  Photoacoustic imaging is a new non-destructive medical imaging technology
based on photoacoustic effect. It can reflect the difference of light
absorption energy by detecting photoacoustic signal. At present, the analysis
methods of photoacoustic signals in biological tissues can be divided into two
categories, namely, time-domain analysis of signals and frequency-domain
analysis of signals. In time domain analysis, the envelope of the received
photoacoustic signal is usually used to reconstruct the image. However, due to
the influence of various external factors, the time domain signal cannot
accurately reflect the characteristics of the absorber itself. Here,
photoacoustic spectrum analysis was performed by using k-Wave to obtains the
relationship between the structure, size, density of the absorber and the
photoacoustic spectrum. Firstly, the relationship between the size of absorber
and the photoacoustic spectrum is studied, and the slope and intercept are used
to analyze the spectrum. Conversely, the relationship was used to predict the
size of the absorber Finally, we used this relationship to predict the size of
blood vessels.
