Keywords:
Lung, Digital radiography, Image manipulation / Reconstruction, Diagnostic procedure, Physics
Authors:
S. Lopez Maurino1, S. Ghanbarzadeh1, S. Ghaffari1, K. S. Karim2; 1Kitchener, ON/CA, 2Waterloo, ON/CA
DOI:
10.26044/ecr2019/C-3350
Aims and objectives
Dual-energy (DE) radiography is a technique that can remove specific anatomical noise from a radiograph and generate tissue-subtracted images.
Typically,
a trio of images is presented comprised of a standard digital radiography (DR) image,
a soft-tissue image –where the bone clutter has been removed,– and a bone image –where the soft tissue is not present.
Such a technique is of particular interest in chest radiography,
where the detection of lung nodules has been shown to be primarily limited by anatomical noise[1].
Here,
the use of DE imaging aids by presenting a soft-tissue image without bone clutter thereby increase nodule conspicuity.
Many studies have shown that this leads to increased nodule detectability[2–6].
Furthermore,
DE imaging can help characterize lung lesions since nodule calcification is an indicator of benignancy.
This is achieved by studying the bone-only image,
which has been shown to be an effective way of evaluating nodule calcification[7].
More recently,
DE chest radiography has also shown potential in scoring of coronary artery calcium[8,9].
Currently,
two distinct technologies exist to obtain DE images.
The more common is that of a dual-shot system,
where two separate exposures of the patient are quickly taken at different source peak voltages[10].
While this technique achieves excellent spectral separation,
the temporal separation between the two exposures invariably leads to motion artifacts in the tissue-subtracted images[11].
Furthermore,
tight integration with a fast-switching source is required,
restricting its availability to fixed systems.
The alternative DE technique is a single-shot system,
where a detector composed of two sensitive layers separated by a metal mid-filter is used.
Two images at different input spectra are obtained thanks to the beam hardening properties of the mid-filter.
This technique is immune to motion artifacts and offers ample system flexibility since all the DE capabilities come from the detector,
but results in poorer spectral separation[11] and lower dose efficiency in its DR images due to the signal lost in the filter.
We proposed,
built and tested a novel single-shot,
multi-energy flat-panel stacked X-ray detector that aims to expand on the capabilities of current single-shot systems by reducing or removing its shortcomings.
Namely,
it can potentially achieve good spectral separation and high DR dose efficiency in a single-shot system.
The purpose of this study is to evaluate the feasibility of such a detector as an alternative to established DE systems for the acquisition of both DE and DR images.