TOPIC: NUCLEAR CHEMISTRY
INTRODUCTION OF NUCLEAR ENERGY
1. The energy released by a nuclear reaction, especially by fission
or fusion.
2. Nuclear
energy regarded as a source of power. Also called atomic energy.
The energy released by the nucleus of an atom as the
result of nuclear fission, nuclear fusion, or radioactive decay. The amount of
energy released by the nuclear fission of a given mass of uranium is about
2,500,000 times greater than that released by the combustion of an equal mass
of carbon. And the amount of energy released by the nuclear fusion of a given
mass of deuterium is about 400 times greater that that released by the nuclear
fission of an equal mass of uranium. Also called atomic energy. Nuclear
energy is energy that is generated through the use of Uranium, a
natural metal that is mined all over the world. Nuclear energy is created
through complex processes in nuclear power stations, and the first nuclear
power station was established in 1956 in Cumbria, England. Today, many military
operations and vessels use nuclear power plants and nuclear energy for their
energy source, and nuclear energy is used in many other capabilities such that
it provides 16% of the Earth’s energy requirements.
Nuclear energy is created through chemical reactions that involve
the splitting or merging of the atoms of nuclei together. The process of
splitting an atom’s nucleus is termed fission, and the process of merging the
nuclei if atoms is termed merging. Converting nuclear masses into energy forms
is known through the popular chemical equation of E = mc2,
where E is known as the amount of energy released, m is known as the mass of
the nuclei, and c is the value of the speed of light. The power from nuclear
energy was first discovered in 1896 by Henri Becquerel, a French physicist who
saw that some photographic plates that had been stored near uranium turned
dark, or black, like X-Ray plates did. Thus, Uranium was seen as a resource for
nuclear energy.
Nuclear energy is created in nuclear
power stations, where uranium rods are the fuel used to create the energy or
heat. The process through fission, where neutrons in the Uranium smash into the
nucleus of atoms of Uranium. The Uranium nuclei will then split in half and release
an energy that comes in a form of heat. At this point, carbon dioxide in gas
form will be pumped into the reactors with the Uranium, removing the heat from
the system. The gas turns very hot, and this heat is used to heat water into
steam. The steam created from this process will drive the turbines which in
turn drive the generators that produce the nuclear energy. The nuclear power
reactor that is creating all of these reactions is controlled through rods of
boron, known as control rods. These Boron rods absorb the neutrons. The rods
will be lowered into the reactor to absorb neutrons and slow down the process
of fission. In order to generate more power, the rods are raised again so that
even more neutrons can crash into the atoms of Uranium.
Creating nuclear energy is a complex chemical process that
can be very dangerous. It does however have many advantages. Nuclear energy is
more affordable to create than coal energy,
and does not use as much fuel in the process. It also produces less waste, and
does not produce carbon dioxide or smoke. These benefits mean that nuclear
energy is more advantageous than coal energy, as the production of
nuclear energy does not contribute to environmental hazards or the greenhouse
effect.
THE USE OF RADIOACTIVE COMPOUND IN
MEDICAL
Nuclear medicine is a medical
specialty involving the application of radioactive
substances in the diagnosis and treatment of disease. In
nuclear medicine procedures, radionuclides are combined with other elements to form
chemical compounds, or else combined with existing pharmaceutical
compounds, to form radiopharmaceuticals. These radiopharmaceuticals,
once administered to the patient, can localize to specific organs or cellular
receptors. This property of radiopharmaceuticals allows nuclear medicine the
ability to image the extent of a disease process in the body, based on the
cellular function and physiology, rather than relying on physical changes in the
tissue anatomy. In some diseases nuclear medicine studies can identify medical
problems at an earlier stage than other diagnostic tests. Nuclear medicine, in
a sense, is "radiology done inside out" or
"endo-radiology" because it records radiation
emitting from within the body rather than radiation that is generated by
external sources like X-rays.
Treatment of diseased tissue, based on metabolism or uptake or
binding of a particular ligand, may also be accomplished, similar to other
areas of pharmacology. However, the treatment effects of radiopharmaceuticals
rely on the tissue-destructive power of short-range ionizing radiation.
In the future nuclear medicine may provide added impetus to the
field known as molecular medicine. As understanding of
biological processes in the cells of living organism expands, specific probes
can be developed to allow visualization, characterization, and quantification
of biologic processes at the cellular and subcellular levels.[1]
Nuclear medicine is a possible specialty for adapting to the new discipline of
molecular medicine, because of its emphasis on function and its utilization of
imaging agents that are specific for a particular disease process.
Diagnostic medical imaging
Diagnostic
Radionuclides
are powerful tools for diagnosing medical disorders for three reasons. First,
many chemical elements tend to concentrate in one part of the body or another.
As an example, nearly all of the iodine that humans consume in their diets goes
to the thyroid gland. There it is used to produce hormones that control the
rate at which the body functions.
Second, the
radioactive form of an element behaves biologically in exactly the same way
that a nonradioactive form of the element behaves. When a person ingests (takes
into the body) the element iodine, for example, it makes no difference whether
the iodine occurs in a radioactive or nonradioactive form. In either case, it
tends to concentrate in the thyroid gland.
Third, any
radioactive material spontaneously decays, breaking down into some other form
with the emission of radiation. That radiation can be detected by simple,
well-known means. When radioactive iodine enters the body, for example, its
progress through the body can be followed with a Geiger counter or some other
detection instrument. Such instruments pick up the radiation given off by the
radionuclide and make a sound, cause a light to flash, or record the radiation
in some other way.
If a physician
suspects that a patient may have a disease of the thyroid gland, that patient
may be given a solution to drink that contains radioactive iodine. The
radioactive iodine passes through the body and into the thyroid gland. Its
presence in the gland can be detected by means of a special device. The
physician knows what the behavior of a normal thyroid gland is from previous
studies; the behavior of this particular patient's thyroid gland can then be
compared to that of a normal gland. The test therefore allows the physician to
determine whether the patient's thyroid is functioning normally.
In nuclear
medicine imaging, radiopharmaceuticals are taken internally, for example
intravenously or orally. Then, external detectors (gamma
cameras) capture and form images from the radiation emitted by the
radiopharmaceuticals. This process is unlike a diagnostic X-ray where external
radiation is passed through the body to form an image.
There are
several techniques of diagnostic nuclear medicine.
1.
A nuclear medicine whole body bone scan. The nuclear medicine whole
body bone scan is generally used in evaluations of various bone related
pathology, such as for bone pain, stress fracture, nonmalignant bone lesions,
bone infections, or the spread of cancer to the bone.
2. · 
Nuclear
medicine myocardial perfusion scan with Thallium-201 for the rest images
(bottom rows) and Tc-Sestamibi for the stress images (top rows). The nuclear
medicine myocardial perfusion scan plays a pivotal role in the noninvasive
evaluation of coronary artery disease. The study not only identifies patients
with coronary artery disease, it also provides overall prognostic information
or overall risk of adverse cardiac events for the patient.
3. · 
A nuclear
medicine parathyroid scan demonstrates a parathyroid adenoma adjacent to the
left inferior pole of the thyroid gland. The above study was performed with
Technetium-Sestamibi (1st column) and Iodine-123 (2nd column) simultaneous
imaging and the subtraction technique (3rd column).
4. · 
Normal
hepatobiliary scan (HIDA scan). The nuclear medicine hepatobiliary scan is
clinically useful in the detection of the gallbladder disease.
5. · 
Normal pulmonary ventilation and
perfusion (V/Q) scan. The nuclear medicine V/Q scan is useful in the evaluation
of pulmonary embolism.
6. 
Thyroid scan with Iodine-123 for
evaluation of hyperthyroidism
7. · 
A nuclear
medicine SPECT liver scan with technetium-99m labeled autologous red blood
cells. A focus of high uptake (arrow) in the liver is consistent with a
hemangioma.
Nuclear medicine tests differ from most other imaging modalities in
that diagnostic tests primarily show the physiological function of the system
being investigated as opposed to traditional anatomical imaging such as CT or
MRI. Nuclear medicine imaging studies are generally more organ or tissue
specific (e.g.: lungs scan, heart scan, bone scan, brain scan, etc.) than those
in conventional radiology imaging, which focus on a particular section of the
body (e.g.: chest X-ray, abdomen/pelvis CT scan, head CT scan, etc.). In
addition, there are nuclear medicine studies that allow imaging of the whole
body based on certain cellular receptors or functions. Examples are whole body PET scan or
PET/CT scans, gallium scans, indium white blood cell scans, MIBG and octreotide
scans.
Iodine-123 whole body scan for thyroid cancer
evaluation. The study above was performed after the total thyroidectomy and TSH
stimulation with thyroid hormone medication withdrawal. The study shows a small
residual thyroid tissue in the neck and a mediastinum lesion, consistent with
the thyroid cancer metastatic disease. The uptakes in the stomach and bowel are
normal physiologic findings.
While the ability of nuclear metabolism to image disease processes
from differences in metabolism is unsurpassed, it is not unique. Certain
techniques such as fMRI
image tissues (particularly cerebral tissues) by blood flow, and thus show
metabolism. Also, contrast-enhancement techniques in both CT and MRI show
regions of tissue which are handling pharmaceuticals differently, due to an
inflammatory process.
Diagnostic tests in nuclear medicine exploit the way that the body
handles substances differently when there is disease or pathology present. The
radionuclide introduced into the body is often chemically bound to a complex
that acts characteristically within the body; this is commonly known as a
tracer. In the presence of disease, a tracer will often be distributed around
the body and/or processed differently. For example, the ligand
methylene-diphosphonate (MDP) can be preferentially taken up by bone. By
chemically attaching technetium-99m to MDP, radioactivity can be
transported and attached to bone via the hydroxyapatite for imaging. Any
increased physiological function, such as due to a fracture in the bone, will
usually mean increased concentration of the tracer. This often results in the
appearance of a 'hot-spot' which is a focal increase in radio-accumulation, or
a general increase in radio-accumulation throughout the physiological system.
Some disease processes result in the exclusion of a tracer, resulting in the
appearance of a 'cold-spot'. Many tracer complexes have been developed to image
or treat many different organs, glands, and physiological processes.
Interventional
nuclear medicine
Radionuclide
therapy can be used to treat conditions such as hyperthyroidism,
thyroid
cancer, and blood disorders.
In nuclear
medicine therapy, the radiation treatment dose is administered internally (e.g.
intravenous or oral routes) rather from an external radiation source.
The
radiopharmaceuticals used in nuclear medicine therapy emit ionizing radiation
that travels only a short distance, thereby minimizing unwanted side effects
and damage to noninvolved organs or nearby structures. Most nuclear medicine
therapies can be performed as outpatient procedures since there are few side
effects from the treatment and the radiation exposure to the general public can
be kept within a safe limit.
Most nuclear medicine therapies will also require appropriate patient preparation prior to a treatment.
Most nuclear medicine therapies will also require appropriate patient preparation prior to a treatment.
Treatment
Radionuclides
can also be used to treat medical disorders because of the radiation they emit.
Radiation has a tendency to kill cells. Under many circumstances, that tendency
can be a dangerous side effect: anyone exposed to high levels of radiation may
become ill and can even die. But the cell-killing potential of radiation also
has its advantages. A major difference between cancer cells and normal cells,
for example, is that the former grow much more rapidly than the latter. For
this reason, radiation can be used to destroy the cells responsible for a
patient's cancer.
A radionuclide
frequently used for this purpose is cobalt-60. It can be used as follows. A
patient with cancer lies on a bed surrounded by a large machine that contains a
sample of cobalt-60. The machine is then rotated in such a way around the
patient's body that the radiation released by the sample is focused directly on
the cancer. That radiation kills cancer cells and, to a lesser extent, some
healthy cells too. If the treatment is successful, the cancer may be destroyed,
producing only modest harm to the patient's healthy cells. That "modest
harm" may occur in the form of nausea, vomiting, loss of hair, and other
symptoms of radiation sickness that accompany radiation treatment.
Words to Know
Diagnosis: Any attempt to identify a disease or other medical disorder.
Isotopes: Two or more forms of an element that have the same chemical
properties but that differ in mass because of differences in the number of
neutrons in their nuclei.
Radioactivity:
The property possessed by some elements of
spontaneously emitting energy in the form of particles or waves by
disintegration of their atomic nuclei.
Radioactive
decay: The process by which an isotope breaks down
to form a different isotope, with the release of radiation.
Radioactive
isotope: A form of an element that gives off
radiation and changes into another isotope.
Radionuclide:
A radioactive isotope.
Radioactive
isotopes can be used in other ways for the treatment of medical disorders. For
example, suppose that a patient has a tumor on his or her thyroid. One way of
treating that tumor might be to give the patient a dose of radioactive iodine.
In this case, the purpose of the iodine is not to diagnose a disorder, but to
treat it. When the iodine travels to the thyroid, the radiation it gives off
may attack the tumor cells present there, killing those cells and thereby
destroying the patient's tumor.
Some Diagnostic Radionuclides Used in Medicine
Radionuclide
|
Use
|
Chromium–51
|
Volume of blood and of red blood cells
|
Cobalt–58
|
Uptake (absorption) of vitamin B 12
|
Gallium–67
|
Detection of tumors and abscesses
|
Iodine–123
|
Thyroid studies
|
Iron–59
|
Rate of formation/lifetime of red blood
cells
|
Sodium–24
|
Studies of the circulatory system
|
Thallium–201
|
Studies of the heart
|
Technetium–99
|
Many kinds of diagnostic studies
|
Common
nuclear medicine (unsealed source) therapies
Substance
|
Condition
|
Iodine-131-sodium iodide
|
|
Yttrium-90-ibritumomab tiuxetan (Zevalin) and
Iodine-131-tositumomab (Bexxar)
|
refractory lymphoma
|
131I-MIBG (metaiodobenzylguanidine)
|
|
palliative bone pain treatment
|
In some centers
the nuclear medicine department may also use implanted capsules of isotopes (brachytherapy)
to treat cancer.
Commonly
used radiation sources (radionuclides) for brachytherapy
Radionuclide
|
Type
|
Half-life
|
Energy
|
Caesium-137 (137Cs)
|
γ-ray
|
30.17 years
|
0.662 MeV
|
Cobalt-60
(60Co)
|
γ-rays
|
5.26 years
|
1.17, 1.33 MeV
|
Iridium-192 (192Ir)
|
β--particles
|
73.8 days
|
0.38 MeV (mean)
|
Iodine-125 (125I)
|
γ-rays
|
59.6 days
|
27.4, 31.4 and 35.5 keV
|
Palladium-103 (103Pd)
|
γ-ray
|
17.0 days
|
21 keV (mean)
|
Ruthenium-106 (106Ru)
|
β--particles
|
1.02 years
|
3.54 MeV
|
Applications of Radioactive Tracers
Radioactive Tracers
A radioactive isotope replacing a stable chemical
element in a compound (said to be radiolabeled) and so able to be followed or
tracked through one or more reactions or systems by means of a radiation
detector; used especially for such a compound that is introduced into the body
for study of the compound's metabolism, distribution, passage through the body
and elimination to be followed in the living animal.
Radioactive
tracers are substances that contain a radioactive atom to allow easier
detection and measurement. (Radioactivity is the property possessed by some
elements of spontaneously emitting energy in the form of particles or waves by
disintegration of their atomic nuclei.) For example, it is possible to make a
molecule of water in which one of the two hydrogen atoms is a radioactive
tritium (hydrogen-3) atom. This molecule behaves in almost the same way as a
normal molecule of water. The main difference between the tracer molecule
containing tritium and the normal molecule is that the tracer molecule continually
gives off radiation that can be detected with a Geiger counter or some other
type of radiation detection instrument.
One application
for the tracer molecule described above would be to monitor plant growth by
watering plants with it. The plants would take up the water and use it in
leaves, roots, stems, flowers, and other parts in the same way it does with
normal water. In this case, however, it would be possible to find out how fast
the water moves into any one part of the plant. One would simply pass a Geiger
counter over the plant at regular intervals and see where the water has gone.
.Radioactive tracer technology has been used
for many years as a tool to make highly sensitive real-time measurements of
wear and corrosion. With this technique, the material of interest is tagged
with radioactive isotopes through either direct
activation of a relatively small number of atoms in the component itself, or
implantation of radioactive isotopes. As the component
wears or corrodes under test, radioactive atoms are
transported from the surface in the form of wear particles or corrosion
products. Wear or corrosion is measured in real-time through either
interrogation of the buildup of radioactivity in the transport fluid, or by the
reduction in activity of the labeled wear component. The process involves
selection of an appropriate labeling technique, labeling of a component or
components of interest, calibration, testing and data reduction and analysis.
Although the majority of the work performed has been in the
automotive engine and lubricant industry, Southwest Research Institute®
has recently extended the application into other fields,
such as hydraulic pump wear, prosthetic hip joint wear, wear in marine engines
and crude oil corrosivity. This paper discusses the various techniques employed
to label components of interest, the advantages of the techniques, and gives
several examples of current applications of this
technology.
Applications
1.Industry
and research.
Radioactive
tracers have applications in medicine, industry, agriculture, research, and
many other fields of science and technology. For example, a number of different
oil companies may take turns using the same pipeline to ship their products
from the oil fields to their refineries. How do companies A, B, and C all know
when their oil is passing through the pipeline? One way to solve that problem
is to add a radioactive tracer to the oil. Each company would be assigned a
different tracer. A technician at the receiving end of the pipeline can use a
Geiger counter to make note of changes in radiation observed in the incoming
oil. Such a change would indicate that oil for a different company was being
received.
Another
application of tracers might be in scientific research on plant nutrition.
Suppose that a scientist wants to find out how plants use some nutrient such as
phosphorus. The scientist could feed a group of plants fertilizer that contains
radioactive phosphorus. As the plant grows, the location of the phosphorus
could be detected by use of a Geiger counter. Another way to trace the movement
of the phosphorus would be to place a piece of photographic film against the
plant. Radiation from the phosphorus tracer would expose the film, in effect
taking its own picture of its role in plant growth.
2.Medical
applications.
Some of the
most interesting and valuable applications of radioactive tracers have been in
the field of medicine. For example, when a person ingests (takes into the body)
the element iodine, that element goes largely to the thyroid gland located at
the base of the throat. There the iodine is used in the production of various
hormones (chemical messengers) that control essential body functions such as
the rate of metabolism (energy production and use).
Suppose that a
physician suspects that a person's thyroid gland is not functioning properly.
To investigate that possibility, the patient can be given a glass of water
containing sodium iodide (similar to sodium chloride, or table salt). The
iodine in the sodium iodide is radioactive. As the patient's body takes up the
sodium iodide, the path of the compound through the body can be traced by means
of a Geiger counter or some other detection device. The physician can determine
whether the rate and location of uptake is normal or abnormal and, from that
information, can diagnose any problems with the patient's thyroid gland.
CONCLUSION
The energy released by the nucleus of an atom as the
result of nuclear fission, nuclear fusion, or radioactive decay. The amount of
energy released by the nuclear fission of a given mass of uranium is about
2,500,000 times greater than that released by the combustion of an equal mass
of carbon. And the amount of energy released by the nuclear fusion of a given
mass of deuterium is about 400 times greater that that released by the nuclear
fission of an equal mass of uranium. Also called atomic energy. Nuclear
energy is energy that is generated through the use of Uranium, a
natural metal that is mined all over the world. Nuclear energy is created
through complex processes in nuclear power stations, and the first nuclear
power station was established in 1956 in Cumbria, England. Today, many military
operations and vessels use nuclear power plants and nuclear energy for their
energy source, and nuclear energy is used in many other capabilities such that
it provides 16% of the Earth’s energy requirements.
Nuclear energy is created through chemical reactions that involve
the splitting or merging of the atoms of nuclei together. The process of
splitting an atom’s nucleus is termed fission, and the process of merging the
nuclei if atoms is termed merging. Converting nuclear masses into energy forms
is known through the popular chemical equation of E = mc2,
where E is known as the amount of energy released, m is known as the mass of
the nuclei, and c is the value of the speed of light. The power from nuclear
energy was first discovered in 1896 by Henri Becquerel, a French physicist who
saw that some photographic plates that had been stored near uranium turned
dark, or black, like X-Ray plates did. Thus, Uranium was seen as a resource for
nuclear energy.
Nuclear medicine is a medical
specialty involving the application of radioactive
substances in the diagnosis and treatment of disease. In
nuclear medicine procedures, radionuclides are combined with other elements to form
chemical compounds, or else combined with existing pharmaceutical
compounds, to form radiopharmaceuticals. These radiopharmaceuticals,
once administered to the patient, can localize to specific organs or cellular
receptors. This property of radiopharmaceuticals allows nuclear medicine the
ability to image the extent of a disease process in the body, based on the
cellular function and physiology, rather than relying on physical changes in the
tissue anatomy. In some diseases nuclear medicine studies can identify medical
problems at an earlier stage than other diagnostic tests. Nuclear medicine, in
a sense, is "radiology done inside out" or
"endo-radiology" because it records radiation
emitting from within the body rather than radiation that is generated by
external sources like X-rays.
Treatment of diseased tissue, based on metabolism or uptake or
binding of a particular ligand, may also be accomplished, similar to other
areas of pharmacology. However, the treatment effects of radiopharmaceuticals
rely on the tissue-destructive power of short-range ionizing radiation.
In the future nuclear medicine may provide added impetus to the
field known as molecular medicine. As understanding of
biological processes in the cells of living organism expands, specific probes
can be developed to allow visualization, characterization, and quantification
of biologic processes at the cellular and subcellular levels.[1]
Nuclear medicine is a possible specialty for adapting to the new discipline of
molecular medicine, because of its emphasis on function and its utilization of
imaging agents that are specific for a particular disease process.
Radioactive
tracers are substances that contain a radioactive atom to allow easier
detection and measurement. (Radioactivity is the property possessed by some
elements of spontaneously emitting energy in the form of particles or waves by
disintegration of their atomic nuclei.) For example, it is possible to make a
molecule of water in which one of the two hydrogen atoms is a radioactive
tritium (hydrogen-3) atom. This molecule behaves in almost the same way as a
normal molecule of water. The main difference between the tracer molecule
containing tritium and the normal molecule is that the tracer molecule
continually gives off radiation that can be detected with a Geiger counter or
some other type of radiation detection instrument.
Some of the
most interesting and valuable applications of radioactive tracers have been in
the field of medicine. For example, when a person ingests (takes into the body)
the element iodine, that element goes largely to the thyroid gland located at
the base of the throat. There the iodine is used in the production of various
hormones (chemical messengers) that control essential body functions such as
the rate of metabolism (energy production and use).
Suppose that a
physician suspects that a person's thyroid gland is not functioning properly.
To investigate that possibility, the patient can be given a glass of water
containing sodium iodide (similar to sodium chloride, or table salt). The
iodine in the sodium iodide is radioactive. As the patient's body takes up the
sodium iodide, the path of the compound through the body can be traced by means
of a Geiger counter or some other detection device. The physician can determine
whether the rate and location of uptake is normal or abnormal and, from that
information, can diagnose any problems with the patient's thyroid gland.
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