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

Abstract

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.

Use of effective detective quantum efficiency to optimise radiographic exposures for chest imaging with computed radiography

“…The eDQE was larger without the anti-scatter grid for both 80 kV and 120 kV. At higher dose level, the efficiency drops this is similar to previous measurements of DQE on CR systems [8] , this has been identified as due to structural noise. The difference between the high dose and low dose is greater when the grid is used which means that the stationary grid is adding some structural noise.…”

Comparison of different computed radiography systems: Physical characterization and contrast detail analysis

“…25 The DQE of the three best systems investigated in this paper is also comparable to some of the flatpanel detectors for radiography available in the market. [26][27][28] The CD results confirm that the improved efficiency helps achieve a lower contrast threshold. In fact, for details with a diameter greater than 1 mm, the FCR ST-VI and the CR975 systems present a statistically significant different response, with respect of both the FCR Velocity unit ͑with p Ͻ 0.01͒ and the DX-S system ͑p Ͻ 0.05͒.…”

A new clinical unit for digital radiography based on a thick amorphous Selenium plate: Physical and psychophysical characterization

“…Further, the response curve presents the lowest sensitivity for RQA3 beam and its maximum for RQA7 beam, as already noted and measured for other detectors. 15,16 The system shows an excellent MTF, as direct conversion detectors usually do, in spite of the great thickness of its a-Se layer. In all the investigated conditions, we did not find appreciable differences between the MTF estimated in the horizontal and vertical direction.…”