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Transcript of NUCLEAR MEDICINE
Branch of medicine that deals with the use of radioactive substances for diagnosis, medical research & treatment
Nuclear medicine imaging documents particular organ function and structure.
In treatment, radioactive substances known as radiopharmaceuticals are used for diagnostic or therapeutic purposes.
Small amounts of radiopharmaceuticals are introduced into the body by injection, swallowing or inhalation.
Radiopharmaceuticals are then detected by a special camera to create 3-D images for physicians to analyze the function of the internal organs.
NUCLEAR MEDICINE PROCEDURES
Nuclear medicine procedures may be:
studies tests body function
procedures treat diseases using radiation
Radionuclide therapy is used in the treatment of both benign & malignant disease
: hypothyroidism & arthritis
: thyroid cancer & hepatocellular carcinoma
The amount of radiation in a typical procedure is comparable with that received during a diagnostic x-ray.
NUCLEAR MEDICINE PROCEDURES
Small amounts of radiopharmaceuticals are introduced into the bloodstream and are attracted to specific organs, bones, or tissues.
A special camera (PET, SPECT, or gamma camera) is then used to take pictures of the body
It detects the radiopharmaceutical in the organ and forms images that provide data and information about the area in question
Nuclear medicine differs from x-ray, ultrasound or other diagnostic testing because it determines the presence of disease based on biological changes rather than changes in anatomy
What is a radiopharmaceutical?
Radiopharmaceutical is a radioactive material administered to patients
It is composed of a radioisotope bond to an organic molecule
The organic molecule conveys the radioisotopes to specific organs, tissues, or cells.
Chemical molecule that determines behavior of the radiopharmaceutical of the body
Emits radiation that may be detected from outside the body by a gamma camera or detected in a sample of body fluid
Must deliver the minimum possible radiation dose to the patient while still obtaining the required diagnostic information
Delivers the maximum radiation dose to the diseased organ or tumor while minimizing the radiation dose to non-target tissues such as the bone marrow.
Ensures minimal irradiation of other parts in the patient’s body
1946 A patient with thyroid cancer treated with iodine-131 ("atomic cocktail")
The thyroid gland took up the radioactive iodine and the radiation eradicated the cancer cells.
1947 Benedict Cassen work with a directional probe lead to the development of the first imaging rectilinear scanner.
1948 Abbott Laboratories began distribution of radioisotopes
1951 FDA approved sodium iodide 1-131 for the use with thyroid patients
1958 Hal Anger invented the scintillation camera, an imaging device that made it possible to conduct dynamic studies.
Benedict Cassen’s rectilinear scanner and Hal Anger’s scintillation camera helped establish nuclear medicine as a fully developed medical imaging specialty
1971 That American Medical Association officially recognized nuclear medicine as a medical specialty.
What is a radiopharmaceutical?
types of radiopharmaceuticals
Hibida: liver, gall bladder
Cardio-SPECT: myocardium, parathyroid glands, tumors
Senti-Scint: sentinel lymph nodes, breast cancer, melanoma
Anti-grangulocyte: inflammations, marrow
Leuro-scint: leukocytes labeled 99mTc- HM-PAO, inflammations
Small amounts of radiopharmaceuticals are introduced into the body
Inhaled as a gas
Ingested as a liquid or as a meal
Requirements depend on particular study
Hal Anger developed the first scintillation camera in 1958
Anger's principles are still used in today's gamma camera
First commercial Anger camera developed in 1962
initial camera used to image a patient's thyroid
how does it work?
if gamma ray is absorbed, the scintillation detector converts the energy of the photon into a flash
The flash of light is converted into an electrical pulse
Depending on the energy absorbed or how the operator sets up the detector, the photon is either counted or rejected.
Single-Photon Emission Computerized Tomography (SPECT)
Utilizes radioactive substances to create three-dimensional images
Allows doctors to analyze the function of internal organs
Unlike X-rays – which show the anatomy of organs, SPECT shows the function of the organs.
i.e. can show how blood flows to the heart or what areas of the brain are more active or less active
Administered intravenously, orally or inhaled
Accumulates in the organs or area of interest and gives out small amount of energy in the form of gamma rays
Combination of SPECT & CT
SPECT image acquisition and reconstruction
A series of gamma camera images are acquired as the camera rotates around the patient
Typically 60 to 120 images will be obtained in 20-30 minutes
Image reconstruction is usually performed using a technique known as “Filtered Back-projection” to produce a series of trans-axial slices
Coronal and/or sagittal slices can be computed from the trans-axial slices
nuclear medicine images
Stroke, Alzheimer’s Disease, Local seizure foci
Identify Metastatic Sites
Detect Urinary Tract Obstruction
Diagnose Renal vascular Hypertension
Diagnose and Treat Hyperthyroidism
Detect Acute Cholecystitis
Detect Testicular Torsion
It must emit photons with a high abundance of energy which can be efficiently detected by the gamma camera
It should not emit charged particles as these are absorbed within a few millimeters of tissue. These can not be detected outside of the body and greatly increase the radiation dose to the patient
It should have a short half-life, to keep the radiation dose as low as possible
radionuclide criteria for diagnostic imaging
examples of radioactive substances
Some examples of radioactive substances include:
Thyroid uptake, imaging, metastases
SPECT imaging of Parkinson's Disease (I123-FP-CIT)
Spleen imaging (Tc99m-Denatured red blood cells)
Lung ventilation studies (inhalation)
Cerebral Blood Flow (IV)
Nuclear medicine is among the safest diagnostic imaging exams available
Because such a small amount is used, the amount of radiation received is comparable to, or often less than, that of a diagnostic x-ray
The nuclear medicine team carefully performs the most appropriate examination for the patient’s particular medical problem and thereby avoid any unnecessary radiation exposure
Wear pathology gown, disposable gloves. Minimize time spent with patient and maximize distance
Most administered radioactive isotopes are excreted as urine
Patient has radioactive substances on their skin and should take extra precaution around other people
If an accident occurs, contamination is radioactive until proven otherwise
nuclear medicine vs sonography
Can take from several hours to days for the radiotracer to accumulate in the body part of interest
Imaging may take up to several hours to perform, though in some cases, newer equipment is available that can substantially shorten the procedure time
Resolution of structures of the body may not be as high as with other imaging techniques, such as CT or MRI
However, more sensitive than other techniques for a variety of indications, and the functional information gained from nuclear medicine exams is often unobtainable by other imaging techniques
An estimated 16 million nuclear medicine imaging procedures are performed each year in the United States
Of these, 40-50% are cardiac exams and 35-40% are cancer related
Nuclear medicine procedures are cost effective
Nearly 100 different nuclear medicine imaging procedures are available today
Unlike other test/procedures, nuclear medicine provides information about the function of virtually every major organ within the body
Children commonly undergo nuclear medicine procedures to evaluate bone pain, injuries, infection or kidney and bladder function
There are approximately 4,000 board-certified nuclear medicine physicians and 15,700 certified nuclear medicine technologists worldwide.
overview of nuclear medicine
ultrasound vs nuclear medicine for gallbladder pathology
ultrasound of the gallbladder
First imaging done
ultrasound can detect:
gallstones in GB
thickened GB wall
Prep and procedure
Fasting for 6 hours before exam, last 15 minutes, not painful, real-time
No know harmful effects
HIDA scan (cholescintigraphy)
May be done when GB disorder is suspected but no gallstones on ultrasound
Prep and procedure
4 hrs fasting, HIDA (HydroxyIminoDiaetic Acid) will be injected into a vein in the arm.
HIDA is excreted by liver into bile and can be traced and recorded by radiodetective camera
Then a hormone cholecystokinin (CCK), which causes GB contraction will be injected into vein and another set of images will be made from this.
Scans may reveal:
Stones in the GB
Obstruction in cystic duct and CBD
Bile leakage (if there is a perforation in the GB or bile ducts)
side effects are rare, allergy to HIDA, pain during CCK, chills, nausea, and rash
types of radiopharmaceuticals
Single-Photon Emission Computerize Tomography
hepatobiliary scan video
1. What is nuclear medicine?
2. what is detected by a special camera to create 3D images for physicians to analyze function of organs?
3. List the 2 types of nuclear medicine procedures.
4. who developed the 1st rectilinear scanner & scintillation camera that helped establish nuclear medicine as a fully developed medical imaging specialty?
5. What camera utilizes radioactive substance and a special camera to create 3D images?
6. What type of radiopharmaceutical must deliver the maximum radiation dose to the diseased organ/tumor while minimizing the radiation dose to non-target tissues?
7. How are radiopharmaceuticals introduced into the body?
8. What does the radioactive substance do when accumulated in the organ or area of interest?
9. T/F It only takes a few minutes for the radiotracer to accumulate in the area of interest.
10. T/F Nuclear medicine provides information about the function of every major organ within the body.