Fill missing parts of the image

I want to separate the part related to the lungs from the CT scans, but in some image, important information from the image is lost.

I find the lungs first by using thresholding and then by using command bwlabel, and I fill in the blank parts of the image using command imfill(x,'holes'), which is for morphology,

Do you think there is a special suggestion to solve this problem ??

Thank you for your help

[Matt J]

which, for example, did not work well in this example.

What's wrong with it?

[Image Analyst]

The stuff you did not get is not lung tissue - it's scar tissue, bone, or other non-lung tissue, right?

[lech king]

Thank you very much for your help

I wish I had found this code sooner

I spent several days writing independent code for lung extraction

In executing your code, when I enter the image that you put as an example, the program runs correctly, but when I enter this CT scan, the result is this.

I could not use your code directly and applied a separate part of your code to this image which results in:

Which has exactly the same problem or lack as my code

In your question, this CT scan actually belongs to a covid-19 person, and those parts that have no place in the end result are the main symptoms of ccovid-19, which are very important for the diagnosis of covid-19.

What do you think I should do to not delete those parts in the final images?