Technical Factors in Radiography Flashcards
is the systematic procedure used by the radiographer to accomplish the task of producing high quality radiograph
radiographic technique
to produce a radiograph, the radiographer selects and manipulates four significant factors:
kvp
ma
exposure time
distance
force that accelerates the electrons from the cathode to the anode
kilovoltage (kvp)
directly controls the energy or quality of the x-ray beam
kilovoltage (kvp)
is the crest of the waveform that represents photon energy
kilovoltage (kvp)
it controls the energy of x-rays produced, also has a direct impact on density, although not proportional; governed by the 15% rule
kilovoltage (kvp)
it means the x-ray photons have sufficient energy to pass through the part and emerge as remnant radiation
penetration of the part
Density Maintenance (kvp and mas)
15% ↓ in kvp = mas _ 2
15% ↑ in kvp = mas _ 2
15% ↓ in kvp = mas ÷ 2
15% ↑ in kvp = mas x 2
exits the body and travels in different directions with many energy levels
scatter radiation
danger to the patient and radiographer, detriment to image quality
scatter radiation
the characteristic radiation produced by the ____________ effect is mostly absorbed by the patient
the characteristic radiation produced by the PHOTOELECTRIC effect is mostly absorbed by the patient
Scatter Radiation
_ kV = _ radiation absorbed by the patient
↑ kV = ↓ radiation absorbed by the patient
is the controlling factor of radiographic contrast
kilovoltage
kilovoltage formula
kVp = _ x 2 + C
kilovoltage formula
kVp = T x 2 + C
kvp increases by 15%; mas decreases by ___
kvp increases by 15%; mas decreases by 1/2
kvp decreases by 15%; mas is _____
kvp decreases by 15%; mas is doubled
represents the current flow through the cathode filament at the time of exposure
milliamperes (mA)
↑ mAs = _ radiation = _ density
↑ mAs = ↑ radiation = ↑ density
↓ mAs = _ radiation = _ density
↓ mAs = ↓ radiation = ↓ density
focal spot blooming
_ tube current (mA) = _focal spot size
focal spot blooming
↑ tube current (mA) = ↑focal spot size
statistical fluctuation in the quantity of x-ray photons that contributes to image per mm^2
quantum mottle/image noise
_ mAs = few x-ray photons – ↑ mottled, splotchy or salt-and-pepper appearance
↓ mAs = few x-ray photons – ↑ mottled, splotchy or salt-and-pepper appearance
factor that sets the length of exposure
time (s/ms)
the ___________ law indicates that blackening in the film remains constant as long as the total energy exposing the film is constant
the RECIPROCITY law indicates that blackening in the film remains constant as long as the total energy exposing the film is constant
it is also a quantitative factor that when combined with mA, determines the exposure rate
time (s)
it refers that the mA is inversely proportional to the time of exposure to attain the same densities
mA and time relationship`
length of space from the focal spot to the recording medium
SID or FFD
if SID is _ 2x, the same number of photons is spread out over an area 4x the original area, intensity of the beam is _ of the original intensity
if SID is ↑ 2x, the same number of photons is spread out over an area 4x the original area, intensity of the beam is 1/4 of the original intensity
represents the length of space from the focal spot to the recording medium and it is called the FFD
distance
SOD
source object distance
SID
source image receptor distance
OID
object image receptor distance
FFD
focal film distance
OFD
object film distance
its new term is SID
distance
in the most diagnostic departments, the ___ is standardized for all procedures
in the most diagnostic departments, the SID is standardized for all procedures
in general radiography, the SID is __ to __ inches
in general radiography, the SID is 40 to 42 inches
in radiography of the structures of the chest and thoracic cavity, the SID is usually __ inches
in radiography of the structures of the chest and thoracic cavity, the SID is usually 72 inches
in radiography of the structures of the chest and thoracic cavity, the SID is usually 72 inches which is called ______-_____ radiography
in radiography of the structures of the chest and thoracic cavity, the SID is usually 72 inches which is called CHEST-TELEO radiography
mAs and distance relationship
mAs is __________ proportional to the squared of the distance (SID)
mAs is directly proportional to the squared of the distance (SID)
as the distance is increased, the mAs must also ________ to maintain adequate blackening of the film
as the distance is increased, the mAs must also increase to maintain adequate blackening of the film
the law states that radiation intensity is inversely proportional to the squared of the distance from the source of radiation
inverse square laq
inverse square law
when SID increases, radiation intensity ___________
when SID decreases, radiation intensity __________
inverse square law
when SID increases, radiation intensity DECREASES
when SID decreases, radiation intensity INCREASES
inverse square law
if distance ↑, the mAs must also _to maintain density
inverse square law
if distance ↑, the mAs must also ↑to maintain density
