In World, the earth, where we live peacefully, there are
certain problems which have made our lives worse, such problems are mainly
related to health issues. Many of such disorders and diseases are curable today
with the help of Modern Medical science and technology. Cancers, Tumors, AIDS,
and many other such diseases are life threatening conditions from which day and
night our doctors and scientists are striving hard to defend our community.
Cancer which leads to death is very common all over the world and there are
many therapeutic methods to cure it like Surgery, Radiation therapy,
Chemotherapy, Immunotherapy, Hormone therapy, Stem cell transplant, etc., and
our main focus in this topic is upon Radiation therapy in the context of drugs
which are radioactive, such drugs are called Radiopharmaceuticals, and the
pharmacy which is involved in the regulation of such drugs is called Radio
definition, a radiopharmaceutical is a radioactive pharmaceutical agent
that is used for diagnostic or therapeutic
So, by definition, we understand that the application of
radiopharmaceuticals is divided into two major areas i.e. Diagnostic and
radiopharmaceuticals may be classified into two categories, (1)
Radiopharmaceuticals used in tracer
techniques for measuring physical parameters and (2) Radiopharmaceuticals used
for diagnostic imaging like in Positron Emission tomography.
radiopharmaceuticals are radiolabeled molecules which deliver
therapeutic doses of radiation to specific disease sites such as Cancerous
tumors. They are only administered with high specificity, for example
radioactive Iodine is administered in case of hyperthyroidism as only thyroid
gland will take up iodine from the systemic circulation in order to synthesize
thyroxine and triiodothyronine.
Unlike other drugs the handling of radioactive drugs is
difficult and requires specialized practitioners, in a hospital there is a
group of special practitioners who deals with Radioisotopes, such group is
called Radioisotope committee, it includes a radiation physicist, a clinical
radiologist, an internist, a hematologist and a surgeon. In addition to them
nursing staff, administration and Nuclear pharmacist are also part of that
committee roster, so they become familiar with the type of work, Radiation
hazards, and safety protocols which are of utmost importance in the field of
radio pharmacy or Nuclear medicine. The team ensure that the specific drug will
be safe for both patient and user as well as it will give high quality clinical
There are 3 main nuclear
radiations called Alpha radiations, Beta radiations and Gamma radiations. Alpha
radiations have the highest energy but less penetrability as compared to beta
and Gamma radiations. Beta radiations have less energy but more penetrability
relative to alpha, while Gamma are actually non-particulate radiations but they
have the highest tissue penetrability.
Radiations in any form are
dangerous for Organisms, they damage the healthy cells, they may damage the
cellular DNA by causing mutations which may lead to cancer and death.
Therefore, high safety protocols should be followed in order to deal such
drugs, the alpha particle radiations are not used in radiopharmaceuticals
because of their high energy which will cause greater damage to the healthy
neighboring tissue as compared to Beta and Gamma radiations. The latter two
radiations, Beta is mainly used in therapeutic procedures while gamma is mainly
used in diagnostic procedures.
It is important to mention
here the main radiation hazards which we encounter in Nuclear medicine.
Basically, there are two types of radiation hazards. (1) Irradiation and (2)
Ingestion of radioactivity. The operator working with radiopharmaceuticals may
undergo radiation exposure like exposure of hands while handling such drugs and
transferring and administering them to the patient, so such type of radiation
exposure is called Irradiation. The ingestion of radioactivity is like
inhalation of volatile radioactive material or airborne fine powder, Oral
ingestion. It includes ingestion of both gamma and beta radiations.
Radionuclide is the main
active ingredient of a radiopharmaceutical agent. United States pharmacopeia
lists 77 official radioactive pharmaceuticals of which the most common used are
technetium (99), strontium (89), Yttrium (90), Thallus (201), Gallium (67),
Gallium (68), Indium (111), Iodine (123), Iodine (131), Samarium (153), Holmium
(166), Lutetium (177), Rhenium (186), Rhenium (188), Carbon (11), Nitrogen
(13), Oxygen (15), Fluorine (18).
Radionuclides can be
artificially produced by 2 ways, (1) Bombardment of Neutrons on the target
nucleus in Nuclear reactor and (2) Bombardment of charged positrons in
cyclotron. In either case the chemistry of the target nucleus changes and it
becomes metastable, and starts radiating. Some of the nuclides emit pure beta
or pure gamma radiations while others emit both. Most of the elements have
multiple isotopes therefore we have the choice to select the most suitable
radioisotope. There is a special table of elements where all the radioisotopes
of all the elements are recoded along with their radioactive half-life and
To choose the most suitable radionuclide for a particular
purpose, we have to take into account 2 major features of a radioactive
radioactivity has to be selectively administered and accumulated by the target
tissue or Organ i.e. site specificity. E.g. Iodine (131) administered in case
of Hyperthyroidism (already quoted).
radiation emitted must be sufficiently energetic to be effective for the
It must be taken into account
that any radioactive nuclide administered will show its effect on target tissue
as well as on the neighboring healthy tissues, so while selecting the
radioactive isotope, we must make sure that the radiation of a specific nuclide
remains localized in the target tissue as much as possible.
The clinical utility of the
radiopharmaceutical is mainly determined by the physical properties of the
radionuclide like radiation, energy, half-life. Therefore, for the diagnostic
purposes the radionuclide should have least half-life and it should be pure
gamma emitter because their interaction with tissues is much less than that of
particulate emitters and they will cause less damage to tissues.
In a hospital where
radioactive drugs are dealt with, there is a separate setup of radio pharmacy
where only radioactive drugs are stored and utilized. When a drug is made
radioactive the process of radioactive decay begins i.e. it starts emitting
radiations either beta, gamma or both. So those drugs having short half-life
cannot be stored and the hospital user should perform the drug formulations on
daily basis. In fact the pharmacist is provided with the list of prescriptions
for the day and every day the same routine follows.
As already described the
hazards and problems encountered with handling radiopharmaceuticals, there are
certain precautionary and safety protocols which are strictly followed in such
There are three basic principles to radiation protection. Shielding, Distance
radiation source (drug) should be placed in a container impermissible to
radiations. Different materials are used for this purpose but in accordance
with the type of radiations. Beta
radiations have low penetrability so low molecular weight shields like
Plastic, Perspex, and metals (low molecular weight) will serve the purpose Gamma radiations have high penetrability
therefore shields having high molecular weight will serve the purpose, like
heavy metals such as Lead and Tungsten.
considerable distance should be maintained between the operator and radiation
source. It is according to inverse square law.
time should be consumed while handing the radioactive source
Instructoins for the radioisotope users
The operator should avoid contamination of
clothing and skin from the body secretions of the patient
In case of dealing patient, the time consumed
in the purpose should be as short as possible
Distance should be maintained from the patient.
Instructions for the nurses:
One nurse should be caring only one radioactive
Close bedside nursing should be reduced as much
Nurses should wear gloves when handling the
patient because the patient belongings like clothes, utensils, and even body
may be contaminated by the radiations.
A plastic apron is to be worn for bedside
nursing. Also the particular nurse for caring for a particular patient wearing
a particular apron should all remain limited to that particular patient.
The utensils should be marked with radioactive
sign and should be reserved for a particular patient.
Anything if gets contaminated with the patient
body discharge should be retained in a plastic bag. It should then be monitored
and appropriate disposal directions should be given by the isotope
administrator. Linen should be retained in large plastic bag while dressings,
tissues etc should be retained in small plastic bags.
of the Users of Radioisotopes:
order to maintain safe environment, and ensure safety of self and others, the
radioisotope users must serve the following responsibilities.
1. To get
knowledge about radiation safety protocols from the radiation safety officers.
low exposure to radiations.
wear recommended dosimeters such as film badges, etc. which would measure the
amount of radiations entering the body
prohibit smoking and eating in radioisotope laboratories.
5. To use
proper labels on equipment being used with radioactive materials.
retain all the active waste in proper containers equipped with proper labels.
decontamination procedures as directed by the radiation safety officer