External Fractional-Order Gradient Vector Perona-Malik Diffusion for Sinogram Restoration of Low-Dosed X-Ray Computed Tomography

Figure 1

Original SDCT and LDCT images ((a)–(d)), LDCT images processed by PMD, RPMD, FOPMD and EFOGV-PMD with fractional-order 𝛼=1 and iteration number is 15.

(a)  Original SDCT image with tube current time product 150 mAs

(b) Original LDCT image with tube current time product 30 mAs

(c) Original SDCT image with tube current time product 150 mAs

(d) Original LDCT image with tube current time product 60 mAs

(e) LDCT image (b) processed by PMD with 𝜎=30, and 𝜆=1/7 and iteration number is 15

(f) LDCT image (d) processed by PMD with 𝜎=30, and 𝜆=1/7 and iteration number is 15

(g) LDCT image (b) processed by RPMD with 𝜎=30, 𝜎₁=1, and 𝜆=1/7 and iteration number is 15

(h) LDCT image (b) processed by FOPMD in [9] with 𝜎=30, 𝛼=1, and 𝜆=1/7 and iteration number is 15

(i) LDCT image (b) processed by EFOGV-PMD with 𝜎=30, 𝛼=1 and 𝜆=1/7 and iteration number is 15

(j) LDCT image (d) processed by RPMD with 𝜎=30, 𝜎₁=1, and 𝜆=1/7 and iteration number is 15

(k) LDCT image (d) processed by FOPMD in [9] with 𝜎=30, 𝛼=1, and 𝜆=1/7 and iteration number is 15

(l) LDCT image (d) processed by EFOGV-PMD with 𝜎=30, 𝛼=1, 𝜆=1/7 and iteration number is 15