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69 Cards in this Set
- Front
- Back
What is radiation safety?
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ALARA
Limit the exposure to ionizing radiation to the smallest amount to the patient an yourself |
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ALARA
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As Low As Reasonably Achievable
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Basic Concepts of Risk vs. Benefit
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82 % natural Radiation
11 % man made |
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Potential threat to the well being of a human
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Risk
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improvement of the quality of life of a human
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Benefit
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Asks individuals or groups their perception of risk
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Perceived risk
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Makes comparisons between 2 or more activities
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Risk comparisons
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Bert
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Background
Equivalent Radiation Time |
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The Risks- Benefit Continuum
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Basic assumption: there is no threshold (level below which no effects will be seen) consequently, all radiation poses a potential risk of some sort
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3 basic categories of radiation hazards
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Somatic effects (to the body)
Genetic effects (future generations) Fetal effects |
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Smoking 11.4 cigarettes or driving 28 miles on a highway or equal to the risk of dying on the way to a hospital
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Chest x-ray
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128 cigarettes or driving 313 miles
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BE
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Diagnostic Radiology may benefit ___ the US population annually
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1/2
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Diagnostic Radiology may also induce up to
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3600 extra mutations
712 cases of leukemia 910 total cancers |
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A lead apron covers approximately ___% of your body’s active bone marow
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75
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Protects you from radiation-induced leukemia
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Lead Apron
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The professional role of the radiologic technologist 3 common goals:
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1. To promote efficacy (to do the best job, the 1st time)
2. Provide radiation protection 3. Provide the highest level of patient care |
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The professional attitude
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Technologists who do not show their professionalism by limiting patient exposure are a burden on the profession
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The public’s first line of defense against excess radiation is ___
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The radiologic technologist
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GSD
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Genetically significant dose
genetic dose index currently the US uses the standard of 20 mrads/per year |
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MMD
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Mean Marrow Dose
Somatic dose index for leukemia/measure of radiation dose |
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Public and Patient Attitudes
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Provide patient with accurate information and protection
ESE (entrance skin exposure) |
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True of False
Do not use fluoroscopy to locate anatomy prior to an overhead film! |
True
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PBL
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Positive beam requirements
Automatic collimation |
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The role of motivation
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A technologist whose only motivation to provide radiation safety is based on requirement of laws is practicing an occupation, not a profession
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RT’s must
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Provide education to the patients
Other health care workers and the general public |
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Six orientations to learning
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Oblivious (does not want to know or learn)
Uninvolved Resistant Previous bad experiences Focused person Comprehensive person |
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Radiologic Technologist as Leader
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Example: Norlin Winkler’s protective curtain
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Are rules of behavior that must be followed (based on ethics)
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Laws
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Call for a higher level of care than law requires
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Ethical standards
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Ethics: to do good
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beneficence
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Ethics: bad
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maleficent
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True or False
Do not fluoro the patient to determine where to center. |
True
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If you use fluoro to determine where to center on a patient it can add up to __ which is higher than a repeat film
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5 rad/min
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What is a RT code of ethics?
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ASRT code of ethics
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Legal issues and Radiation protection
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1.Pregnancy laws
2.Radiation exposure 3.Equipment laws (both state and federal) |
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Authorizes civil penalties to technologists and other health care workers who do not report defects and failures in medical devices
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Safe Medical Devices Act, 1991
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Permission given to qualify a person to perform specific activities
Goal is to protect the public |
Licensure
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Lawsuits and other legal actions
To prove negligence: |
1.It must be shown that a duty on the part of the professional exists
2.If a duty is shown, a breach of duty must be shown 3.The cause must be due to an action on the part of the professional 4.If cause is proven, an injury must be proven |
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Determined that if permissible dose limits were not exceeded for occupational workers in the industry, no breach of duty occurred
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1990 ILLINOIS COURT DECISION
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What is the student’s role in radiation protection?
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ALWAYS USE ALARA
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A form of electromagnetic radiation
Similar to visible light but are shorter in wavelength Behave as both waves and particles They have no mass/ no charge |
x-radiation
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Physical properties of x-rays
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1.Ability to pass through matter (extremely penetrating)
2.They are heterogeneous (many different wavelengths), polyenergenic (many different energies 3.Travel in a straight line X-rays 4.cannot be focused by a lens 5.Electrically neutral 6.Produce secondary and scatter radiation when interacting with matter 7.They are luminescent- cause certain crystals to fluoresce (give off light) 8.Affect photographic film 9.They ionize gases 10.Cause biologic changes |
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Some x-rays will pass through some will be absorbed
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Differential absorption
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Examples of diagnostic uses:
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Diagnostic radiology
Fluroscopy Tomography Mammography Digital radiography CT |
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Other uses of radiation
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Forensic studies
Authenticate painting (uses grenz rays/low energy) Crystallography buildings |
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X-ray tube components
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X-ray tube generates x-rays (vacuum diode tube)
3 basic components evacuated glass envelope cathode anode |
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1.Prevents radiation leakage
2.Supports the tube 3.Insulates against electric hazards |
Lead lined housing
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Pyrex (2 electrodes)
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Glass envelope
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Negatively charges electrode source of electrons
1.large filament (tungsten wire) 2.Small filament (tungsten wire) 3.Negatively charged focusing cup |
cathode
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Positive most have rotating tubes to help dissipate heat receives the electrons
Target Stem Rotor |
Anode
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Basic operation of the x-ray tube:
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Filament of the cathode is heated (mAs)
Generates a stationary cloud of electrons They are weakly repelled by the negative filament (called a space charge) Thermionic emission (production of electrons by heat) |
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Controls the # of electrons
Quantity density range of .25 -2.5 Controls radiation produced @ the target Direct relationship between mAs and radiation production |
mAs
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Increases the negativity of the cathode
Increases the forces if attraction of electrons to target --- makes the anode more positive Contrast penetration Quality Kinetic energy is charged to 99% heat and 1% x-ray @ the target |
kVp
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X-rays are generated by 2 processes when the high speed electrons are stopped at the target
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1.Bremsstrahlung (braking radiation)
2.Characteristic radiation (binding energy of the k-shell of tungsten) |
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Radiation produced in the tube
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Primary radiation
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Radiation passes through the window
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Useful or primary beam radiation
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Mostly inside the tube
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Leakage radiation
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Portions of the primary beam that pass through the patient
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Remnant radiationorExitorImage Forming Radiation
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Interacted with the patient and has changed direction and energy
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Scatter radiation
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From the patient’s body
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Secondary radiation
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Utilizes only 70.7% of the peak voltage @ 80 kVp = 57 kiloelectron volts (70.7 x 80)
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Single phase
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Utilizes as high as 97% of the peak voltage @ 80 kVp= 78 kiloelectron volts (97 x 80)
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Three-phase
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Not Commonstart at the highest mA and falls during the exposure allows better use of tube limits(we cannot control mA or mAs)
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Falling Load
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Dynamic imaging or imaging of motion
Low mA ( 1-3 ) High kVp (90 – 120) TV monitor displays 1-2 line pairs per millimeter of resolution Diagnostic film displays 9 line line per mm (lp/mm) |
Fluoroscopic Equipment
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Amplifies the brightness of the image
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Image intensifier
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Ratio of the area of the screen (input phosphor) to the output screen square
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Minification gain
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X-ray Beams
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mA Time kVp
Diagnostic 10-120 0.001-10 sec 20-150 kVp Therapy below 20 1-60 min 4-40 MV |
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The target is removed and a scattering foil is added uses MeV monoenergetic electron beam is left used to treat superficial tumors (head and neck)
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Electron beams
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