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Positron Emission Tomography

About your PET-CT

PET-CT is considered particularly effective in identifying whether cancer is present or not, if it has spread, if it is responding to treatment, and if a person is cancer free after treatment.  Cancers for which PET-CT is considered particularly effective include lung, head and neck, colorectal, oesophageal, lymphoma, melanoma, breast, thyroid, cervical, pancreatic, and brain as well as other less-frequently occuring cancers.

  • PET is a test that uses special imaging cameras and a radioactive type of sugar to produce pictures of the function and metabolism of the cells in the body.  CT is an X-ray test that generates a detailed view of the anatomy or structure of organs and tissues in the body.  The CT scan can show the dimension of vessels, lymph nodes and organ systems.
  • A PET/CT scan merges both technologies into a single machine.  It provides a picture of function (PET), a picture of anatomy (CT) and a merged picture of both the body’s metabolism and structure.
  • PET-CT is considered particularly effective in identifying whether cancer is present or not, if it has spread, if it is responding to treatment, and if a person is cancer free after treatment.  Cancers for which PET-CT is considered particularly effective include lung, head and neck, colorectal, oesophageal, lymphoma, melanoma, breast, thyroid, cervical, pancreatic, and brain as well as other less-frequently-occurring cancers.

Before your PET-CT

  • There is very little preparation needed for a PET/CT exam.  Typically you will be asked not to eat 6-8 hours prior to the exam but you can drink water.
  • If you’re taking medication please consult with your physician before the exam.
  • Most medications can be taken the day of the exam. Please avoid strenuous exercise 24 hours before your appointment.
  • You may be asked to put on a gown for the exam so dress comfortably and expect to change your clothes. Please do not wear any jewellery.

What to expect

  • To begin the procedure, a small amount of radioactive glucose (or similar tracer) is injected into your bloodstream.
  • After the injection, you will wait approximately an hour, while the injected material is distributed throughout your body.
  • Then, you will be asked to lie on a table that passes slowly through the scanner.
  • The scanner resembles a CT scanner, but has a much larger opening.
  • Some people fall asleep during the scan.

 For best results

  • It is important that you don’t move for the duration of the scan.
  • The length of the exam is determined by your height and area of interest.
  • Most PET/CT scans are typically completed within 20-40 minutes.

After PET-CT

  • Once the total scan has been performed, you may resume normal daily activity.
  • Even though the FDG will quickly leave your body, you can expedite the process by drinking plenty of water after your scan is complete.
  • Your PET/CT results will not be available immediately, but the reading physician will contact your referring physician to convey all pertinent information gathered from the scan.
  • Please call your referring physician for scan results.

 Let the Radiographer know

  • You are or may be pregnant,
  • You are diabetic,
  • You are unsure if you should take your medication, or
  • You have had recent radiation therapy.

PET-CT Risks

The risks associated  with  a PET  scan are minimal.  Most  studies  are  conducted with  an  injection  made  up  of  radioactive  glucose (sugar).  The  radiation  exposure associated  with  PET  is  similar  to  a  conventional  whole-body  diagnostic  CT scan.

The main use of PET/CT is the detection and evaluation of primary and metastatic cancer.  It is used to determine the correct stage of the cancer at the beginning and to evaluate the response to treatment as well as recurrence of disease after treatment.

PET/CT combines anatomical imaging (CT) with physiological and pathological imaging (PET).

A radioactive isotope, which is bound to sugar, is injected into the body.  This concentrates in areas with a high metabolic rate, in other words which uses a large amount of sugar.  This is the case in most primary cancers and cancers that have spread to other parts of the body (metastatic).

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