2. Nuclear Medicine
• Administration of radiopharmaceuticals,
whether oral, IV, or intra-articular, for the
purpose of imaging, diagnosis or treatment
3. Radiopharmacy
• Senyawa penanda yang dipakai dalam kedokteran nuklir
disebut radiofarmaka.
• Radiofarmaka terdiri dari dua komponen, yaitu radioisotop
dan senyawa pembawanya.
• Radioisotop memungkinkan suatu radiofarmaka dapat
dideteksi dan diketahui lokasinya, sedang senyawa pembawa
menentukan tempat akumulasi radiofarmaka tersebut.
• Setelah masuk ke dalam tubuh, radiofarmaka akan menuju ke
organ tertentu. Karena senyawa tersebut dapat memancarkan
radiasi gamma, maka keberadaannya di dalam organ tubuh
dapat diketahui dengan pemantau radiasi, baik kinetik
maupun distribusinya.
4. Pendahuluan
All substances are made of atoms.
• These have electrons (e) around the outside (negatively
charged), and a nucleus in the middle.
• The nucleus consists of protons (positively charged)
and neutrons (neutral).
• The atomic number of an atom is the number of
protons in its nucleus.
• The atomic mass is the number of protons + neutrons
in its nucleus.
5.
6. Pendahuluan
Isotopes of an atom have the same number of protons, but a
different number of neutrons.
• Example:
• Consider a carbon atom:
It has 6 protons and 6 neutrons - we call it "carbon-12" because
it has an atomic mass of 12 (6 plus 6).
• One useful isotope of carbon is "carbon-14", which has 6
protons and 8 neutrons.
• Radioisotopes, Radionuclides: unstable isotopes which are
distinguishable by radioactive transformation.
• Radioactivity: the process in which an unstable isotope undergoes
changes until a stable state is reached and in the transformation
emits energy in the form of radiation (alpha particles, beta particles
and gamma rays).
7. Radioaktif
Radiation refers to particles or waves coming from the
nucleus of the atom (radioisotope or radionuclide)
through which the atom attempts to attain a more stable
configuration.
8. Radiasi
Type of Radiation Alpha particle Beta particle Gamma ray
Symbol or
Charge +2 -1 0
Speed slow fast Very fast
Ionising ability high medium 0
Penetrating power low medium high
Stopped by: paper aluminium lead
11. Peluruhan Bahan Radioaktif
• Half life — symbol t1/2 — the time taken for
the activity of a given amount of a radioactive
substance to decay to half of its initial value.
12. Diagnostic Radioisotopes
To be useful as a diagnostic tool, a radioisotope must
meet certain criteria. It must:
• have a short half life, ideally about the same as the
time required to perform the diagnosis.
• not emit alpha or beta radiation, because they would
be trapped inside the patient and could not be
detected externally.
• emit gamma radiation which is energetic enough to
allow its exact source to be identified.
• be energetic enough to provide useful clinical
information but not so energetic as to be dangerous to
the patient
13. Diagnostic Radioisotopes
• From a field of more than 2300 radioisotopes,
only a handful come close to satisfying the
criteria for use as diagnostic tools.
• Of these, the reactor produced Technetium –
99m, is by far the best, being used in more that
80% of all nuclear diagnostic tests performed.
• Note: the m in the symbol 99mTc means this is
the “metastable” form of Tc, which radiates
gamma rays and low energy electrons.
14. Technetium 99m
a.It has a half-life of six hours which is long enough to
examine metabolic processes yet short enough to
minimise the radiation dose to the patient.
b.Technetium-99m decays by an "isomeric" process
which emits gamma rays and low energy electrons.
Since there is no high energy beta emission the
radiation dose to the patient is low.
c.The low energy gamma rays it emits easily escape the
human body and are accurately detected by a gamma
camera. Once again the radiation dose to the patient
is minimised.
d.The chemistry of technetium is so versatile it can form
tracers by being incorporated into a range of
biologically-active substances to ensure that it
concentrates in the tissue or organ of interest
16. Gamma Camera
• Once a radiopharmaceutical has been
administered, it is necessary to detect the
gamma ray emissions in order to attain the
functional information. The instrument used
in Nuclear Medicine for the detection of
gamma rays is known as the Gamma camera.
• The components making up the gamma
camera are the collimator, detector crystal,
photomultiplier tube array, position logic
circuits, and the data analysis computer.
21. Bone Scan
• Bone scans are typically
performed in order to
assess bone growth and
to look for bone tumors.
The tumors are the dark
areas seen in the picture.
