FAST IMAGE-RECONSTRUCTION FOR OPTICAL-ABSORPTION TOMOGRAPHY IN MEDIA WITH RADIALLY SYMMETRICAL BOUNDARIES

In this paper we present a reconstruction algorithm to invert the line arized problem in optical absorption tomography for objects with radia lly symmetric boundaries. This is a relevant geometry for functional v olume imaging of body regions that are sensitive to ionizing radiation , e.g., breast and testis. From the principles of diffuse light propag ation in scattering media we derive the governing integral equations d escribing the effects of absorption variations on changes in the measu rement data. Expansion of these equations into a Neumann series and tr uncation of higher-order terms yields the linearized forward imaging o perator. For the proposed geometry we utilize an invariance property o f this operator, which greatly reduces the problem dimensionality, Thi s allows us to compute the inverse by singular value decomposition and consequently to apply regularization techniques based on the knowledg e of the singular value spectrum. The inversion algorithm is highly ef ficient computing slice images as fast as convolution-backprojection a lgorithms in computed tomography (CT). To demonstrate the capacity of the inversion scheme we present reconstruction results for synthetic a nd phantom measurement data. (C) 1998 American Association of Physicis ts in Medicine.