Algorithm 5.

(Nested EM-TV Algorithm for MAP ECT Reconstruction)

Initialization: f(0) = 1.

repeat

EM Step: $f^{(k+\frac{1}{2})}\leftarrow \text{diag }\left(\frac{f^{(k)}}{A^{\top }1}\right)A^{\top }\left(\frac{g}{{\mathit{\text{Af}}}^{(k)}+\gamma }\right)$.

TV Step: $f^{(k+1)}\leftarrow \text{argmin }\{\frac{1}{2}\langle f-f^{(k+\frac{1}{2})},\frac{A^{\top }1}{f^{(k)}}\odot (f-f^{(k+\frac{1}{2})})\rangle +\lambda \phi (\mathit{\text{Bf}}):f\in {ℝ}_{+}^d\}$.

until “convergence”