PET Scans – Positron Emission Tomography
How DO they work?
A small amount of radioactive material (fluorodeoxyglucose) is injected into the patient.
This is a tracer substance attached to glucose. The tracer gets absorbed into the
bloodstream and as the brain is working, the glucose gets used up as a form of energy. The
radioactive atom breaks down emitting positrons and gamma rays. The gamma rays are
those that are picked up by the scanner. High concentrations of gamma rays are found in
the high activity levels and show in warmer colours.
Evaluation:
Strengths: Weaknesses:
o Useful for investigating areas o Invasive scan, as radioactive
of the brain that don’t substance is used.
function normally . this may o Not advisable for patients to
indicate damage or tumours. have too many of this type of
o Helps researchers predict scan and it’s unclear as to what
what kind of issues patients the long term effects are.
may face when looking at the
brain activity.
Validity:
▪ Accurately measures brain activity.
▪ Objective interpretation with red/blue concentration scale (quantitative data).
Reliability:
▪ High- everyone has to be injected with the radioactive tracer and scan is easily
repeated following the same procedure.
Generalisability:
▪ Not suitable for pregnant women and young children.
Ethics:
▪ Invasive- involves the injection of the radioactive tracer.
▪ There are issues with claustrophobia and radiation.
Time/Cost:
▪ Around £1500
▪ Not time efficient as it can take 2-4 hours.
How DO they work?
A small amount of radioactive material (fluorodeoxyglucose) is injected into the patient.
This is a tracer substance attached to glucose. The tracer gets absorbed into the
bloodstream and as the brain is working, the glucose gets used up as a form of energy. The
radioactive atom breaks down emitting positrons and gamma rays. The gamma rays are
those that are picked up by the scanner. High concentrations of gamma rays are found in
the high activity levels and show in warmer colours.
Evaluation:
Strengths: Weaknesses:
o Useful for investigating areas o Invasive scan, as radioactive
of the brain that don’t substance is used.
function normally . this may o Not advisable for patients to
indicate damage or tumours. have too many of this type of
o Helps researchers predict scan and it’s unclear as to what
what kind of issues patients the long term effects are.
may face when looking at the
brain activity.
Validity:
▪ Accurately measures brain activity.
▪ Objective interpretation with red/blue concentration scale (quantitative data).
Reliability:
▪ High- everyone has to be injected with the radioactive tracer and scan is easily
repeated following the same procedure.
Generalisability:
▪ Not suitable for pregnant women and young children.
Ethics:
▪ Invasive- involves the injection of the radioactive tracer.
▪ There are issues with claustrophobia and radiation.
Time/Cost:
▪ Around £1500
▪ Not time efficient as it can take 2-4 hours.
