unit 2 orientation to imaging
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chpt 5, 7, 8 ,9
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101 Terms
what are the three areas of learning
cognitive, affective, psychomotor
what is transfer of learning
when learning emphasis shifts from classroom to clinical
what does the cognitive domain of learning deal with
concepts, information, knowledge
what does the affective domain of learning deal with
values, attitudes, emotions, feelings
what does the psychomotor domain of learning deal with
connection between cognitive learning and motor skills
learning process is based on ___
performance objectives
what are objectives
descriptions of observable behaviors to be achieved by students
how is learning observed and measured
by way of competencies
what are learning outcomes
program level measurable expectations for student learning
what agency establishes the minimum number of clinical competencies
American registry of radiologic technologists (ARRT)
what agency is for program accreditation
JRCERT (joint review committee on education in radiologic technology)
what agency is for individual certification
ARRT (American registry of radiologic technologists)
what is the agency for representation
ASRT (American society of Radiologic Technologists)
what does the ASRT do
develops and publishes practice standards for medical imaging
student supervision can be __
direct and indirect
what are the two categories for competencies
procedural , general patient care
what are the three phases of clinical learning
observation
assistance
performance
what are the 5 key principles of TeamSTEPPS
team structure
communication
leadership
situation monitoring
mutual support
what is SBAR used for
to improve communication when handing off patients
what are the 4 elements of SBAR
situation
background
assessment
recommendation
when were xrays discovered
November 8th 1895
how is xray beam energy produced
high voltage electricity
what are the steps of image production
High-voltage electricity produces X-ray beam energy
X-rays pass through matter and strike an IR
IR converts the energy of X-rays into an electronic data set of signal values
Computer processing converts signal values into viewable image
what are the requirements of xray production
xray tube w a vacuum inside
source of electrons (cathode filament)
method to accelerate electrons (voltage / kVp)
method to stop electrons and cause energy transformation (target / focal spot)
what are the classes of radiation
primary radiation, scatter radiation, absorbed radiation, remnant radiation
what is attenuation
the loss of radiation energy as a result of passing through an absorbing material, such as the human body
what is differential absorption
different materials absorb radiation energy differently, primarily based on density and atomic number
does high attenuation occur in radiopaque or radiolucent matter
radiopaque
does low attenuation occur in radiopaque or radiolucent matter
radiolucent
what is radiolucent
a material or body structure allows X-rays to pass through it easily
appear darker or black on images
what is radiopaque
a substance or structure blocks or absorbs X-rays and other forms of radiation instead of letting them pass through
appears lighter or white on images
what are technical exposure factors
Milliamperage (mA) and time (seconds) = mAs
kilovoltage peak (kVp)
Source-to-image receptor distance (SID)
what does mAs represent
the QUANTITY of xray production
how is mAs calculated?
Multiplication of mA and time (s)
mA x Seconds = mAs
what is the relationship between mAs and radiation output?
direct linear relationship
if mAs is increased, the # of xrays reaching the patient increases
what is the mAs if there is 200 mA and .5 seconds
100 mAs
what does kVp control
beam quality, penetrability
what is kVp’s relationship with signal value
direct, not linear
As kVp increases, the signal value also increases, but not by the same amount
what is signal value
how much radiation information the image receptor receives and records
what is kVp’s relationship with signal value
INVERSE
↑ kVp → ↓ mAs (½)
↓ kVp → ↑ mAs (×2)
what is the 15% rule
increasing kvp by 15% will double IR exposure, decreasing kVP by 15% will reduce exposure to half
what is the relationship between SID and beam intensity
inverse
what is the inverse square law formula
I1/I2 = D2 squared/D1 squared
if you want to double kVp of 65, what would the answer be
65 x .15 = 9.75
65 + 9.75 = 74.75
74.75 = new kVp
what is signal value determined by
total xray exposure to IR
what is quantum mottle
image noise
signal value is ____ proportional to xray exposure
directly
what are the signal value variable
exposure (mAs)
beam quality (kVp)
patient characteristics
distance
radiographic grids
xray beam modifications
IR characteristics
what is the relationship of signal value and subject density
inverse
can the xray beam be modified before and after it enters the patient
yes
primary beam modification
scatter control
what are the 2 types of primary beam modification
filtration
collimation (beam limitation)
what are radiographic grids for
to reduce the amount of scatter radiation reaching the IR
what are the two distortion types
size and shape
what is automatic rescaling
computer software optimizes image quality
what is fluoroscopy
use of xrays to create real time images
what side of the xray tube is the cathode
the posterior side, negative
what side of the xray tube is the anode
anterior side, positive
what is the red
stator
what is the red
bearing
what is the red
tungsten anode
what is the red
glass envelope
what is the red
filament
what is the red
electron beam
what is the red
xray beam
what is the red
molybdenum neck and base
what is the red
rotor
what is diagnostic yield
the amount of clinically useful information on an image
what is diagnostic efficacy
the accuracy of diagnostic information on an image
what are things on the generator control
kvp, mAs, focal spot size, automatic exposure control (AEC), anatomical programming (APR) ,
what does automatic exposure control (AEC) determine
time
what are the 2 types of xray tubes
wall and floor mounted
the only radiation that is of any clinical value is ____
remnant radiation absorbed in the detector
what are the sources of ionizing radiation
natural, manmade
what are the 3 conditions for xray production
source of electrons
means for setting them in high speed motion
mechanism for decelerating them
xray tube is a ____ tube
diode
what maintains a vacuum in the xray tube
glass envelope
is the xray beam homogenous or heterogenous
heterogenous
made up of different things
what is the energy of the beam expressed in
kiloelectron volts (keV)
steps of xray production
filament gets hot and releases electrons
kVp pushes electrons from cathode to anode (potential difference)
electrons hit tungsten target
electrons interact w/ tungsten atoms and get converted into mostly heat and small amount into xrays
the useful xray beams exit through the tube window
what is primary beam
the xray beams that leave the tube and go toward the patient
what is classic coherent scattering
An X-ray photon interacts with an atom as a whole and does NOT lose energy
doesn’t contribute to image or patient dose
no ionization
what is photoelectric effect
An X-ray photon is completely absorbed by an inner-shell electron
occurs within diagnostic energy range
greatest hazard to patient dose
what is compton scattering
An X-ray photon hits an outer-shell electron, knocks it out, and changes direction.
occurs within diagnostic energy range
contributes to tech dose
what does air kerma measure
transfer of kinetic energy to tissue or air, measured in joules per kilogram
replaces traditional unit of exposure (x)
what is absorbed dose
expressed as Gray (Gy)
measures amount of energy absorbed in any tissue
WHAT is effective dose
expressed as sievert (Sv)
accounts for overall risk of exposure
what is the annual dose limit for radiation workers
50 MSV
what are standards of exposure regulated by
FDA
what are somatic cells
body cells
can affect YOU
what are genetic cells
reproductive cells
can affect FUTURE OFFSPRING
what is the dose response?
linear non threshold
there is always a risk
what is the direct hit theory
radiation hits the dna directly and immediately damages it
what is the indirect hit theory
radiation hits water molecules first, which create free radicals that damage the dna
what cells are less sensitive
nerve cells, brain cells
what cells are more sensitive
germ cells, skin cells
what are results to radiation to a cell
cellular death
delayed mitosis
altered mitotic rate
what are the stages of acute radiation syndrom
prodromal: first symptoms
latent: symptoms decrease
manifest: main illness
cell recovery or cell death
cardinal rules
time
distance
shielding
what is the dose limit for pregnancy term
5 mSv
what dosimeter do we wear?
thermoluminescent dosimeter (TLD)