Optical tomography method that accounts for tilted chest wall in breast imaging

The chest wall underneath breast tissue distorts light reflection measurements, especially measurements obtained from distant source-detector pairs. For patients with a chest wall located at a shallower depth, the chest-wall effect needs to be considered in the image reconstruction procedure. Following our previous studies, this work systemically evaluates the performance of a two-layer model-based reconstruction using the finite element method, and compares it with the performance of the semi-infinite model. The results obtained from simulations and phantom experiments show that the two-layer model improves the light quantification of the targets. The improvements are attributed to improved background estimation and more accurate weight matrix calculation using a two-layer model compared to the semi-infinite model. Fitted two-layer background optical properties obtained from a group of ten patients with chest walls located less than 2 cm deep are more representative of breast tissue and chest-wall optical properties.