Nuclear Medicine Physician
Encyclopedia
Nuclear Medicine Physicians are medical specialists that use tracers, usually radiopharmaceuticals, for diagnosis and therapy. Nuclear medicine
procedures are the major clinical applications of molecular imaging
and molecular therapy. In the United States, nuclear medicine physicians are certified by the American Board of Nuclear Medicine
.
discovered radioactivity. It was only a little over a quarter of a century (1925) until the first radioactive tracer study in animals was performed by George de Hevesy
, and the next year (1926) the first diagnostic tracer study in humans was performed by Herman Blumgart and Otto Yens.
Some of the earliest applications of radioisotopes were therapy of hematologic malignancies and therapy of both benign and malignant thyroid disease. In the 1950s radioimmunoassay
was developed by Solomon Berson
and Rosalyn Yalow. Dr. Yalow was co-winner of the 1997 Nobel Prize in Physiology or Medicine (Dr. Berson had already died so was not eligible). Radioimmunoassay was used extensively in clinical medicine but more recently has been largely replaced by non-radioactive methods.
In 1950, human imaging of both gamma
and positron
emitting radioisotopes was performed. Benedict Cassen's work with a directional probe lead to the development of the first imaging with a rectilinear scanner
. Gordon Brownell developed the first positron scanner
. In the same decade (1954) the Society of Nuclear Medicine
(SNM) was organized, and (1958) Hal Anger
developed the gamma scintillation camera
, which could image a whole region at the same time.
Initial introduction of radioisotopes into medicine required individuals to acquire of a considerable background information which was foreign to their medical training. Often a particular application drove the introduction of radioisotopes into a health care facility. As other applications developed the physician or group that had developed knowledge of and experience with radioisotopes usually provided the new service. Consequently, the radioisotope service found homes in several established specialties – commonly in radiology due to an interest in imaging, in pathology (clinical pathology
) due to an interest in radioimmunoassay, and in endocrinology due to the early application of 131I to thyroid disease.
Nuclear medicine became widespread and there was a need to develop a new specialty. In the United States, the American Board of Nuclear Medicine
was formed in 1972. At that time, the specialty include all of the uses of radioisotopes in medicine – radioimmunoassay, diagnostic imaging, and therapy. As use of and experience with radioisotopes became more widespread in medicine, radioimmunoassay generally transferred from nuclear medicine to clinical pathology. Today, nuclear medicine is based on the use of the tracer principle
applied to diagnostic imaging and therapy.
(ACGME) accredits nuclear medicine residency programs, and the American Board of Nuclear Medicine
(ABNM) certifies nuclear medicine physicians. After completing medical school
, a post-graduate clinical year is followed by three years of nuclear medicine residency
. A common alternate path for physicians who have completed a radiology residency is a one year residency in nuclear medicine. A less common path for physicians who have completed another residency is a two year residency in nuclear medicine.
, health physicists
, radiobiologists
, radiochemists
, and radiopharmacists
.
Nuclear medicine physicians have the most extensive training, including all aspects of diagnosis and radionuclide therapy. However, other physicians may interpret nuclear medicine studies and perform radionuclide therapy. Radiologists often limit their practice to diagnostic imaging in nuclear medicine. Some cardiologists, especially non-invasive cardiologists, interpret diagnostic cardiology studies including nuclear medicine studies. Radiation oncologists perform all forms of radiation therapy including radionuclide therapy. Some endocrinologists treat hyperthyroidism and thyroid cancer with 131I. The mix of physicians rendering nuclear medicine services varies both between different countries and within a single country.
Nuclear medicine
In nuclear medicine procedures, elemental 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...
procedures are the major clinical applications of molecular imaging
Molecular imaging
Molecular imaging originated from the field of radiopharmacology due to the need to better understand the fundamental molecular pathways inside organisms in a noninvasive manner.- Overview :...
and molecular therapy. In the United States, nuclear medicine physicians are certified by the American Board of Nuclear Medicine
American Board of Nuclear Medicine
The American Board of Nuclear Medicine certifies physicians as specialists in the practice of nuclear medicine. Diplomates of the ABNM are called nuclear medicine physicians...
.
History
In 1896, Henri BecquerelHenri Becquerel
Antoine Henri Becquerel was a French physicist, Nobel laureate, and the discoverer of radioactivity along with Marie Curie and Pierre Curie, for which all three won the 1903 Nobel Prize in Physics.-Early life:...
discovered radioactivity. It was only a little over a quarter of a century (1925) until the first radioactive tracer study in animals was performed by George de Hevesy
George de Hevesy
George Charles de Hevesy, Georg Karl von Hevesy, was a Hungarian radiochemist and Nobel laureate, recognized in 1943 for his key role in the development of radioactive tracers to study chemical processes such as in the metabolism of animals.- Early years :Hevesy György was born in Budapest,...
, and the next year (1926) the first diagnostic tracer study in humans was performed by Herman Blumgart and Otto Yens.
Some of the earliest applications of radioisotopes were therapy of hematologic malignancies and therapy of both benign and malignant thyroid disease. In the 1950s radioimmunoassay
Radioimmunoassay
Radioimmunoassay is a very sensitive in vitro assay technique used to measure concentrations of antigens by use of antibodies...
was developed by Solomon Berson
Solomon Berson
Solomon Aaron Berson was an American physician and scientist whose discoveries, mostly together with Rosalyn Yalow, caused major advances in clinical biochemistry....
and Rosalyn Yalow. Dr. Yalow was co-winner of the 1997 Nobel Prize in Physiology or Medicine (Dr. Berson had already died so was not eligible). Radioimmunoassay was used extensively in clinical medicine but more recently has been largely replaced by non-radioactive methods.
In 1950, human imaging of both gamma
Gamma ray
Gamma radiation, also known as gamma rays or hyphenated as gamma-rays and denoted as γ, is electromagnetic radiation of high frequency . Gamma rays are usually naturally produced on Earth by decay of high energy states in atomic nuclei...
and positron
Positron
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has an electric charge of +1e, a spin of ½, and has the same mass as an electron...
emitting radioisotopes was performed. Benedict Cassen's work with a directional probe lead to the development of the first imaging with a rectilinear scanner
Rectilinear scanner
A rectilinear scanner is an imaging device once used in nuclear medicine.-History:Before the invention of the rectilinear scanner in 1950 by Benedict Cassen, nuclear medicine pioneers used to move their insensitive Geiger Counters over different parts of the body, which resulted in a fairly crude...
. Gordon Brownell developed the first positron scanner
Positron emission tomography
Positron emission tomography is nuclear medicine imaging technique that produces a three-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide , which is introduced into the body on a...
. In the same decade (1954) the Society of Nuclear Medicine
Society of Nuclear Medicine
The Society of Nuclear Medicine, or SNM, based in Reston, Virginia, is a nonprofit organization founded in 1954. There are 17,000 members: physicians, pharmacists, physicists and scientists, except for a separate section of 10,000 technologists...
(SNM) was organized, and (1958) Hal Anger
Hal Anger
Hal Oscar Anger was an American electrical engineer and biophysicist at Donner Laboratory, University of California, Berkeley, known for his invention of the Anger camera....
developed the gamma scintillation camera
Gamma camera
A gamma camera, also called a scintillation camera or Anger camera, is a device used to image gamma radiation emitting radioisotopes, a technique known as scintigraphy...
, which could image a whole region at the same time.
Initial introduction of radioisotopes into medicine required individuals to acquire of a considerable background information which was foreign to their medical training. Often a particular application drove the introduction of radioisotopes into a health care facility. As other applications developed the physician or group that had developed knowledge of and experience with radioisotopes usually provided the new service. Consequently, the radioisotope service found homes in several established specialties – commonly in radiology due to an interest in imaging, in pathology (clinical pathology
Clinical pathology
Clinical pathology , Laboratory Medicine , Clinical analysis or Clinical/Medical Biology , is a medical specialty that is concerned with the diagnosis of disease based on the laboratory analysis of bodily fluids, such as...
) due to an interest in radioimmunoassay, and in endocrinology due to the early application of 131I to thyroid disease.
Nuclear medicine became widespread and there was a need to develop a new specialty. In the United States, the American Board of Nuclear Medicine
American Board of Nuclear Medicine
The American Board of Nuclear Medicine certifies physicians as specialists in the practice of nuclear medicine. Diplomates of the ABNM are called nuclear medicine physicians...
was formed in 1972. At that time, the specialty include all of the uses of radioisotopes in medicine – radioimmunoassay, diagnostic imaging, and therapy. As use of and experience with radioisotopes became more widespread in medicine, radioimmunoassay generally transferred from nuclear medicine to clinical pathology. Today, nuclear medicine is based on the use of the tracer principle
Multi-compartment model
A multi-compartment model is a type of mathematical model used for describing the way materials or energies are transmitted among the compartments of a system. Each compartment is assumed to be a homogenous entity within which the entities being modelled are equivalent...
applied to diagnostic imaging and therapy.
Procedures
- Examples of the most common clinical nuclear medicine procedures are
- glucose metabolic imaging with 18F-fluorodeoxyglucoseFluorodeoxyglucoseFludeoxyglucose or fluorodeoxyglucose , commonly abbreviated 18F-FDG or FDG, is a radiopharmaceutical used in the medical imaging modality positron emission tomography...
(FDG) for cancer, - myocardial perfusion imaging for coronary artery disease, and
- skeletal imaging for both benign and malignant bone disease.
- glucose metabolic imaging with 18F-fluorodeoxyglucose
- Examples of common procedures are
- brain perfusion and glucose metabolic imaging for seizureSeizureAn epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement or as mild as a brief loss of awareness...
and dementiaDementiaDementia is a serious loss of cognitive ability in a previously unimpaired person, beyond what might be expected from normal aging...
, - blood pool imaging for myocardial function and gastrointestinal bleedingGastrointestinal bleedingGastrointestinal bleeding or gastrointestinal hemorrhage describes every form of hemorrhage in the gastrointestinal tract, from the pharynx to the rectum. It has diverse causes, and a medical history, as well as physical examination, generally distinguishes between the main forms...
, - gastric emptying studies for gastroparesisGastroparesisGastroparesis, also called delayed gastric emptying, is a medical condition consisting of a paresis of the stomach, resulting in food remaining in the stomach for a longer period of time than normal. Normally, the stomach contracts to move food down into the small intestine for digestion. The...
, - hepatobiliary imaging for acute cholecystitisCholecystitis-Signs and symptoms:Cholecystitis usually presents as a pain in the right upper quadrant. This is known as biliary colic. This is initially intermittent, but later usually presents as a constant, severe pain. During the initial stages, the pain may be felt in an area totally separate from the site...
and gallbladder dysfunction, - lymphoscintigraphy for sentinel lymph nodeSentinel lymph nodeThe sentinel lymph node is the hypothetical first lymph node or group of nodes reached by metastasizing cancer cells from a primary tumor.-Physiology:...
biopsy, - parathyroid imaging for hyperparathyroidismHyperparathyroidismHyperparathyroidism is overactivity of the parathyroid glands resulting in excess production of parathyroid hormone . The parathyroid hormone regulates calcium and phosphate levels and helps to maintain these levels...
, - pulmonary perfusion and ventilation imaing for pulmonary embolismPulmonary embolismPulmonary embolism is a blockage of the main artery of the lung or one of its branches by a substance that has travelled from elsewhere in the body through the bloodstream . Usually this is due to embolism of a thrombus from the deep veins in the legs, a process termed venous thromboembolism...
, - renal function imaging for various renal disorders,
- thyroid imaging for hyperthyroidismHyperthyroidismHyperthyroidism is the term for overactive tissue within the thyroid gland causing an overproduction of thyroid hormones . Hyperthyroidism is thus a cause of thyrotoxicosis, the clinical condition of increased thyroid hormones in the blood. Hyperthyroidism and thyrotoxicosis are not synonymous...
, - thyroid whole body imaging for thyroid cancerThyroid cancerThyroid neoplasm is a neoplasm or tumor of the thyroid. It can be a benign tumor such as thyroid adenoma, or it can be a malignant neoplasm , such as papillary, follicular, medullary or anaplastic thyroid cancer. Most patients are 25 to 65 years of age when first diagnosed; women are more affected...
, - urinary tract imaging for vesicoureteral refluxVesicoureteral refluxVesicoureteral reflux is an abnormal movement of urine from the bladder into ureters or kidneys. Urine normally travels from the kidneys via the ureters to the bladder...
, and - white blood cell studies for infection.
- brain perfusion and glucose metabolic imaging for seizure
- Examples of uncommon but valuable procedures are
- octreotideOctreotideOctreotide is an octapeptide that mimics natural somatostatin pharmacologically, though it is a more potent inhibitor of growth hormone, glucagon, and insulin than the natural hormone...
(pentetreotide) imaging for somatostatinSomatostatinSomatostatin is a peptide hormone that regulates the endocrine system and affects neurotransmission and cell proliferation via interaction with G-protein-coupled somatostatin receptors and inhibition of the release of numerous secondary hormones.Somatostatin...
receptors found on the surface of many tumors, - meta-iodobenzylguanidineIobenguaneIobenguane, also known as metaiodobenzylguanidine or mIBG, or MIBG is a radiopharmaceutical, used in a scintigraphy method called MIBG scan...
(MIBG) imaging for neuroendocrine tumorsNeuroendocrine tumorsNeuroendocrine tumors are neoplasms that arise from cells of the endocrine and nervous systems. Many are benign, while some are cancers...
, - heat-damaged red blood cell imaging for identifying ectopic splenic tissue, and
- gastric mucosa imaging for Meckel's diverticulumMeckel's diverticulumA Meckel's diverticulum, a true congenital diverticulum, is a small bulge in the small intestine present at birth. It is a vestigial remnant of the omphalomesenteric duct , and is the most frequent malformation of the gastrointestinal tract...
(especially in pediatrics).
- octreotide
- Examples of radionuclide therapeutic procedures are
- 131I treatment of hyperthyroidismHyperthyroidismHyperthyroidism is the term for overactive tissue within the thyroid gland causing an overproduction of thyroid hormones . Hyperthyroidism is thus a cause of thyrotoxicosis, the clinical condition of increased thyroid hormones in the blood. Hyperthyroidism and thyrotoxicosis are not synonymous...
, - 131I treatment of thyroid cancerThyroid cancerThyroid neoplasm is a neoplasm or tumor of the thyroid. It can be a benign tumor such as thyroid adenoma, or it can be a malignant neoplasm , such as papillary, follicular, medullary or anaplastic thyroid cancer. Most patients are 25 to 65 years of age when first diagnosed; women are more affected...
, and - radioimmunotherapyRadioimmunotherapyRadioimmunotherapy uses an antibody labeled with a radionuclide to deliver cytotoxic radiation to a target cell. In cancer therapy, an antibody with specificity for a tumor-associated antigen is used to deliver a lethal dose of radiation to the tumor cells...
with 90Y ibritumomab tiuxetanIbritumomab tiuxetanIbritumomab tiuxetan, sold under the trade name Zevalin, is a monoclonal antibody radioimmunotherapy treatment for some forms of B cell non-Hodgkin's lymphoma, a lymphoproliferative disorder and thus affects the lymphatic system...
(Zevalin) & 131I tositumomabTositumomabTositumomab is a drug for the treatment of follicular lymphoma. It is a IgG2a anti-CD20 monoclonal antibody derived from immortalized mouse cells....
(Bexxar) therapy of low-grade non-Hodgkin's lymphoma.
- 131I treatment of hyperthyroidism
Instrumentation
- Planar imaging
- Most radionuclides give off gamma-rays when they decay. A 2-dimensional image of the radionuclide distribution can be made with a gamma cameraGamma cameraA gamma camera, also called a scintillation camera or Anger camera, is a device used to image gamma radiation emitting radioisotopes, a technique known as scintigraphy...
, often called an Anger scintillation camera after its inventor, Hal AngerHal AngerHal Oscar Anger was an American electrical engineer and biophysicist at Donner Laboratory, University of California, Berkeley, known for his invention of the Anger camera....
.- Single photon emission computed tomography (SPECT)
- Multiple planar images taken from different angles around a patient can be reconstructedTomographic reconstructionThe mathematical basis for tomographic imaging was laid down by Johann Radon. It is applied in computed tomography to obtain cross-sectional images of patients...
to form a stack of cross-sectional, tomographic images.- Positron emission tomographyPositron emission tomographyPositron emission tomography is nuclear medicine imaging technique that produces a three-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide , which is introduced into the body on a...
(PET)
- Positron emission tomography
- Some isotopes emit positronPositronThe positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has an electric charge of +1e, a spin of ½, and has the same mass as an electron...
s (the anti-matter equivalent of an electron) when they decay. The positrons travel a short distance in tissue and then annihilate with an electron giving off two nearly back-to-back gamma rays. Positron emission tomography takes advantage of these back-to-back gamma rays to localize the distribution of the radioisotopes.- Combined molecular and anatomic imaging: SPECT/CT, PET/CT, and PET/MRI
- The advantage of nuclear medicine is that it provides molecular and physiologic information, but it is relatively poor at providing anatomic information and the resolution is relatively poor. In recent years, instruments have been developed which allow both radioisotope and anatomic imaging. Most widespread are PET/CT scanners combining PET and computed tomography. Increasingly common are SPECT/CT scanners. Instruments combining PET with magnetic resonance, PET/MRI, are starting to be used.
- Non-imaging instrumentation
- Non-imaging instruments are used for measuring radioisotope dosesProportional counterA proportional counter is a measurement device to count particles of ionizing radiation and measure their energy.A proportional counter is a type of gaseous ionization detector. Its operation is similar to that of a Geiger-Müller counter, but uses a lower operating voltage. An inert gas is used to...
, for counting samples, and for radiation safetyGaseous ionization detectorsIn particle physics, gaseous ionization detectors are detectors designed to seek the presence of particles . If a particle has enough energy to ionize a gas atom or molecule, the resulting electrons and ions cause a current flow which can be measured in different ways...
.
Training
In the United States, the Accreditation Council for Graduate Medical EducationAccreditation Council for Graduate Medical Education
The Accreditation Council for Graduate Medical Education is the body responsible for the accreditation for graduate medical training programs for medical doctors in the United States. It is a non-profit private council that evaluates and accredits medical residency and internship programs...
(ACGME) accredits nuclear medicine residency programs, and the American Board of Nuclear Medicine
American Board of Nuclear Medicine
The American Board of Nuclear Medicine certifies physicians as specialists in the practice of nuclear medicine. Diplomates of the ABNM are called nuclear medicine physicians...
(ABNM) certifies nuclear medicine physicians. After completing medical school
Medical school
A medical school is a tertiary educational institution—or part of such an institution—that teaches medicine. Degree programs offered at medical schools often include Doctor of Osteopathic Medicine, Bachelor/Doctor of Medicine, Doctor of Philosophy, master's degree, or other post-secondary...
, a post-graduate clinical year is followed by three years of nuclear medicine residency
Residency (medicine)
Residency is a stage of graduate medical training. A resident physician or resident is a person who has received a medical degree , Podiatric degree , Dental Degree and who practices...
. A common alternate path for physicians who have completed a radiology residency is a one year residency in nuclear medicine. A less common path for physicians who have completed another residency is a two year residency in nuclear medicine.
Other professionals
Nuclear medicine procedures are performed by nuclear medicine technologists, who require extensive training both in underlying principles (physics, instrumentation) but also in the clinical applications. Nursing support, especially in the hospital setting, is valuable, but may be shared with other services. Nuclear medicine is a technology embedded specialty depending upon a large number of non-physician professional, including medical physicistsMedical physics
Medical physics is the application of physics to medicine. It generally concerns physics as applied to medical imaging and radiotherapy, although a medical physicist may also work in many other areas of healthcare...
, health physicists
Health physics
Health physics is a field of science concerned with radiation physics and radiation biology with the goal of providing technical information and proper techniques regarding the safe use of ionizing radiation...
, radiobiologists
Radiobiology
Radiobiology , as a field of clinical and basic medical sciences, originated from Leopold Freund's 1896 demonstration of the therapeutic treatment of a hairy mole using a new type of electromagnetic radiation called x-rays, which was discovered 1 year previously by the German physicist, Wilhelm...
, radiochemists
Radiochemistry
Radiochemistry is the chemistry of radioactive materials, where radioactive isotopes of elements are used to study the properties and chemical reactions of non-radioactive isotopes...
, and radiopharmacists
Radiopharmacology
Radiopharmacology is the study and preparation of radiopharmaceuticals, which are radioactive pharmaceuticals. Radiopharmaceuticals are used in the field of nuclear medicine as tracers in the diagnosis and treatment of many diseases. Many radiopharmaceuticals use technetium-99m which has many...
.
Nuclear medicine physicians have the most extensive training, including all aspects of diagnosis and radionuclide therapy. However, other physicians may interpret nuclear medicine studies and perform radionuclide therapy. Radiologists often limit their practice to diagnostic imaging in nuclear medicine. Some cardiologists, especially non-invasive cardiologists, interpret diagnostic cardiology studies including nuclear medicine studies. Radiation oncologists perform all forms of radiation therapy including radionuclide therapy. Some endocrinologists treat hyperthyroidism and thyroid cancer with 131I. The mix of physicians rendering nuclear medicine services varies both between different countries and within a single country.