RADIOPHARMACEUTICALS
Radiopharmaceuticals are drugs containing a radionuclide and are used routinely in nuclear medicine for the diagnosis and therapy of various diseases. Depending upon their medical applications radiopharmaceuticals are divided into two classes’ viz. diagnostic radiopharmaceuticals and therapeutic radiopharmaceuticals. They are briefly discussed below.
Radiopharmaceuticals are drugs containing a radionuclide and are used routinely in nuclear medicine for the diagnosis and therapy of various diseases. Depending upon their medical applications radiopharmaceuticals are divided into two classes’ viz. diagnostic radiopharmaceuticals and therapeutic radiopharmaceuticals. They are briefly discussed below.
Diagnostics Radiopharmaceuticals
Diagnostic radiopharmaceuticals are molecules which are tagged with a gamma ray emitting radioisotope. Such agents when administered into the body localize in certain organs or tissue, for which they are designed for, and the radiation emitted by the associated radionuclide could be detected from outside with the help of suitable instrument like gamma camera. The analysis of the resultant images obtained from the gamma camera could reveal useful information regarding the disease condition of the patient.
Diagnostic radiopharmaceuticals are molecules which are tagged with a gamma ray emitting radioisotope. Such agents when administered into the body localize in certain organs or tissue, for which they are designed for, and the radiation emitted by the associated radionuclide could be detected from outside with the help of suitable instrument like gamma camera. The analysis of the resultant images obtained from the gamma camera could reveal useful information regarding the disease condition of the patient.
Therapeutic Radiopharmaceuticals
Therapeutic Radiopharmaceuticals are very similar much to the diagnostic radiopharmaceuticals but the only difference being the use of a therapeutic radionuclide instead of a diagnostic radionuclide. In this case the primary aim is not to get diagnostic information but to deliver therapeutic doses of ionizing radiations to specific diseased sites. Further discussion on therapeutic radiopharmaceuticals is beyond the scope of present work. The various isotope used as therapeutic, diagnostic or research work are listed below in table-1 [6]
Therapeutic Radiopharmaceuticals are very similar much to the diagnostic radiopharmaceuticals but the only difference being the use of a therapeutic radionuclide instead of a diagnostic radionuclide. In this case the primary aim is not to get diagnostic information but to deliver therapeutic doses of ionizing radiations to specific diseased sites. Further discussion on therapeutic radiopharmaceuticals is beyond the scope of present work. The various isotope used as therapeutic, diagnostic or research work are listed below in table-1 [6]
Isotopes used in radiopharmaceuticals with application
Table-1
ISOTOPE
|
t1/2
|
APPLICATION
|
198Au
|
2.7 d
|
Therapeutic
Diagnostic
|
14C
|
5700 Y
|
Research
|
45Ca
|
165 d
|
Diagnostic
|
47Ca
|
4.5 d
|
Diagnostic
|
57Co
|
270 d
|
Diagnostic
|
58Co
|
71 d
|
Diagnostic
|
60Co
|
5.27 y
|
Therapeutic
Diagnostic
|
51Cr
|
27.8 d
|
Diagnostic
|
121Cs
|
9.7 d
|
Diagnostic
|
137Cs
|
30 y
|
Research
|
18F
|
1.7 H
|
Diagnostic
|
3H
|
12.3 y
|
Diagnostic
Research
|
59Fe
|
45 d
|
Diagnostic
|
197Hg
|
2.7 d
|
Diagnostic
|
203Hg
|
46.9 d
|
Diagnostic
|
125I
|
60 d
|
Diagnostic
Therapeutic
|
131I
|
8.08 d
|
Diagnostic
Therapeutic
Research
|
113In
|
1.66 h
|
Diagnostic
|
192Ir
|
74.4 d
|
Therapeutic
|
42K
|
12.4 h
|
Research
|
99Mo
|
2.8 d
|
Source of 99mTc
|
22Na
|
2.6 y
|
Diagnostic
|
24Na
|
15 h
|
Diagnostic
|
32P
|
14.3 d
|
Diagnostic
Therapeutic
Research
|
226Ra
|
1620 y
|
Therapeutic
|
86Rb
|
18.8 d
|
Diagnostic
|
222Rn
|
3.8 d
|
Therapeutic
|
35S
|
88 d
|
Research
|
75Se
|
120 d
|
Diagnostic
|
85Sr
|
64 d
|
Diagnostic
|
90Sr
|
28 y
|
Therapeutic
|
182Ta
|
115 d
|
Therapeutic
|
99mTc
|
6.0 h
|
Diagnostic
|
90Y
|
2.6 d
|
Diagnostic
Therapeutic
|
169Yb
|
32 d
|
Diagnostic
|
65Zn
|
245 d
|
Research
|
The use of radioisotope in medicine is different upon the type of radiation emitted by it. Usually beta and gamma radiation are utilized for medical purpose because of the case with which they can be detected and measure.
Uses of radioactivity/radiation
There are many practical applications to the use of radioactivity/radiation. Radioactive sources are used to study living organisms, to diagnose and treat diseases, to sterilize medical instruments and food, to produce energy for heat and electric power, and to monitor various steps in all types of industrial processes.
There are many practical applications to the use of radioactivity/radiation. Radioactive sources are used to study living organisms, to diagnose and treat diseases, to sterilize medical instruments and food, to produce energy for heat and electric power, and to monitor various steps in all types of industrial processes.
Tracers
Tracersare a common application of radioisotopes. A tracer is a radioactive element whose pathway through which a chemical reaction can be followed. Tracers are commonly used in the medical field and in the study of plants and animals. Radioactive Iodine-131 can be used to study the function of the thyroid gland assisting in detecting disease.
Tracersare a common application of radioisotopes. A tracer is a radioactive element whose pathway through which a chemical reaction can be followed. Tracers are commonly used in the medical field and in the study of plants and animals. Radioactive Iodine-131 can be used to study the function of the thyroid gland assisting in detecting disease.
Nuclear reactors
Nuclear reactorsare devices that control fission reactions producing new substances from the fission product and energy. Recall our discussion earlier about the fission process in the making of a radioisotope. Nuclear power stations use uranium in fission reactions as a fuel to produce energy. Steam is generated by the heat released during the fission process. It is this steam that turns a turbine to produce electric energy.
Nuclear reactorsare devices that control fission reactions producing new substances from the fission product and energy. Recall our discussion earlier about the fission process in the making of a radioisotope. Nuclear power stations use uranium in fission reactions as a fuel to produce energy. Steam is generated by the heat released during the fission process. It is this steam that turns a turbine to produce electric energy.
Other uses of radioactivity
Sterilization of medical instruments and food is another common application of radiation. By subjecting the instruments and food to concentrated beams of radiation, we can kill microorganisms that cause contamination and disease. Because this is done with high energy radiation sources using electromagnetic energy, there is no fear of residual radiation. Also, the instruments and food may be handled without fear of radiation poisoning.
Radiation sources are extremely important to the manufacturing industries throughout the world. They are commonly employed by nondestructive testing personnel to monitor materials and processes in the making of the products we see and use every day. Trained technicians use radiography to image materials and products much like a dentist uses radiation to x-ray your teeth for cavities. There are many industrial applications that rely on radioactivity to assist in determining if the material or product is internally sound and fit for its application. Radioactive isotopes have many useful applications. In medicine, for example, cobalt-60 is extensively employed as a radiation source to arrest the development of cancer. Other radioactive isotopes are utilized as tracers for diagnostic purposes, as well as in research on metabolic processes. When a radioactive isotope is added in small amounts to comparatively large quantities of the stable element, it behaves exactly the same as the ordinary isotope chemically; it can, however, be traced with a Geiger counter or other detection device. Iodine-131 has proved effective in locating brain tumours, measuring cardiac output, and determining liver and thyroid activity. Another medically important radioactive isotope is carbon-14, which is useful in studying abnormalities of metabolism that underlie diabetes, gout, anemia, and acromegaly. In industry, radioactive isotopes of various kinds are used for measuring the thickness of metal or plastic sheets; their precise thickness is indicated by the strength of the radiations that penetrate the material being inspected. They also may be employed in place of large X-ray machines to examine manufactured metal parts for structural defects. Other significant applications include the use of radioactive isotopes as compact sources of electrical power—e.g., plutonium-238 in cardiac pacemakers and spacecraft. In such cases, the heat produced in the decay of the radioactive isotope is converted into electricity by means of thermoelectric junction circuits or related devices
Sterilization of medical instruments and food is another common application of radiation. By subjecting the instruments and food to concentrated beams of radiation, we can kill microorganisms that cause contamination and disease. Because this is done with high energy radiation sources using electromagnetic energy, there is no fear of residual radiation. Also, the instruments and food may be handled without fear of radiation poisoning.
Radiation sources are extremely important to the manufacturing industries throughout the world. They are commonly employed by nondestructive testing personnel to monitor materials and processes in the making of the products we see and use every day. Trained technicians use radiography to image materials and products much like a dentist uses radiation to x-ray your teeth for cavities. There are many industrial applications that rely on radioactivity to assist in determining if the material or product is internally sound and fit for its application. Radioactive isotopes have many useful applications. In medicine, for example, cobalt-60 is extensively employed as a radiation source to arrest the development of cancer. Other radioactive isotopes are utilized as tracers for diagnostic purposes, as well as in research on metabolic processes. When a radioactive isotope is added in small amounts to comparatively large quantities of the stable element, it behaves exactly the same as the ordinary isotope chemically; it can, however, be traced with a Geiger counter or other detection device. Iodine-131 has proved effective in locating brain tumours, measuring cardiac output, and determining liver and thyroid activity. Another medically important radioactive isotope is carbon-14, which is useful in studying abnormalities of metabolism that underlie diabetes, gout, anemia, and acromegaly. In industry, radioactive isotopes of various kinds are used for measuring the thickness of metal or plastic sheets; their precise thickness is indicated by the strength of the radiations that penetrate the material being inspected. They also may be employed in place of large X-ray machines to examine manufactured metal parts for structural defects. Other significant applications include the use of radioactive isotopes as compact sources of electrical power—e.g., plutonium-238 in cardiac pacemakers and spacecraft. In such cases, the heat produced in the decay of the radioactive isotope is converted into electricity by means of thermoelectric junction circuits or related devices
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