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PET/CT & PET/MRI
Radiopharmacy
Positron emission tomography (PET) and computerized
tomography (CT) are both state-of-the-art imaging tools
that allow physicians to pinpoint the location of cancer
within the body before making treatment plan.
The highly sensitive PET scan images detects the
biological (physiological) disorders at the molecular level,
while the CT scan provides a detailed picture of the
body's internal anatomy.
The PET/CT scan combines the strengths of these two
well-established imaging modalities into a single scan.
A CT scan is able to detect and localize changes in the body
structure or anatomy, such as the size, shape and exact
location of an abnormal growth, a sizeable tumour or a
musculoskeletal injury.
A PET scan is very different from an ultrasound, X-ray, MRI, or
CT scan. A PET scan allows the physician to distinguish
between living and dead tissue or between benign and
malignant disorders.
Since a PET scan images the biology of disorders at the
molecular level, as it can help the physician detect
abnormalities in cellular activity at a very early stage, generally
before anatomic changes are visible
PET/CT
PET/CT
PET/CT
The majority of PET/CT scans are performed for oncologic
applications. Physicians utilize PET/CT scans for
diagnosing, staging and evaluating treatments for their
cancer patients.
A PET scan helps the physician distinguish between living
and dead tissue or between benign and malignant
disorders.
PET imaging provides the physician with additional
information about cellular activity which guides the
characterization of a questionable abnormality as
malignant or benign.
Positron Emitters
C-11
N-13
O-15
F-18
Fluorine F-18 decays by positron (β+) emission and has a half-life
of 110 minutes (less than 2 hours). The principal photons useful
for diagnostic imaging are the 511 keV gamma photons,
resulting from the interaction of the emitted positron with an
electron.
F-18 FDG - Fluorodeoxyglucose
FDG is the most common Positron-Emitting Radiopharmaceutical
used in 95% of PET scan procedures.
Simply stated, FDG is radioactive glucose and is useful in determining
abnormal metabolic processes within the body.
FDG is of tremendous value in the early detection of critical disease
using PET technology.
F-18 flurodeoxyglucose FDG
Is a cyclotron produced, which is a glucose analog. This agent has
utility as a tumour- imaging agent because of an increased
demand for glucose by tumours with an advanced state of
malignancy.
Not only can F-18 flurodeoxyglucose locate and differentiate
tumours but it can also help distinguish between recurrent
tumour and radiation necrosis in patients receiving radiation
therapy
FDG concentrates in metabolically active cells, where it
is phosphorylated but does not undergo subsequent
metabolism because of the replacement of the hydroxyl
group in the 2 position with a fluorine atom.
It is metabolically trapped for a sufficient time to allow
imaging.
Administration and dosage. IV, 15 mCi
Cyclotron
A medical cyclotron is necessary to manufacture the most common
radiopharmaceuticals used for PET scanning.
The cyclotron is a circular particle accelerator that makes use of
magnetic force to propel atomic particles (negative hydrogen ions)
in a circular pattern.
These accelerated particles are stripped of their electrons resulting
in positively charged particles (protons) that are then targeted onto
a specially enriched form of water.
This bombardment results in the formation of radioactive material,
which is then transported to the radiopharmacy or “hot lab”, where
it is purified and finally incorporated into an FDG molecule.
Cyclotron
PET/MRI
Thank you and Good Luck
Prof. Dr. Omar Shebl Zahra