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. Author manuscript; available in PMC: 2010 May 1.
Published in final edited form as: IEEE Trans Med Imaging. 2009 Jan 13;28(5):739–751. doi: 10.1109/TMI.2008.2012034

Fig. 11.

Fig. 11

Contrast of 10-mm spheres as a function of iteration number for short (truncated) and long (continuous) phantoms, for data grouped into 1 and 3 co-polar intervals (phantom diameter 35 cm, 600-ps TOF resolution, DIRECT reconstruction using RAMLA with resolution modeling, 40 azimuthal intervals; one relative iteration represents equivalent total computation time to one iteration of the 3-tilt case). Abrupt truncation of the attenuation and emission objects does not negatively affect DIRECT performance as seen on the contrast measures and as illustrated by images and profiles shown in Figs. 9 and 10 for 15-th iteration marked with gray ellipse in this plot.