A method for quantifying an absolute concentration of fluorophore in a target turbid medium, the method comprising: detecting fluorescence emission from a target surface of the target turbid medium, the detected fluorescence emission including fluorescence emission of the fluorophore generated using a fluorescence excitation wavelength provided to the target turbid medium; detecting diffuse reflectance over a spectral range of wavelengths detected from the target surface at two different predetermined distances from one or more broadband excitation sources (2', 4', 5', 6', 7') to obtain two respective diffuse reflectance spectra; determining an absorption coefficient (μ α) and a transport scattering coefficient (μ' s) of the target turbid medium using the two respective diffuse reflectance spectra and a priori knowledge of absorption and transport scattering spectra of a reference turbid medium; and determining the absolute concentration of the fluorophore in the target turbid medium using the detected fluorescence emission and the determined absorption and transport scattering coefficients; wherein determining the absorption coefficient (μ α) and transport scattering coefficient (μ' s) comprises: receiving an a priori absorption coefficient spectrum (μ α (λ)) and an a priori transport scattering coefficient spectrum (μ' s (λ)) as functions of wavelength from the two diffuse reflectance spectra, and calculating the determined absorption coefficient (μ α) and transport scattering coefficient (μ' s) in absolute units for the fluorescence excitation wavelength based on the a priori absorption and transport scattering coefficient spectra and detected diffuse reflectance over the spectral range of wavelengths at the two different predetermined distances; wherein the detected fluorescence emission comprises a detected fluorescence spectrum, the method comprising calculating a quantitative fluorescence spectrum in absolute units from the detected fluorescence spectrum using the determined absorption and transport scattering coefficients of the target turbid medium. detecting fluorescence emission from a target surface of the target turbid medium, the detected fluorescence emission including fluorescence emission of the fluorophore generated using a fluorescence excitation wavelength provided to the target turbid medium; detecting diffuse reflectance over a spectral range of wavelengths detected from the target surface at two different predetermined distances from one or more broadband excitation sources (2', 4', 5', 6', 7') to obtain two respective diffuse reflectance spectra; determining an absorption coefficient (μ α) and a transport scattering coefficient (μ' s) of the target turbid medium using the two respective diffuse reflectance spectra and a priori knowledge of absorption and transport scattering spectra of a reference turbid medium; and determining the absolute concentration of the fluorophore in the target turbid medium using the detected fluorescence emission and the determined absorption and transport scattering coefficients; wherein determining the absorption coefficient (μ α) and transport scattering coefficient (μ' s) comprises: receiving an a priori absorption coefficient spectrum (μ α (λ)) and an a priori transport scattering coefficient spectrum (μ' s (λ)) as functions of wavelength from the two diffuse reflectance spectra, and calculating the determined absorption coefficient (μ α) and transport scattering coefficient (μ' s) in absolute units for the fluorescence excitation wavelength based on the a priori absorption and transport scattering coefficient spectra and detected diffuse reflectance over the spectral range of wavelengths at the two different predetermined distances; receiving an a priori absorption coefficient spectrum (μ α (λ)) and an a priori transport scattering coefficient spectrum (μ' s (λ)) as functions of wavelength from the two diffuse reflectance spectra, and calculating the determined absorption coefficient (μ α) and transport scattering coefficient (μ' s) in absolute units for the fluorescence excitation wavelength based on the a priori absorption and transport scattering coefficient spectra and detected diffuse reflectance over the spectral range of wavelengths at the two different predetermined distances; wherein the detected fluorescence emission comprises a detected fluorescence spectrum, the method comprising calculating a quantitative fluorescence spectrum in absolute units from the detected fluorescence spectrum using the determined absorption and transport scattering coefficients of the target turbid medium.