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What is Nuclear Medicine?Nuclear medicine specialists use safe, painless, andcost-effective techniques to image the body andtreat disease. Nuclear medicine imaging is unique,because it provides doctors with information aboutboth structure and function. It is a way to gathermedical information that would otherwise beunavailable, require surgery, or necessitate moreexpensive diagnostic tests. Nuclear medicine imag-ing procedures often identify abnormalities veryearly in the progress of a disease—long beforemany medical problems are apparent with otherdiagnostic tests.

Nuclear medicine uses very small amounts ofradioactive materials (radiopharmaceuticals) todiagnose and treat disease. In imaging, the radio-pharmaceuticals are detected by special types ofcameras that work with computers to provide veryprecise pictures about the area of the body beingimaged. In treatment, the radiopharmaceuticals godirectly to the organ being treated. The amount ofradiation in a typical nuclear imaging procedure iscomparable with that received during a diagnosticx-ray, and the amount received in a typical treat-ment procedure is kept within safe limits.

Today, nuclear medicine offers procedures that areessential in many medical specialties, from pedi-atrics to cardiology to psychiatry. New and innova-tive nuclear medicine treatments that target andpinpoint molecular levels within the body are revo-lutionizing our understanding of and approach to arange of diseases and conditions.

Nuclear medicine tests (also known as scans, examinations, or procedures) aresafe and painless. In a nuclear medicine test, small amounts of radiopharmaceu-ticals are introduced into the body by injection, swallowing, or inhalation.Radiopharmaceuticals are substances that are attracted to specific organs,bones, or tissues. The amount of radiopharmaceutical used is carefully selectedto provide the least amount of radiation exposure to the patient but ensure anaccurate test. A special camera (PET, SPECT or gamma camera) is then used totake pictures of your body. The camera detects the radiopharmaceutical in theorgan, bone or tissue and forms images that provide data and information aboutthe area in question. Nuclear medicine differs from an x-ray, ultrasound orother diagnostic test because it determines the presence of disease based onbiological changes rather than changes in anatomy.

What Happens During a Nuclear Medicine Procedure?

SafetyNuclear medicine procedures are among the safest diagnostic imaging examsavailable.To obtain diagnostic information, a patient is given a very smallamount of a radiopharmaceutical. Because such a small amount is used, theamount of radiation received from a nuclear medicine procedure is comparableto, or often times less than, that of a diagnostic x-ray.The nuclear medicineteam will carefully perform the most appropriate examination for the patient’sparticular medical problem and thereby avoid any unnecessary radiation expo-sure.

Although we don’t think much about it, everyone is continually exposed toradiation from natural and manmade sources. For most people, natural back-ground radiation from air and space, rocks, soil, and even atoms in your ownbody, accounts for 85 percent of the radiation you receive annually. Additionalexposure to radiation comes from consumer products such as household smokedetectors, color television sets, and luminous clock dials.The remaining radia-tion is from x-rays and radioactive materials used for medical diagnosis andtherapy. Most nuclear medicine procedures expose patients to about the sameamount of radiation as they receive in a few months of normal living.

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The History of Nuclear MedicineOne of the earliest instances ofnuclear medicine occurred in 1946when radioactive iodine, via an “atom-ic cocktail,” was first used to treatthyroid cancer.The thyroid gland tookup the radioactive iodine and the radi-ation eradicated the cancer cells, cur-ing the patient.Widespread clinicaluse of nuclear medicine began in theearly 1950s.

In addition to curing thyroid cancer,radioactive iodine, in much smallerdoses, was used to measure the func-tion of the thyroid and to diagnosethyroid disease. Physicians began touse “nuclear medicine” for the treat-ment of hyperthyroidism, a conditionwhere the thyroid over-produces thy-roid hormones.

As more knowledge was gained aboutbasic biochemical processes, usingradioactive versions of certain ele-ments to “trace” these metabolicprocesses led to dramatic break-throughs in diagnostic medicine.(Unlike a diagnostic X-ray whereradiation is passed through the body,nuclear medicine tracers are takeninternally; external detectors measurethe radiation that they emit.Theamount of radiation that a patient isexposed to is about the same.)

In the 1960s and the years that fol-lowed, the growth of nuclear medi-cine as a specialty discipline was phe-nomenal. Initially, techniques were

developed to measure blood flow tothe lungs and to identify cancer “hotspots.”

By the 1970s most organs of the bodycould be visualized with nuclear med-icine procedures, including liver andspleen scanning, brain tumor localiza-tion, and studies of the gastrointesti-nal tract. In 1971 the AmericanMedical Association officially recog-nized nuclear medicine as a medicalspecialty.

In the 1980s, radiopharmaceuticalswere designed for such critical diag-noses as heart disease and cancer. Alsoin the 1980s compounds were devel-oped, including monoclonal antibod-ies and FDG, that carried radioactiveelements directly and specifically tocancer cells. At small doses, theseradiopharmaceuticals can be used toidentify the existence and location ofcancer cells long before they are visi-ble using traditional imaging methods.At higher doses, radiolabeled mono-clonal antibodies are used today todeliver a therapeutic dose of radiationdirectly to cancer cells.

In 1989 the FDA approved the firstpositron radiopharmaceutical(Rubidium-82) for myocardial perfu-sion imaging. Special cameras candetect photons, not normally emittedby the body but produced in theblood stream by certain radiopharma-ceuticals, and compute a map of the

way that blood is being distributed toheart tissue.

By the 1990s, PET (Positron EmissionTomography) was becoming animportant diagnostic tool. PET alsouses photos produced by positrons,but PET provides more detailedimages.The history of PET has beenone of continuous improvement inthe resolution and sensitivity of theimaging devices. Despite advances inother imaging methods such as CTand MRI, the ability to image themetabolic abnormalities associatedwith disease has made PET one of themost significant diagnostic tools everdeveloped.

The next generation in PET technolo-gy, PET/CT fusion imaging, has theability to combine CT structuralinformation with PET’s metabolicinformation into a single set ofimages.This ability to detect the exactlocation of a metabolic “hot spot” byoverlaying the PET and CT imagesprovides priceless information forphysicians in the treatment of cancerand other metabolic diseases.

In the years to come, as more islearned about the fundamentalprocesses of diseases and as newradiopharmaceuticals and analysis

tools are developed, PET and PET/CT scanning will prove to be an inval-uable tool in the diagnosis and treat-ment of some of the most critical dis-eases challenging modern medicine.

Top:The first scanner was introduced by Benedict Cassen in 1951.Middle:The Image Display and Analysis minicomputer system in 1968.Bottom: Nuclear Medicine team evaluates patient scan.

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PhysiciansPhysicians certified by the American Board of Nuclear Medicinemust first receive a medical degree and have one or more yearsof training in a medical specialty other than nuclear medicine. A

further two years of training in nuclear medicine is then required during whichspecial instruction is given in physics, radiopharmacy and radiation biology, aswell as patient evaluation, radionuclide therapy and diagnostic studies. Cost-effective approaches to patient care are emphasized.

TechnologistsApproximately 100 accredited Nuclear Medicine Technologyprograms currently offer instruction and clinical internships.Thegeneral prerequisites depend on the type of program offered,

but usually include a science and mathematics background along with an inter-est in working with patients.

The programs currently available are:• A one-year certificate program• A two-year associates program• A four-year bachelors programThe student must then pass a certification to be designated as a CertifiedNuclear Medicine Technologist (CNMT).

ScientistsLeading universities and teaching hospitals provide specializedtraining to (1) physicists, who ensure the reliability and qualityof the instruments used in the performance of tests; (2) pharma-

cists, who specialize in providing reliable and safe radiopharmaceuticals forpatient exams; and (3) radiochemists, who develop and improve radiopharma-ceuticals.

High Degree of TrainingNuclear medicine is practiced only by licensed physicians who are assisted bycertified technologists and supported by specially trained physicists and phar-macists. Nuclear medicine combines chemistry, physics, mathematics, computertechnology, and medicine in using radioactivity to diagnose and treat disease.

Neurologic Applications: Stroke Alzheimer’s Disease Demonstrate Changes in AIDS Dementia Evaluate Patients for Carotid Surgery Localize Seizure Foci Evaluate Post Concussion Syndrome Diagnose Multi-Infarct Dementia

Oncologic Applications: Tumor Localization Tumor Staging Identify Metastatic Sites Judge Response to Therapy Relieve Bone Pain Caused by Cancer

Orthopedic Applications: Identify Occult Bone Trauma (Sports

Injuries) Diagnose Osteomyelitis Evaluate Arthritic Changes and Extent Localize Sites for Tumor BiopsyMeasure Extent of Certain Tumors Identify Bone Infarcts in Sickle Cell Disease

Renal Applications: Detect Urinary Tract Obstruction Diagnose Renovascular Hypertension Measure Differential Renal Function Detect Renal Transplant Rejection Detect Pyelonephritis Detect Renal Scars

Cardiac Applications: Coronary Artery Disease Measure Effectiveness of Bypass Surgery Measure Effectiveness of Therapy for Heart

Failure Detect Heart Transplant Rejection Select Patients for Bypass or Angioplasty Identify Surgical Patients at High Risk for

Heart AttacksIdentify Right Heart Failure Measure Chemotherapy Cardiac Toxicity Evaluate Valvular Heart Disease Identify Shunts and Quantify Them Diagnose and Localize Acute Heart Attacks

Before Enzyme Changes

Pulmonary Applications: Diagnose Pulmonary Emboli Detect Pulmonary Complications of AIDS Quantify Lung Ventilation and Perfusion Detect Lung Transplant Rejection Detect Inhalation Injury in Burn Patients

Other Applications: Diagnose and Treat Hyperthyroidism

(Graves’ Disease) Detect Acute Cholecystitis Chronic Biliary Tract DisfunctionDetect Acute Gastrointestinal Bleeding Detect Testicular Torsion Detect Occult Infections Diagnose and Treat Blood Cell Disorders

Nuclear Medicine: An Integral Part of Patient CareNuclear medicine studies can help diagnosisand treat many diseases. Some areas in whichnuclear medicine is used include:

Ask your physician or local nuclear medicine department formore details on specific nuclear medicine procedures.

« An estimated 16 million nuclear medi-cine imaging and therapeutic proceduresare performed each year in the UnitedStates. Of these, 40-50% are cardiacexams and 35-40% are cancer related.

« Nuclear medicine procedures are cost-effective.

« There are nearly 100 different nuclearmedicine imaging procedures availabletoday.

« Unlike other tests/procedures, etc.,nuclear medicine provides informationabout the function of virtually everymajor organ system within the body.

« Nuclear medicine procedures are amongthe safest diagnostic imaging tests avail-able.

« The amount of radiation in a nuclearmedicine procedure is comparable tothat received during a diagnostic x-ray.

« Children commonly undergo nuclearmedicine procedures to evaluate bonepain, injuries, infection, or kidney andbladder function.

« Nuclear medicine procedures are pain-less and do not require anesthesia.

« Common nuclear medicine applicationsinclude diagnosis and treatment ofhyperthyroidism (Graves’ Disease), car-diac stress tests to analyze heart func-tion, bone scans for orthopedic injuries,lung scans for blood clots, and liver andgall bladder procedures to diagnoseabnormal function or blockages.

« There are approximately 4,000 board-certified nuclear medicine physiciansand 15,700 certified nuclear medicinetechnologists worldwide.

« Nuclear medicine is an integral part ofpatient care and contributes to the wellbeing of patients worldwide.

Nuclear Medicine

Fast Facts

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Brochure images courtesy of Henry N. Wagner,Jr., M.D.; Siemens Medical Solutions, USA,Inc.; Philips Medical Systems; and Digirad.