Nuclear Medicine

nu·cle·ar med·i·cine


Nuclear medicine is a branch of medical imaging that uses very small amounts of radioactive materials to diagnose and treat disease. Nuclear imaging is different than standard medical imaging techniques in that it assesses the physiological processes instead of the anatomic. This function-based approach has made tremendous advancements in the understanding of many organs.

In a standard procedure, radiopharmaceuticals are given to the patient intravenously, orally, or by inhalation. The radiopharmaceuticals are interpreted by the body as any other element would be.

For example, a diagnostic procedure to evaluate the thyroid gland utilizes a modified version of iodine. The radioactive iodine localizes in the thyroid and is able to be analyzed. These cameras, with the assistance of modern computers, are capable of forming an image that doctors can use to see the inner-workings of a particular organ or segment of the body.


There are many different tools at the disposal of doctors in the use of nuclear medicine. There are several types of scans that have been developed over the last 60 years. Most known is the PET (Positron emission tomography) scan. The modern version of PET is often used in conjunction with a CT (Computed Tomography) scan to create a co-registered image that shows the biochemical activity and the anatomic status of the body. These images can be rendered in 2D or 3D depending on the software and hardware implemented.

If a true 3D image is required, SPECT (Single Photon Emission Computed Tomography) imaging may be necessary. Again, often used in conjunction with a CT scan, SPECT is able to offer accurate localized function of internal organs. This often used for brain scans to diagnose stroke, tumors, or aneurisms.


The history of nuclear medicine is rich with contributions from gifted scientists across different disciplines in physics, chemistry, engineering, and medicine.

The multidisciplinary nature of Nuclear Medicine makes it difficult for medical historians to determine the birthdate of Nuclear Medicine. This can probably be best placed between the discovery of artificial radioactivity in 1934 and the production of radionuclides by Oak Ridge National Laboratory for medicine related use, in 1946. Many historians consider the discovery of artificially produced radioisotopes by Frédéric Joliot-Curie and Irène Joliot-Curie in 1934 as the most significant milestone in Nuclear Medicine.

Widespread clinical use of Nuclear Medicine began in the early 1950s, as knowledge expanded about radionuclides, detection of radioactivity, and using certain radionuclides to trace biochemical processes.

By the 1970s most organs of the body could be visualized using Nuclear Medicine procedures. In 1971, American Medical Association officially recognized nuclear medicine as a medical specialty. In 1972, the American Board of Nuclear Medicine was established, cementing Nuclear Medicine as a medical specialty.


The job discription of a Phyisican in Nuclear Medicine include:
  • Uses of radioactive material to diagose and treat disease
  • Monitor quality control of nadionuclide preparation, administration, and disposition, and ensure that all activities comply with the standards of the Nuclear Regulatory Commission
  • Instruct and directs nuclear medicine technologists regarding desired dosages, techniques, positions, and projections
The median annual wage of Physician in Nuclear Medicine is $277,710

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Images & Video

A complete body PET / CT Fusion image
Standard PET/CT Scanner

Use in Diagnosis
Nuclear medicine, or radionuclide, diagnostic imaging procedures are noninvasive and, with the exception of intravenous injections, are usually painless medical tests that help physicians diagnose and evaluate medical conditions. These imaging scans use radioactive materials called radiopharmaceuticals or radiotracers. Depending on the type of nuclear medicine exam, the radiotracer is either injected into the body, swallowed or inhaled as a gas and eventually accumulates in the organ or area of the body being examined. Radioactive emissions from the radiotracer are detected by a special camera or imaging device that produces pictures and detailed molecular information. In many centers, nuclear medicine images can be superimposed with computed tomography (CT) or magnetic resonance imaging (MRI) to produce special views, a practice known as image fusion or co-registration. These views allow the information from two different exams to be correlated and interpreted on one image, leading to more precise information and accurate diagnoses. In addition, manufacturers are now making single photon emission computed tomography/computed tomography (SPECT/CT) and positron emission tomography/computed tomography (PET/CT) units that are able to perform both imaging exams at the same time. An emerging imaging technology, but not readily available at this time is PET/MRI.


How & what can Nuclear Medicine be used for?
  • Stage cancer by determining the presence or spread of cancer in various parts of the body
  • Localize sentinel lymph nodes before surgery in patients with breast cancer or melanoma
  • Plan treatment
  • Evaluate response to therapy
  • Detect the recurrence of cancer
  • Detect rare tumors of the pancreas and adrenal glands
  • Analyze native and transplant kidney function
  • Detect urinary tract obstruction
  • Evaluate for hypertension related to the kidney arteries
  • Evaluate kidneys for infection versus scar
  • Evaluate and follow-up urinary reflux in pediatric patients
  • Visualize heart blood flow and function (such as a myocardial perfusion scan)
  • Detect coronary artery disease and the extent of coronary stenosis
  • Assess damage to the heart following a heart attack
  • Evaluate treatment options such as bypass heart surgery and angioplasty
  • Evaluate the results of revascularization procedures
  • Detect heart transplant rejection
  • Evaluate heart function before and after chemotherapy (MUGA)
  • Scan lungs for respiratory and blood flow problems
  • Assess differential lung function for lung reduction or transplant surgery
  • Detect lung transplant rejection
  • Evaluate bones for fractures, infection and arthritis
  • Evaluate for metastatic bone disease
  • Evaluate painful prosthetic joints
  • Evaluate bone tumors
  • Identify sites for biopsy
  • Investigate abnormalities in the brain, such as seizures, memory loss and abnormalities in blood flow
  • Detect the early onset of neurological disorders such as Alzheimer disease
  • Plan surgery and localize seizure foci
  • Evaluate post-concussion syndrome
Other Systems
  • Identify inflammation or abnormal function of the gallbladder
  • Identify bleeding into the bowel
  • Assess post operative complication of gallbladder surgery
  • Evaluate lymphedema
  • Evaluate fever of unknown origin
  • Locate the presence of infection
  • Measure thyroid function to detect an overactive or underactive thyroid
  • Help diagnose hyperthyroidism and blood cell disorders
  • Evaluate for hyperparathyroidism
  • Evaluate stomach emptying
  • Evaluate spinal fluid flow and potential spinal fluid leaks
In children, nuclear medicine is also used to:
  • Investigate abnormalities in the esophagus, kidneys and intestines
  • Evaluate the openness of tear ducts and shunts in the brain and heart
Nuclear medicine therapies include:
  • Radioactive iodine (I-131) therapy used to treat some causes of hyperthyroidism (overactive thyroid gland, for example, Graves' disease) and thyroid cancer
  • Radioactive antibodies used to treat certain forms of lymphoma (cancer of the lymphatic system)
  • Radioactive phosphorus (P-32) used to treat certain blood disorders
  • Radioactive materials used to treat painful tumor metastases to the bones
  • I-131 MIBG (radioactive iodine laced with metaiodobenzylguanidine) used to treat adrenal gland tumors in adults and nerve tissue tumors in children


How is the procedure performed?
Nuclear medicine imaging is usually performed on an outpatient basis, but is often performed on hospitalized patients as well.
You will be positioned on an examination table. If necessary, a nurse or technologist will insert an intravenous (IV) line into a vein in your hand or arm.
Depending on the type of nuclear medicine exam you are undergoing, the dose of radiotracer is then injected intravenously, swallowed or inhaled as a gas.
It can take anywhere from several seconds to several days for the radiotracer to travel through your body and accumulate in the organ or area being studied. As a result, imaging may be done immediately, a few hours later, or even several days after you have received the radioactive material.
When it is time for the imaging to begin, the camera or scanner will take a series of images. The camera may rotate around you or it may stay in one position and you will be asked to change positions in between images. While the camera is taking pictures, you will need to remain still for brief periods of time. In some cases, the camera may move very close to your body. This is necessary to obtain the best quality images. If you are claustrophobic, you should inform the technologist before your exam begins.
If a probe is used, this small hand-held device will be passed over the area of the body being studied to measure levels of radioactivity. Other nuclear medicine tests measure radioactivity levels in blood, urine or breath.
The length of time for nuclear medicine procedures varies greatly, depending on the type of exam. Actual scanning time for nuclear imaging exams can take from 20 minutes to several hours and may be conducted over several days.
Young children may require gentle wrapping or sedation to help them hold still. If your doctor feels sedation is needed for your child, you will receive specific instructions regarding when and if you can feed your child on the day of the exam. A physician or nurse specializing in the administration of sedation to children will be available during the exam to ensure your child's safety while under the effects of sedation.
When the examination is completed, you may be asked to wait until the technologist checks the images in case additional images are needed. Occasionally, more images are obtained for clarification or better visualization of certain areas or structures. The need for additional images does not necessarily mean there was a problem with the exam or that something abnormal was found, and should not be a cause of concern for you.
If you had an intravenous line inserted for the procedure, it will usually be removed unless you are scheduled for an additional procedure that same day that requires an intravenous line.
During radioactive iodine (I-131) therapy, which is most often an outpatient procedure, the radioactive iodine is swallowed, either in capsule or liquid form.
Radioimmunotherapy (RIT), also typically an outpatient procedure, is delivered through injection.