Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: In situ phase contrast X-ray brain CT   Phase contrast X-ray imaging (PCXI) is an emerging imaging modality that has
the potential to greatly improve radiography for medical imaging and materials
analysis. PCXI makes it possible to visualise soft-tissue structures that are
otherwise unresolved with conventional CT by rendering phase gradients in the
X-ray wavefield visible. This can improve the contrast resolution of soft
tissues structures, like the lungs and brain, by orders of magnitude. Phase
retrieval suppresses noise, revealing weakly-attenuating soft tissue
structures, however it does not remove the artefacts from the highly
attenuating bone of the skull and from imperfections in the imaging system that
can obscure those structures. The primary causes of these artefacts are
investigated and a simple method to visualise the features they obstruct is
proposed, which can easily be implemented for preclinical animal studies. We
show that phase contrast X-ray CT (PCXI-CT) can resolve the soft tissues of the
brain in situ without a need for contrast agents at a dose $\sim$400 times
lower than would be required by standard absorption contrast CT. We generalise
a well-known phase retrieval algorithm for multiple-material samples
specifically for CT, validate its use for brain CT, and demonstrate its high
stability in the presence of noise.

31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
17
The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int