What the risks are:

Risks are about the same as for x-rays (radiation) and needle pricks.

No radiation is released from the scanner. Instead, it detects radiation and converts it into an image.

There is a small exposure to radiation from the radioisotope. The radioisotopes used during scans are short-lived. All of the radiation leaves the body in a few days. However, as with any radiation exposure, caution is advised for pregnant or breast-feeding women.

There is a slight risk for infection or bleeding at the site where the needle is inserted. The risk with perfusion scan is the same as with inserting an intravenous needle for any other purpose.

In rare cases, a person may develop an allergy to the radioisotope. This may include a serious anaphylactic reaction.

Special considerations:

A pulmonary ventilation and perfusion scan may be a lower-risk alternative to pulmonary angiography for evaluating disorders of the lung blood supply.

This test may not provide an definite diagnosis, especially in people with lung disease. Other tests may be needed to confirm or rule out the findings of a pulmonary ventilation and perfusion scan.