April 19, 2016

Modelling the Penumbra in Computed Tomography

Kueh, A., Warnett, J. W., Gibbons, G. J., Brettschneider, J., Nichols, T. E., Williams, M. A., & Kendall, W. S. (2016). Modelling the Penumbra in Computed Tomography. Journal of X-Ray Science and Technology, to appear, 14pp.

BACKGROUND: In computed tomography (CT), spot geometry is one of the main sources of error in CT images. Since X-ray tubes do not arise from a point source, artefacts are produced. In particular there is a penumbra effect, leading to poorly defined edges within a reconstructed volume. Penumbra models can be simulated given a fixed spot geometry and the known experimental setup.

OBJECTIVE: This paper proposes to use a penumbra model, derived from Beer’s law, to confirm spot geometry from penumbra data, as well as quantify blurring in the image.

METHODS: Two models for the spot geometry are considered; one consists of a single Gaussian spot, the other is a mixture model consisting of a Gaussian spot together with a larger uniform spot.

RESULTS: The model consisting of a single Gaussian spot has fits which are poor. The mixture model (which adds a larger uniform spot) exhibits much improved fits. The parameters corresponding to the uniform spot are similar across all powers, and further experiments suggest that the uniform spot produces only soft X-rays of relatively low-energy.

CONCLUSIONS: Thus, the precision of radiographs can be estimated from the penumbra effect in the image. The use of a thin copper filter reduces the size of the effective penumbra.


December 10, 2013

Neuroimaging Statistics Research at Warwick

Writing about web page http://www.warwick.ac.uk/tenichols/research/neuro-stat

There are weekly meetings on Thursdays, 12-1, in Zeeman C1.06 on Neuroimaging Statistics, where we discuss papers and our on-going research. All are welcome to join in! Details of each week's topic are in the referenced web-page.


Applied Topology and Stochastic Geometry fortnightly seminar

Writing about web page http://www2.warwick.ac.uk/fac/sci/statistics/staff/academic-research/kueh/topgeomseminar/

A fortnightly seminar to survey recent progress in the two fields mentioned in the title. Details in attached web-page. All are welcome.


June 11, 2013

EPSRC announcement

Writing about web page http://www.epsrc.ac.uk/newsevents/pubs/mags/connect/2013/90/Pages/futuremanufacturingwithmathematicalsciences.aspx

The grant for this project is one of six forming an announcement on EPSRC's webpages:

http://www.epsrc.ac.uk/newsevents/pubs/mags/connect/2013/90/Pages/futuremanufacturingwithmathematicalsciences.aspx


May 23, 2013

£1.6m funding at the interface of statistics, healthcare and manufacturing

See http://www2.warwick.ac.uk/newsandevents/pressreleases/16316m_funding_at/ for a press release partly about the award of this grant.


May 01, 2013

EPSRC Project Proposal

Writing about web page http://gow.epsrc.ac.uk/NGBOViewGrant.aspx?GrantRef=EP/K031066/1

Here is a PDF of the successful proposal for this EPSRC-funded project. It is placed here for the benefit of anyone interested in applying for the Statistics PDRA post which currently being advertised.


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