Fig. 1. Diagram of the coordinate conversion of side wall of the fiber-optical

Fig. 2. Incidence, reflection and refraction in a new coordinate system

Fig. 3. Coordinate transformation of sphere boundary

Fig. 4. Different situation of photon's translation near the boundary of sphere. (a) Photon does not strike the boundary; (b) photon strikes the boundary

Fig. 5. Diagram of organizational structure

Fig. 6. Absorption contrast diagrams of multi-layer tissue with or without optical fiber. (a) at z=0.01 cm; (b) at y=0.04 cm; (c) at z=-0.01 cm; (d) at y=0.04 cm

Fig. 7. Absorption of tissue obtained with traditional multi-layer MC model and sphere model. (a) at y=0 cm; (b) at z=0 cm

Fig. 8. Photon energy absorption at different inner radius of sphere model