Test 3 Digitial Imaging Nuclear Medicine
Terms
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is a medical specialty that uses radioactive materials for diagnosis, therapy, and medical research.
- Nuclear Medicine
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Nuclear Medicine
Determine the cause of a medical problem based on ______ -
organ or tissue function (physiology)
- Tracer is introduced into the body by
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injection, inhalation, or swallowing
- used to transform emissions into images
- gamma or scintillation camera
- What is the purpose of the gamma scintillation camera
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Camera provides information about function and anatomy of the organ/tissue
Records information on a computer or film
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– the father of the modern theory of atoms and molecules. He measured the atomic weights and compared them to hydrogen.
- John Dalton
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discovered naturally occurring radioactive substances
- Henry Becquerel –
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Marie Curie – discovered two radioactive elements – ___ ____. She coined the term radiosensitivity and radioactivity.
- polonium and radium
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– Father of Nuclear Medicine. He developed the tracer principle. Coined the term radioindicator.
The first indicators where naturally occurring. With the advent of the cyclotron, man-made indicators became available. Earnst Lawrence invented the cy - 1923 – Georg de Hevesy
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External Radiation Detectors
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Thyroid -1st
Then liver, spleen, brain, and Kidneys
Now- microscopic function
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_____ is only required by certain states and mostly due to insurance reimbursement to clinics and institutions.
- Licensure and Certification
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_____ is provided by the state that the certified technologist practices.
- Licensure
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Radiation-
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Latin meaning “Radiiâ€
Refers to the spokes of a wheel leading out from a central point
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Radioactivity-
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Radiation of energy in the form of high speed alpha or beta particles (or waves- gamma rays) from the nucleus of an atom
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Atom-
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Basic components of nucleus containing various numbers of neutrons and protons; with electrons circling around the nucleus
Neutrons and protons have nearly 2000 times the mass of the electron
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Nuclide-
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An atomic species with a particle arrangement of protons and neutrons
- isotope
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Elements with the same number of protons but a different number of neutrons
Similarities and differences?
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Decay-
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At certain ratios atoms instability attempts to regain stability and releases energy
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Ground State-
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when decay allows atoms to return to stabile state
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Most radionuclides reach ____through various decay processes
- ground state
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Decay schemes are unique for each radionuclide and identify:
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the type of decay,
the energy associated with each process,
the probability of a particular decay process,
and
the rate of change into the ground state element ( known as the half life of the radionuclide).
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Half-Life (T ½ )
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is the time it takes for a quantity of a particular radionuclide to decay to one-half of its original activity.
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Nuclear Medicine get the Radionuclides that it uses?
Those used in Nuclear Medicine are produced in ______)
- reactors (Particle Accelerators
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How does Nuc Med get Radionuclides?
Naturally occurring ones have long half-lives, are limited in availability, and have too high of an ____for the patient.
- absorbed dose
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How does Nuc Med get radionuclides?
Produced in high speed reactions between -
target chemicals and high-speed charged particles.
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How does nuc med get radionuclides?
The number of protons of the target nuclei is changed when the nuclei is ______ -
bombarded by the high-speed charged particles.
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Most common nucleoide
- 99 Technitium
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99 techtium
Uses ____ as parent (66.7 hour half-life) and decays at 86% to a daughter product metastable Technetium
Because the two are chemically different they can be easily separated through ion-exchange
- molybdenum-99;
- Why is 99 Technitium the most ideal?
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short physical half-life at about 6 hours
High yielding (98.6%) 140keV
Low energy, gamma photon
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Because these are used as radiopharmaceuticals and administered to patients, they need to be:
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sterile and pyrogen free, and
Undergo quality control measures just as any other conventional drug.
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Radiopharmaceutical is made of two parts:
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Radionuclide
Pharmaceutical
- Pharmaceutical is chosen because of
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it’s participation in the physiologic process within the body.
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1st step
The Nuclear Medicine Technologist Administers and within the desired time frame -
localizes the targeted organ with gamma camera.
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Step 2
The camera or imaging device picks up the radiation that is being given off by the _____
- Radionuclide.
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Step 3
The resulting imaging shows the _____or ____ by the organ or part and the radiologist interprets these images for possible diagnosis of the patient.
- function or dysfunction
- Ideal imaging with radiopharmaceutical would be:
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Easy to produce and readily available
Low cost
Lowest possible radiation dose
Primary photon energy between 100 and 400 keV
Physical half-life greater than the time required to prepare the material for injection
Effective half-life longer than the examination time
Suitable chemical forms for rapid localization
Different uptake in the structure to the detected
than in the surrounding tissue
Low toxicity in the chemical form administered to the patient
Stability or near stability
- Radionuclides used in Nuclear Medicine come in
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liquid, gas, and solid forms
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High concentrations and activities necessitates the need for:
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special preparation area with vented hood
Protective lead and glass shielding for handling vials and syringes
Absorbent materials
Gloves
- Shielding and gloves effectively reduces dose to
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fingers and hands when administering to patients
- All nuclear Medicine technologists are required to wear appropriate radiation monitoring devices called
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dosimeters.
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gas filled detectors-
For radioactivity to be detected, it must 1st interact with -
matter and give off energy
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When this happens(interacting with matter and give off energy)- Then.....
The gas ionizes (becomes charged) creating a ___potential between two electrodes
The voltage potential is then used as a measure of the radioactivity present.
< - voltage
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One of the 2 gas-filled radiation detectors commonly used to detect and estimate the amount of radiation present
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Geiger Counter (Geiger-Muller Survey Meter)
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An ionization chamber used to measure the amount of radioactivity in a sample (syringe, vial, or test tube)
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Dose Calibrator
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Term- ____- to emit light photons
Becquerel discovered that ionizing radiation caused certain materials to glow
- Scintillate
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detector is a sensitive element used to detect ionizing radiation by observing the emission of light photons induced in a material
- Scintillation Detector-
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Scintillation Detectors
The flash of light can be changed into _____ (when a light-sensitive device is affixed to this material)
Electrical impulses amplified
Sorted and counted to determine the amount and nature of the radiation striking - small electrical impulses
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Used in the development of first-generation nuclear medicine (rectilinear scanner) built in 1950
- Scintillation Scanner
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detect gamma rays and are very complex imaging systems
- Modern Camera
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Still a type of Scintillation Camera
Uses Thallium-activated sodium iodide crystal
- Modern Day gamma camera
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To detect and transform _____ These light photons are amplified and their locations are electronically recorded to produce an image that is displayed as a hard copy or on computer output systems
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radioactive emissions into light photons
- Modern Day gamma camera
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Single or Multiple Crystals used today
Now has many components that work together to produce an image.
- Mobile gamma camera
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Typically have limitations
Smaller field of view
Less detector shielding
Therefore- types and quality of exams are restricted
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Located at the face of the detector (where radioactive photons first enter)
- collimator
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Used to separate gamma rays from scattered rays from entering scintillation material
- collimator
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term used to determine the fraction of photons that are actually transmitted through the collimator and strike the face of the camera crystal
- Sensitivity-
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term used to describe the capability of a system to produce an image in which the small details are observable.
- Resolution-
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Usually made of lead (high atomic number) to absorb scattered gamma rays
Differ depending on photon energy and desired level of sensitivity and resolution
- collimator
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Crystals commonly used are (added to increase light production)
- sodium iodide with trace quantities of thallium
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is most effective for stopping gamma rays emitted from radiopharmaceuticals
- Composition
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Thickness varies ¼ to ½ inch
Thicker is better -
for higher energies, but have decreased resolution
- Thinner is better for
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resolution but cannot image photons with higher keV’s.
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used to attach the crystals to photomultiplier tubes (PMT)
- Light Pipe-
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A disk of optically transparent material that helps direct photons from the crystal into the PMT’s
- light pipe