Methods and apparatus for correcting scatter

A medical imaging system for removing scatter in an image, said medical imaging system comprising:

• a detector array;
• at least one radiation source;
• and
• a computer coupled to said detector array and radiation source and configured to:
• acquire data of an object of interest;
• estimate a re-normalization map according to N(m)˜eμdb(m):
• where:
• N(m) is the re-normalization map of a pixel m;
• μ is a mean attenuation coefficient for an X-ray photon spectrum in
• breast equivalent material;
• and
• db(m) is a distance between pixel m and a closest pixel belonging to an object boundary;
• use an iterative equation including a thickness-dependent kernel modulation factor in accordance with a k = p _ k p _ k 0 ,
• where:
• {overscore (p)}k is a norm of a scatter kernel p;
• and
• {overscore (p)}k00 is a norm of a scatter kernel for a compression thickness of the object;
• and
• incorporate the re-normalization map into the iterative equation b(n) according to:
• b ( n ) = y 2 l + ( 2 l - 1 2 l ) ⁢ b ( n - 1 ) - N ⁢ ⁢ p * ab 1 ( n - 1 ) 2 l - p * ab 2 ( n - 1 ) 2 l .
• where:
• y is a measured image;
• p is a scatter kernel;
• {overscore (p)}k is a norm of a scatter kernel p;
• l is an integer that satisfies the condition {overscore (p)}<2l;
• subscript 1 is the direct events outside of the object boundary;
• subscript 2 is the direct events inside the object boundary;
• α is the kernel modulation factor;
• N is the kernel re-normalization map;
• bn is an estimate of the image formed by directly transmitted photons;
• and
• n is a quantity of iterations.

A computer readable medium encoded with a program executable by a computer for removing scatter from an image, said program configured to instruct the computer to:

• acquire data of an object of interest;
• define an initial scatter signal estimation in accordance with s ( 0 ) = p * y 1 + p _ = p * ( b + p * b ) 1 + p _ = p * b * ( δ + p ) 1 + p _ ,
• where:
• y is a measured image;
• δ is the Kronecker delta function;
• p is a scatter kernel;
• {overscore (p)} is a scatter kernel norm;
• l is an integer that satisfies the condition {overscore (p)}<2l;
• b is a direct image;
• re-define a direct image;
• define an initial direct estimation in accordance with b ( n ) = b 2 l + p * b 2 l + ( 2 l - 1 2 l ⁢ ⁢ δ - p 2 l ) * b ( n - 1 ) ;
• where:
• n is a quantity of iterations;
• use an iterative equation to reconstruct an image of the object when a scatter fraction is greater than approximately 0.5;
• and
• select a sub-iteration quantity l such that {overscore (p)}<2l.

A medical imaging system for removing scatter in an image, said medical imaging system comprising:

• a detector array;
• at least one radiation source;
• and
• a computer coupled to said detector array and radiation source and configured to:
• acquire data of an object of interest;
• and
• use an iterative equation to reconstruct an image of the object when a scatter fraction is greater than approximately 0.5.