Increasing complexity of endovascular interventional procedures requires superior x-ray imaging quality. Present stateof-
the-art x-ray imaging detectors may not be adequate due to their inherent noise and resolution limitations. With recent
developments, CMOS based detectors are presenting an option to fulfill the need for better image quality. For this work,
a new CMOS detector has been analyzed experimentally and theoretically in terms of sensitivity, MTF and DQE.
The detector (Dexela Model 1207, Perkin-Elmer Co., London, UK) features 14-bit image acquisition, a CsI phosphor, 75
μm pixels and an active area of 12 cm x 7 cm with over 30 fps frame rate. This detector has two modes of operations
with two different full-well capacities: high and low sensitivity. The sensitivity and instrumentation noise equivalent
exposure (INEE) were calculated for both modes. The detector modulation-transfer function (MTF), noise-power spectra
(NPS) and detective quantum efficiency (DQE) were measured using an RQA5 spectrum. For the theoretical
performance evaluation, a linear cascade model with an added aliasing stage was used.
The detector showed excellent linearity in both modes. The sensitivity and the INEE of the detector were found to be
31.55 DN/μR and 0.55 μR in high sensitivity mode, while they were 9.87 DN/μR and 2.77 μR in low sensitivity mode.
The theoretical and experimental values for the MTF and DQE showed close agreement with good DQE even at
fluoroscopic exposure levels.
In summary, the Dexela detector’s imaging performance in terms of sensitivity, linear system metrics, and INEE
demonstrates that it can overcome the noise and resolution limitations of present state-of-the-art x-ray detectors.