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PubMed1995

Digital chest radiography at the University of Chicago: present status and future plans.

Storage-phosphor computed radiography and film digitization systems have been in routine clinical use at the University of Chicago for several years. During this time we have implemented numerous modifications including techniques for scatter reduction, image processing enhancements and display systems to improve the image quality and utility of these devices. We have also evaluated the image quality and functionality of digital systems relative to conventional screen-film radiography. In this paper, we review our experience and summarize our impressions. In addition, we summarize our plans for a rapid transition into picture archiving and communication systems, with hardcopy interpretation being phased out for most modalities over the next 2 to 5 years.

Chicago↗
PubMed1995

Clinical application of computed radiography in orthopedic surgery.

Since 1988, Fuji Computed Radiography (FCR) system (Fuji Medical Systems, Tokyo, Japan) has been used at Osaka Prefectural Hospital (Osaka, Japan) for all kinds of images. In this paper, we discuss the advantages and disadvantages of computed radiography (CR) images from the standpoint of an orthopedic surgeon. Contours, which can not be seen on conventional radiographs, are clearly visualized on the CR image. Adequate information for diagnosis can be obtained with a great reduction in x-ray exposure during the screening of scoliosis or congenital dislocation of hip joint. However, because the scale is reduced by one half in antero-posterior views of the bilateral hip joint, CR images are unsuitable for postoperative measurement of total hip arthroplasty (THA). Furthermore, caution is required because the clear zone after THA is emphasized on edge-enhanced CR image.

Absorptiometry, Photon↗
PubMed1997

A computerized analysis system in chest radiography: evaluation of interstitial lung abnormalities.

We evaluated the usefulness of a computerized analysis system in the detection of interstitial lung abnormalities in digitized chest radiography. This system uses the processes of four-directional Laplacian-Gaussian filtering, linear opacity judgment, and linear opacity subtraction. For qualitative analysis, we employed a combined radiographic index, which was calculated from two normalized radiographic indices obtained by linear opacity judgment and subtraction of linear opacities. We selected 50 regions of interest (ROIs) in patients with mild interstitial lung abnormalities, 50 ROIs in patients with severe interstitial lung abnormalities, and 50 ROIs in individuals with normal lung parenchyma. High-resolution computed radiography (HRCT) findings were used as the standard of reference for this study. These ROIs were processed by our computerized analysis system, and radiographic indices were obtained from each ROI. The area under the receiver operating characteristic curve (Az) was used as the measure of performance. The combined radiographic index provided better results in the mild interstitial lung abnormality group (Az = 0.94 +/- 0.02), but it also yielded good results in the severe interstitial lung abnormality group (Az = 0.98 +/- 0.01). These results indicate that this system of combining radiographic indices has improved the detection performance over that with our previous system.

Evaluation Studies as Topic↗
PubMed1999

Computed radiography dual energy subtraction: performance evaluation when detecting low-contrast lung nodules in an anthropomorphic phantom.

A dedicated chest computed radiography (CR) system has an option of energy subtraction (ES) acquisition. Two imaging plates, rather than one, are separated by a copper filter to give a high-energy and low-energy image. This study compares the diagnostic accuracy of conventional computed radiography to that of ES obtained with two radiographic techniques. One soft tissue only image was obtained at the conventional CR technique (s = 254) and the second was obtained at twice the radiation exposure (s = 131) to reduce noise. An anthropomorphic phantom with superimposed low-contrast lung nodules was imaged 53 times for each radiographic technique. Fifteen images had no nodules; 38 images had a total of 90 nodules placed on the phantom. Three chest radiologists read the three sets of images in a receiver operating characteristic (ROC) study. Significant differences in Az were only found between (1) the higher exposure energy subtracted images and the conventional dose energy subtracted images (P = .095, 90% confidence), and (2) the conventional CR and the energy subtracted image obtained at the same technique (P = .024, 98% confidence). As a result of this study, energy subtracted images cannot be substituted for conventional CR images when detecting low-contrast nodules, even when twice the exposure is used to obtain them.

Analysis of Variance↗
PubMed1989

Image optimization in a computed-radiography/photostimulable-phosphor system.

Photostimulable phosphor imaging is an exciting new technology that has several advantages over film/screen radiography, the most important of which is the linearity of the photostimulable phosphor system over a wide exposure latitude. The photostimulable phosphor image is digital, and as such, provides options of how the image is viewed by radiologists. This report discusses the various image-processing parameters available for a photostimulable phosphor system and describes a rational approach for selecting these parameters in portable chest radiography. As photostimulable phosphor imaging becomes more widely implemented, an understanding of the processing parameters will facilitate the production of images that take full advantage of the benefits of these systems.

Humans↗
PubMed2001

A comparison of image characteristics and convenience in panoramic radiography using charge-coupled device, storage phosphor, and film receptors.

This study compared the image layer characteristics, dose requirements, and convenience in use of panoramic radiography using each of four different image receptors including traditional indirect exposure x-ray film, a storage phosphor system, and two solid-state sensors. The OP 100 D (Instrumentarium Imaging, Tuusula, Finland) charge-coupled device (CCD) sensor provided an instant image with a wide focal trough, making patient positioning error unlikely, but at the same time required a patient dose higher than that used with film. While the DigiPan (Trex/Trophy, Marne-la-Vallée, France) CCD significantly reduced the patient dose to radiation and also provided an instant image, the focal trough was narrower making patient positioning error more likely. The storage phosphor system provided high resolution and a reasonable focal trough width, but the procedure took longer than traditional film radiography and did not provide a dose saving.

Humans↗
PubMed2003

[Digital thorax radiography: flat-panel detector or storage phosphor plates].

Flat panel detectors are characterized by improved handling and increased dose efficiency. This allows for increasing of work flow efficiency and for reducing the exposure dose by about 50% compared to current systems with a sensitivity of 400. Whether the increased dose efficiency should be used to reduce acquisition dose or to increase image quality in the chest, will be shown by further clinical experience and will be also determined by the subjective preference of the radiologists. The decreased level of image noise opens new perspectives for image processing that way that elaborated multifrequency processing allows for optimizing the display of very small and low contrast structures that was so far limited by overlying image noise. Specialized applications of dual energy subtraction and temporal subtraction will also profit by the new detector technology and will be further driven forward in context with applications such as computed assisted diagnosis even though this is currently not yet broadly applied. Storage phosphor radiography still represents an important alternative technique based on its larger flexibility with respect to equipment configuration, its broader application options in intensive care and emergency radiology and due to economic reasons. These facts are further underlined by the fact that image quality also in storage phosphor radiography could be constantly increased by improving detector technology and image processing and consequently has a high standard.

Artifacts↗
PubMed2003

[Digital radiography of the chest in pediatric patients].

The hopes placed in digital radiography have been fulfilled only partly in pediatric radiology. Specifically, the option of gaining reduced radiation exposure in combination with a similar or even improved image quality was hard to realize. The only portable digital system available for a long time were storage phosphors which were disadvantaged by an extremely limited dose-quantum-efficiency (DQE) in comparison to digital flat panel detectors. New developments and the introduction of the dual-reading system led to image qualities comparable to film-screen-systems with high resolution and achievable without dose increase, sometimes even with dose reduction. A study using an animal model suggests that these systems can even be used in preterm infants with very low birth weights. A new portable flat panel detector by Canon may improve digital chest radiography in pediatric patients.

Animals↗
PubMedDate not supplied

Chest radiography and the evaluation of the neonate for congenital heart disease.

We assessed the utility of the chest film as a screening tool for term and preterm neonates with suspected structural heart disease. Three independent observers, blinded to patient diagnosis, retrospectively evaluated the initial chest film for each of 128 consecutive neonates with suspected heart disease (gestational age, 23-42 weeks; birth weight, 500-4,621 g) who had undergone both chest radiography and echocardiography. These evaluations were subsequently compared with the results of the respective echocardiograms, read by board-certified pediatric cardiologists blinded to the chest film and chest film interpretation. Kappa statistics demonstrated moderate correlation (0.42-0.48) among different observers in their interpretation of the chest films but poor correlation (0.15-0.34) between chest radiography and echocardiography. The chest film had a low sensitivity for structural heart disease (26-59%), with a negative predictive value of 46-52%. Among neonates less than 2 kg or younger than 35 weeks of gestation, the chest film had still lower sensitivity for detecting heart disease. Despite agreement among observers in chest film interpretation, the chest film does not function as a screening test for neonates with suspected heart disease, particularly in small or premature neonates. In neonates with suspected heart disease, echocardiography should be considered, even in patients with chest films that do not suggest congenital heart disease.

Diagnosis, Differential↗
PubMed2003

Comparison of visual grading analysis and determination of detective quantum efficiency for evaluating system performance in digital chest radiography.

A study was conducted to compare physical and clinical system performance in digital chest radiography. Four digital X-ray modalities, two storage-phosphor based systems and two generations of a CCD-based system, were evaluated in terms of both their imaging properties (determination of presampling MTF and DQE) and clinical image quality (grading of the reproduction of anatomical details of 23 healthy volunteers using both absolute and relative visual grading analysis). One of the two storage-phosphor systems performed best in both evaluations and the first generation of the CCD-based system was rated worst; however, the other two systems were ranked differently with the two methods. The newest CCD-based system yielded a higher clinical image quality than the second storage-phosphor system, although the latter presented a DQE substantially higher than the former. The results show that clinical performance cannot be predicted from determinations of DQE alone, and that a system with lower DQE, under the quantum-saturated conditions in chest radiography, can outperform a system with higher DQE if the image processing used on the former is more effective in presenting the information in the image to the radiologist.

Equipment Design↗
PubMed2004

Dose reduction in skeletal and chest radiography using a large-area flat-panel detector based on amorphous silicon and thallium-doped cesium iodide: technical background, basic image quality parameters, and review of the literature.

The two most frequently performed diagnostic X-ray examinations are those of the extremities and of the chest. Thus, dose reduction in the field of conventional skeletal and chest radiography is an important issue and there is a need to reduce man-made ionizing radiation. The large-area flat-panel detector based on amorphous silicon and thallium-doped cesium iodide provides a significant reduction of radiation dose in skeletal and chest radiography compared with traditional imaging systems. This article describes the technical background and basic image quality parameters of this 43 x 43-cm digital system, and summarizes the available literature (years 2000-2003) concerning dose reduction in experimental and clinical studies. Due to its high detective quantum efficiency and dynamic range compared with traditional screen-film systems, a dose reduction of up to 50% is possible without loss of image quality.

Cesium↗
PubMed2006

Chondroid lipoma: findings on radiography and MRI (2006:7b).

We present a case of chondroid lipoma with various tumor components on MRI and ossified components on radiography. Information from both imaging modalities is required to make the correct diagnosis, and the role of radiography as a first choice imaging modality is highlighted.

Aged↗
PubMed2006

Computer-aided nodule detection on digital chest radiography: validation test on consecutive T1 cases of resectable lung cancer.

PURPOSE: To evaluate the usefulness of a commercially available computer-assisted diagnosis (CAD) system on operable T1 cases of lung cancer by use of digital chest radiography equipment. MATERIALS AND METHODS: Fifty consecutive patients underwent surgery for primary lung cancer, and 50 normal cases were selected. All cancer cases were histopathologically confirmed T1 cases. All normal individuals were selected on the basis of chest computed tomography (CT) confirmation and were matched with cancer cases in terms of age and gender distributions. All chest radiographs were obtained with one computed radiography or two flat-panel detector systems. Eight radiologists (four chest radiologists and four residents) participated in observer tests and interpreted soft copy images by using an exclusive display system without and with CAD output. When radiologists diagnosed cases as positives, the locations of lesions were recorded on hard copies. The observers' performance was evaluated by receiver operating characteristic analysis. RESULTS: The overall detectability of lung cancer cases with CAD system was 74% (37/50), and the false-positive rate was 2.28 (114/50) false positives per case for normal cases. The mean A(z) value increased significantly from 0.896 without CAD output to 0.923 with CAD output (P = 0.018). The main cause of the improvement in performance is attributable to changes from false negatives without CAD to true positives with CAD (19/31, 61%). Moreover, improvement in the location of the tumor was observed in 1.5 cases, on average, for radiology residents. CONCLUSION: This CAD system for digital chest radiographs is useful in assisting radiologists in the detection of early resectable lung cancer.

Adult↗
PubMed1982

Head injuries and skull radiography: clinical factors predicting a fracture.

Five hundred and ninety-eight cases were studied where the patients had been subjected to skull radiography because of a head injury. Concussion had been established in 231 patients and a more severe brain injury in 8. Forty-nine patients (8.2 per cent) had skull fractures. The relative frequency of fractures was the highest among those aged between 40 and 59 years (16 per cent). From among 16 variables, either clinical or pertaining to the history, 4 had clearly sustained a fracture of the skull, the statistically significant features being amnesia, unconsciousness for over 30 minutes, a wound and subcutaneous haematoma in the scalp and a reduced level of consciousness. On the basis of these signs the patients could be divided into two groups which differed in the frequency of skull fractures by a factor of five. The skull fracture was not observed to have influenced the patient's care or recovery, particularly if the patient had a concurrent brain injury. Based on the results, the indications for skull radiography in patients with head injuries can be identified and this can reduce the need for X-ray examinations to one-half and still reveal 80 per cent of skull fractures.

Adolescent↗
PubMed1995

Diagnostic value of ultrasonography and conventional radiography for the assessment of sternal fractures.

This study compares the sonographic and conventional radiographic examination of sternal fractures. Forty-five patients with a suspected sternal fracture were examined radiographically and sonographically. Sixteen had a sternal fracture which could be identified sonographically. In 15 of the 16 cases an equivalent diagnosis could be made radiologically. In one case no definite statement could be made radiologically but the sonographic finding together with the clinical aspect of the patient proved the diagnosis of a fracture. In four sternal fractures displaced by more than one anteroposterior thickness, the fracture itself was shown by sonography whereas the extent of the injury could not be displayed. Ultrasonic investigation of the sternum is a useful way to demonstrate fractures that provides a similar sensitivity to conventional radiography. In contrast sonography is not suited for portraying the grade of displacement. In case of doubt after radiological examination the ultrasonic examination serves as a valuable tool but conventional plain radiography remains the standard means of documenting a sternal fracture.

Adult↗
PubMed1996

The effect on patients of non-referral for skull radiography following mild head injury.

This paper assesses the attitude of 705 patients who attended the Accident department of a large metropolitan district general hospital, with a mild head injury and who were not referred for skull radiography. A questionnaire was sent to patients 5-7 months after they had attended. Fifty-one per cent had expected an X-ray, and when this did not occur, the majority of this group (63 per cent) left the Accident department disappointed. Furthermore, the duration of symptoms in this group was prolonged. The introduction of guidelines may reduce clinically unnecessary X-ray examinations, but some of the consequences may not be fully appreciated. In this study, a significant number of patients were dissatisfied with the lack of X-ray referral. The main cause for the associated prolongation of symptoms is not clear, but a contributory factory may be that lack of referral for radiography led to anxiety concerning the thoroughness of their management.

Attitude to Health↗
PubMed1976

Doses to critical organs from dental radiography.

Participants in the jointly sponsored Atomic Bomb Casualty Commission and Japanese National Institute of Health (ABCC-JNIH) Adult Health Study, a fixed-population sample under continual observation for late effects of the atomic bombs, are also being evaluated for their exposure to other sources of ionizing radiation. In the present study, the subjects' thyroid, lens, pituitary, bone marrow, and gonadal doses acquired during dental radiography were estimated from dosimetry of simulated human material exposed according to technical factors as ascertained in previously reported surveys of patients, dental clinics and hospitals, and dosimetry with phantom human material containing lithium fluoride thermoluminescence dosimeters and ionization chambers. Dental radiography comprised a relatively small segment of the contaminating sources of ionizing radiation exposure among this population sample. Efforts should be made to improve exposure conditions, especially in view of the increasing frequency of dental x-ray examinations.

Head↗
PubMed1977

An estimation of somatic hazards to the United States population from dental radiography.

Recently, data have become available pertaining both to the estimated somatic hazard from exposure of populations to low doses of ionizing radiation and to the extent of exposure resulting from dental radiography. This has made possible an estimation of the somatic hazard to the United States population from dental radiography. It is concluded that the greatest risk of lethality would result from induction of leukemia, but that the actual hazard is probably quite low. It is advised that all procedures which will reduce the radiation exposure to the patient consistent with diagnostic requirements should be employed in order to minimize the potential risk.

Dose-Response Relationship, Radiation↗