High resolution imaging capabilities are essential for accurately guiding successful endovascular
interventional procedures. Present x-ray imaging detectors are not always adequate due to their
inherent limitations. The newly-developed high-resolution micro-angiographic fluoroscope
(MAF-CCD) detector has demonstrated excellent clinical image quality; however, further
improvement in performance and physical design may be possible using CMOS sensors. We
have thus calculated the theoretical performance of two proposed CMOS detectors which may be
used as a successor to the MAF.
The proposed detectors have a 300 μm thick HL-type CsI phosphor, a 50 μm-pixel CMOS
sensor with and without a variable gain light image intensifier (LII), and are designated MAFCMOS-
LII and MAF-CMOS, respectively. For the performance evaluation, linear cascade
modeling was used. The detector imaging chains were divided into individual stages
characterized by one of the basic processes (quantum gain, binomial selection, stochastic and
deterministic blurring, additive noise). Ranges of readout noise and exposure were used to
calculate the detectors' MTF and DQE.
The MAF-CMOS showed slightly better MTF than the MAF-CMOS-LII, but the MAF-CMOSLII
showed far better DQE, especially for lower exposures.
The proposed detectors can have improved MTF and DQE compared with the present high
resolution MAF detector. The performance of the MAF-CMOS is excellent for the angiography
exposure range; however it is limited at fluoroscopic levels due to additive instrumentation noise.
The MAF-CMOS-LII, having the advantage of the variable LII gain, can overcome the noise
limitation and hence may perform exceptionally for the full range of required exposures;
however, it is more complex and hence more expensive.