Is a CT scan specific to an organ?

Question

Is a CT Scan specific to an organ?

What I mean by that question is the following: if you google a bit you will often find list with radiation exposure due to the CT scan, see for example here. In these lists the dose varies depending on what exactly gets scanned. But its not unusual to find lists that are divided by bodyparts, rather than organs (the examples for this would be in German, so I'm not sure if linking them is alright). What I now would like to know is if one scan of a body part can be used to evaluate different organs.

For example, if your urologist sends you to a CT scan of your kidneys can the same CT scan be used to evaluate your gastrointestinal tract, or your colon, etc.? What are the limitations of this and does it make a difference if contrast material was used or not?

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Note: I am not interested in answers about the radiation dose due to CT scans!

Answer 1

In general, a CT scan of an organ is intended to check only that organ, not the entire body region, even if some other organs are seen on the image. A CT of one organ can accidentally reveal a disorder in some other organ, though.

Below is a CT image of the kidneys that reveals tumors (red arrows) in both kidneys. The image also shows parts of some other abdominal organs that are on the same horizontal level. A single CT investigation of the kidneys will give more images on different levels, but it still won't show the entire abdominal cavity.

Picture 1. A CT of the kidneys (Image source: Wikipedia)

On the other hand, a doctor who is searching, for example, for a cause of abdominal pain, can order a CT scan of the "abdomen and pelvis", which will show all abdominal and pelvic organs. Such investigation usually gives more than just 3 images you can see below.

Picture 2. A CT of the abdominal cavity (source: Wikipedia)

A contrast substance used during a CT scan of a single organ can provide more details about that organ and possibly some nearby organs, but not of the entire body region.