Multiresolution iterative reconstruction in high-resolution extremity cone-beam CT.
Application of model-based iterative reconstruction (MBIR) to high resolution cone-beam CT (CBCT) is computationally challenging because of the very fine discretization (voxel size  <100 µm) of the reconstructed volume. Moreover, standard MBIR techniques require that the complete transaxial support for the acquired projections is reconstructed, thus precluding acceleration by restricting the reconstruction to a region-of-interest. To reduce the computational burden of high resolution MBIR, we propose a multiresolution penalized-weighted least squares (PWLS) algorithm, where the volume is parameterized as a union of fine and coarse voxel grids as well as selective binning of detector pixels. We introduce a penalty function designed to regularize across the boundaries between the two grids. The algorithm was evaluated in simulation studies emulating an extremity CBCT system and in a physical study on a test-bench. Artifacts arising from the mismatched discretization of the fine and coarse sub-volumes were investigated. The fine grid region was parameterized using 0.15 mm voxels and the voxel size in the coarse grid region was varied by changing a downsampling factor. No significant artifacts were found in either of the regions for downsampling factors of up to 4×. For a typical extremities CBCT volume size, this downsampling corresponds to an acceleration of the reconstruction that is more than five times faster than a brute force solution that applies fine voxel parameterization to the entire volume. For certain configurations of the coarse and fine grid regions, in particular when the boundary between the regions does not cross high attenuation gradients, downsampling factors as high as 10×  can be used without introducing artifacts, yielding a ~50×  speedup in PWLS. The proposed multiresolution algorithm significantly reduces the computational burden of high resolution iterative CBCT reconstruction and can be extended to other applications of MBIR where computationally expensive, high-fidelity forward models are applied only to a sub-region of the field-of-view.
Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA.
Qian
Q
Cao
Wojciech
W
Zbijewski
Alejandro
A
Sisniega
John
J
Yorkston
Jeffrey H
JH
Siewerdsen
J Webster
JW
Stayman
D000465:Algorithms; D016477:Artifacts; D054893:Cone-Beam Computed Tomography / Q000295:instrumentation*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007719:Knee Joint / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging
Conf Proc IEEE Eng Med Biol Soc. 2007;2007:739-42
18002062
Phys Med Biol. 1999 Nov;44(11):2835-51
10588288
IEEE Trans Med Imaging. 2010 Nov;29(11):1839-50
20529732
Stem Cell Res Ther. 2014 Dec 29;5(6):144
25689288
AJR Am J Roentgenol. 2010 Aug;195(2):496-509
20651210
Eur Ann Otorhinolaryngol Head Neck Dis. 2011 Apr;128(2):65-78
21459066
Curr Osteoporos Rep. 2013 Jun;11(2):147-55
23504496
Med Phys. 2012 Aug;39(8):4932-42
22894419
Med Phys. 2012 Nov;39(11):7080-93
23127099
Med Phys. 2007 Nov;34(11):4526-44
18072519
Phys Med Biol. 2016 Jan 7;61(1):296-319
26649783
Med Phys. 2010 Sep;37(9):4577-89
20964175
Med Phys. 2011 May;38(5):2685-97
21776805
IEEE Trans Med Imaging. 1999 Sep;18(9):801-14
10571385
IEEE Trans Med Imaging. 2012 Oct;31(10):1837-48
22614574
IEEE Trans Med Imaging. 2004 Feb;23 (2):202-12
14964565
Med Phys. 2008 Apr;35(4):1317-27
18491526
IEEE Trans Image Process. 2002;11(7):756-70
18244672
Med Phys. 2004 Nov;31(11):3057-67
15587659
Phys Med. 2014 Sep;30(6):619-34
24974176
IEEE Trans Med Imaging. 2002 Feb;21(2):89-99
11929108
Med Phys. 2013 Oct;40(10 ):101915
24089917
Med Phys. 2011 Aug;38(8):4700-13
21928644
AJR Am J Roentgenol. 2013 Jan;200(1):146-8
23255755
Radiology. 2001 Dec;221(3):657-67
11719660
Med Phys. 2014 Jun;41(6):061909
24877820
AJR Am J Roentgenol. 2007 Dec;189(6):1312-5
18029864
Phys Med Biol. 2014 Feb 21;59(4):1005-26
24504126
Radiology. 2014 Mar;270(3):816-24
24475803
Int J Oral Maxillofac Surg. 2009 Jun;38(6):609-25
19464146
IEEE Trans Med Imaging. 2006 Sep;25(9):1172-9
16967802