Fig. 1. Wheat grain projection data for different infestation periods. (a) Egg stage; (b) young larval stage; (c) old larval stage

Fig. 2. Structural of cone beam circumferential scanning

Fig. 3. Schematic of Radon data missing for circular trajectory scanning

Fig. 4. Schematic of conjugate ray

Fig. 5. Reconstruction results at x=0 mm. (a) Head model; (b) FDK algorithm; (c) z-FDK algorithm

Fig. 6. Profile curve comparison of reconstructed images at white line position

Fig. 7. Reconstruction results and comparison chart of two algorithms for wheat grain in egg stage. (a) FDK algorithm; (b) z-FDK algorithm; (c) curve comparison at white line position

Fig. 8. Reconstruction results and comparison chart of two algorithms for wheat grain in young larval stage. (a) FDK algorithm; (b) z-FDK algorithm; (c) curve comparison at white line position

Fig. 9. Reconstruction results and comparison chart of two algorithms for wheat grain in advanced larvae. (a) FDK algorithm; (b) z-FDK algorithm; (c) curve comparison at white line position