Digital Image Intensifier Radiography Research Articles

Clinical aspects of quality criteria in digital radiography.

In clinical radiological practice two main questions regarding image quality have to be looked at: Which degree of image quality is needed? and: How can this image quality be objective? Image quality requirements depend on size, density and contrast of the objects of interest and on the clinical question which has to be answered. In comparison to conventional radiography, the digital radiographic techniques offer additional features concerning optimisation of image quality and dose, like a wider dynamic range, digital fluoroscopic techniques and post-processing. Therefore it is necessary to define new quality criteria for these techniques. In the following, typical examples demonstrate the development of the 'Diagnostic Requirements for Digital Radiographic Procedures'. These examinations include projection radiographs with digital luminiscent radiography, fluoroscopic procedures with digital image intensifier radiography and angiographic procedures with digital subtraction angiography. The clinical question of a radiological examination also forms the background to optimisation strategies considering image quality and radiation dose.

Need for New Optimisation Strategies in CR and Direct Digital Radiography

Digital imaging techniques such as Digital Image Intensifier Radiography and Digital Storage Phosphor (Selenium) Radiography are replacing conventional film-screen radiography more and more. The aim of this development is the extension of diagnostic capabilities and the reduction of side effects such as radiation dose. Conventional film-screen radiography and digital radiography are very different ways of imaging. For digital radiography specific post-processing is the link between imaging conditions and film documentation. Optimisation of the images includes new possibilities of post-processing and a broad range for variation of the dose. Especially in fluoroscopy, dose can be reduced significantly by new technical features like pulsed fluoroscopy. For digital radiography the European guidelines on quality criteria have to be applied to projection radiography, digital subtraction radiography and to fluoroscopy. Further work should lead to a definition of reference values for the dose and the image quality. This has to be done first for single exposures and fluoroscopic mode and secondly for diagnostic and interventional procedures.

Adaption of the Quality Criteria Concept to Digital Radiology

In recent years conventional film-screen radiography has been more and more replaced by digital techniques like 'Digital Image Intensifier Radiography' and 'Digital Storage Phosphor (Selen) Radiography'. These new digital imaging methods can be used for all areas of radiography except mammography. Digital radiography offers the advantage of additional diagnostic information, digital image format, lower radiation risk to the patient and a favourable cost/benefit relation. With digital techniques, dose can be varied over a wide range without losing diagnostic information. Thus, dose can be reduced in comparison to film-screen radiography. Inadequate technique can, in certain applications, however, lead to a significant increase of dose. Therefore, special reference dose values have to be established and controlled continuously. Different possibilities of pre- and post-processing make the evaluation of image quality of digital technique more complex compared with conventional film-screen radiography. New parameters like signal to noise ratio are more appropriate in assessing image quality. However, in daily routine well known parameters like spatial resolution, contrast detectability and dose can be more easily used for the assessment of image quality of the whole imaging chain including image processing and documentation. Special guidelines for digital radiography are necessary to guarantee high image quality and to avoid overexposure and misdiagnoses. These guidelines should be based on the Quality Criteria Concept of the EC. They should include criteria for the detectability of specific anatomic details, technical parameters for good radiographic technique and imaging performance and reference dose values. Assessment of image quality by suitable phantoms and constancy testing are prerequisites for quality assurance. The activities of an European quality criteria working group in the 'Concerted Action Programme' are focused on these subjects.

Digital image-intensifier radiography at a level I trauma center.

Digital image-intensifier radiography at a level I trauma center.

Digital radiography Results of a survey (part A) and a consensus conference (part B)

Digital imaging (digital image intensifier radiography, storage phosphor/selenium radiography) is increasingly becoming commonplace in radiology departments for diagnostic purposes. Despite 10 years of experience, the advantages and disadvantages of those methods are still heavily discussed among users, financiers and prescribers. This paper is to offer additional arguments for a thorough and objective discussion. No further comments or interpretations have been added to this paper. This paper consists of two main parts, A and B. The first part deals with the results of a user survey, the other part presents the results, i. e. statements, of a consensus conference.

Image Quality Criteria Applied to Digital Radiography

Film-screen radiography has been replaced more and more by digital imaging methods. The aim of this development is the extension of diagnostic capabilities and the reduction of patient discomfort and side effects such as radiation dose. For digital image intensifier radiography and luminescence radiography the image quality and the dose value can be adapted to the diagnostic problem in a broad range. Capabilities of digital radiography have changed the strategy of imaging. To decrease the dose value image quality has to be chosen to be not as good as possible but as good as necessary to answer the diagnostic question. Digital image intensifier radiography, for example, allows a dose reduction to 10% in comparison with film screen for special diagnostic problems. Digital radiography increases the diagnostic information and gives, additionally, the chance to lower the dose values significantly.

Bildgütebestimmung und Dosisbedarf der digitalen Bildverstärkerradiographie

In the course of a study of the advantages and disadvantages of digital image intensifier radiography, image quality and dose requirements were measured, using a phantom. Spatial resolution was related to exposure parameters, the differentiation of structural details at varying contrast concentrations and the phantom entry doses. Spatial resolution was approximately 1.8-2.0 line pairs/mm (lp/mm) and there was no recognisable effect from increasing the dose or the thickness of the phantom. Additional subsequent edge enhancement led to increased detail recognition up to 2.0 lp/mm. Also, phase inversion of the image (negative image) can improve detail recognition. Radiation dose can be reduced to 15% compared with conventional imaging methods. Digital radiography with image intensifier techniques can therefore be recommended. Optimal spatial and contrast resolution is obtained at 80-90 keV. However, some reduction in perception of the finest structural details must be accepted.

Test Phantoms in Digital Radiography

At present two techniques for digital radiography are available: storage phosphor radiography and image intensifier radiography. In Mannheim test phantoms have been used for evaluation of performance characteristics and for quality assurance measurements for two years. Different methods were developed for digital image intensifier radiography, but they can be transferred to digital storage radiography. The aim of our test phantom measurements was the development of effective test procedures for performance characteristics and quality control, which are easy to handle with limited additional equipment, not time consuming and representative for clinical imaging. A summary of results and experience is given.

Digital fluoroscopic radiology: evaluation of the clinical impact

The use of digital image intensifier radiography (DIIR) for examinations in projection radiography is becoming more common. Fluoroscopic controlled contrast studies (barium- or iodine-based), particularly of the gastrointestinal tract, can be performed quickly and easily with a considerable decrease in radiation exposure. A wide dynamic range permits a constant high image quality with fewer incorrect exposure. The limited spatial resolution of large image intensifier input screens is the major drawback of DIIR. Digital image acquisition enables post-processing, digital storage and transfer of images, thus allowing an integration into PACS-systems. Imaging capabilities and clinical applications are described here.

New chest imaging techniques: a comparison of five analogue and digital methods

In recent years new analogue and digital techniques have become available for chest imaging. This study compares conventional film/screen, asymmetric film/screen (InSight), equalization (Amber), storage phosphor and digital image intensifier techniques by phantom exposures and patient examinations. The quality of chest images of 43 patients was classified by seven observers in four different hospitals. According to the results of phantom measurements and a previous study, digital image intensifier radiography was excluded from the patient examinations because of its low image quality. The Amber system had the best image quality. Images of the storage phosphor system were of good quality in both mediastinal and peripheral fields of the chest. Compared to conventional film/screen, the asymmetric film/screen (InSight) was graded higher in the mediastinal field, but lower in the peripheral field.

Digital image intensifier radiography and a conventional radiography system for diagnosing pulmonary nodules (In German) : Dolken W, Krahe Th, Landwehr P, Jenett M (Institut für Rbntgendiagnostik der Universitat Wiirzburg, Josef-Schneider-Straat, D-8700 Wiirzburg, FRG). ROFO 1989;151:131–137 78

Digital image intensifier radiography and a conventional radiography system for diagnosing pulmonary nodules (In German) : Dolken W, Krahe Th, Landwehr P, Jenett M (Institut für Rbntgendiagnostik der Universitat Wiirzburg, Josef-Schneider-Straat, D-8700 Wiirzburg, FRG). ROFO 1989;151:131–137 78

Die digitale Bildverstärkerradiographie: Ein neues Konzept für die traumatologische Röntgendiagnostik?

Digital image intensifier radiography visualises all traumatological changes of clinical relevance and can therefore be used in traumatology. However, the quality of conventional radiographs cannot be attained as yet. Radiation exposure is markedly reduced, and radiographs are obtained directly after exposure, so that this is an extremely rapid radiographic procedure. Images can be quickly transmitted by video cable to the relevant departments and working places.

Geburtshilfliche Beckenvermessung mit der digitalen Bildverstärkerradiographie

Obstetric pelvimetry can be performed by digital image intensifier radiography using very low exposure doses. Comparative measurements show a reduction of the entrance dose to 5% of conventional respectively 15% of high speed film-screen radiography. Phantom measurements have shown an accuracy of +/- 5 mm. In 30 patients the transverse diameter of the pelvic entrance, of the interspinous and of the intertuberous level as well as the sagittal diameter of the pelvic entrance and outlet were measured. Pelvimetry is indicated for the early recognition of certain risks if anamnestic (previous Caesarean section), clinical (eg. external pelvimetry) or fetometric features indicate the evidence of disproportion. As a radiological method the image intensifier radiography appears particularly recommendable in respect of its low exposure dose and the possibility of interactive measurements with subsequent documentation of the diameters and values.

Digitale Bildverstärker-Radiographie - Einjährige Erfahrung mit einem Polytron-System

Since January 1988, digital image intensifier radiography has been used in the Clinic in Mannheim for DSA examinations and also in place of conventional screen/film examinations. Measurements have shown that compared with 100 mm and film/screen formats, digital radiography has poorer spatial resolution, but improved contrast resolution. The most common use of digital radiography was for examinations of the gastrointestinal tract. Using the demonstration of the mucosal fine relief pattern as a criterion of image quality, digital image intensifier radiography was able to achieve this satisfactorily. Comparison with film/screen examinations showed no loss of diagnostic information. Advantages of image intensifier radiography are reduced radiation dose, the possibility of postprocessing and economy. On the basis of 399 examinations, digital image intensifier radiography is now firmly established as part of the daily routine of the Mannheim Clinic.

Digitale BV-Radiographie und Film-Folien-Kombination bei Lungenrundherden

30 patients with known or suspected pulmonary nodules were examined using a digital image intensifier radiography system, a conventional radiography system and a tomography of the whole lung. 73.8% of the pulmonary nodules detected with tomography were also detected with the digital system, 69.1% with the conventional system. There was no significant difference between the two systems comparing false positive and false negative diagnoses. Regarding the dose reduction to nearly 25% of that of a conventional examination the digital technique should be preferred to the conventional technique, if pulmonary nodules are suspected.

Digitale Bildverstärkerradiographie - Anwendung in der Angiographie, Urographie und Skelettdiagnostik

In a retrospective study, the clinical usefulness of digital image intensifier radiography was analysed. It could be demonstrated that for angiographic procedures the image quality of a 1024(2) matrix is superior to a 512(2) matrix. For digital excretory urography it could be seen that in 80 to 90% the images were at least sufficient to analyse the renal pelvis. Digital image intensifier radiography of bones was diagnostically sufficient in 76% and analysis of bone architecture was possible in 85%.