74 research outputs found
3D Anisotropic Hybrid Network: Transferring Convolutional Features from 2D Images to 3D Anisotropic Volumes
While deep convolutional neural networks (CNN) have been successfully applied
for 2D image analysis, it is still challenging to apply them to 3D anisotropic
volumes, especially when the within-slice resolution is much higher than the
between-slice resolution and when the amount of 3D volumes is relatively small.
On one hand, direct learning of CNN with 3D convolution kernels suffers from
the lack of data and likely ends up with poor generalization; insufficient GPU
memory limits the model size or representational power. On the other hand,
applying 2D CNN with generalizable features to 2D slices ignores between-slice
information. Coupling 2D network with LSTM to further handle the between-slice
information is not optimal due to the difficulty in LSTM learning. To overcome
the above challenges, we propose a 3D Anisotropic Hybrid Network (AH-Net) that
transfers convolutional features learned from 2D images to 3D anisotropic
volumes. Such a transfer inherits the desired strong generalization capability
for within-slice information while naturally exploiting between-slice
information for more effective modelling. The focal loss is further utilized
for more effective end-to-end learning. We experiment with the proposed 3D
AH-Net on two different medical image analysis tasks, namely lesion detection
from a Digital Breast Tomosynthesis volume, and liver and liver tumor
segmentation from a Computed Tomography volume and obtain the state-of-the-art
results
Alpha scattering and capture reactions in the A = 7 system at low energies
Differential cross sections for He- scattering were measured in
the energy range up to 3 MeV. These data together with other available
experimental results for He and H scattering were
analyzed in the framework of the optical model using double-folded potentials.
The optical potentials obtained were used to calculate the astrophysical
S-factors of the capture reactions HeBe and
HLi, and the branching ratios for the transitions into
the two final Be and Li bound states, respectively. For
HeBe excellent agreement between calculated and
experimental data is obtained. For HLi a value
has been found which is a factor of about 1.5 larger than the adopted value.
For both capture reactions a similar branching ratio of has been obtained.Comment: submitted to Phys.Rev.C, 34 pages, figures available from one of the
authors, LaTeX with RevTeX, IK-TUW-Preprint 930540
Stand-Alone Artificial Intelligence for Breast Cancer Detection in Mammography: Comparison With 101 Radiologists.
BACKGROUND: Artificial intelligence (AI) systems performing at radiologist-like levels in the evaluation of digital mammography (DM) would improve breast cancer screening accuracy and efficiency. We aimed to compare the stand-alone performance of an AI system to that of radiologists in detecting breast cancer in DM. METHODS: Nine multi-reader, multi-case study datasets previously used for different research purposes in seven countries were collected. Each dataset consisted of DM exams acquired with systems from four different vendors, multiple radiologists' assessments per exam, and ground truth verified by histopathological analysis or follow-up, yielding a total of 2652 exams (653 malignant) and interpretations by 101 radiologists (28 296 independent interpretations). An AI system analyzed these exams yielding a level of suspicion of cancer present between 1 and 10. The detection performance between the radiologists and the AI system was compared using a noninferiority null hypothesis at a margin of 0.05. RESULTS: The performance of the AI system was statistically noninferior to that of the average of the 101 radiologists. The AI system had a 0.840 (95% confidence interval [CI] = 0.820 to 0.860) area under the ROC curve and the average of the radiologists was 0.814 (95% CI = 0.787 to 0.841) (difference 95% CI = -0.003 to 0.055). The AI system had an AUC higher than 61.4% of the radiologists. CONCLUSIONS: The evaluated AI system achieved a cancer detection accuracy comparable to an average breast radiologist in this retrospective setting. Although promising, the performance and impact of such a system in a screening setting needs further investigation
Modern theories of low-energy astrophysical reactions
We summarize recent ab initio studies of low-energy electroweak reactions of
astrophysical interest, relevant for both big bang nucleosynthesis and solar
neutrino production. The calculational methods include direct integration for
np radiative and pp weak capture, correlated hyperspherical harmonics for
reactions of A=3,4 nuclei, and variational Monte Carlo for A=6,7 nuclei.
Realistic nucleon-nucleon and three-nucleon interactions and consistent current
operators are used as input.Comment: 29 pages, 4 figure
Off-shell effects in the energy dependence of the Be7(p,gamma)B8 astrophysical S factor
I show that off-shell effects, like antisymmetrization and Be-7 distortions,
can significantly influence the energy dependence of the nonresonant
Be7(p,gamma)B8 astrophysical S factor at higher energies. The proper treatment
of these effects results in a vitrually flat E1 component of the S factor at
E_cm = 0.3-1.5 MeV energies in the present eight-body model. The energy
dependence of the nonresonant S factor, predicted by the present model, is in
agreement with the low-energy direct capture data and the existing high-energy
Coulomb dissociation data. Irrespective of whether or not the present energy
dependence is correct, off-shell effects can cause 15--20% changes in the value
of S(0) extrapolated from high-energy (E_cm > 0.7 MeV) data.Comment: 9 pages, 1 figur
A microscopic three-cluster model with nuclear polarization applied to the resonances of 7Be and the reaction 6Li(p,3He)4He
A microscopic model for three-cluster configurations in light nuclei is
presented. It uses an expansion in terms of Faddeev components for which the
dynamic eqations are derived. The model is designed to investigate binary
channel processes in a compound system. Gaussian and oscillator bases are used
to expand the wave function and to represent appropriate boundary conditions.
We study the effect of cluster polarization on ground and resonance states of
7Be, and on the astrophysical S-factor of the reaction 6Li(p,3He)4He.Comment: 20 pages, 8 Postscript figures, uses elsart1p.sty, submitted to Nucl.
Phys.
A Study of Various Filter Setups with FBP Reconstruction for Digital Breast Tomosynthesis
Evaluation of low contrast detectability after scatter correction in digital breast tomosynthesis
A task-based comparison of two reconstruction algorithms for digital breast tomosynthesis
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