document: Statistical analysis of nonlinearly reconstructed near-infrared tomographic images . II . Experimental interpretation For pt . I see ibid. , vol . 21 , no. 7 , p. 755-63 -LRB- 2002 -RRB- . Image error analysis of a diffuse near-infrared tomography -LRB- NIR -RRB- system has been carried out on simulated data using a statistical approach described in pt . I of this paper -LRB- Pogue et al. , 2002 -RRB- . The methodology is used here with experimental data acquired on phantoms with a prototype imaging system intended for characterizing breast tissue . Results show that imaging performance is not limited by random measurement error , but rather by calibration issues . The image error over the entire field of view is generally not minimized when an accurate homogeneous estimate of the phantom properties is available ; however , local image error over a target region of interest -LRB- ROI -RRB- is reduced . The image reconstruction process which includes a Levenberg-Marquardt style regularization provides good minimization of the objective function , yet its reduction is not always correlated with an overall image error decrease . Minimization of the bias in an ROI which contains localized changes in the optical properties can be achieved through five to nine iterations of the algorithm . Precalibration of the algorithm through statistical evaluation of phantom studies may provide a better measure of the image accuracy than that implied by minimization of the standard objective function
doc_bio_tags: O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O B I O O O O O O O O O O O O B I I O O B I O O O O O O B I O O B I I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O