Keywords: Urinalysis; Bioassay; Tracer; Carbon dating
Radioisotopes are widely used for a number of purposes following are some major applications of radioisotope.
Biochemical assays are used to detect the presence and absence of radioisotopes. Therefore radioactive isotopes are used to label biological molecules. Such assays estimate the concentration of different constituents of plasma, body fluids, urine, blood etc. This technique is called radioimmuno-assays. An example is iodine bioassay which uses gamma emitters’ radionuclides of Iodine-125 and Iodine-131 that accrues inside thyroid. Therefore gamma detector can be used to quantify the iodine content (uptake and intake) of the person’s thyroid. The amount of measured radioiodine in the thyroid is compared with the Annual Limit on Intake (ALI) .
Radioisotopes are eliminated from the body in body fluids. By determining the active contents in urine one can analyse the uptake and intake of a specific radionuclide .
Radioisotope is used for biological labelling of cells or entities for identification or tracing specific molecules in an organism. S 35 P 32 and I 125 are widely used radioisotopes used for labelling .
Radioactive carbon-14 decay could be used to estimate the age of organic materials. For example carbon dating revealed that the burial cloth of Jesus Christ originated during the medieval times between A.D. 1260-1390. Similarly mummified remains found frozen in the Italian Alps were at least 5000 years old .
Radio potassium-40 decays to stable 40Ar. Thus, by measuring relative ratio of 40K and 40Ar in rocks enable us to determine the age of rocks since its formation .
Positron Emission Tomography (PET) and PETCT make use of radionuclides emitting positron particle that is injected in to the target cell or tissue. Radionuclide decay release positron particles which interact with the nearby negatively charged particle resulting in the emission of gamma rays which is detected by a PET or gamma camera to give an exact image of the target .
Radionuclide Therapy (RNT)
This therapy makes use of radioisotopes that emits radiations upon their decay. These emitted radiations are used to target specific cancerous cells, tumours etc. to control their abnormal growth or completely eradicate it. For example cobalt-60 is use as a source of gamma radiation for radionuclide therapy, gamma knife radiosurgery and brachytherapy. Similarly targeted alpha therapy uses alpha-emitting radionuclide such as Bi-213, Lead-212, and Boron-10 to for treating pancreatic, ovarian and melanoma cancers .
Sterilization of surgical instruments such as syringes, gloves, clothing and instruments using gamma mitting radionuclides including Cobalt-60, Cs-137 etc. .
Incorporation of radioisotopes to biologically active substances is introduced into body in order to observe the functioning of an organ functioning or a metabolic path way etc. For example Yttrium-90 and Iodine-131 is used as radiopharmaceuticals for the treatment of non-Hodgkin’s lymphoma and hyperthyroidism respectively (Table 1) .
|Am-241||432y||Detection of osteoporosis|
|Be-7||53.2d||Used in berylliosis (chronic lung disease) studies|
|Bi-212||1.10h||Cancer treatment, cellular dosimetry studies|
|Br-77||57h||Monoclonal antibody labeling|
|C-11||20.3m||Radiotracer in PET scans|
|C-14||5730y||Radiolabeling for tumors detection|
|Cd-109||462d||Cancer detection, pediatric imaging|
|Ce-139||138d||Calibration of germanium gamma detectors|
|Ce-141||32.5d||diagnosis of gastrointestinal tract, myocardial blood flow measurement|
|Co-55||17.5h||Planar and SPECT /PET imaging|
|Co-57||272d||In radiotracer, source for X-ray fluorescence spectroscopy|
|Co-60||5.27y||Teletherapy, disinfectant, radiotherapy|
|Cr-51||27.7d||Radiolabeling and dosimetry|
|Cs-130||29.2m||Myocardial localizing agent|
|Cs-131||9.69d||Intracavity implants for radiotherapy|
|Cs-137||30.2y||Blood irradiators, PET imaging, and tumor treatment|
|Cu-61||3.35h||Planar imaging, SPECT or PET|
|Positron emitting radionuclide|
|Cu-62||4.7m||Tracer, PET/SPETC imaging|
|Cu-67||61.9h||Cancer treatment/diagnostics, radio immunotherapy, SPECT or PET|
|Dy-165||2.33h||Radiation synovectomy, rheumatoid arthritis treatment|
|Ga-64||2.63m||Treatment of pulmonary diseases ending in fibrosis of lungs. detection of Hodgkin’s/non-Hodgkins lymphoma|
|Ga-68||68.1m||Imaging, detection, treatment of pancreatic cancer|
|Gd-153||242d||Photon source, detection, imaging|
|I-123||13.1h||Imaging, cancer treatment|
|Detection of osteoporosis,
imaging, tracer, brain
|I-131||8.04d||Tumor treatment, antibody labeling, radio immunotherapy, cellular dosimetry, SPECT imaging, treatment of prostate cancer|
|I-132||2.28h||Mapping of areas|
|In-111||2.81d||Detection of transplant rejection, imaging, labeling, treatment of tumors|
|Ir-192||73.8d||treatment of cancers|
|Lu-177||6.68d||Heart disease treatment), cancer therapy|
|Mn-51||46.2m||Myocardial localizing agent|
|N-13||9.97m||PET imaging, myocardial perfusion|
|Nb-95||35d||Myocardial tracer, PET imaging|
|O-15||122s||PET imaging / SPECT imaging|
|P-32||14.3d||Cancer treatment, imaging, radiolabeling|
|Pb-203||2.16d||Planar imaging, SPECT or PET, cellular dosimetry|
|Pb-212||10.6h||Radioactive labelling, cellular dosimetry|
|Pd-103||17d||Prostate cancer treatment|
|Pd-109||13.4h||Potential radio therapeutic agent|
|Ra-226||1.60e3y||Target isotope to make Ac-227, Th-228, Th-229|
|Rb-82||1.27m||Myocardial imaging agent, PET imaging, blood flow tracers|
|Rh-105||35.4h||Potential therapeutic applications, radiolabeling|
|Ru-97||2.89d||Monoclonal antibodies labelling, imaging|
|S-35||87.2d||Radiolabeling, cellular dosimetry|
|Sc-47||3.34d||Treatment of cancer/diagnostics|
|Se-72||8.4d||Brain imaging, immunotherapy|
|Si-28||Stable||Radiation therapy of cancer|
|Sm-145||340d||Brain cancer treatment|
|Sr-85||65.0d||Detection and imaging|
|Sr-89||50d||Cancer treatment, cellular dosimetry|
|Ta-179||1.8y||Source of X-ray|
|Ta-182||115d||Urinary cancer treatment|
|Tl-201||73.1h||Imaging, cellular dosimetry|
|Tm-170||129d||Treatment of cancers|
|W-188||69.4d||Treatment of tumors|
|Y-88||107d||Cancer tumor therapy|
|Y-90||64h||cellular dosimetry, treating rheumatoid arthritis and cancers|
|Y-91||58.5d||Tumor treatment, dosimetry|
|Zn-62||9.22h||Study of neurology|
Radioisotopes are used for numerous medical purposes which marks it potential in the field of medical science.