DQE of wireless digital detectors: Comparative performance with differing filtration schemes
- Carl E. Ravin Advanced Imaging Laboratories, Departments of Radiology, Biomedical Engineering, Physics, and Electrical and Computer Engineering, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705 (United States)
- Medical Physics Graduate Program, Duke University, Durham, North Carolina 27705 (United States)
Purpose: Wireless flat panel detectors are gaining increased usage in portable medical imaging. Two such detectors were evaluated and compared with a conventional flat-panel detector using the formalism of the International Electrotechnical Commission (IEC 62220-1) for measuring modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) using two different filtration schemes.Methods: Raw images were acquired for three image receptors (DRX-1C and DRX-1, Carestream Health; Inc., Pixium 4600, Trixell) using a radiographic system with a well-characterized output (Philips Super80 CP, Philips Healthcare). Free in-air exposures were measured using a calibrated radiation meter (Unfors Mult-O-Meter Type 407, Unfors Instruments AB). Additional aluminum filtration and a new alternative combined copper-aluminum filtration were used to conform the x ray output to IEC-specified beam quality definitions RQA5 and RQA9. Using the IEC 62220-1 formalism, each detector was evaluated at X{sub N}/2, X{sub N}, and 2X{sub N}, where the normal exposure level to the detector surface (X{sub N}) was set to 8.73 μGy (1.0 mR). The prescribed edge test device was used to evaluate the MTF, while the NNPS was measured using uniform images. The DQE was then calculated from the MTF and NNPS and compared across detectors, exposures, and filtration schemes.Results: The three DR systems had largely comparable MTFs with DRX-1 demonstrating lower values above 1.0 cycles/mm. At each exposure, DRX-1C and Pixium detectors demonstrated better noise performance than that of DRX-1. Zero-frequency DQEs for DRX-1C, Pixium, and DRX-1 detectors were approximately 74%, 63%, and 38% for RQA5 and 50%, 42%, and 28% for RQA9, respectively.Conclusions: DRX-1C detector exhibited superior DQE performance compared to Pixium and DRX-1. In terms of filtration, the alternative filtration was found to provide comparable performance in terms of rank ordering of different detectors with the added convenience of being less bulky for in-the-field measurements.
- OSTI ID:
- 22220518
- Journal Information:
- Medical Physics, Vol. 40, Issue 8; Other Information: (c) 2013 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-2405
- Country of Publication:
- United States
- Language:
- English
Similar Records
Validation of a Custom-made Software for DQE Assessment in Mammography Digital Detectors
Intercomparison of methods for image quality characterization. I. Modulation transfer function