clear?all
clc
L?=?256;%phantom?size
I?=?phantom（L）;%create?a?phantom
x0?=?ones（L）*0.2;%the?first?iterative?array
factor?=?1.0;%relaxation?factor
ray_num?=?L/2*90;%the?number?of?rays?in?total
ite_num?=?0;%iteration?number
while（ite_num?????for?theta?=?0:2:180
????????for?ii=1:L/2
????????????Ori?=?zeros（L）;
????????????Ori（:（2*ii-1）:2*ii）?=?1;%ray?length?is?2?pixels
????????????proj?=?imrotate（Ori?theta?‘crop‘