Schiller Institute on YouTube Schiller Institute on Facebook RSS

Home >

Medical Isotopes
In the 21st Century

by Robert E. Schenter, Ph.D.
September 2007

Robert E. Schenter, Ph.D., reviews the diagnostic and therapeutic applications for all major diseases, in a paper for the Schiller Institute conference on “Making the Eurasian Land-Bridge a Reality,” Sept. 15-16, 2007.

Radioactive isotopes should and will play a major role in the advancement of 21st-Century medicine. These medical isotopes are currently showing outstanding results in both diagnostic and therapeutic medical applications, which should continue to expand for application for essentially all the major diseases (cancer, heart, Alzheimer’s, arthritis, et al.) for the rest of this century. There have also been promising research results in killing the HIV virus with medical isotopes.

This paper briefly presents examples of these developments and their future promise for two forms of cancer (breast and liver), Alzheimer’s disease, and HIV. The promise of treatment with radioactive isotopes can be seen from one patient who was told, “You have three months to live” four years ago. Now, as a result of treatment with the medical isotope yttrium-90, applied using what are called Y90 microspheres, the patient not only is alive, but works out with her personal trainer every other day, and is living life to the fullest.


DOE Photo
Brookhaven National Laboratory scientists preparing for a Positron Emission Tomography (PET) scan of a patient. The PET technology uses the radioisotope fluorine-18 in combination with glucose (together called FDG or fluorodeoxyglucose). Cancer tumors overutilize glucose, and the PET scan identifies the metabolic difference between normal tissue and the tumor, thus identifying tumors.

Diagnostic and therapeutic medical isotope applications have made major advances for the past 50 years, and these advances should accelerate as we continue through the 21st Century. In the United States, and probably in the rest of the world, the aging of the World War II Baby Boomers will create an exponentially increasing demand for the medical application of these isotopes, as people live longer and acquire the diseases of aging.

A good example of this increase in demand is the explosion in the diagnostic application of Positron Emission Tomography (PET) for essentially all major diseases.

The PET application uses several radioisotopes, which have a whole range of half-lives, predominantly led by fluorine-18. The list of isotopes used with PET and their half-lives and applications is given in Table 1.1

In the area of therapy, the isotopes of iodine-131 and yttrium-90 are applied very effectively in treating follicular non-Hodgkin’s lymphoma. They are used in Food and Drug Administration-approved radiopharmaceuticals called

DOE Photo
This PET scan shows the chemical uptake in a monkey’s brain, to test the effectiveness of a Parkinson’s disease treatment. The research is being carried out by the Lawrence Berkeley National Laboratory in collaboration with Somatix Therapy Corporation. By restoring levels of important brain chemicals in animals, the hope is to develop a similar treatment for human Parkinson’s patients.

BEXXAR (I-131) and Zevalin (Y-90). This procedure is called radioimmunotherapy, or RIT, where the goal is to kill all the cancer cells without harming the healthy cells. This is also known as cell-directed therapy.

Four additional examples of medical isotope application for both diagnostic and therapeutic procedures are presented below, for two types of cancer (breast and liver), Alzheimer’s disease, and HIV.

Examples of Medical Isotope Applications

Forty thousand women currently in the United States die each year as a result of breast cancer. That number could double as the Baby Boomers age. Consequently, better treatments for this devastating disease should be aggressively pursued.

An important method of treating breast cancer is the application of brachytherapy. This procedure involves placing a tiny radioactive seed inside the breast, up against tissues harboring the breast cancer. The radiation is focussed on the breast tumor area, which significantly reduces the destruction of the healthy breast cells.

The isotopes irridium-192 and iodine-125 are used for this application.

Robert R. Kuske, M.D., a radiation oncologist with Arizona Oncology Services, discussed advantages of Accelerated Partial Breast Irradiation (APBI) at the July 2004 meeting of the Radiological Society of North America (RSNA).2 APBI combines surgery with brachytherapy as a breast conservation therapy.

Radiological Society of North America
An ultrasound-guided breast brachytherapy procedure, in which a radioactive ``seed'' is inserted into a tiny balloon, placed at the site of the surgically removed tumor. The seed delivers the prescribed dose of radiation directly to the site where cancer recurrence is most likely, minimizing exposure to healthy tissue in the breast, skin, ribs, lungs, and heart. This outpatient treatment can be for one to five days. No source of radiation remains in the patient's body between treatments or after the procedure is completed.

Northshore Medical Accelerator
A similar radioactive “seed” treatment is used for prostate cancer. This shows the actual size of a prstate seed implant.

A medical breakthrough called microsphere brachytherapy is giving new hope to patients with liver cancer.3 This therapy works by delivering radiation from the medical isotope yttrium-90 through a catheter tube, directly to tumors inside the liver. The yttrium-90 is contained in tiny glass bead microspheres. Several million of these Y-90 microspheres are used in a single treatment.

According to Dr. Andrew Kennedy of Raleigh, N.C., the Y-90 microspheres are delivered into the liver, where they reside permanently in the tumors, and the radiation is designed to penetrate only about one-quarter of an inch into the tissue. So, as the tumor is being destroyed, the nearby normal liver tissue is not being affected. The outpatient procedure takes about one hour.

Currently, more than 5 million Americans have Alzheimer’s disease. Symptoms vary considerably, but usually begin with a tendency to forget, which becomes so severe that it affects the patient’s social life, family life, work, and recreational hobbies. Alzheimer’s is the most common form of dementia and is the result of brain aging.

The two major methods of diagnosing Alzheimer’s disease both use medical isotopes: Single Photon Emission Tomography (SPECT) and Positron Emission Tomography (PET).

With SPECT, a small amount of gamma-ray-emitting isotope (for example, technetium-99m or thallium-201) is bound to neuro-specific pharmaceuticals and then injected into a patient’s vein, from where it is taken into the brain tissue. The isotope fixes itself onto the brain with proportional flow, emitting a gamma ray which is picked up and detected by a SPECT gamma camera.

PET is a way of getting three-dimensional images or maps of functional processes of the body (see box). For Alzheimer’s disease, PET scan images use the isotopes carbon-11 or fluorine-18, to compare normal brain activity to reduced brain activity. A PET scan can show the brain’s biological changes attributable to Alzheimer’s disease earlier than any other diagnostic test can provide this information. Alzheimer’s disease can even be detected several years earlier than the onset of symptoms.4

The application of PET for Alzheimer’s disease is rapidly spreading in use at medical clinics and hospitals all over the world. There were 25 papers on this presented at the 2006 Society of Nuclear Medicine meeting in San Diego.

Twenty-five years from the start of the epidemic, HIV is still an incurable disease. It is clear that something completely different needs to be done to eradicate it, commented Dr. Ekaterina Dadachova of the Albert Einstein College of Medicine in New York City.5

Using radioactive antibodies, as is done in many successful cancer treatments, Dr. Dadachova and her colleagues have been doing research directed towards killing HIV-infected cells. This involves treating mice infected with HIV and has been reported in the online journal PLOS MED3.6

Dadachova’s team linked radioactive bismuth-213 and rhenium-188 to antibodies designed to stick to two HIV proteins (gp4) and (gp20), displaced on the surface of the infected cells. The initial results reported showed significant killing of HIV cells in the mice, providing support to the concept that radioimmunotherapy could work against HIV/AIDS.


Major medical advances in the 21st Century should occur through the application of medical isotopes. This paper presented several examples of the diagnostic and therapeutic applications of essentially current results and indicate promise for future significant developments.

For more information on the medical isotope/disease connection for the examples presented here and several other examples, please contact the author at 2521 SW Luradel St., Portland, Ore., U.S.A. 97219, or via e-mail:


Courtesy of Dr. Robert Schenter
Robert Schenter

Dr. Robert E. Schenter is one of the leading U.S. experts on fission reactor production of isotopes. Based on his 39 years as an expert on neutron cross-section and decay data information, he has become a world authority on isotope production. Now the chief science officer of the Advanced Medical Isotope Corporation, Schenter previously worked as the site director and deputy site director in the Isotope Program Office at the Westinghouse Hanford Company (WHC) and the Pacific Northwest National Laboratory (PNNL). In 1991, he was responsible for the relief of a world shortage of gadolinium-153, which is used in instruments for early detection of osteoporosis. He also defined the project and directed the production in the Fast Flux Test Facility (FFTF) in Richland, Washington.

Related Pages

Landbridge Conference in Kiedrich, Germany, 2007

Completing the Nuclear Fuel Cycle

PBMR: Clean, Safe, And Affordable Energy


1. R.E. Schenter, “Major PET Isotopes and Their Applications,” AMIC Report-1002, Sept. 1, 2007.

2. “Brachytherapy Saves Breast, Decreases Treatment Time,” AAGL 2007, online, Aug. 10, 2004.

3. “New Therapy Offers Hope to Cancer Patients,”, Nov. 7, 2006.

4. “Delivering the Power of Molecular Imaging, Alzheimer’s, PET Scan,” Arizona, July 30, 2007.

5. “Radioactive Antibody Missiles Home In on HIV,” Scientific American News, Nov. 6, 2006.

6. E. Dadachova et al., “Targeted Killing of Virally Infected Cells by Radiolabeled Antibodies to Viral
     Proteins,” PLOS Med3, No. 11, 2006.

back to article

Major PET Isotopes and Their Applications
Isotope Half-Life
Diagnostic Application
Bromine-76 16.0h Anti-Carcinoembryonic
Antigens, Anti-CEA Antibodies, DNA Studies, Nerves of the
Heart, Quantitative Imaging
Carbon-11 20.3m Cancers: Chest, Chronic
Lymphocytic, Glioblastoma, Liver, Multiple Myeloma,
Prostate, Urinary Tract

Diseases: Alzheimer's, Brain, Epilepsy, Heart, Parkinson’s

Alcohol Addiction, Amphetamine Release, Drug Addiction, Neuropsychiatric, Nicotine Dependence, Pain Processing, Schizophrenia, Small Animal Imaging, Tobacco Addiction
Copper-62 9.74m Cerebral and Myocardial Perfusion, Colorectal Cancer, Human
Biodistribution, Liver Cancer, Renal Blood Flow, Renal Injury
Copper-64 12.70h Cancers: Cervical, Colon, Colorectal, Lymphoma, Melanoma, Pancreatic, Prostate

Diseases: Angiogeneses, Brain, Hypoxia, Parkinson’s, Wilson's

Stem Cell Research
Fluorine-18 1.83h Cancers: Adrenal Gland, Anal, Bone, Bone Marrow Transplants, Bowel, Breast, Cervical, Chest, Colorectal, Esophageal, Gastric, Head & Neck, Hodgkins Disease, Laryngeal, Leukemia, Liver, Lung (NSCLC), Lung(SCLC), Melanoma, Multiple Myeloma, non-Hodgkin's Lymphoma, Osseous, Ovarian, Pancreatic, Prostate, Rectal, Rhabdomjo Sarcoma, Squamous Cell, Thyroid, Urinary, Vocal Cord

Diseases: Alcohol Addiction, Alzheimer's, Anorexia, Atherscierosis, Brain, Depression, Diabetes, Heart, Herpes, HIV, Hypoxia, Infection, Liver, Muscle, Kennedy, Narcolepsy, Lung Inflammation, Osteomyelitin, Parkinson's, Pneumonia, Ulcerative Colitis, Schizophrenia, Tourettes Syndrome

Infection: Pen-Prosthetic, Hip-Prosthetic, Joint-Prosthetic

Small Animal Imaging, Chemotherapy Research
Gallium-68 1.13h Breast Cancer, Heart Imaging, Immunoscintigraphy, Molecular Imaging, Neuroendrocrine Tumors, Pancreatic Cancer
Iodine-124 4.18d poptosis, Cancer Biotherapy, Glioma, Heart Disease, Mediastinal Micrometastates, Scouting of Therapeutic Radioimmunoconjugates, Thyroid Cancer
Iron-52 8.28h Anemia, Human Bone Marrow
Nitrogen-13 9.97m Ammonia Dog Studies, Coronary Artery Disease, Diabetes, Gamma Camera, Heart Disease, Imaging of Heart, Pancreas and Liver, Lupus Erythematosus, Myocardial Perfusion, Pulmonary Ventilation
Oxygen-15 122.s Acute Brain Injury, Arterial Blood Flow, Brain Cancer, Oxygen Utilization, Brain Studies, Cerebral Blood Volume, Cerebral Responses, Coronary Artery Vasospasm, Coronary Reserve, Heart Disease, Ischemic Stroke Disease, Kinetics of Oxygen, Liver Cancer, Myocardial Viability, Oxygen Metabolism, Pain Control, Venous Ulceration
Rubidium-82 1.26m Heart Disease, Myocardial Perfusion, Sarcoidosis
Yttrium-86 14.74h Distribution of Y90, Lung Cancer, Melanoma, Renal Cell Carcinoma
Zirconium-89 3.27d Brain Tumors, Head and Neck Cancers, non-Hodgkin's Lymphoma

back to article