging was rarely, if ever, used for evaluating head trauma. Skull radiography continues to be employed at a high rate for the evaluation of head trauma long after it has been demonstrated to provide little or no useful information in such cases.

Acute Disease↗
PubMed1994

Stress radiography of the medial elbow ligaments.

PURPOSE: To study the usefulness of stress radiography for evaluation of injury to the medial collateral ligament (MCL). MATERIALS AND METHODS: Forty-two injured athletes and four healthy athletes without symptoms underwent examination performed with a stress device. The increase in joint space width between the medial epicondyle and coronoid process, measured on anteroposterior radiographs obtained after 0 and 15 daN force was applied to the lateral elbow joint, was used to assess the extent of ligament tear. The validity of this technique was tested with study of selectively severed cadaveric MCLs. RESULTS: All complete and large partial tears were correctly diagnosed with stress radiography when the increase in joint space width was larger by 0.5 mm in the affected elbow compared with the opposite normal elbow. In subjects with values less than 0.5 mm, the MCLs were normal or showed a small tear that could be managed conservatively. CONCLUSION: Stress radiography of the MCL enables accurate diagnosis of large and complete tears and distinction between such tears and small partial tears and normal ligaments.

Arthrography↗
PubMed1994

Chronic ankle instability: evaluation with MR arthrography, MR imaging, and stress radiography.

PURPOSE: To compare the efficacy of conventional magnetic resonance (MR) imaging, MR arthrography, and stress radiography in the detection of lateral collateral ligament abnormalities in patients with chronic ankle instability. MATERIALS AND METHODS: Seventeen patients with chronic lateral ankle instability underwent stress radiography, MR imaging, and MR arthrography after intraarticular injection of gadopentetate dimeglumine. Imaging findings were correlated with surgical findings. RESULTS: The anterior talofibular (ATF) ligament was torn in 14 patients, and the calcaneofibular (CF) ligament was torn in 10. MR arthrography was more accurate and sensitive in the detection of ATF tears than was MR imaging or stress radiography (P < or = .05). Associated injuries were detected with both MR imaging and MR arthrography. CONCLUSION: MR arthrography is a sensitive technique for detecting and staging tears of the lateral collateral ligaments.

Adult↗
PubMed1997

Accuracy of detection and measurement of renal calculi: in vitro comparison of three-dimensional spiral CT, radiography, and nephrotomography.

PURPOSE: To compare accuracy of three-dimensional (3D) spiral computed tomography (CT) performed without administration of contrast material with that of radiography and linear nephrotomography in detection and measurement of renal calculi. MATERIALS AND METHODS: Fifty renal calculi within an abdominal phantom were imaged with 3D spiral CT, radiography, and linear nephrotomography. Spiral CT data were analyzed with workstation-based 3D imaging software, with a thresholding procedure based on the maximally attenuating voxel within each calculus during measurement. Measurement accuracy and detection rates were compared according to modality. Conventional and magnification-corrected measurements from radiography and linear nephrotomography were included. RESULTS: Spiral CT depicted calculi and allowed determination of the collective two-dimensional and 3D linear measurements statistically significantly more accurately than the other techniques; the mean linear measurement errors along individual axes did not exceed 3.6%. With 3D spiral CT, calculus volumes were determined with a mean error of -4.8%. CONCLUSION: 3D spiral CT enabled highly accurate determination of the volumes and all three linear dimensions of renal calculi. In addition, 3D spiral CT depicted calculi more sensitively than traditional techniques and provided new information and improved accuracy in the evaluation of nephrolithiasis.

Bias↗
PubMed1996

Radiation dose reduction in computed skeletal radiography. Effect on image quality.

PURPOSE: To evaluate the effect of radiation dose reduction on image ++quality in computed musculoskeletal radiography and determine optimal exposure range. MATERIAL AND METHODS: In 11 corpses, 1 hand and 1 hip were examined with film-screen radiography, and a series of computed radiographs was obtained using exactly the same technique except for the exposure, which was 100, 50, 25, 12.5, 6.25, and 1.56% of the mAs numbers used for the film-screen images. The computed hip radiographs were processed in 2 different ways, one simulating the film-screen images and one using contrast enhancement. Four radiologists reviewed the images regarding the following parameters: cortical bone, trabecular bone, joint space, and soft tissue, giving each a diagnostic quality rating on a scale from 1 to 5. The median and mean values were found for the pooled results. RESULTS: For the hands, the computed radiographs were ranked inferior to the film-screen images for all parameters except soft tissue, where the computed radiographs scored higher. The computed images with 50 and 25% exposure were ranked equal to the 100% ones. The quality rating slowly declined with lower exposures. For the hips, the 100 and 50% computed radiographs were generally similar to or slightly better than the film-screen images. The decline was somewhat faster than for the hands. The contrast-enhanced hip images scored less than the nonenhanced images at any given exposure for all parameters except soft tissue, where the contrast-enhanced images scored better at all exposures. The difference between nonenhanced and enhanced images became less at the lower exposures. CONCLUSION: Lowering the exposure in computed musculoskeletal radioagrphy below the level of film-screen radiography is feasible, especially in the peripheral skeleton. Contrast enhancement seems to be valuable only in the evaluation of soft-tissue structures.

Bone and Bones↗
PubMedDate not supplied

Magnification and high-resolution radiography in sports-related injuries.

Magnification, or high-resolution radiography, is a widely accepted technique and is currently used in angiography, mammography and pediatric chest radiographs. Small avulsion fractures of the bones of the hand and stress fractures of th tibia are examples of two areas where the fracture may not be apparent on conventional films, although in many cases magnification radiography will demonstrate the lesions. Six representative case histories are provided to illustrate the use of magnification radiography in sports-related injuries.

Adolescent↗
PubMed2006

Ultrasonography of the metacarpophalangeal and proximal interphalangeal joints in rheumatoid arthritis: a comparison with magnetic resonance imaging, conventional radiography and clinical examination.

Signs of inflammation and destruction in the finger joints are the principal features of rheumatoid arthritis (RA). There are few studies assessing the sensitivity and specificity of ultrasonography in detecting these signs. The objective of the present study was to investigate whether ultrasonography can provide information on signs of inflammation and destruction in RA finger joints that are not available with conventional radiography and clinical examination, and comparable to the information provided by magnetic resonance imaging (MRI). The second to fifth metacarpophalangeal and proximal interphalangeal joints of 40 RA patients and 20 control persons were assessed with ultrasonography, clinical examination, radiography and MRI. With MRI as the reference method, the sensitivity, specificity and accuracy of ultrasonography in detecting bone erosions in the finger joints were 0.59, 0.98 and 0.96, respectively; they were 0.42, 0.99 and 0.95 for radiography. The sensitivity, specificity and accuracy of ultrasonography, with signs of inflammation on T1-weighted MRI sequences as the reference method, were 0.70, 0.78 and 0.76, respectively; they were 0.40, 0.85 and 0.72 for the clinical examination. With MRI as the reference method, ultrasonography had higher sensitivity and accuracy in detecting signs of inflammation and destruction in RA finger joints than did clinical and radiographic examinations, without loss of specificity. This study shows that ultrasonography has the potential to improve assessment of patients with RA.

Adult↗
PubMed2001

Artefacts found in computed radiography.

Artefacts on radiographic images are distracting and may compromise accurate diagnosis. Although most artefacts that occur in conventional radiography have become familiar, computed radiography (CR) systems produce artefacts that differ from those found in conventional radiography. We have encountered a variety of artefacts in CR images that were produced from four different models plate reader. These artefacts have been identified and traced to the imaging plate, plate reader, image processing software or laser printer or to operator error. Understanding the potential sources of CR artefacts will aid in identifying and resolving problems quickly and help prevent future occurrences.

Artifacts↗
PubMed1982

Cine radiography in cervical spondylosis as a means of determining the level for anterior fusion.

A series of 75 patients who had undergone anterior cervical fusion between 1965 and 1977 were reviewed. The patients were divided into two groups: those in Group A had had the level of fusion indicated by cine radiography, whereas in Group B the level had been determined by plain radiographs and clinical symptoms and signs. Results showed that cine radiography was the more accurate diagnostic technique. Accurate diagnosis of the level to be fused, the careful clinical selection of patients and sound bony union were found to be vital to the success of anterior cervical fusion. The incidence of pseudarthrosis was significant in single-level fusions and was even greater in double-level fusions and in patients with a history of trauma, especially whiplash injuries. It was rare to develop recurrence of symptoms in adjacent levels after fusion of a level localised by cine radiography.

Adult↗
PubMed2005

Comparison of dual-energy X-ray absorptiometry and conventional radiography for the detection of vertebral fractures.

Prevalent vertebral fractures confer a high risk of subsequent fractures; therefore, fracture identification is a key issue in osteoporosis management. Dual-energy X-ray absorptiometry has become the most widespread technique for the assessment of bone density, and can also provide images for assessment of vertebral morphometry (MXA) that are undistorted by parallax. The radiation dose is very low compared with conventional radiography. Whether the resolution of MXA is adequate for vertebral morphometry is uncertain. The present study compares MXA with conventional radiography in detecting vertebral deformities. MXA scans and lateral radiographs were performed in 61 women with osteoporosis. Adequate images were obtained in 99.1% of the 793 vertebrae by radiography and 95.6% by MXA. Poor image quality was mostly at T4-6 by MXA. Precision of repeat analyses was comparable between the techniques. Heights measured by MXA were 24 to 35% less than the radiographic values, the methods produced equivalent results for the ratio of anterior to posterior heights, but the MXA values for middle to posterior ratios were about 10% lower than for the radiographs (p < 0.0001). The extent of agreement between the techniques in identifying vertebral fractures was dependent on the strictness of the fracture definition used. With a 3 standard deviation (SD) criterion, the techniques found similar numbers of patients to have vertebral deformities, and the concordance in classification of individual vertebrae was 94%. At a 2 SD, cut-off concordance was 79%, and at 4 SD, it was 96%. Receiver-operating characteristic curves using cut-offs of > or = 3 SDs also showed excellent diagnostic accuracy. We conclude that MXA shows acceptable performance for clinical use in diagnosing vertebral deformities, as long as cut-offs of > or = 3 SDs are used, although a few percent of vertebrae in the upper thoracic region cannot be imaged adequately using this technique.

Absorptiometry, Photon↗
PubMed2006

MDCT versus digital radiography in the evaluation of bone healing in orthopedic patients.

OBJECTIVE: Assessment of bone healing in orthopedic patients is usually monitored by radiographs in two views. The purpose of our study was to compare multiplanar reconstructions from MDCT data sets with digital radiographs for assessing the extent of bone healing. MATERIALS AND METHODS: Forty-three orthopedic patients (19 women, 24 men) who underwent MDCT and radiography after arthrodesis, fractures, or spinal fusions were included in our study. MDCT was performed on an MX 8000IDT scanner and served as the gold standard. The technical parameters were adapted to the anatomic region. A bone algorithm for reconstruction was used (3,500/600 H). Multiplanar reconstructions were calculated in two orthogonal planes. All patients underwent digital radiography on a Multix FD system in two views according to standard procedures. Multiplanar reconstructions and radiographs were analyzed by two musculoskeletal radiologists in a consensus interpretation to determine bone healing using a semiquantitative approach. RESULTS: In 27 patients (63%), MDCT and digital radiography were concordant with regard to the extent of bone healing, whereas in 16 patients (37%) the results were not concordant. In eight patients (19%) digital radiographs underestimated the extent of bone healing, whereas in another eight patients (19%) they overestimated the degree of fusion. CONCLUSION: MDCT using high-quality 2D reformatting is recommended as the primary imaging technique for the evaluation of bone healing.

Female↗
PubMed1982

CT of acetabular fractures: comparison with conventional radiography.

Computed tomography (CT) and plain radiography of the pelvis were compared in 26 adult patients in whom acetabular fractures or posterior femoral head dislocations were demonstrated or suspected on initial radiographs. The detection of abnormalities of the sacrum, sacroiliac joint, iliac wing, acetabular roof, joint space, anterior pelvic column, posterior pelvic column, posterior acetabular lip, pubic rami, and quadrilateral surface of the ilium by the two methods was compared. The ability of the two techniques to establish the stable fragment was also examined. Three independent readings of each examination for each pelvic region were tabulated, and sensitivity and specificity values were calculated. There was no significant difference between plain radiography and computed tomography in detection of fractures of the iliac wing, anterior pelvic column, posterior pelvic column, and the pubic rami, with high sensitivity and specificity for both examinations. CT was more sensitive than plain radiography in detecting fractures involving the sacrum, quadrilateral surface, acetabular roof, and posterior acetabular lip. In addition, abnormalities of the hip joint space, principally loose bone fragments, were detected more often by CT. Sensitivity of both examinations for abnormalities of the sacroiliac joint was relatively poor, but examinations were highly specific. Determination of the stable fracture fragment(s) was readily accomplished by CT scanning in all 26 patients; in five patients incorrect determinations were made with conventional radiographs alone.

Acetabulum↗
PubMed1984

Pulmonary evaluation of patients with osteosarcoma: roles of standard radiography, tomography, CT, scintigraphy, and tomoscintigraphy.

Sixty-one radiologic evaluations were performed on 32 patients with possible pulmonary metastases from osteosarcoma. CT scanning was performed 61 times; standard chest radiography, 58; tomography, 36; scintigraphy, 40; and tomoscintigraphy, 33. Using CT as a reference (positive or negative results only), the sensitivities of the other examinations were 57% (32% of total metastases) for standard radiography, 88% (48%) for tomography, 21% (5%) for scintigraphy, and 41% (8%) for tomoscintigraphy. Of the 193 metastases, 98 were subpleural and 95 were parenchymatous. Five patients had surgery and the others had follow-up. One false-positive CT scan was thus detected. The authors' current evaluation of patients with metastases from osteosarcoma includes chest radiography and CT; the other three examinations are performed only before surgery.

Adolescent↗
PubMed1987

Direct radiographic magnification with computed radiography.

Computed radiography was combined with a 0.1-mm microfocus radiographic tube to obtain radiographic magnification of a x3 to x5. Gray-scale image processing compensated for the loss of radiographic contrast associated with the high-kilovoltage, short-exposure technique. The high-pass spatial frequency filtering capability of the computed radiography resulted in enhanced edges and increased displayed latitude. The improved image quality obtained by magnification computed radiography allowed delineation of subtle abnormalities and small anatomic structures not apparent on conventional screen-film contact or magnification radiographs.

Humans↗