Soft body tissue, such as a female breast, is imaged using X-ray projection techniques and optical tomography techniques. First image data for a first image of a breast (17) are acquired by X-ray projection using an X-ray source (3) and an X-ray detector (5). Second image data for a second image are acquired using optical tomography equipment comprising a light source (9) and a light detector (11). From the first image data, estimated bulk optical properties of the breast (17) are be derived. Based on such estimated bulk optical properties, an optical tomography image is reconstructed from the second image data with high image quality. Performing mammography acquisition at different compression states of the breast (17) improves patient comfort. Mammograms are acquired at two different compression states wherein a first compression state is adapted to provide high image resolution. At a second compression state, another mammogram may be acquired together with an optical tomography image. The two mammograms are used for image registration thereby possibly providing information for a deformation transform. Additional information on tissue composition within the breast is received by acquiring the first and second mammogram at different X-ray settings.