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69 Cards in this Set

  • Front
  • Back
What is radiation safety?
Limit the exposure to ionizing radiation to the smallest amount to the patient an yourself
As Low As Reasonably Achievable
Basic Concepts of Risk vs. Benefit
82 % natural Radiation
11 % man made
Potential threat to the well being of a human
improvement of the quality of life of a human
Asks individuals or groups their perception of risk
Perceived risk
Makes comparisons between 2 or more activities
Risk comparisons
The Risks- Benefit Continuum
Basic assumption: there is no threshold (level below which no effects will be seen) consequently, all radiation poses a potential risk of some sort
3 basic categories of radiation hazards
Somatic effects (to the body)
Genetic effects (future generations)
Fetal effects
Smoking 11.4 cigarettes or driving 28 miles on a highway or equal to the risk of dying on the way to a hospital
Chest x-ray
128 cigarettes or driving 313 miles
Diagnostic Radiology may benefit ___ the US population annually
Diagnostic Radiology may also induce up to
3600 extra mutations
712 cases of leukemia
910 total cancers
A lead apron covers approximately ___% of your body’s active bone marow
Protects you from radiation-induced leukemia
Lead Apron
The professional role of the radiologic technologist 3 common goals:
1. To promote efficacy (to do the best job, the 1st time)
2. Provide radiation protection
3. Provide the highest level of patient care
The professional attitude
Technologists who do not show their professionalism by limiting patient exposure are a burden on the profession
The public’s first line of defense against excess radiation is ___
The radiologic technologist
Genetically significant dose
genetic dose index
currently the US uses the standard of 20 mrads/per year
Mean Marrow Dose
Somatic dose index for leukemia/measure of radiation dose
Public and Patient Attitudes
Provide patient with accurate information and protection
ESE (entrance skin exposure)
True of False
Do not use fluoroscopy to locate anatomy prior to an overhead film!
Positive beam requirements
Automatic collimation
The role of motivation
A technologist whose only motivation to provide radiation safety is based on requirement of laws is practicing an occupation, not a profession
RT’s must
Provide education to the patients
Other health care workers and the general public
Six orientations to learning
Oblivious (does not want to know or learn)
Previous bad experiences
Focused person
Comprehensive person
Radiologic Technologist as Leader
Example: Norlin Winkler’s protective curtain
Are rules of behavior that must be followed (based on ethics)
Call for a higher level of care than law requires
Ethical standards
Ethics: to do good
Ethics: bad
True or False
Do not fluoro the patient to determine where to center.
If you use fluoro to determine where to center on a patient it can add up to __ which is higher than a repeat film
5 rad/min
What is a RT code of ethics?
ASRT code of ethics
Legal issues and Radiation protection
1.Pregnancy laws
2.Radiation exposure
3.Equipment laws (both state and federal)
Authorizes civil penalties to technologists and other health care workers who do not report defects and failures in medical devices
Safe Medical Devices Act, 1991
Permission given to qualify a person to perform specific activities

Goal is to protect the public
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
Determined that if permissible dose limits were not exceeded for occupational workers in the industry, no breach of duty occurred
What is the student’s role in radiation protection?
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
Physical properties of x-rays
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
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
Some x-rays will pass through some will be absorbed
Differential absorption
Examples of diagnostic uses:
Diagnostic radiology
Digital radiography
Other uses of radiation
Forensic studies
Authenticate painting (uses grenz rays/low energy)
X-ray tube components
X-ray tube generates x-rays (vacuum diode tube)
3 basic components
evacuated glass envelope
1.Prevents radiation leakage
2.Supports the tube
3.Insulates against electric hazards
Lead lined housing
Pyrex (2 electrodes)
Glass envelope
Negatively charges electrode source of electrons
1.large filament (tungsten wire)
2.Small filament (tungsten wire)
3.Negatively charged focusing cup
Positive most have rotating tubes to help dissipate heat receives the electrons
Basic operation of the x-ray tube:
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)
Controls the # of electrons
Quantity density range of .25 -2.5
Controls radiation produced @ the target
Direct relationship between mAs and radiation production
Increases the negativity of the cathode
Increases the forces if attraction of electrons to target --- makes the anode more positive
Contrast penetration
Kinetic energy is charged to 99% heat and 1% x-ray @ the target
X-rays are generated by 2 processes when the high speed electrons are stopped at the target
1.Bremsstrahlung (braking radiation)
2.Characteristic radiation (binding energy of the k-shell of tungsten)
Radiation produced in the tube
Primary radiation
Radiation passes through the window
Useful or primary beam radiation
Mostly inside the tube
Leakage radiation
Portions of the primary beam that pass through the patient
Remnant radiation or Exit or Image Forming Radiation
Interacted with the patient and has changed direction and energy
Scatter radiation
From the patient’s body
Secondary radiation
Utilizes only 70.7% of the peak voltage @ 80 kVp = 57 kiloelectron volts (70.7 x 80)
Single phase
Utilizes as high as 97% of the peak voltage @ 80 kVp= 78 kiloelectron volts (97 x 80)
Not Common start at the highest mA and falls during the exposure allows better use of tube limits(we cannot control mA or mAs)
Falling Load
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
Amplifies the brightness of the image
Image intensifier
Ratio of the area of the screen (input phosphor) to the output screen square
Minification gain
X-ray Beams
mA Time kVp
Diagnostic 10-120 0.001-10 sec
20-150 kVp

below 20 1-60 min 4-40 MV
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)
Electron beams