Abstract
Multiplexed x-ray imaging was recently proposed as a way to possibly reduce x-ray source power requirements while
maintaining temporal resolution and imaging speed. Rather than measuring projections sequentially, with multiplexing
multiple sources send photons to the same detector corresponding to different projections. Data for the multiple
projections that are measured by the same detector are separated by energizing the sources with different temporal
sequences. This concept could be used for radiography, tomosynthesis, or CT imaging. Multiplexed measurements are
used very successfully in other modalities. For example, in magnetic resonance imaging (MRI) data from multiple
voxels, perhaps even the entire object, can be measured through a single channel. In MRI, the simultaneous
interrogation of multiple regions has no SNR penalty. It is important to examine the noise impact of
multiplexing/demultiplexing in x-ray imaging. We examined the propagation of noise due to the quantum statistics of
the measured x-rays. The analysis showed that for quantum limited acquisitions, the noise penalty of multiplexing can
be severe. Indeed, if both the multiplexed and sequential methods are quantum limited, the simpler sequential method
always outperforms multiplexing.
