How to exclude/remove ribcage shadow in an Xray image?

How can I remove the shadow of the rib cage so that I can do proper image segmentation and analysis. Below is the sample Xray image that I wish to enhance.

Thank you!

Answer 1

[Shubham]

Hi Arturo,

Removing the shadow of the rib cage in X-ray images to enhance segmentation and analysis can be approached through several steps in MATLAB. Here’s a simplified guide to get you started, focusing on techniques that can be implemented in MATLAB.

Step 1: Load the Image

First, you need to load the X-ray image into MATLAB:

img = imread('path_to_your_image.jpg');
imgGray = rgb2gray(img); % Convert to grayscale if it's a color image
imshow(imgGray);
title('Original Image');

Step 2: Contrast Enhancement

Improving the image contrast can help differentiate the rib cage from the organs:

imgEnhanced = imadjust(imgGray);
figure;
imshow(imgEnhanced);
title('Contrast Enhanced Image');

Step 3: Noise Reduction

Apply a noise reduction filter to minimize artifacts:

imgSmooth = imgaussfilt(imgEnhanced, 2); % Gaussian blur with a sigma of 2
figure;
imshow(imgSmooth);
title('Smoothed Image');

Step 4: Rib Cage Shadow Suppression

This step is more complex and can be approached in different ways. One method is to use morphological operations to highlight the rib cage and then subtract it from the original image. Another approach is using edge detection to identify the ribs and then perform image reconstruction to remove them. Here’s a simple morphological approach:

% Enhance features (ribs)
se = strel('disk', 10);
imgTopHat = imtophat(imgSmooth, se);
figure;
imshow(imgTopHat);
title('Top-Hat Filtered Image');

% Subtract rib features from the original image
imgSubtracted = imsubtract(imgSmooth, imgTopHat);
figure;
imshow(imgSubtracted);
title('Rib Shadows Suppressed');

Step 5: Image Segmentation

After suppressing the rib shadows, you can perform segmentation on the lungs or other areas of interest. A simple global thresholding can be a starting point:

thresholdValue = graythresh(imgSubtracted); % Otsu's method
imgSegmented = imbinarize(imgSubtracted, thresholdValue);
figure;
imshow(imgSegmented);
title('Segmented Image');

Advanced Techniques

For more sophisticated rib suppression and segmentation, consider exploring deep learning approaches. MATLAB supports deep learning through its Deep Learning Toolbox, where you can design, train, and deploy deep neural networks. Pre-trained models or custom networks like U-Net can be particularly effective for medical image segmentation tasks.

Note:

The effectiveness of these steps can vary depending on the specific characteristics of the X-ray images you're working with. You might need to adjust parameters or explore more advanced techniques based on deep learning for better results.

MATLAB Toolboxes for Advanced Processing:

• Image Processing Toolbox: Provides comprehensive tools for image processing and analysis.
• Computer Vision Toolbox: Offers algorithms, functions, and apps for designing and testing computer vision, 3D vision, and video processing systems.
• Deep Learning Toolbox: Enables designing, training, and deploying deep neural networks in MATLAB.

Experiment with different techniques and parameters to find the best approach for your specific application.