A Modelling of Ultrasound Generation by Laser in a breast tumor and Study of tumor Parameters effect on Generated Ultrasound Properties

Nowadays cancer detection in preliminary stages is one of the most important problems for physicians. One of the new imaging techniques, which have special capability in the detection of small size lesions, is optoacoustic imaging. In this paper have introduced this technique and have simulated optoacoustic wave generation in spherical tumors of breast.

In this research for the generation of acoustic pressure as a result of laser energy reception in an absorbing sphere, a transfer functions in backward mode has been introduced. Then using this model effect of changes in laser pulse width, dimensions and depth of tumor and absorption coefficient of tumor and media on properties of generated ultrasound have been surveyed. All of simulations have been accomplished in MATLAB7 software platform.

investigation of pulse width effect on generated optoacoustic wave illustrated that increase of laser pulse duration causes to increase in ultrasound amplitude. Investigation of tumor absorption coefficient as a function of tumor type showed that Increase of absorption coefficient of tumor causes to increase in ultrasound amplitude, but more increase in absorption coefficient causes to saturation in ultrasound amplitude and in high absorption coefficient relation between generated ultrasound amplitude and absorption coefficient because of order two.

For designing a laser- ultrasound system with maximum efficiency, we can choose optimum system using this model and simulation results with testing of various parameters of available laser systems. In addition, we can use obtained results for tumor specification in clinical applications of this technique.