The effective detective quantum efficiency (eDQE) was recently introduced to assess the performance of the digital radiographic systems in clinical examinations since it includes the effects of scatter and focal spot unsharpness [1,2,3]. The aim of this work is to investigate the influence of these factors on eDQE. An alternative calculation of eDQE is also suggested in this work that includes the influence of scatter in the MTF measurement.

A wireless flat panel imaging detector (Carestream DRX1) based on indirect conversion with a CsI phosphor with pixel size of 0.139 mm was used with an analog X-ray system (GE Silhouuette VR) including a wall-stand bucky. Focus to detector distance was 180 cm and a stationary grid with 10:1 grid ratio and grid density of 60 lines per cm was employed. In order to see the effects of scatter and focus blurring, edge phantom and uniformity images were collected at three different acquisition geometries for...

Fig. 1 , Fig. 2 and Fig. 3 give the MTF, NNPS and eDQE results for three different acquisition geometries. MTF is degraded with focus blur and scatter. The use of grid suppresses the effect of scatter, and therefore, focus blurring becomes dominant (Fig. 1). Lower influence of The same uniformity images were used for the first and second geometries, so NNPS is the same for these geometries (Fig. 2). Although the detector exposures are the same (3 uGy), scatter image has a lower NNPS....

The eDQE has been demonstrated as a useful technique in evaluating the performance of digital radiographic imaging for clinical radiographic examinations. It is shown that eDQE can demonstrate the effect of different blurring factors. Although the use of an LSF without any processing can introduce noise into the MTF and subsequently into the eDQE, inclusion of scatter in the LSF for MTF calculation simplifies the eDQE estimation since the measurements for scatter fraction can be omitted.

[1] Samei, E., Ranger, N. T., MacKenzie, A., Honey, I. D., Dobbins, J. T., & Ravin, C. E. (2009). Effective DQE (eDQE) and speed of digital radiographic systems: an experimental methodology. Medical Physics, 36(8), 3806–3817. [2] Samei, E., Ranger, N. T., MacKenzie, A., Honey, I. D., Dobbins, J. T., & Ravin, C. E. (2009). Effective DQE (eDQE) and speed of digital radiographic systems: an experimental methodology. Medical Physics, 36(8), 3806–3817. [3] Salvagnini E., Bosmans H., Struelen L., Marshalls N. W. (2012). Effective detective quamtum efficiency...