Nuclear Medicine Procedures: V/Q Lung Scan


A V/Q (ventilation/perfusion) lung scan can detect blood clots (pulmonary emboli) in the lungs. This two-part test looks at the flow of air and blood in the lungs. During both tests, the patient is lying under a gamma camera, which makes images from emitted gamma radiation.

For the ventilation test, which determines the air flow to the lungs, the patient inhales a small amount of radioactive gas. In the perfusion test, the patient is injected with a radiopharmaceutical.


For the ventilation procedure, the patient lies on the exam table. A mask that delivers 100 percent oxygen is placed over the patient's face, which enables him or her to breathe freely. The ventilation procedure takes six minutes.

For the perfusion procedure, a radiopharmaceutical is injected and is trapped by the capillary bed in the patient's lungs. Eight images are taken around the patient’s lungs, followed by a single photon emission computed tomography (SPECT) lung scan. The perfusion lung scan takes about 15 minutes and the SPECT lung scan takes about 10 minutes. Together, the procedures take about 45 minutes.


There is no patient preparation for a V/Q scan. Patients must have a chest X-ray within 24 hours before or after the V/Q scan.


The exam table's weight limit is 350 pounds. If the patient cannot lie down because of shortness of breath, he or she can sit in a chair. Patients who have had previous nuclear medicine exams may need to wait a few days before receiving a V/Q scan, depending upon the isotope received in the previous exams.


V/Q scans can be done on an emergency basis 24 hours a day, seven days a week. Outpatient procedures are scheduled every hour from 7 a.m.-4 p.m. Monday through Friday at the main hospital campus and our Westwood campus.

Clinical Considerations

V/Q scans are performed to detect blood clots in the lungs, which can be a serious and possibly fatal condition. Prior to lung resection surgery, we may perform a V/Q scan and a lung quantification study.

Sedation Considerations

Patients cannot be sedated to have a V/Q scan.

Frequently Asked Questions

Does a V/Q scan make me radioactive?

You receive a tiny amount of radiopharmaceutical. Usually, it loses its radioactivity within hours, and will pass out of the body within 24 hours.

Do V/Q scans hurt?

Other than the minor discomfort of a needle stick, V/Q scans are painless.

Who should not get a V/Q scan?

Generally, women who are pregnant or breastfeeding should not receive this procedure. It is safe for most other patients.

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Edward Hunter, PhD

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