1. Inhomogeneity Detection in Diffuse Optical Tomography Using Late Arriving Photons Biomedical Engineering, Tambov State Technical University, Russia A.Yu.Potlov, S.N.Abdulkareem, K.E.S.Ghaleb, S.V. Frolov, S.G. Proskurin

2. immediate inhomogeneity detection Methods are based on detection of late arriving photons (LAP), which are scattered and diffusely travel through the phantom or biological object are used for the purpose. In experiment, near infrared femtosecond pulsed laser is used as a source of irradiation. Theoretical part describes diffusion model of a bunch of photons – model of a drop, which is uniformly fills the object with time and moves to the centre of it.

3. Late Arriving Photons Late arriving photons of TPSF that diffuse through the scattering object are used. Method of diffuse optical tomography is proposed for detecting directly and determining the region of spatial localisation of absorbing and scattering inhomogeneities as a cyst, a hematoma, a tumour, etc. The issues of detecting the inhomogeneities are studied aimed at mapping the distribution of absorption and scattering in soft tissues. (LAP) are used

4. What wavelength?

5. Experiment early arriving photons late arriving photons mean time of flight

6. TPSF (experiment) Homogeneous phantom Inhomogeneous phantom (180º) Proskurin S.G., Quantum Electronics, 41, p.402-406 (2011)

7. TPSF (numerical simulation) Homogeneous phantom

8. TPSF (numerical simulation) Inhomogeneous phantom (180º)

9. 3D representation of all TPSFs (numerical simulation) Homogeneous phantom Inhomogeneous phantom

10. 3D representation of all TPSFs (experiment)

11. Homogeneity Index HI(t) simulation

12. Conclusion If one collects all curves into one 3D picture, then in the homogeneous case a plane will appear, while in the inhomogeneous case there will be planes with dips at the angles, near which the inhomogeneity is located. Such a 3D representation will allow direct detection of the presence or absence of an inhomogeneity in real time for the majority of asymmetric cases without solving the inverse problem. To find the solution of the DOT problem it necessary to find the difference in time dependent point spread functions at the times, exceeding 2 ns. Then one should proceed to the central part of TPSF, and then to early arriving photons.

13. References Proskurin S.G., Using late arriving photons for diffuse optical tomography of biological objects // Quantum Electronics, Vol. 41(5), p.402-406, 2011. Proskurin S.G., Frolov S.V., Potlov A.Yu., Absorbing inhomogeneity detection of biological tissues in diffuse optical tomography using late arriving photons // Biomedical Engineering, No.5, 2012. (submitted) Proskurin S.G., Frolov S.V., Potlov A.Yu., Oshurkov V.Yu., Detection of Absorbing Heterogeneity in Diffuse Optical Tomography // Transactions TSTU, Vol.18, No.1, p.212-215, 2012. (in Russian)