Computed radiography in musculoskeletal imaging: state of the art.

Manufacturers offer exposure indices as a safeguard against overexposure in computed radiography, but the basis for recommended values is unclear. This study establishes an optimum exposure index to be used as a guideline for a specific CR system to minimise radiation exposures for computed mobile chest radiography, and compares this with manufacturer guidelines and current practice. An anthropomorphic phantom was employed to establish the minimum milliamperes consistent with acceptable image quality for mobile chest radiography images. This was found to be 2 mAs. Consecutively, 10 patients were exposed with this optimised milliampere value and 10 patients were exposed with the 3.2 mAs routinely used in the department of the study. Image quality was objectively assessed using anatomical criteria. Retrospective analyses of 717 exposure indices recorded over 2 months from mobile chest examinations were performed. The optimised milliampere value provided a significant reduction of the average exposure index from 1840 to 1570 ( p<0.0001). This new "optimum" exposure index is substantially lower than manufacturer guidelines of 2000 and significantly lower than exposure indices from the retrospective study (1890). Retrospective data showed a significant increase in exposure indices if the examination was performed out of hours. The data provided by this study emphasise the need for clinicians and personnel to consider establishing their own optimum exposure indices for digital investigations rather than simply accepting manufacturers' guidelines. Such an approach, along with regular monitoring of indices, may result in a substantial reduction in patient exposure.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Digital radiography: are the manufacturers' settings too high? Optimisation of the Kodak digital radiography system with aid of the computed radiography dose index

Peters¹,

Brennan²

2001

“…It is possible that with computerised systems, digital techniques, such as windowing and image enhancement, may offer some advantages over carbon-fibre-fronted cassettes, but these advantages must be balanced against much higher costs and loss of image resolution [17,18]. The effect of PPCR on radiation doses, compared with more conventional systems, is still under debate [19]. The authors, however, acknowledge the importance of evaluating the cost-effectiveness of PPCR for mobile chest radiography.…”

Section: Discussionmentioning

confidence: 99%

The cost-effectiveness of carbon-fibre cassettes in mobile chest radiography

Brennan¹,

Hourihan²

1998

Employment of carbon fibre materials is an effective method of reducing radiation dose, yet the increased associated costs have led to a reluctance in implementation. This study investigates the level of dose reduction achievable, while maintaining image quality, in mobile chest radiography using carbon-fibre cassettes, compared with plastic cassettes, and balances this against increased expense of the cassettes. Dose measurements using thermoluminescent dosimeters were carried out on intensive therapy unit (ITU) patients undergoing an anteroposterior chest X-ray examination. Resultant image quality was assessed using objective Commission of European Communities (CEC) criteria. A retrospective audit recorded number of ITU patients currently having chest X-rays to determine total dose savings over the life of the cassettes. The results show significant reductions (p < 0.0001) of 32 % for entrance surface and effective dose with carbon-fibre cassettes. No deterioration in total image quality was noted. The added expense of

“…This effect is particularly useful in areas of the body that have a large range of subject contrasts and thicknesses. In examinations of cervical, thoracic and lumbar spine examinations, and lateral hip views, PPCR has resulted in improved visualisation of these difficult areas and a decrease in the number of repeat radiographs [12].…”

Section: Photo-stimulable Phosphor Computed Radiographymentioning

confidence: 99%

Developments in digital radiography: an equipment update

et al. 2001

Digital X-ray imaging technology has advanced rapidly over the past few years. This review, particularly aimed at those involved in using and purchasing such technology, is an attempt to unravel some of the complexities of this potentially confusing subject. The main groups of X-ray imaging devices that are considered are digitisers of conventional radiographs, image-intensifier-based fluorography systems, photostimulable phosphor computed radiography, amorphous selenium-based technology for thorax imaging and flat-panel systems. As well as describing these different systems, we look at ways of objectively assessing their image quality. Concepts that are used and explained include spatial resolution, grey-scale bit resolution, signal-to-noise ratio and detective quantum efficiency. An understanding of these basic parameters is vital in making a scientific assessment of a system's performance. Image processing and techniques are also briefly discussed, particularly with reference to their potential effects on image quality. This review aims to provide a basic understanding of digital X-ray imaging technology and enables the reader to make an independent and educated assessment of the relative merits of each system.