Abstract
The amorphous silicon flat panel X-ray detector
(FPD) has gained significant adoption in digital radiography such
as chest radiography due to its large size and superior performance.
As a fundamental building block of a FPD, the pixel is composed of
sensor, storage and readout units to collect charges and transfer
them to external electronics. In all current pixel architectures,
however, these three aforementioned components are unanimously separate.
It would inevitably compromise spatial resolution due to increased
pixel size. Thus, we propose a compact design of a “smart”
pixel to combine sensor, storage and readout units into one single
dual-gate photo thin-film transistor (TFT). Simulation results indicated
that an implementation of a
$\pi$
-shape channel structure would
enhance photo absorption and preserve switching performance as well.
The sensitivity of the device is dependent on the threshold voltage
shift induced by light illumination, which in turn enlarges the photocurrent.
A numerical study also showed a total noise of approximately
${\sim} {{700}}$
e and a dynamic range of 120 dB can be achieved, which
potentially outperforms current available amorphous silicon passive
pixel sensor. The “smart” pixel therefore holds a great
promise for high-resolution and low-dose X-ray imaging, which may
potentially reduce the cancer risk induced by X-ray radiation, especially
for pediatric patients.
© 2015 IEEE
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