Low-dose CT


With the help of a CT, ionizing radiation is used to obtain high-resolution images of the body. A low-dose CT uses a particularly low radiation dose compared to a normal CT. This reduces the radiation dose to the patient, which is associated with risks. Low-dose CT is used, among other things, to detect stones in the kidney. In this case it is also called a stone CT.


The Low-Dose-CT is used when a good contrast is already available. This means that the structures to be examined can be easily distinguished from each other. The stone CT is used in particular to detect kidney stones (urolithiasis).

Ultrasound also offers an alternative. However, the results of ultrasound are inferior to those of stone CT. In patients with an increased risk of lung cancer, such as long-term heavy smokers, a low-dose CT can be used as a screening procedure for early detection.

A CT of the lung can detect a possible cancer earlier than with an X-ray examination. However, the introduction of an official screening procedure for the early detection of lung cancer is highly controversial. The low-dose CT can also be used if the skeleton is to be examined.


If there is a need for a low-dose CT, the patient must first be informed about the examination by a physician. The patient must then sign a consent form to undergo the examination. He also has the opportunity to ask questions.

Shortly before the examination, objects such as jewelry, glasses, hearing aids, etc. must be taken off. In addition, an artificial denture must be removed, if one is worn. If a contrast medium is given, a venous access must also be made.


The procedure is similar to a normal CT examination. Before the CT examination, all jewelry, etc. should be discarded, as this can lead to other structures in the surrounding area no longer being displayed correctly.

A low-dose CT is performed with a normal CT machine, on which the settings are adjusted. During the CT examination the patient lies down. If possible, he should not move during this procedure, as this will affect the image quality.

During a CT examination of the lungs, the patient must hold his breath for a few seconds. During the image acquisition, other persons must leave the room due to the radiation exposure. If the CT scan is performed with contrast medium, contrast medium is administered via a venous access during the examination.