SU‐FF‐I‐48: Assessment of Detective Quantum Efficiency: Inter‐Comparison of IEC 62220‐1 with Representative Prior Methods

Purpose: To evaluate a new international standard method for the measurement of detective quantum efficiency (DQE) of digital radiography systems in comparison with representative prior methods. Methods and Materials: Three DQE evaluation methods were considered: 1) a relatively recent international standard method published by the International Electrotechnical Commission (IEC, 62220‐1, 2003) which was evaluated in comparison with previously published methods by 2) Dobbins et al (Med Phys 22:1581–1593, 1995) and 3) Samei et al (Med Phys 30: 608–622, 2003). In addition to an overall comparison of the methods, the impact of the defining factors that comprise each method were evaluated including: beam quality, the presence of beam‐limiting devices (apertures or collimators), the NNPS analysis algorithm and processing parameters, and the MTF test device and associated analysis methodology. Results: The IEC DQE results at low/mid‐frequencies were lower than those obtained using the method of Dobbins et al and Samei et al by 3.3% and 6.5%, respectively. Averaged over 1.5–2.5 mm−1, the DQE estimate according to the IEC method was 7.1% lower and ̃12.4% higher than that of the other two methods, respectively. The overall DQE methods of Dobbins et al and Samei et al agreed well (within 2.0%) in the low‐ to mid‐frequency range but diverged by up to 10% at higher frequencies. Of the influencing factors on the DQE estimate considered, the most significant impact was seen with the MTF measurement method, followed by the beam‐limitation method. Conclusions: Comparison of DQE estimates using the new standard technique with results using prior methods demonstrated that measurement method can impact the DQE estimate by as much as 12%. Specifically, the results suggest the use of beam limitation using internal collimation (rather than external apertures) and use of a radio‐opaque edge MTF test device for more accurate estimation of the DQE. © 2006, American Association of Physicists in Medicine. All rights reserved.

Duke Scholars

Author Ehsan Samei Radiology

Author James T. Dobbins III Radiology

Author Carl Eric Ravin Radiology, Cardiothoracic Imaging