Nuclear Medicine

Guided By
Prof(Dr) G Subhas Babu
Dr Shruthi Hegde
Dr Renita Castelino
Dr Kumuda Rao
Dr Supriya Bhat
MODERATOR
Dr Vidya Ajila
Presenter
Dr Sajad Ahmad Buch

NUCLEAR MEDICINE
 Imaging specialty that focuses on the use of
radioactive materials called
“radiopharmaceuticals” for diagnosis, therapy, and
medical research.

NM
 Determine the cause of a medical problem based
on organ or tissue function.
 Physiology

NM TEST
 Radioactive material, or “tracer”, is introduced into
the body by injection, swallowing, or inhalation.
 Different tracers are used to study different parts of
the body

TRACERS
 Are selected that localize in specific organs or
tissues
 Ex: GLUCOSE
 The amount of radioactive tracer material is
selected carefully to provide the lowest amount of
radiation exposure

RADIOACTIVE TRACERS
 Produce Alpha, Gamma or Beta emission from
within the organ being studied
 Emissions are transformed into image that provide
information about the function of the organ or
system being studied.

FUNCTION VS ANATOMY
 The emphasis of nuclear medicine studies is more
on function and chemistry than anatomical
structure

HISTORY
 A few months after “William Roentgen” discovered
x-rays
 Henri becquerel discovered naturally occurring
radioactive substances.

 THE ATOMIC AGE
one of history's most important events,
took centuries to arrive, as events in science and international affairs
evolved.
The Atomic Theory, a cornerstone of modern science, was proposed
by an early Greek thinker, Democritus 460 BCE-370 BCE.

 Atomic Weights 1808
 John Dalton, an English chemist, stated that each atom of any
given element is identical to every other atom of that element,
including weight.
 The Periodic Table 1871 Dmitry Mendeleyev, a Russian chemist,
revealed the basic importance of atomic weights and of nuclear
structure. His work also showed the significance of structure in
comprehending the behaviour and properties of matter.

 Cathode rays 1887 sir William Crookes, an English
chemist and physicist ,pioneered work on cathode
rays.
 X-rays 1895
 German physicist Wilhelm Röentgen noticed some
glowing barium Platinocyanide across the room from
his experiment. This led to the discovery of x-rays. His
work helped found a major new medical technique
and played an important role in revealing the secrets
of the atom and its nucleus.

A.H.Becquerel
Henri Becquerel, in early 1896, the French physicist, Henri
Becquerel, discovered that a mysterious X-ray was produced by
uranium.
Becquerel's achievement was itself based on the work of the
German scientist, Wilhelm Conrad Roentgen ,who had discovered
X-rays only a few months earlier in November 1895

 Radium 1902
Marie Curie and her husband ,Pierre, discovered the radioactive
elements polonium and radium.
Their work confirmed the existence of radioactivity.
Curie: basic unit of radioactivity
1 gm radium : 2.22x1012
disintegrations per minute/dpm

 The Nuclear Model 1909
Sir Ernest Rutherford's great contribution to modern science was to
show what happens to an element during radioactive decay .
This enabled him to construct the first nuclear model of the atom,
a cornerstone of present-day physics
 The Electron Orbit 1913
Niels Bohr modified Rutherford's model of the atom to incorporate
the ideas of quantum physics. This required a new mechanism for
the way electrons emitted energy.

 Transformation of Atoms 1919
Rutherford's work, which he published in 1919,demonstrated that
atoms could be transformed from those of one element into
those of another by means of artificial tampering with the
nucleus. Far more important, his experiment demonstrated that
the nucleus of an atom could be breached.
 The Neutron 1932
British physicist Sir James Chadwick is best known for discovering
the neutron, one of the fundamental particles making up the
nucleus of atoms. The neutron differed from all other particles
then known by having no electrical charge.

 The Atom is Split 1932
Sir John Douglas Cockroft and his colleague ,Ernest T. S. Walton,
developed the Cockroft-Walton particle accelerator. Using it in
1932, they managed to boost the speed of protons to the point
where the voltage was high enough to energize each atom of
lithium, their target metal, to form two atoms of helium.
This was the first example of man-made nuclear transformation.

 Uranium and Fission 1938
German scientists Otto Hahn and Fritz Strassmann discovered that a
tiny portion of the uranium atom's mass could be converted into
an estimated 200 million electron volts of potentially usable
energy. This process was to be called fission.

 Ernest O. Lawrence In 1929
Ernest O. Lawrence, working at the University of California at
Berkeley, invented the cyclotron which could create a number
of radioisotopes that are useful in biological and medical work.

 Glenn T. Seaborg and John J. Livingood
 Using an advanced cyclotron, scientists John Livingood, Fred
Fairbrother, and Glenn T.Seaborg produced iron-59 (Fe-59) in
1937.Iron-59 was useful in the studies of the haemoglobin in
human blood.
 In 1938, iodine-131(I-131) was discovered by Livingood and
Seaborg. Iodine-131is used across the world to treat thyroid
disease.

 Dr Glenn Seaborg was considered one of the "founding fathers" of
nuclear medicine. Dr Seaborg was the most prolific discoverer of
radioisotopes that are used today in diagnosis and treatment.
Seaborg was active in the field up until the time of his death in
1999.

10000 cosmic ray particles/hr
15million potassium
atoms decay/hr
30000 decay/hr
lungs
Natural radioactivity in the earth and in materials
around us send over 200 million gamma rays/hr

RADIOACTIVITY
 Is used to describe the radiation of energy in
the form of high-speed alpha, gamma or
beta particles or waves (gamma rays), from
the nucleus of an atom

THYROID
 Was one of the first organs to be examined by
nuclear medicine studies in the 1940s-1950s
 Endocrine emphasis, initially using iodine-131 to
diagnose and then treat thyroid disease.

ISOTOPES
 ELEMENTS WITH THE SAME NUMBER OF PROTONS BUT
A DIFFERENT NUMBER OF neutrons ARE REFERED TO
AS ISOTOPES
 The neutron-to-proton ratio in the nucleus
determins the stability of the atom

ISOTOPES
 At certain ratios, atoms may be unstable, a process
known as spontaneous decay can occur as the
atom attempts to regain stability.
 Any nuclide with an atomic number greater than 83
is radioactive

ISOTOPES
 Energy is released in various ways during this decay,
or return to ground state
 Radionuclides decay by the emission of alpha,
beta, and gamma radiation
 Alpha : 2 protons, helium nuclei
 Beta : electrons
 Gamma: photons

 These three forms of radiation can be distinguished by a
magnetic field since the
Positively-charged alpha particles curve in one direction,
Negatively-charged beta particles curve in the opposite
direction,
Electrically-neutral gamma radiation doesn't curve at all.
Alpha particle :sheet of paper.
Beta particles :aluminium.
Gamma radiation :block of lead.

Curie and Bequerel
2.2x1012
dis/min
3.7x1010
dis/sec
Becquerel: 1dis/sec

HALF-LIFE
 Describes the time it takes for a particular
radionuclide to decay to one half of its original
activity
 Half-lives of most radionuclides used in nuclear
medicine range from several hours to several days

NUCLEAR PHARMACY
 Naturally occurring radionuclides have very long
half-lives and deliver high absorbed dose to the
patients
 Nm radionuclides are man made

TECHNETIUM
 Is the most
commonly used
radionuclide in
nm today

 Iodine-131,
 samarium-153 ethylene diamine tetra methylene phosphonate
 phosphorus-32 .
 iodine-131 is used to treat the thyroid for cancers and other
abnormal conditions such as hyperthyroidism (over-active
thyroid).
 In a disease called Polycythemia vera, an excess of red blood
cells is produced in the bone marrow. Phosphorus-32 is used to
control this excess
 Myocardial perfusion imaging (MPI) uses thallium-201 chloride or
technetium-99m and is important for detection and prognosis of
coronary artery disease

99MTc
 Exhibits nearly ideal characteristics for use in n
 It has a half-life of six hours which is long enough to examine
metabolic processes,yet
 Technetium-99m decays by a process called "isomeric"; which
emits gamma rays and low energy electrons. Radiation low(no
beta)
 The low energy gamma rays it emits easily escaped(dose
reduced) the human body and are accurately detected by a
gamma camera.
 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.

RADIOPHARMACEUTICALS
• ARE ADMINISTERED
TO PATIENTS, THEY
NEED TO BE STERILE

 RADIONUCLIDE
 IS TAGGED TO A
PHARMACEUTICAL
 PHARMACEUTICALPHARMACEUTICAL
 CHOOSEN BASEDCHOOSEN BASED
ON THEON THE
PARTICIPATION INPARTICIPATION IN
THE PHYSIOLOGICTHE PHYSIOLOGIC
FUNCTION OF AFUNCTION OF A
GIVEN ORGANGIVEN ORGAN

Radionuclides
 Artificial radionuclides are generally
produced in a cyclotron or some other
particle accelerator, in which a stable
nucleus is bombarded with specific
particles (neutrons, protons, electrons or
some combination of these). By doing so,
the nucleus of starting material becomes
unstable, and this nucleus will then try to
become stable by emitting radioactivity.

 Radioactive material is obtained from a
manufacturer, or from an in house generator
system.
 "Milking" the generator - sodium chloride is passed
over the molybdenum-99(66) column, which
removes the radioactive material.

 A similar generator system is used to produce rubidium-82 for PET
imaging from strontium-82 - which has a half-life of 25 days.

 Canadian 2006 data shows that
56% of Tc-99 myocardial ischemia perfusion,
17% in bone scans,
7% in liver/hepatobiliary,
4% respiratory,
3% renal,
3% thyroid.

Up quarks and down quarks
Up-quarks and down-
quarks are embedded
deep inside protons
and neutrons in the
atomic nucleus. They
are bound so tightly
that it is impossible to
pull an individual one
out.

Kinds of quarks
Quarks are fundamental
building blocks of
matter. There are six
different types of
quarks. Each quark
type is called a flavor

Flavor Mass
(GeV/c2
)
Electric Charge
(e)
u up 0.004 +2/3
d down 0.008 -1/3
c charm 1.5 +2/3
s strange 0.15 -1/3
t top 176 +2/3
b bottom 4.7 -1/3

LINEAR ENERGY TRANSFER
Linear energy transfer (LET) is the energy transferred per
unit length of the track.
Unit : kiloelectron volt per micrometer (keV/µm)of unit
density material.
The International Commission on Radiological Units
(1962) defined as:
 The linear energy transfer(L) of the charged particles in the
medium is the quotient of the dE/dl where dE is the average
energy locally imparted to the medium by a charged particle
of specified energy in traversing a distance of dl. That is
L=dE/dl

High and Low LET Radiations
 High LET Radiation:
 This is a type of ionizing radiation that deposit a large
amount of energy in a small distance.
 Eg. Neutrons , alpha particles
 Low LET Radiation:
 This is a type of ionizing radiation that deposit less amount
of energy along the track or have infrequent or widely
spaced ionizing events.
 Eg. x-rays, gamma rays

High vs Low LET Radiations
 High-LET radiations are more destructive to biological
material than low-LET radiations.
 The localized DNA damage caused by dense ionizations
from high-LET radiations is more difficult to repair than the
diffuse DNA damage caused by the sparse ionizations from
low-LET radiations.
 High LET radiation results in lower cell survival per absorbed
dose than low LET radiation.
 High LET radiation is aimed at efficiently killing tumor cells
while minimizing dose to normal tissues to prevent toxicity.
 Biological effectiveness of high LET radiation is not affected
by the time or stage in the life cycle of cancer cells, as it is
with low LET radiation.

 RADIOPHARMACEUTICALS
DEFINITION:
A Radiopharmaceutical is a Radioactive Drug used for Diagnosis or
Therapy in a Tracer Quantities with no Pharmacological Effect.
Composed of two parts
 Radionuclide
 Pharmaceutical
They Should undergo all quality control measures required of a
conventional drug.

 PROPERTIES OF AN IDEAL RADIOPHARMACEUTICAL
1.Pure Gamma Emitter
Optimal performance of a radiopharmaceutical requires that it
possess certain characteristics.
Other non-penetrating kinds of radiation, e.g., alpha and beta
particles, are undesirable:
 the fraction of energy deposited per cm of travel is very high)
This results in almost quantitative absorption in the body.
 Alphas and betas are not image able.(no interaction with crystal)
 Significant radiation dose to the patient.

2.100 to 250 KeV
The ideal imaging energy range is 100-250 keV.
Tl201 and Xe133 emit photons 70-80 keV,
Ga67 : 300 keV
I131 : 364.5 keV.
compromises image quality since greater collimation is required,
decreasing both sensitivity and resolution.
Ideal From Energy Standpoint: Tc99m, In111, and I123

3.Effective half-life = 1.5 X test duration.
This provides a good compromise between desire to minimize
radiation dose to the patient and
to maximize the dose to be injected so counting statistics are good
and image quality is optimal.
With the sole exception of Xe133 , there is no other procedure in
which images are acquired and the radiopharmaceutical is expelled
from the body almost quantitatively within a few minutes of
completing the study.
Most compounds exhibit exponential clearance patterns so their
effective half-life is moderately long (measured in hours or days as
opposed to seconds or minutes).

Tc99m MDP(methylene diphosphonate),
Half-life = 6 hr
Bone imaging is a 4 hr procedure,
the ratio of effective half-life to duration of the test is 1.5:1
Tc99m sulfur colloid : half-life of 6 hr in the liver
but the procedure takes only 1 hr. Ratio 6:1
Tc99m microaggregated albumin(MAA) ,
lowering the ratio of effective half-life to procedure length to 3:1.

4. High target : nontarget ratio
A high target:nontarget ratio is critical
(5:1 minimum for planar imaging, about 2:1 for SPECT imaging),
No diagnostic scan can result, making it difficult or impossible to
distinguish pathology from background.
For example, when performing a thyroid scan, ideally, all the
radioactivity will be in the thyroid and nowhere else in the neck
region.
While liver uptake of the radioiodide would be undesirable
dosimetrically,
It would have no impact on the actual imaging process since it is not
in the field of view.

Bone imaging, there are two target:nontarget ratios
Bones against soft tissue.
Tumour against Bone.
These ratios are multiplicative; if the tumor:bone ratio is 5:1 and the
bone : soft tissue ratio is also 5:1.
The result of a very low target: non target ratio may be a non
diagnostic scan, resulting in
an unnecessary radiation dose,
a delay in the diagnosis
necessity of repeating the procedure.
Product Formulations
Patient factors(Renal, Medications)

5.Minimal radiation dose to patient and Nuclear Medicine personnel
Radiation dosimetry to both the patient and the Nuclear Medicine
Technologist requires special attention, especially if one is to maintain
compliance with the ALARA guidelines. The smallest dose possible
should be injected, consistent with good image quality.
In addition, for pediatric patients, the dose should be scaled down
based on the patient's body mass.

Radiation workers, the Maximum Permissible Dose (MPD), whole
body,1 Rem per year for every year.
For families and other non-radiation workers, the MPD is one-tenth of
our MPD, or 0.1 Rem per year.
•1 Rem= 10 mS
NM diagnostic procedure : 4.6 mS
CXR : 0.008 mS
UGI series : 4.5 mS
Lower GI series : 6 mS
CT Head : 1.5 mS
CT Chest : 5.4 mS
CT Abdomen : 3.9-6.1 mS

 For radiation workers,
 the extremities are permitted 15 times the whole body dose, or 75
Rem. This is an acceptable level for the hands since there is
essentially no bone marrow to be irradiated. Lifetime cumulative
records are maintained and transferred from one institution to
another when job changes are made.

 6. Patient Safety
Patient safety is also critical. Ideally, the radiopharmaceutical
should exhibit no toxicity to the patient. While most commonly
used compounds are inherently safe and provide wide margins of
safety.
Thallous ion (Tl1+), for example, is known to be a potent
cardiotoxin and yet routinely injected Tl-201 thallous chloride
intravenously into patients.
 the amount of Tl-201 contained in the typical 3 mCi dose (only 42
ng) is very small and significantly below the level required for a
physiological response from the patient

 7. Chemical Reactivity
 Tc-99m's versatility in forming compounds, from simple molecules
like pyrophosphate to sugar analogues like glucoheptonate; from
peptides to antibodies; from insoluble colloids and
macroaggregates to antibiotics and other complex molecules.
 In addition, special consideration must be given to the availability
of substrates for radiolabeling reactions.
 Not every compound can be labeled with every isotope and, in
fact, labeling is often quite selective.
 Compounds which demonstrate acceptable biodistribution often
become useless when a radiometal is added or the molecule is
iodinated.
 Even minimal changes in the molecular structure are often
enough to completely change the biodistribution.
 Extensive research is required to determine the optimal molecular
structure for a particular molecule to be labeled with a specific
isotope.

 8. Inexpensive, readily available radiopharmaceutical.
 Radiopharmaceuticals must be stable both pre- and post-
reconstitution.
 If a particular compound performs well for a particular procedure,
but is only available at 1 hospital nationwide, its use will be
extremely limited.
 In addition, in the current economic climate, use of
radiopharmaceuticals costing hundreds of dollars is limited,
especially if less expensive alternates are available

 9. Simple preparation and quality control if manufactured in house.
 Preparation of the drug should be simple and require relatively
little manipulation on the part of the preparer.
 Procedures with more than 3 steps generally do not meet this
requirement.
 In addition, no complicated equipment or time consuming steps
should be involved.
If radiopharmaceuticals are manufactured in-house, it is essential
that quality control be performed on every batch of drug
prepared to ensure that each individual preparation that will
produce a high-quality image while minimizing the radiation dose
to the patient.
 Altered bio distribution caused by an improperly prepared drug
can destroy image quality and have a
significant impact on the internal radiation dose conferred to the
patient.

PROPERTIES OF THERAPEUTIC

 1. Pure beta minus emitter.
therapeutic products are designed to destroy cells.
The preferred : pure beta minus emission.
Due to their high LET, beta particle emitters are quite capable of
destroying tissue.
controllable than alpha emitting radionuclides from the standpoint
of distribution in tissue
Almost perfect distribution is required for effective therapy with
alpha emitters,
whereas a less-than-perfect tissue distribution is not critical to
effective therapy with beta- emitters.
Range (several micrometers for alpha emitters)
(several mm to cm for betas).
Gamma-rays and X-rays are also acceptable, although they
contribute significantly less to tissue damage than beta emitters.

The decay scheme for I-131 indicates emission of six beta-minus
particles of varying energies and emission of 14 gamma rays of
different energies. The total types of emissions is 20. Therefore,
6/20ths of the total tissue damage caused by I-131 is due to
presence of beta-minus emission?
It has been estimated that 90% of the tissue damage from I-131 is
caused by beta particles, even though there are far more gamma
rays emitted during the decay process.
The deciding factor is that the LET, the Linear Energy Transfer rate for
beta-minus particles, is much higher than for gamma rays.

 2. Medium/high energy (>1 meV).
High energy particles are preferred.
beta emitters with Emax >1 meV are preferred.
The LET of these high energy particles is sufficient to cause
adequate but regulated tissue damage. Some therapeutic
isotopes, e.g., I-131, are image able and add to the information
obtained during therapeutic treatment

 3. Effective half-life = moderately long, e.g., days.
Therapeutic effects are generally desired relatively quickly
following radionuclide therapy;
therefore, the effective half-life should ideally be measured in
hours or days as opposed to longer time units.
Good examples of therapeutic radiopharmaceuticals with an
ideal
teff include I-131 sodium iodide for treatment of hyperthyroidism
(teff is 6 days)
Ho(holmium)-166 FHMA9ferric hydrooxide microaggregate) for
intraarticular radiation synovectomy (teff is 1.2 days).

 4. High target:nontarget ratio.
 Target:non-target ratio is critical in therapeutic procedures. A low
target:non-target ratio may result in inadequate treatment of the
primary disease and delivery of a potentially lethal radiation dose
to bone marrow or other radiosensitive tissues. It is especially
important therefore to assure the radiochemical purity of these
drugs

 5. Minimal radiation dose to patient and Nuclear Medicine
personnel
The goal is a minimal radiation dose absorbed by both the
patient, who is probably having a one-time therapeutic
procedure, and the Physician or Nuclear Medicine Technologist,
who is routinely exposed to radioactive patients on a daily basis.
TDS concept apply: minimize TIME, maximize DISTANCE, SHIELDING.
There are specific rules governing the release of patients from the
hospital after administration of a therapeutic
radiopharmaceutical; in routine clinical practice not involving
IND's,
they apply most often to I-131.
burden becomes <30 mCi or
when a reading taken 1 meter from the patient's chest is <5 mR/hr,

 6. Patient Safety
No toxicity to the patient.
While most commonly used compounds are inherently safe and
provide wide margins of safety,
we routinely inject drugs that are potentially toxic.
Thallous ion (Tl1+), for example, is known to be a potent cardiotoxin
and yet we routinely inject Tl-201 thallous chloride intravenously
into our patients.
the amount of Tl-201 contained in the typical 3 mCi dose (only 42
ng) is very small.
One of the concerns regarding treating a patient with I-131 NaI
therapy solution is whether the patient is allergic to iodine.
A calculation will show that 10 mCi of carrier-free I-131 contains only
80 ng of elemental iodine, far too small an amount to have a
physiological effect on the patient.

 7. Inexpensive, readily available radiopharmaceutical.
Inexpensive and readily available therapeutic radiopharmaceuticals
are a necessity. Many valuable procedures are being performed
infrequently or not at all because of the general unavailability of
the isotope or its great expense.

 8. Simple preparation and quality control if manufactured in
house.
Preparation of the drug should be simple and require relatively little
manipulation on the part of the preparer.
Procedures with more than 3 steps generally do not meet this
requirement. In addition, no complicated equipment or time
consuming steps should be involved.
If radiopharmaceuticals are manufactured in-house, it is essential
that quality control be performed on every batch of drug
prepared to ensure that each individual preparation that will
produce the appropriate level of therapy while minimizing the
radiation dose to the patient.
Altered bio distribution caused by an improperly prepared drug can
confer very high radiation dose to undesired locations

Radionuclide Pharmaceutical Organ Parameter
+ Colloid Liver RE
Tc-99m + MAA Lungs Regional
( Macro aggregated albumin) perfusion
+ DTPA
(Diethylenetriamine pentaacetic acid) Kidneys Kidney
function
I-123 NaI Thyroid Uptake/
I-131 NaI Thyroid Therapy
F-18 FDG Whole Body Tumor
Localization
Radiopharmaceuticals

RADIATION SAFETY IN NM
 RADIATION PROTECTION PRACTICES DIFFER
SOMEWHAT FROM THE GENERAL SAFETY RULES
 RADIONUCLIDES ARE LIQUID, SOLID, OR GASEOUS
FORM.
 BECAUSE OF THE NATURE OF DECAY, RADIATION
EMITS AFTER INJECTION

INSTRUMENTATION
• RADIOACTIVE DETECTORS
– GEIGER COUNTER
– DOSE CALIBRATOR

Exposure vs Effective dose
the mean effective dose:
• NM diagnostic procedure
• CXR
• UGI series
• Lower GI series
• CT Head
• CT Chest
• CT Abdomen
4.6 mSv
0.008 mSv
4.5 mSv
6 mSv
1.5 mSv
5.4 mSv
3.9 mSV – 6.1 mSv

Difference between x-ray and Nuclear Medicine (NM)
imaging.

Hal Anger
Hal Anger revolutionized the field of nuclear medicine with his
development of the gamma camera in the late 1950s.He also
developed the well counter, widely used in laboratory tests with small
samples of radioactive materials.

Gamma Camera
• Rectilinear scanners have evolved in complex imaging
systems – gamma cameras
• Still use scintillation detectors: use thallium activated sodium
iodide crystal to detect and transform radioactive emissions
into light photons.
• Light photons are amplified and an image is recorded

Gamma Cameras
• Can be stationary or mobile
• Mobile cameras can move throughout the hospital.
– Mobile cameras have limitations of
smaller field of view and quality of
images

 GAMMA CAMERA:
Also called Anger Camera are means of forming an image
Capture photons : Light : Voltage signal.
Signal is reconstructed to a planar image
Shows distribution.

Gamma Camera
• Collimator: used to separate gamma rays and keep scattered
rays from entering the scintillation crystal
– Resolution and sensitivity are terms
used to describe the physical
characteristics of collimators
– Made of material with a high atomic
number, lead, to absorb scattered
gamma rays

 Collimator: First part
 Absorbs Gamma rays that do not travel parallel to plates and thus
increases image resolution.
 SCINTILLATION CRYSTAL:
Gamma rays passing thru collimator strike crystal.
Crystal fluoresces when it absorbs gamma rays.
Scintillation crystals commonly used are sodium iodide with trace
amounts of thallium to increase light production

PHOTOMULTIPLIER TUBES:
Flashes of light detected by an array of photomultiplier tubes
coupled to crystal with light pipes(lucite Light Pipes)
Capture the flash and amplify the signal.
Size of the signal proportional to energy of absorbed photon.

 Signals from photomultiplier tubes go through
An analog to digital converter and
Pulse height analyser
This device : Intensity of signal( energy of incident absorbed
photons)
Uses only photons from the radionuclide in final Image.
Many of the gamma rays released from the radionuclide in patient
undergo Compton absorption.

Gamma Camera Systems
• Standard camera: Single detector that is moved in various
positions around the PT
• Dual-head camera: Allows simultaneous anterior and posterior
imaging and may be used for whole-body bone or tumor
imaging.
• Triple-head systems may be used for brain and heart studies

Imaging Methods
• Examination can be described on the basis of imaging
method used:
– Static
– Whole body
– Dynamic
– Single photon emission computed tomography, SPECT
– Positron emission tomography, PET

There are several techniques for nuclear imaging:There are several techniques for nuclear imaging:
Static planar scintigraphy which provides two-dimensionalStatic planar scintigraphy which provides two-dimensional
representations of a three dimensional object by measuring therepresentations of a three dimensional object by measuring the
spatial distribution of the radioisotope in the body, (comparablespatial distribution of the radioisotope in the body, (comparable
to a plain X-ray projection).to a plain X-ray projection).
Dynamic planar scintigraphy which measures temporalDynamic planar scintigraphy which measures temporal
changes in the spatial distribution of the radioisotopes in thechanges in the spatial distribution of the radioisotopes in the
body, by taking multiple images over periods of time whichbody, by taking multiple images over periods of time which
may vary from milliseconds to hours depending on themay vary from milliseconds to hours depending on the
timescale for the basic function of the organ to be examinedtimescale for the basic function of the organ to be examined..
Single photon emission tomography (SPECT) or positronSingle photon emission tomography (SPECT) or positron
emission tomography (PET) which allows to form threeemission tomography (PET) which allows to form three
dimensional static or dynamic representations of the organ anddimensional static or dynamic representations of the organ and
organ functions by taking multiple images from differentorgan functions by taking multiple images from different
directions.directions.

STATIC
• A “snapshot” of the radiopharmaceutical distribution within a
part of the body.
• Ex: lung scans, spot bone scans images, thyroid images
• Static images of the organ or structure are usually obtained in
various orientations, anterior, posterior, and oblique

STUDY TYPE TRACER REGION PATHOLOGY
BONE SCAN
Tc-MDP, Tc-HDP
Hydroxymethylene
diphosphonate, methylene
diphosphonate
Whole Body
Bone Tumors,
Fractures,
Paget's Disease
LIVER SPLEEN
SCAN
Tc-MAA Abdomen
Tumors, Cysts,
Hepatocellular
Disease
BRAIN SCAN
Tc-HMPAO
hexamethyl propyleneamine
oxime
Brain
Tumors,
Trauma,
Dementia
TUMOR SCAN Ga-67 Citrate Whole Body
Malignant
Tumors,
Metastatic
Disease
1. Static studies

Whole-Body Imaging
• Uses a specially designed moving detector system to produce
and image of the entire body or a large body section. The
gamma camera collect data as it passes over the body
• Ex: whole-body bone scans, tumor or abscess imaging.

Dynamic Imaging
• Display the distribution of a particular radiopharmaceutical
over a specific period.
• “Flow” study of a particular structure is generally used to
evaluate blood perfusion to the tissue
• Time-lapse images
• Ex: cardiac, hepatibiliary, gastric emptying studies

STUDY TYPE TRACER REGION PATHOLOGY
CARDIOANGIOGRAPHY
Tc-RBC, Tc-
HSA
Chest
Aneurysms, Congenital Heart Defects, Myocardia
Dyskinesia, Cardiomegaly
CEREBRAL BLOOD
FLOW
TcO4 Head,Neck Cerebral Death, AVM
CHOLECYSTOGRAPHY Tc-DISIDA Abdomen Obstructive Disease, diisopropylacetanilido iminodiacetic acid
CISTERNOGRAM In-111 DTPA Head, Neck Blockage, Slowed CSF Flow, dethylenetriamine pentaacetate
DYNAMIC KIDNEY Tc-DTPA Back Obstructive Disease
GASTRIC EMPTYING
Tc-
Ovalbumin,
Abdomen Abnormal GE Rates
PULMONARY
VENTILATION
Xe-133 gas Upper Back Obstructed Airways
RENOGRAM
I-131,
TcMag3
Back Renal Dysfunction
VENOGRAM Tc-MAA Legs Thrombosis
2. Dynamic studies

SPECT
• SPECT: Produces image similar to CT & MRI in that a computer
creates thin slices through a particular organ.
• Ex: cardiac perfusion, brain, liver and bone studies

What is PET
 PET is a noninvasive, diagnostic imaging
technique for measuring the metabolic activity of
cells in the human body.
 It was developed in the mid 1970s and it was the
first scanning method to give functional
information about the brain.
Htt://www.nucmed.buffalo.edu/petdef.htm

A little history about the
positron
 Existence first postulated in 1928 by Paul Dirac
 First observed in 1932 by Carl D. Anderson, who
gave the positron its name.
http://en.wikipedia.org/wiki/Positron

What is a Positron?
 A Positron is an anti-matter electron, it is identical in mass but has an
opposite charge of +1.
 Positron can come from different number of sources, but for PET they are
produced by nuclear decay.
 Nuclear decay is basically when unstable nuclei are produced in a
cyclotron by bombarding the target material with protons, and as a result
a neutron is released.
 In PET the target material is chosen so that the product of the
bombardment decays to a more stable state isotope by emitting a
positron, for instance 18-F has too many protons, so one of these protons
decays into a neutron emitting in the process a positron.
 After decay, we’re left with 18-O
http://www.nucmed.buffalo.edu/positron.htmhttp://www.nucmed.buffalo.edu/positron.htm

What happens after the positron is
obtained?
 Left over energy from the nuclear decay process is
shared between the positron and the departing
neutrino. Kinetic energy.
 Because of conservation of energy and momentum
the positron is forced to stay and thus become useful.
 Positron begins its activity in colliding with other
particles and gradually losing its kinetic energy and thus
slowing down.
http://www.nucmed.buffalo.edu/positron.htm

Annihilation of a positron and
electron
 The positron will encounter an electron and completely annihilate each
other resulting in converting all their masses into energy. This is the result
of two photons, or gamma rays.
 Because of conservation of energy and momentum, each photon has
energy of 511keV and head in an almost 180 degrees from each other.
 511keV is the ideal rest state annihilation value.

How do we detect photons
(gamma rays)?

Normal brain Image of the brain of a 9 year old
female with a history of seizures
poorly controlled by medication. PET
imaging identifies the area (indicated
by the arrow) of the brain responsible
for the seizures. Through surgical
removal of this area of the brain, the
patient is rendered "seizure-free".

Heart Conditions
 PET scans of the heart are used to determine
blood flow to the heart muscle and help
evaluate signs of coronary artery disease. PET
scans of the heart can also be used to
determine if areas of the heart that show
decreased function are alive rather than
scarred as a result of a prior heart attack,
called a myocardial infarction.
 PET scans allow differentiation of
nonfunctioning heart muscle from heart
muscle that would benefit from a procedure,
such as coronary bypass for instance.
http://www.radiologyinfo.org/content/petomography.htm

Image of heart which has had a
mycardial infarction (heart
attack). The arrow points to areas
that have been damaged by the
attack, indicating "dead"
myocardial tissue. Therefore, the
patient will not benefit from heart
surgery, but may have other
forms of treatment prescribed.
Normal heart

Cancer Patients
 Used to determine if there are new or advancing
cancers by analysis of biochemical changes.
 It is used to examine the effects of cancer
therapy by characterizing biochemical changes
in the cancer. PET scans can be performed on
the whole body.

Image showing malignant breast
mass that was not revealed by
conventional imaging techniques
such as CT, MRI, and
mammogram.
Image of same patient with enlarged left
axillary lymph nodes (indicated by arrows),
which through biopsy were found to be
metastatic (spread from another location).
The whole body scan reveals a mass in
the left breast (indicated by arrow), that
was malignant and subsequently
removed.

Alzheimer’s disease
 With Alzheimer’s disease there is no gross
structural abnormality, but PET is able to show a
biochemical change.

Neurological disorders
 Positron emission tomography (PET) imaging has recently been
shown to aid in the diagnosis of particular neurological
syndromes associated with cancer.
 Before their cancer is even diagnosed, patients can develop
problems with the brain, spinal cord or nerves, though the
cancer has not spread to the nervous system. Called
"paraneoplastic neurological disorders," these neurological
problems occur as the body's immune system begins to fight the
cancer cells, but accidentally attacks the brain or nerves as well.
 These problems are uncommon, difficult to diagnose, and
usually appear in patients whose primary cancer is extremely
difficult to find. Abnormal antibodies in the blood or spinal fluid
are often associated with these disorders, though they cannot
help identify the primary tumor.
http://interactive.snm.org/index.cfm?PageID=2367&RPID=535

How does it work?
A radioactive substance is produced in a
machine called a cyclotron and attached, or
tagged, to a natural body compound, most
commonly glucose.
Once this substance is administered to the
patient, the radioactivity localizes in the
appropriate areas of the body and is detected
by the PET scanner.
Different colors or degrees of brightness on a
PET image represent different levels of tissue or
organ function. For example, because healthy
tissue uses glucose for energy, it accumulates
some of the tagged glucose.

Labeling
One of the big advantages of PET is that the atoms which can be labeled
(turned into positron emitters) are the same atoms which naturally comprise
the organic molecules utilized in the body.
These atoms include oxygen, carbon and nitrogen. Since these atoms
occur naturally in organic compounds, replacing the naturally occurring
atoms in a compound with a labeled atom leaves you a compound that is
chemically and biologically identical to the original (so it will behave in a
manner identical to its unlabeled sibling) and that is traceable.
In addition to naturally occurring compounds such as neurotransmitters,
sugars, etc., it is also possible to label synthesized compounds (such as
drugs) and follow them as well.
http://www.nucmed.buffalo.edu/petdef.htm

Tracers
 A second important attribute of PET is that it can follow labeled
compounds in trace quantities.
 This means that the labeled compounds can be introduced
into the body without affecting the normal processes of the
body.
 For example, labeling a pound of sugar and ingesting that
sugar would be a good example of a non-trace quantity of
labeled compound.
 At these quantities, blood chemistry would be altered (e.g.
insulin produced in response to rising blood sugar levels). Often
you want to follow the time course of a compound in the body
by introducing trace quantities of a compound that will
behave the same as the unlabeled compound without altering
the ongoing physiological state of chemical processes of the
body.
 PET is sensitive enough to detect trace amounts of labeled
compound and so is well suited to this kind of investigation.
http://www.nucmed.buffalo.edu/petdef.htm

How is it performed?
 A nurse or technologist will take you into a special
injection room, where the radioactive substance is
administered as an intravenous injection (although in
some cases, it will be given through an existing
intravenous line or inhaled as a gas). It will then take
approximately 30 to 90 minutes for the substance to
travel through your body and accumulate in the tissue
under study. During this time, you will be asked to rest
quietly and avoid significant movement or talking,
which may alter the localization of the administered
substance. After that time, scanning begins. This may
take 30 to 45 minutes.
 Some patients, specifically those with heart disease,
may undergo a stress test in which PET scans are
obtained while they are at rest and again after
undergoing the administration of a pharmaceutical to
alter the blood flow to the heart.
 Usually, there are no restrictions on daily routine after
the test, although you should drink plenty of fluids to
flush the radioactive substance from your body.

Summary of P.E.T
 PET produces images of the body by detecting the
radiation emitted from radioactive substances.
 These substances are injected into the body, and are usually
tagged with a radioactive atom (C-11, Fl-18, O-15 or N-13) that
has short decay time.
 These radioactive atoms are formed by bombarding normal
chemicals with neutrons to create short-lived radioactive
isotopes. PET detects the gamma rays given off at the site where
a positron emitted from the radioactive substance collides with
an electron in the tissue.
 The results are evaluated by a trained expert.
http://science.howstuffworks.com/nuclear-medicine2.htm

PET/CT & SPECT/CT
• Now available is a blending of imaging function and form. By
merging the functional imaging of PET and SPECT with the
anatomical landmarks of CT
• More powerful diagnostic information is obtainable.

NUCLEAR MEDICINE
FIRST PART PRESENTED ON 22/02/2016
SECOND PART PRESENTED ON 27/02/2016
 Part III (04/03/2016)

41 PATIENTS,
22 ADULTS AND
19 CHILDREN,
WITH MEDICALLY INTRACTABLE SEIZURES OPERATED ON FROM 1996
TO 2002. ALL WERE SUBMITTED TO STANDARDIZED PRESURGICAL
EVALUATION INCLUDING HIGH-RESOLUTION MRI, SPECT.
OF THE TOTAL 26 PATIENTS (63.4%) REACHED SEIZURE-FREE STATUS
POST-OPERATIVELY.
Alexandre V, Walz R, Bianchin M, Velasco T, Terra-Bustamante V, Wichert-Ana L
et al. Seizure outcome after surgery for epilepsy due to focal cortical dysplastic
lesions. Seizure. 2006;15(6):420-427.

Surgical treatment of epilepsy is an important consideration for
patients with medically intractable epilepsy and epilepsy syndromes
with underlying lesions.
Localization-related epilepsies that are good candidates for surgery
include
MTS(mesial temporal sclerosis),
FCD(focal cortical dysplasia,
neoplasms.
Kelly K, Chung S. Surgical Treatment for Refractory Epilepsy: Review of Patient
Evaluation and Surgical Options. Epilepsy Research and Treatment. 2011;2011:1-10.

123
I gives approximately 20 times the counting rate of 131
I for the same
administered dose.
The radiation burden to the thyroid is far less (1%) than that of 131
I.
Moreover, scanning a thyroid remnant or metastasis with 123
I does not
cause "stunning" of the tissue (with loss of uptake),
because of the low radiation burden of this isotope
123
I is never used for thyroid cancer or Graves disease treatment, and
this role is reserved for 131
I.
Park HM (January 2002). "123I: almost a designer radioiodine for thyroid scanning". J. Nucl.
Med. 43 (1): 77–8.

What is nuclear medicine?
 The use of radioactive tracers (radiopharmaceuticals) to obtain
diagnostic information [and for targeted radiotherapy].
 Radiation is emitted from inside the human body and
transmitted out to be captured and changed into images.
Tracers :-
 Trace the paths of various biochemical molecules in our body.
 Hence can obtain functional information about the bodies
workings (i.e. physiology).

+
Biochemical
Bonding
Pharmaceutical
Traces physiology /
localises in organs
of interest
Radioactive
nuclide
Emits radiation for
detection or therapy

THE PHARMACEUTICAL
 The ideal tracer/pharmaceutical should follow only
the specific pathways of interest, e.g. there is
uptake of the tracer only in the organ of interest
and nowhere else in the body. In reality this is
never actually achieved.
 Typically want no physiological response from the
patient
 The mechanism of localisation can be as simple
as the physical trapping of particles or as
sophisticated as an antigen-antibody reaction

RADIONUCLIDES IN NUCLEAR MEDICINE
The ideal radionuclide for in-vivo diagnosis :
 Optimum half life
 of same order as the length of the test (this minimises the radiation dose to
the patient)
 Pure gamma emitter
 No alpha or beta particles, these do not leave the body so merely increase
the radiation dose.
 Optimum energy for γ emissions
 High enough to exit the body but low enough to be easily detected. Useful
range for gamma cameras is 50 - 500 keV (optimum ~ 150 keV).
 Suitable for incorporating into a pharmaceutical without
altering its biochemical behaviour

DETECTION OF THE RADIOPHARMACEUTICAL
 In Vivo imaging - the gamma camera
Patient
Radioactive
tracer
Gamma
rays
Gamma
camera
Image

The Gamma Camera
Position
circuitry
X Y Z
Collimator
NaI
Crystal
Photo Multiplier
Tubes
Analogue to
Digital Converters
Digital
circuitry
Output position
& energy signals

SCINTILLATION CRYSTAL
The gamma ray causes an electron release in the
crystal via the Photoelectric Effect, Compton Scattering
or the electron-positron pair production (Eγ > 1.022 MeV),
this excess energy gives rise to subsequent visible light
emission within the crystal (scintillation).
Incident
gamma
ray
NaI(Tl) Scintillation
crystal
Light
Photons (~415nm)

IMAGE TYPES
In Nuclear Medicine various forms of data acquisition can be performed:
 Static Imaging
 The distribution of the radiopharmaceutical is fixed
over the imaging period.
 Multiple images can be acquired, viewing from different
angles (e.g. anterior, oblique).
 e.g. kidneys (DMSA), thyroids, bone, lung
99
Tcm
Thyroid Scan
• Whole Body imaging
– the camera scans over the whole body to cover more
widespread distributions or unknown locations
– e.g. bone scan, infection imaging, tumour imaging
99Tcm HDP Bone Scan
• Dynamic Imaging
– Consecutive images are acquired over a period of time
(with the camera in a fixed position) showing the changing
distribution of the radiopharmaceutical in the organ of interest.
– e.g. renogram, GI bleed, meckel’s diverticulum
99
Tcm
labelled red blood cells
– GI bleed

UREA BREATH TEST:
Radioactively labelled urea to test for urease,
a specific enzyme produced by H. pylori.
H. pylori naturally produces the enzyme urease which breaks the
urea into two components: ammonia and bicarbonate.
The urea will be broken down into ammonia and radiolabelled
bicarbonate.

The radiolabelled bicarbonate will be metabolized by the body into
carbon dioxide
The radioactive label can be detected in a scintillation beta counter
30 minutes after ingestion of the radiolabelled urea.
The urea breath test is the preferred diagnostic test used after
treatment to show that the H. Pylori has been eradicated.

Stress/Rest Myocardial Perfusion Imaging (MPI)

Stress/Rest Myocardial Perfusion Imaging (MPI)
PET or SPECT imaging of a patient’s heart before and after exercise
to determine the effect of physical stress on the flow of blood
through the coronary arteries and the heart muscle.
Normal blood flow during exercise and rest. may not need further
tests.
Normal blood flow during rest, but not during exercise. Part of heart
isn't receiving enough blood when exerting, which may indicate
one or more blocked arteries (coronary artery disease).
Low blood flow during rest and exercise. Part of heart isn't getting
enough blood at all times, which could be due to severe coronary
artery disease or previous heart attack.
Lack of radioactive dye in parts of heart. Areas of heart that don't
show the radioactive dye have tissue damage from a heart attack.

 Head and neck tumors,
 Salivary gland disease, and
 Various metabolic and infectious processes of the
head and neck region.
 Computed tomography (CT) and Magnetic resonance
imaging (MRI) with, and without, contrast
enhancement can provide high quality static images
of the soft and hard tissue under study.
 Little physiologic information about a disease process.
 Nuclear medicine scans dynamically detect
abnormalities at an earlier stage,
 before morphological changes are evident.

 BONE SCANNING
 Bone scanning is one of the most frequently performed nuclear
medicine studies.
 Bone scans can be used to diagnose and differentiate
osteomyelitis from cellulitis, as well as detect primary and
metastatic malignant disease.
 They can also be used to assess the vascularity of bone grafts and
contribute to the diagnosis of various metabolic bone diseases
such as fibrous dysplasia, Paget’s disease, osteoarthritis, and
rheumatoid arthritis (RA).
 It is important to keep in mind a bone scan can detect 10-15%
mineral loss, while standard radiographs will only visualize a bony
defect after 35-50% mineral loss. Overall the scan has a high
sensitivity but low specificity.

 The bone scan uses a technetium 99 m methylene diphosphonate
radiopharmaceutical with a half-life of 6 hours.
 It is thought the diphosphonate molecule is taken up in areas of
increased osteoblastic activity and vascularity.
 The metabolic activity of osteoblasts incorporates calcium
phosphate during the process of ossification.
 It is thought the diphosphonate molecule preferentially
accumulates in areas of increased osteoblastic activity as it binds
to calcium ions to form calcium phosphate.
 A normal bone scan should demonstrate symmetry around the
midline with uniform uptake of the radiopharmaceutical. There is
usually increased activity at joint margins and vertebral bodies.
 Uptake is typically visualized in the kidneys and bladder.

A three-phase bone scan is often performed to obtain additional diagnostic information,
especially when the clinician is trying to distinguish osteomyelitis from cellulitis.
The three phases include:
The dynamic vascular flow phase: where imaging is performed every 2-3
seconds for the first 30 seconds. In this phase, each side can be
compared and differences in vascularity can be seen.
The blood pool image at five minutes, where the radiopharmaceutical is
mostly in the vascular compartment but is starting to appear in bone.
This phase demonstrates regional differences In blood flow and
vascular permeability.
Two to four hours later, the osseous delayed static image is obtained
usually for the entire body demonstrating regional distribution in the
skeleton. This phase reflects the metabolic activity of the bone in
question. In non inflammatory conditions, the third phase is usually
the only image obtained

 Occasionally, a fourth phase study is performed 24 hours later when
there may be improved contrast between normal bone and
inflammatory conditions.
 In osteomyelitis there is abnormal accumulation of the
radiopharmaceutical in all three phases, with a more focal bony
uptake in the third and fourth phases.
 Cellulitis presents as a diffusely increased uptake in phases one
and two, followed by a decreased activity in phase three.
 In addition to osteomyelitis, bony lesions that are “hot” (increased
accumulation) in all three phases are seen in acute fractures and
hyper vascular tumours.

Both benign and malignant bone tumors as well as metastatic
lesions to bone demonstrate increased uptake of technetium 99.
However, areas of increased uptake are non-specific, since a
fracture, neoplastic lesion, and inflammatory lesion all produce
images of similar appearance.
In metastatic bone lesions, the most common sites of the primary
tumour are lung, breast, prostate, thyroid, and kidney. Metabolic
diseases such as fibrous dysplasia and Paget’s disease also show
increased uptake on the scan.

 Inflammatory conditions of the TMJ demonstrate increased uptake
as does condylar hyperplasia.
 The clinician must carefully assess the history, clinical exam,
laboratory data, and imaging data to arrive at the proper
diagnosis
 Certain conditions and situations can confound the results of the
bone scan. For example, active periodontal disease can result in
an increased uptake of the radiopharmaceutical in the alveolar
processes of the mandible and maxilla.
 Increased activity in the cervical spine can be due to arthritis. In
growing children, there is increased activity in the epiphyseal
plates.

 Photopenic (areas of decreased uptake) lesions can also be seen
on the bone scan. Those most commonly observed include lesions
resulting from radiation treatment, local vascular compromise,
prosthetic joint, early osteomyelitis, multiple myeloma, and
avascular necrosis.
 A slow growing lesion may demonstrate a lack of uptake. Activity
can occasionally occur in the soft tissue of a bone scan. In the
head and neck region, the clinician should consider such causes
as dystrophic calcifications, chronic inflammatory changes,
infarction, hyperparathyroidism, hematomas, and renal failure

Bone scans can also use Single Photon Emission Computed
Tomography (SPECT) technology where tomographic images
obtained in three planes (axial, coronal, and sagittal) allows a more
accurate interpretation and better localization of bone pathology.
SPECT images are obtained from different angles and then
reconstructed by a computer. SPECT can be used for evaluation of
TMJ disease, with sensitivity equal to that of a MRI for bone
pathology.

 Gallium Scan Gallium 67 citrate, once given intravenously,
accumulates non-specifically in areas of inflammation, infection,
and neoplasm having an affinity for rapidly dividing cells, i.e., WBC
and tumor cells.
 Gallium can be used in evaluating abscesses, lymphomas,
sarcoid, and osteomyelitis. Because of Gallium’s long half-life (78
hrs), if a technetium bone (half-life of 6 hours) scan is being
contemplated, it should be performed first.

Gallium is especially useful in the evaluation of suspected
osteomyelitis.
A triple phase bone scan is the diagnostic test of choice for
confirming the diagnosis of osteomyelitis. Gallium imaging may
increase the specificity of a positive bone scan, especially if
osteomyelitis is superimposed on another underlying acute or chronic
bone disease.
A positive Gallium scan with concomitant technetium uptake is
highly suggestive of osteomyelitis. A normal Gallium scan with a
positive or normal bone scan is not suggestive of an infection. The
Gallium scan is also useful for monitoring the response to treatment,
with a reduction in Gallium 67 accumulation a good indicator of a
resolving osteomyelitis.

 SALIVARY GLAND STUDIES
The major salivary glands with a functioning parenchyma have the
ability to take up technetium 99m pertechnetate in sufficient
quantities to be imaged, since the Te99 mimics chloride influx
into the acinar cells.
Scintigraphy of these glands is used for functional evaluation and
evaluating mass lesions. Scintigraphy involves administering a
radioactive tracer with an affinity for the organ or tissue of interest;
the distribution of the radioactivity is then recorded with a
scintillation camera.

Other uses include detecting aplasia or agenesis of the gland,
evaluating obstructive disorders, traumatic lesions, fistulas, or
function after surgery. By itself, this study is rarely diagnostic but is a
useful adjunct.
Initially, images are obtained five minutes after injection of
technetium 99m pertechnetate.
After ten minutes, the gland is stimulated by a sour drink or candy.
Repeat images are then obtained

 Mass lesions in a gland usually present as areas of decreased
uptake, with the notable exception of Warthin’s tumor and
oncocytomas which demonstrate increased uptake and
decreased washout time.
 Patients with Sjogren’s Syndrome may have poor uptake of the
radiopharmaceutical and poor response to stimulation.
 Acute inflammation of the glands usually demonstrates increased
uptake and increased washout, whereas chronic inflammation
shows decreased uptake

 PET Scan
The use of positron emission tomography (PET) metabolic imaging has
increased significantly over the last several years. PET imaging has
value in cardiovascular, neurological, psychiatric, and oncological
diagnosis.
PET is a functional imaging modality that allows the measurement of
metabolic reactions within the whole body.
 18F-fluorodeoxyglocose (FDG) is the radiopharmaceutical most
commonly used in PET scanning.
 FDG is a glucose analogue that is transported into cells and
phosphorylated like glucose, but the metabolism stops at this point
and the phosphorylated FDG becomes trapped in the cell and starts
to accumulate.

 Most tumours, with a more rapid growth rate, have an increased
rate of glucose use due to an increased rate of glycolysis
compared to normal tissue or scar tissue.
 Consequently, FDG preferentially accumulates in tumour cells and
demonstrates an increased uptake especially in poorly
differentiated tumours.
 The accumulated FDG is detectable to the PET camera. To assure
adequate uptake of FDG, the patients are required to fast to
prevent hyperglycaemia which would confound the result.

 There are many clinical uses for PET in head and neck cancer.
 PET can detect nodal neck disease in oral squamous cell
carcinoma (OSCCA), often at an earlier stage than CT or MRI
which rely on morphological change.

 PET can be used to assess the response of a tumor to treatment,
diagnose recurrence, detect residual disease, or detect distant
unknown metastases.
 PET scanning is helpful in evaluating a neck mass or evaluating a
neck without palpable adenopathy (staged as a N0 neck) in oral
squamous cell carcinoma.
 PET is especially useful when trying to localize an occult primary
tumor.

 In OSCCA, there has been a great deal of interest in using PET to
evaluate the clinically N0 neck for occult or micro metastasis
before any changes are visible on CT or MRI.
 Preliminary studies in this area have been very encouraging.
 If the sensitivity and specificity of PET in evaluating nodal neck
disease in OSCCA is found to be clinically acceptable, then many
patients will be spared an elective neck dissection.

 However, PET can give false positive results.
 FDG may accumulate in non-neoplastic tissue such as new
granulation tissue, areas of inflammation, and early post-op
scarring.
 For example, the OSCCA patient with a recently irradiated neck
would likely have a false positive result for two to three months
after the conclusion of radiation treatment. False positives can
also occur in conditions such as tuberculosis and sarcoidosis.

NUCLEAR MEDICINE
FIRST PART PRESENTED ON 22/02/2016
SECOND PART PRESENTED ON 27/02/2016
THIRD PART PRESENTED ON 04/03/2016
 FOURTH PART (07/03/2016)

 LYMPHOSCINTIGRAPHY
 Lymphoscintigraphy is an exciting technique that is receiving
much clinical research attention in the treatment of oral and
head/neck malignancy, especially OSCCA.
 Lymphoscintigraphy is already used routinely in the treatment and
staging of breast cancer and malignant melanoma. Briefly,
technetium 99m sulfur-colloid is injected in four to six
subcutaneous sites around the neoplastic lesion.
 The radioactive colloid will be carried away in the lymphatic
channels to the first echelon lymph node draining that area, the
so-called sentinel node. The sentinel node is felt to be the best
predictor of nodal spread of the tumor. The pattern of lymphatic
spread and the sentinel node can then be imaged using a
gamma camera. One to two hours later, in the operating room,
the surgeon using a hand held

 gamma counter is able to localize the node and remove it. The
sentinel node is evaluated for metastatic disease.
 If the sentinel node is free of disease, it is presumed the remaining
nodes in the regional nodal basin are free of disease.
 On the other hand, if the sentinel node is positive for disease, then
the remaining nodes are removed.
 Because of sentinel node mapping, many women with breast
cancer have been spared full axillary nodal dissections and the
sequella of persistent upper extremity lymphadema

 The sentinal node is any node that receives drainage from any
given anatomic location. It can be located in the neck, axillae,
groin, or elsewhere in the body.
 It can theoretically be in any of the 6 levels of the neck, if it is the
primary first echelon node draining the site of a primary
malignancy.

This again could play an important role in the management of the
N0 neck, where the sentinel node is removed and evaluated. If the
node is disease free, the patient is spared an elective neck
dissection. On the other hand, if the node is positive, the patient
goes on to a more formal neck dissection.

Since its introduction in 1976,
Fluorine-18 fluorodeoxyglucose (18F-FDG) has been and still is the
most widely used radiotracer for oncological PET studies. In fact, 18F-
FDG-PET is used in more than 90% of cancer patients in clinical
practice.
18F-FDG-PET as a single imaging modality will remain the dominant
tool for assessing a multitude of malignant disorders in the future.
Non-18F-FDG
11C-choline & 18F-choline for prostate cancer,
11C-methionine for brain tumors,
18F-dihydroxyphenylalanineand 68Ga-labeled somatostatin analogues for neuroendocrine tumors,
and 11C-acetate for prostate cancer and hepatic tumors,
18F-FDG, as a single imaging agent in assessing cancer, shows the ongoing biological
phenomena in many domains: do we need additional tracers for clinical purposes? Thomas C.
Kweea, Saeid Gholami, Thomas J, Domenico Rubello, Abass Alavi and Poul F. Høilund-Carlsen,
Nuclear Medicine Communications 2016, 37:333–337

Nuclear diagnostic techniques are being used commonly in routine
practice, and
it is important for the dentists to be familiar with commonly used
scans in nuclear medicine with respect to oral lesions.
dental practitioners should be well versed with the various indications
for nuclear imaging techniques in oral/dental pathologies
Shazia M. Role of nuclear medicine in dentistry:GJMEDPH 2012;vol.1 issue6.

A 65-YEAR-OLD WOMAN UNDERWENT FLUORODEOXYGLUCOSE POSITRON EMISSION
TOMOGRAPHY AND COMPUTED TOMOGRAPHY (FDG-PET/CT [PHILIPS GXL, PHILIPS
MEDICAL SYSTEMS, MILPITAS, CALIF, USA])
TO STAGE A NEWLY DIAGNOSED SQUAMOUS CELL CARCINOMA OF THE TONGUE.
ONE IN THE LEFT AXILLA (B)
THE OTHER IN THE SIGMOID COLON (C).
THE PATIENT UNDERWENT SUBTOTAL GLOSSECTOMY, AFTER WHICH FURTHER
INVESTIGATIONS CONFIRMED A NODE-POSITIVE NEUROENDOCRINE CARCINOMA OF THE
LEFT BREAST AND A DYSPLASTIC COLONIC TUBULOVILLOUS ADENOMA.
THE DETECTION OF THREE SYNCHRONOUS TUMOURS OF DIFFERENT AETIOLOGY IN THE
ONE PATIENT ON PET IS RARE.
Choi JY, Lee KS, Kwon OJ, et al. Improved detection of second
primary cancer using integrated [18F] fluorodeoxyglucose positron
emission tomography and computed tomography for initial tumour
staging. J Clin Oncol 2005; 23: 7654-7659.

For solitary calvarial focal lesions, it is estimated that approximately
20% of such lesions in patients with underlying extraosseous tumors
are metastasis
Thang SP, Tan A, Goh A. Bone Scan "Hot Spot" at the Superior Lateral Orbital Margin Fronto-zygomatic Suture
Uptake Characterized with Tc-99m MDP SPECT/CT. World J Nucl Med 2011;10:139-40.

 Benign MDP tracer uptake along cranial suture lines is known, and
various explanations have included
 cartilaginous inclusion bodies or “os incae”
 bony reactive changes from underlying pacchionian granulations
Thang SP, Tan A, Goh A. Bone Scan "Hot Spot" at the Superior Lateral Orbital Margin Fronto-zygomatic Suture
Uptake Characterized with Tc-99m MDP SPECT/CT. World J Nucl Med 2011;10:139-40.

18
F-FDG PET/CT alters the initial clinical staging and TNM category of
the tumor in 14% to 57% of the patients when compared with CT-
based evaluation alone
has an accuracy of approximately 90% compared with 86% for
conventional
. Almuhaideb A, Papathanasiou N, Bomanji J. 18 F-FDG PET/CT imaging in
oncology. Annals of Saudi Medicine. 2011;31(1):3.

 CONCLUSION
 With the expansion of diagnostic imaging ,it has been customary
for dental practitioners should be well versed with the various
indications for nuclear imaging techniques in oral/dental
pathologies.
 PET/CT imaging increases the accuracy of diagnosis by
combining anatomic information with functional imaging.
 Although not specific, exquisite sensitivity makes it useful
screening procedure for many pathological conditions.
 For a proper diagnostic approach and follow up, morphologic
and physiologic imaging modalities, in combination, should
support each other in offer valuable information in the diagnosis of
maxillofacial jaw bone lesions.

 REFERENCES
 1. BurketLw, Greenberg Ms, Glick MBurketLw, Greenberg Ms GM. Burkets Oral Medicine:
Diagnosis & Treatment. 10th ed. spain: Bc Decker Inc; 2003.
 2. Jacobs E. Medical Imaging: A Concise Textbook [Internet]. New York: Igaku-ShoinInc; 1987 .
 3. Baur DA, Heston TF, Helman JI. Nuclear medicine in oral and maxillofacial diagnosis: a
review for the practicing dental professional. J Contemp Dent Pract [Internet]. 2004 Feb 15
 4. Oral and Maxillofacial Infections: : Richard G. Topazian, James R. Hupp, Morton H.
Goldberg: Fremdsprachige Bücher .
 5. Mushtaq S. Role of nuclear medicine in dentistry. 2012;1(6):1–5.
 6. Tow DE, Garcia DA, Jansons D, Sullivan TM, Niederman R, Drive SM, et al. Bone Scan in
Dental Diseases NOTES. 1978;845–7.
 7. Bóscolo FN, Ph D, Santos AO, Camargo EE. Bone Scintigraphy as an Adjunct for the
Diagnosis of Oral Diseases. 2002; (December):1381–7.
 8. Craemer TD, Ficara AJ. The value of the nuclear medical scan in the diagnosis of
temporomandibular joint disease. Oral Surg Oral Med Oral Pathol [Internet]. 1984 Oct [cited
2014 Nov 14];58(4):382–5. Available from: http://www.ncbi.nlm.nih.gov/pubmed/6593662
 9. Lurie AG, Puri S, James RB, Warnich Jensen T. Radionuclide bone imaging in the surgical
treatment planning of odontogenic keratocysts. Oral Surg Oral Med Oral Pathol [Internet].
1976 Dec [cited 2014 Nov 1 5 ] ; 4 2 ( 6 ) : 7 2 6 – 3 0 . A v a i l a b l e f r o m :
http://www.ncbi.nlm.nih.gov/pubmed/1069216

 10. Francis MD, Horn PA TA. Controversial Mechanism Of Technetium99m Deposition On Bone. J
Nucl Med. 1981;22:72.
 11. Henken RE, Boles MA, Dillehay GL et. al. eds. Nuclear medicine. St. Louis: mosby; 1996.
 12. Wilson M. Textbook Of Nuclear Medicine. philadelphia: , LippincottRaven; 1998.
 13. Merrick MV. Essentials Of Nuclear Medicine. london: SpringerVerlag; 1998. 14. Maisey MN,
Britton, KE, Collier BD eds. Clinical Nuclear medicine. london: Chapman and Hall; 1998.

 1. All the American flags placed on the moon are now white due
to radiation from the sun.
 2. After Radium was discovered by Marie Curie (who died from
radiation), people used it in things like condoms, candy,
toothpaste, and health tonics. One man drank large number of
bottles bottles ultimately diagnosed as cancer.
 3. The Manhattan Project secretly tested the effects of radiation
on its own citizens, including injecting pregnant women
radioactive mixtures and feeding children radioactive oatmeal.

4. Bananas are slightly radioactive and eating a banana exposes
a person to radiation.
5. During the Manhattan Project, a man was injected with
Plutonium without his knowledge or consent and he survived it
for 20 years, eventually surviving the highest radiation dose
known for any human. Plutonium remained present in his body for
the remainder of his life, the amount decaying slowly through
radioactive decay and biological elimination. Stevens died of heart
disease some 20 years later, having accumulated an
effective radiation dose of 64 Sv (6400 rem)

6. There is a type fungi inside the Chernobyl reactors that thrives on
radiation
7. Smokers receive a radiation dose equivalent to about 300 chest
x-rays annually due to the radioactive isotope Polonium-210
contained in tobacco smoke that comes from the ingredients of
the fertilizers that are used in farming tobacco

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