Ultrasonic determination of optical absorption coefficients

摘要

The invention relates to an examination apparatus and a method for the determination of optical coefficients, particularly of the optical absorption coefficient (μa) in an object (1) like the body of a patient. The apparatus comprises an ultrasonic scanner (20) for recording first and second pulse echoes before and after the object (1) has been illuminated with a heating light beam (11) from a (e.g. laser) light source (10). An evaluation unit (30) determines a map of temperature increase (ΔT(r)) caused by the heating light beam (11) inside the object (1) based on apparent displacements showing up between the second and first pulse echoes. Furthermore, the evaluation of locally adjacent temperature increases inside the object (1) allows to determine a map of the effective scattering coefficient (μeff(r)), from which the distribution of light intensity (I(r)) inside the object (1) can be calculated. Finally, the desired optical absorption coefficient (μa) at a measuring location (r) can be determined from the light intensity and the temperature increase at this location.