In some cases, a computer tomography (CT) scan is necessary to assess changes in the lungs or other parts of the body more accurately. This involves lying in an open apparatus for a few minutes while a series of X-ray images are taken. It is important to lie still during the examination and to follow instructions such as holding your breath for a short time. To improve the image quality, a contrast agent is occasionally injected into the bloodstream. To ensure that the contrast medium is well tolerated, current blood values are required to check kidney and thyroid function.

CT provides very detailed information and can also reveal changes that cannot be seen on a normal X-ray. As the radiation exposure is somewhat higher with a CT scan, an X-ray is often taken first. Only then is it decided whether an additional CT scan is necessary. Whether a CT with a lower radiation dose (low dose CT) is sufficient or a CT with a higher radiation dose but also higher (high resolution CT) image resolution is necessary must be decided on an individual basis.