Abstract
Breast X-ray CT imaging is being considered in
screening as an extension to mammography. As a large fraction of
the population will be exposed to radiation, low·dose imaging is
essential. Iterative image reconstruction based on solving an optimization
problem, such as Total-Variation minimization, shows
potential for reconstruction from sparse-view data. For iterative
methods it is important to ensure convergence to an accurate
solution, since important diagnostic image features, such as
presence of microcalcifications indicating breast cancer, may not
be visible in a non-converged reconstruction, and this can have
clinical significance. To prevent excessively long computational
times, which is a practical concern for the large image arrays in
CT, it is desirable to keep the number of iterations low, while
still ensuring a sufficiently accurate reconstruction for the specific
imaging task. This motivates the study of accurate convergence
criteria for iterative image reconstruction. In simulation studies
with a realistic breast phantom with microcalcifications we
investigate the issue of ensuring sufficiently converged solution
for reliable reconstruction. Our results show that it can be
challenging to ensure a sufficiently accurate microcalcification
reconstruction, when using standard convergence criteria. In
particular, the gray level of the small microcalcifications may not
have converged long after the background tissue is reconstructed
uniformly. We propose the use of the individual objective function
gradient components to better monitor possible regions of nonconverged
variables. For microcalcifications we find empirically a
large correlation between nonzero gradient components and nonconverged
variables, which occur precisely within the microcalcifications.
This supports our claim that gradient components
can be used to ensure convergence to a sufficiently accurate
reconstruction.
Original language | English |
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Title of host publication | 2011 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) |
Publisher | IEEE |
Publication date | 2011 |
Pages | 2640-2643 |
ISBN (Print) | 978-1-4673-0118-3 |
DOIs | |
Publication status | Published - 2011 |
Event | 2011 IEEE Nuclear Science Symposium and Medical Imaging Conference - Valencia, Spain Duration: 23 Oct 2011 → 29 Oct 2011 https://ewh.ieee.org/soc/nps/nss-mic/2011/ |
Conference
Conference | 2011 IEEE Nuclear Science Symposium and Medical Imaging Conference |
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Country/Territory | Spain |
City | Valencia |
Period | 23/10/2011 → 29/10/2011 |
Internet address |
Keywords
- Total variation
- Algorithm convergence
- Breast CT
- Compressed sensing
- X-ray CT