The systems and methods of the present disclosure are directed to ultrasound-based concentration measurement techniques in which both scatterer count and image volume are measured concurrently to provide absolute concentration measurements. In particular, through the techniques of the present disclosure, the effective thickness of an ultrasound beam can be determined based on the spreading of individual scatterers within ultrasound images. Based on the effective thickness of the ultrasound beam, the volume of the image and, thus, the concentration of particles in the image can be determined directly, without the need for estimation, approximation, or use of a reference sample.