Image fusion scheme for differential phase contrast imaging

Patent metadata

Field	Value
Publication number	US-9916655-B2
Application number	US-201414896531-A
Country	US
Kind code	B2
Filing date	May 28, 2014
Priority date	Jun 7, 2013
Publication date	Mar 13, 2018
Grant date	Mar 13, 2018

Abstract

The latest progresses in breast imaging using differential phase contrast techniques pose the question of how to fuse multiple information sources, yielded by absorption, differential phase, and scattering signals, into a single, informative image for clinical diagnosis. It is proposed to use an image fusion scheme based on a multiple-resolution framework. The three signals are first transformed into multiple bands presenting information at different frequencies and then a two-step processing follows: (1) intra-band processing enhances the local signal-to-noise ratio using a novel noise estimation method and context modeling; and (2) inter-band processing weights each band by considering their characteristics and contributions, and suppressing the global noise level. The fused image, looking similar to a conventional mammogram but with significantly enhanced detail features, is reconstructed by inverse transform. The fused image is compatible with clinical settings and enables the radiologists to use their years of diagnosis experiences in mammography.

First claim

The invention claimed is:

1. A method for calculated image fusion in medical X-ray imaging, which comprises the steps of:
merging absorption data, differential phase contrast data and small-angle scattering data of images of an underlying sample by a fusion algorithm into one single, grey-level image with enhanced details;
basing the calculated image fusion on a multiple-resolution framework, where an original image is decomposed into several sub-images containing information of the original image at different spatial frequencies;
obtaining the absorption data, the differential phase contrast data and the small-angle scattering data of the images from X-ray investigations based on grating-based interferometry, analyzer-crystal-based imaging, or coded aperture imaging, and using an arrangement for X-rays for obtaining quantitative X-ray images from a sample, the arrangement for X-rays containing:
an X-ray source;
at least two gratings; and
a position-sensitive detector with spatially modulated detection sensitivity having a number of individual pixels;

transforming the absorption data, the differential phase contrast data and the small-angle scattering data of the images into a multiple-resolution (MR) domain consisting of multiple levels (s denotes a level index), each level containing several sub-bands (o denotes a band index);
processing and merging sub-band images in the MR domain by performing intra-band processing, inter-band processing or both the intra-band processing and the inter-band processing, wherein a fused sub-band F l ({circumflex over (t)}) can be generally expressed by

F
l

⁡

(

t
^

)

=

∑

X
∈

[

A
⁢

⁢
C

,
DPC
,
DFC

]

⁢

wn

X
,
l

·

wb

X
,
l

·

w

X
,
l

⁡

(

t
^

)

·

D

X
,
l

⁡

(

t
^

)

,

where X represents one of possible image types: an absorption contrast (AC), a differential phase contrast (DPC) or a dark-field contrast (DFC);
D X,l ({circumflex over (t)}) represents an unprocessed coefficients of band l;
l denotes a pair (s,o), indicating a certain band at level S and of band o, oε{HL,LH,HH} when a wavelet transform is used for a decomposition;
{circumflex over (t)}=(m,n) denotes 2D coordinates in a sub-band image:
the intra-band processing, which is represented by w X,l ({circumflex over (t)})·D X,l ({circumflex over (t)}), assigns a weighting factor w X,l ({circumflex over (t)}) to each coefficient within the band l to increase a local signal-to-noise ratio;
the inter-band processing gives a global weighting factor wn X,l ·wb X,l to each band for selecting useful information according to image characteristics and constraining a global noise level; and
wb X,l denotes a band selection weighting factor and wn X,l denotes a noise constraint weighting factor; and

reconstructing a merged image by an inverse multiple-resolution transform.

2. The method according to claim 1 , wherein the weighting factor w X,l ({circumflex over (t)}) in the intra-band processing is possibly given by

w

X
,
l

⁡

(

t
^

)

=

ϕ
⁡

(

σ
Sw

(

s
,
o

)

⁡

(

t
^

)

σ
Nw

(

s
,
o

)

⁡

(

t
^

)

)

,

Assignees

• Scherrer Inst Paul

Inventors

• Stampanoni Marco
• Wang Zhentian

Classifications

• A61B6/484 Primary

  involving phase contrast X-ray imaging · CPC title

• G06T7/0012 Primary

  Biomedical image inspection · CPC title

• G06T12/00

  Tomographic reconstruction from projections · CPC title

• G06T2207/20064

  Wavelet transform [DWT] · CPC title

• A61B6/5258

  involving detection or reduction of artifacts or noise · CPC title