PET Scan

A positron emission tomography (PET) scan is an imaging test that uses a radioactive substance called a tracer that a technologist will inject into your arm to look for disease in the body. 

You will need to wait nearby as the tracer is absorbed by your body. Then, you will lie on a narrow table that slides into a large tunnel-shaped scanner.

Patient Preparation Instructions

Before testing

Arrival Time

Please plan to arrive 30 minutes prior to your scheduled appointment to allow time for registration, screening and consultation, glucose reading, and radioisotope injection. The radioisotope is very expensive and a specific dose must be created for each patient. This dose is time sensitive to the appointment time due to the radioactive half-life, and cannot be used for any other patient. Therefore, it is critical that patients keep their scheduled appointment time or cancel 48 hours prior to the scheduled scan.


PET Scans are completely painless


Dress comfortably and warmly, as some scanner rooms may be cool. It is a mobile unit.

Food and Drink

Non-diabetic patients should not consume any food or drink for 6 hours before their scan. Diabetic patients should not consumer any food or drink for 4 hours prior to their scan.


You make take your regularly scheduled medications prior to arriving for your scan if they can be tolerated on an empty stomach

Diabetic Patients

Generally, you should test your blood sugar level before the scan; it should be approximately 100-200 mg/dL. 

  • Non-Insulin dependent diabetics should take oral meds as prescribed. Also, please have a light meal 4 hours prior to exam, then nothing except for water until after the exam. 
  • Insulin dependent diabetics please take insulin as prescribed. Please monitor your glucose levels at home. Have a small meal 4 hours prior to the exam, then nothing except for water until after the procedure.


Upon arriving to the PET center, the technologist will check your blood sugar (for both diabetic and non-diabetic patients) to make sure it is within an acceptable range, usually under 200 mg/dL. You will then receive an injection of radioactive glucose (FDG), which will take approximately 45 minutes to distribute throughout your body. You will be asked to empty your bladder and then lie down on the scanner bed. The scan takes approximately 20 - 30 minutes, depending upon the type of scan you are having and the type of scanner being used. It is important that you lie still during this process. If you need pain medication please bring it with you. You should plan on being at the PET center for approximately 2 hours.

After testing

Once the PET scan is complete, you will be able to leave the PET center. Make sure you drink plenty of water or other fluids throughout the day to flush the FDG from your body.


The PET scan is interpreted by a trained nuclear medicine physician or radiologist, and the results are usually sent to the referring physician within 24 - 48 hours. You should contact your doctor to discuss the results.


These are preparation guidelines for imaging exams performed at Knox Community Hospital (KCH). If you have any questions regarding prep for your exam, please contact us at 740.393.9038.