Deblurring algorithms accounting for the finite detector size in photoacoustic tomography.
Most reconstruction algorithms for photoacoustic tomography, like back projection or time reversal, work ideally for point-like detectors. For real detectors, which integrate the pressure over their finite size, images reconstructed by these algorithms show some blurring. Iterative reconstruction algorithms using an imaging matrix can take the finite size of real detectors directly into account, but the numerical effort is significantly higher compared to the use of direct algorithms. For spherical or cylindrical detection surfaces, the blurring caused by a finite detector size is proportional to the distance from the rotation center (spin blur) and is equal to the detector size at the detection surface. In this work, we apply deconvolution algorithms to reduce this type of blurring on simulated and on experimental data. Two particular deconvolution methods are compared, which both utilize the fact that a representation of the blurred image in polar coordinates decouples pixels at different radii from the rotation center. Experimental data have been obtained with a flat, rectangular piezoelectric detector measuring signals around a plastisol cylinder containing various small photoacoustic sources with variable distance from the center. Both simulated and experimental results demonstrate a nearly complete elimination of spin blur.
Research Center for Non Destructive Testing GmbH, 4040 Linz, Austria.
Heinz
H
Roitner
Leopold-Franzens-University, Department of Mathematics, 6020 Innsbruck, Austria.
Markus
M
Haltmeier
Karl-Franzens-University, Department of Physics, 8010 Graz, Austria.
Robert
R
Nuster
University of Maryland, Computer Science Department and Institute for Advanced Computer Studies, College Park, Maryland 20742.
Dianne P
DP
O'Leary
Research Center for Non Destructive Testing GmbH, 4040 Linz, Austria.
Thomas
T
Berer
Karl-Franzens-University, Department of Physics, 8010 Graz, Austria.
Guenther
G
Paltauf
Research Center for Non Destructive Testing GmbH, 4040 Linz, Austria.
Hubert
H
Grün
Research Center for Non Destructive Testing GmbH, 4040 Linz, Austria.
Peter
P
Burgholzer
D000465:Algorithms; D003198:Computer Simulation; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019047:Phantoms, Imaging; D061088:Photoacoustic Techniques / Q000379:methods*; D014054:Tomography / Q000379:methods*