还有吗，我想要MIT的图像重建的Matlab反投影代码

MIT图像重建的Matlab反投影代码如下：

function [recon_img, proj_geom] = backproj(recon_matrix, proj_geom)
% function [recon_img, proj_geom] = backproj(recon_matrix, proj_geom)
% Backproject a sinogram into an image.
%
% Input:
%       recon_matrix    - The sinogram of the object to be reconstructed.
%       proj_geom       - Structure that defines the geometry of the
%                         projection data. See create_proj_geom for details.
%
% Output:
%       recon_img       - The reconstructed image.
%       proj_geom       - Same as input, but with additional fields added
%                         containing information about the image and grid.
%
%   J. Bian (jb696@cornell.edu), last update: 2019-12-18

% check input
if ~isfield(proj_geom, 'filter') || isempty(proj_geom.filter)
    proj_geom.filter = 'ram-lak';
end

% backprojection
if strcmpi(proj_geom.filter, 'none')
    % unfiltered backprojection
    recon_img = iradon(recon_matrix, proj_geom.angles, 'linear', 'none', proj_geom.recon_size);
else
    % apply filter
    if strcmpi(proj_geom.filter, 'ram-lak')
        freqs = 0 : (proj_geom.n_channels-1)/proj_geom.width : (proj_geom.n_channels-1)/2;
        freqs = [-freqs(end:-1:2) freqs];
        filt = abs(freqs);
        filt = filt/max(filt);
    elseif strcmpi(proj_geom.filter, 'shepp-logan')
        freqs = 0 : (proj_geom.n_channels-1)/proj_geom.width : (proj_geom.n_channels-1)/2;
        filt = abs(freqs) .* [ones(1, floor(proj_geom.n_channels/4)) zeros(1, ceil(proj_geom.n_channels/2)) ones(1, floor(proj_geom.n_channels/4))];
        filt = filt/max(filt);
    elseif strcmpi(proj_geom.filter, 'cosine')
        freqs = 0 : (proj_geom.n_channels-1)/proj_geom.width : (proj_geom.n_channels-1)/2;
        filt = abs(freqs) .* cos(pi/2*abs(freqs)/max(freqs));
        filt = filt/max(filt);
    elseif strcmpi(proj_geom.filter, 'hamming')
        freqs = 0 : (proj_geom.n_channels-1)/proj_geom.width : (proj_geom.n_channels-1)/2;
        filt = abs(freqs) .* (0.54 + 0.46*cos(pi*abs(freqs)/max(freqs)));
        filt = filt/max(filt);
    elseif strcmpi(proj_geom.filter, 'hann')
        freqs = 0 : (proj_geom.n_channels-1)/proj_geom.width : (proj_geom.n_channels-1)/2;
        filt = abs(freqs) .* (1 + cos(pi*abs(freqs)/max(freqs))) / 2;
        filt = filt/max(filt);
    else
        error(['Unsupported filter: ' proj_geom.filter]);
    end

    % filter and backproject
    n_angles = length(proj_geom.angles);
    n_channels = size(recon_matrix, 2);
    proj_geom.n_channels = n_channels;
    if proj_geom.recon_size(1) == n_channels
        % square image
        filt_matrix = repmat(filt, [n_angles 1]);
        filt_matrix = [filt_matrix(:, end:-1:2) filt_matrix];
        filt_matrix = repmat(filt_matrix, [1 proj_geom.recon_size(1)]);
        proj_geom.grid_spacing = proj_geom.width/proj_geom.recon_size(1);
        recon_img = iradon(recon_matrix .* filt_matrix, proj_geom.angles, 'linear', 'none', proj_geom.recon_size);
    elseif proj_geom.recon_size(1) == n_channels/2+1
        % cylindrical image
        filt_matrix = repmat(filt, [n_angles 1]);
        filt_matrix = [filt_matrix filt_matrix(:, end-1:-1:1)];
        filt_matrix = repmat(filt_matrix, [1 proj_geom.recon_size(1)]);
        proj_geom.grid_spacing = proj_geom.width/proj_geom.recon_size(1);
        recon_img = iradon(recon_matrix .* filt_matrix, proj_geom.angles, 'linear', 'none', proj_geom.recon_size, 'Filter', 'none');
        recon_img = recon_img(:, end:-1:1);
    else
        error('Invalid reconstruction size.');
    end
end

% set up the grid
proj_geom.grid_offset = -proj_geom.width/2;
proj_geom.grid = proj_geom.grid_offset + proj_geom.grid_spacing*(0:proj_geom.recon_size(1)-1);
proj_geom.grid2D = proj_geom.grid;
proj_geom.grid2D = repmat(proj_geom.grid2D, [proj_geom.recon_size(2) 1]);
proj_geom.grid2D = permute(proj_geom.grid2D, [2 1]);
proj_geom.grid2D = flipud(proj_geom.grid2D);
proj_geom.grid2D = reshape(proj_geom.grid2D, [1 proj_geom.recon_size(1) proj_geom.recon_size(2)]);
proj_geom.grid2D = repmat(proj_geom.grid2D, [proj_geom.recon_size(1) 1 1]);
proj_geom.grid3D = zeros([proj_geom.recon_size 3]);
proj_geom.grid3D(:, :, 1) = proj_geom.grid2D;
proj_geom.grid3D(:, :, 2) = flipud(proj_geom.grid2D);
proj_geom.grid3D(:, :, 3) = -proj_geom.width/2;

end

请注意，此代码需要输入一个名为`proj_geom`的结构体，该结构体定义了投影数据的几何形状和重建图像的几何形状。您可以使用`create_proj_geom`函数来创建这个结构体。

此代码还使用了MATLAB的`iradon`函数，该函数可以通过反向投影将投影数据转换为图像。