Reducing the Radiation Dose During Excretory Urography:Flat-Panel Silicon X-Ray Detector Versus Computed Radiography

Modeling the performance characteristics of computed radiography (CR) systems

Computed radiography (CR) using storage phosphors is widely used in digital radiography and mammography. A cascaded linear systems approach wherein several parameter values were estimated using Monte Carlo methods was used to model the image formation process of a single-side read ;;flying spot'' CR system using a granular phosphor. Objective image quality metrics such as modulation transfer function and detective quantum efficiency were determined using this model and show good agreement with published empirical data. A model such as that addressed in this work could allow for improved understanding of the effect of storage phosphor physical properties and CR reader parameters on objective image quality metrics for existing and evolving CR systems.

Évaluation médico-économique d’un système capteur-plan grand champ en radiopédiatrie

PURPOSE

To evaluate the impact of a completely automated digital radiography (DR) unit in a pediatric radiology department on productivity. Materials and methods. Comparative evaluation of DR and computerized radiography (CR) units on 193 patients imaged in a pediatric radiology department. The time to complete each step of all examinations was recorded. Half of the exams were performed using CR and the other half was performed using DR.

RESULTS

There was a 52% time gain for simple projection exams using DR and a 51% time gain for dual projection exams using DR (p<0.001). A workflow study performed a 9 month period showed that DR could absorb 84% of work previously performed on two conventional radiography units.

CONCLUSION

DR is necessary for digital imaging departments to increase productivity, while providing added ergonomic comfort and flexibility. It is particularly well suited for pediatric imaging departments.

Reducing dose in urography while maintaining image quality—a comparison of storage phosphor plates and a flat-panel detector

The introduction of new flat-panel detector technology often forces us to accept too high dose levels as proposed by the manufacturers. We need a tool to compare the image quality of a new system with the accepted standard. The aim of this study was to obtain a comparable image quality for two systems-storage phosphor plates and a flat-panel system using intravenous urography (IVU) as a clinical model. The image quality figure was calculated using a contrast-detail phantom (CDRAD) for the two evaluated systems. This allowed us to set a dose for the flat-panel system that gave equivalent image quality to the storage phosphor plates. This reduced detector dose was used in an evaluation of clinical images to find out if the dose reduction from the phantom study indeed resulted in images of equal clinical image quality. The image quality was assessed using image criteria of the European guidelines for IVU with visual grading analysis. Equivalent image quality in image pairs was achieved at 30% of the dose. The CDRAD contrast-detail phantom makes it possible to find dose levels that give equal image quality using different imaging systems.