Flashcards in Radiographic Technique Deck (101):
What controls quantity?
What influences and determines the quantity and quality of x-rays ?
Radiation quality refers to x-ray beam penetrability, best measured by what?
HVL (Half Value Life)
What are the (4) prime exposure factors?
3. Exposure time
High kVp _____ image contrast.
What controls how fast the electrons are sent across the tube?
What controls beam quality?
What controls beam penetrability?
What controls the radiographic scale of contrast?
What determines the # of photons, radiation quantity, OD and patient dose?
What affects the number of x-rays produced?
What are the available mA stations?
50, 100, 200, 300, 400 & 600
Does changing the mA change the kinetic energy of e-?
What relationship does mA quantity and patient dose have?
They are directly proportional
Short exposure time _____ image blur
What must you do when using short exposure times to maintain x-ray intensity?
Single phase can not produce an image under...
Three phase can produce an image under...
What does mAs control?
-Changes the number of electrons
Does mAs change the energy of x-rays produced?
No, just the number
mAs is a key factor in the control of ________ ________.
What is the reciprocity law?
OD will be constant for any combination of mA and exposure time that results in constant mAs
Does distance have much affect on quality?
Does distance have an affect on density?
Does distance affect x-ray intensity?
What does the square law do?
Determines the required change in mAs after a change in SID to maintain OD
What are some patient factors when determining technique?
-Thickness of part
What are the (4) types of body habitus?
-Short & wide
-Chest and abdomen are broad
-Lungs are short and wide
-Stomach is high and transverse
-Average body type
-50% of population
-Active or strong
-Slender version of Hypersthenic
-Opposite of Hypersthenic
-10% of population
-Frail, poor muscle tone
-Narrow, long, shallow
-Diaphragm is low
-Abdominal cavity rests in pelvic region
-High splenic flexure
-Stomach is J shaped and extends into iliac crest region
In general, what kind of technique does a soft tissue neck require?
Low kVp & high mAs
In general, what kind of technique do extremities require?
In general, what kind of technique does a chest require?
In general, what kind of technique does an abdomen require?
What are the (4) image quality factors?
Key word DICO
2. Image Detail
4. Optical Density
What is OD?
The degree of blackening of the finished radiograph
When OD is high=
When OD is low=
OD can be controlled by mAs and SID? T/F
What is more efficient, a single phase or a three phase?
When SID is shortened, what happens to your mAs?
It goes down
When SID is increased, what happens to your mAs?
It goes up
What are the (4) types of generators?
1. Half wave rectification
2. Full wave rectification
3. 3 phase power
4. High frequency generator
-Only produces x-rays half the time
-Drops to zero every time
-x-rays are not produced on negative side
-Consistant, but drops to zero
3 phase power:
-6 & 12 pulse
-Nearly constant output & exposure
-energy is higher
-Higher quantity & quality
-Less than 1% ripple
What are the effects of a destructive disease?
-Destroying part of tissue, bone, ligaments
-Taking away, making more lucent
What are the effects of a constructive disease?
How much of in increase is required for a visible change in OD?
When mAs is doubled, you get...
Double the density
When only mAs is changed it is either ____ or ____.
Halved or doubled
When mAs is doubled=
Your density is doubled
When kVp is changed it must be increased by __% to produce a visible change in OD.
The 15% rule is the same as?
Doubling the mAs
To maintain OD a 15% increase in kVp would require a reduction of ____ the mAs.
Does the 15% rule apply to kVp or mAs?
A strip that goes from black to white quickly would have a...
-Black and white
A strip that goes from black to white slowly would have a...
-Many shades of gray
What is contrast?
Differences between things that are adjacent to one another
Contrast is controlled by...
A result of the differences in attenuation of the x-ray beam as it penetrates various structures.
The variation in OD between adjacent anatomic structures.
A chest would have what scale of contrast?
Long scale of contrast
Short scale contrast gives you ___ contrast radiographs.
High contrast radiographs would have...
-Short scale contrast
-Fewer shades from white to dark
Bone work would have short scale ____ contrast
Long scale contrast produces _____ shades of gray.
How much kVp is requited to see a difference in contrast?
At low kVp, how much change is needed to see a difference?
At high kVp, how much kVp is needed to see a difference?
High kVp will give you ___ contrast.
A chest has ___ subject contrast.
High subject contrast has ____ variations in tissue composition
A hand has ____ subject contrast.
An abdomen has ____ subject contrast.
What is the 5% rule?
An increase in kVp by 5% requires a reduction in 30% mAs
What is image detail?
Sharpness of small structures or spatial resolution of the image
How is image detail evaluated?
Sharpness of image detail
Visibility of image detail
What is sharpness?
Clarity or blur of the structural lines
What is visibility?
Seeing that there is anatomy
Sharpness is controlled by...
-Focal spot size (FSS)
What can reduce visibility?
What is distortion?
Misrepresentation of an object and shape due to position of the tube or anatomic part
What are disadvantages of distortion?
What is an advantage of distortion?
Allows for better visualization of anatomy
Variable kVp chart:
-kVp varies according to thickness of anatomic part
-Provides radiographs with shorter scales of contrast
-Other factors stay the same
Fixed kVp chart:
-kVp stays constant
-Developed by Arthur Fuchs
-Provides longer scales of contrast
High kVp chart:
-Used for barium exams, contrast exams, CXR
-Ensures adequate penetration
-Decrease in mAs
-Reduces patient dose
-Use of computer assisted automatic/ electric timers and photocells
-Patient positioning must be accurate
-Terminated when the image receptor has received the appropriate radiation exposure
-Most have 2s override
An increase of 15% in kVp is equivalent to...
Doubling the mAs in terms of density
Long scale contrast:
-Many shades of gray
Short scale contrast:
-Black and white
What controls contrast?
What controls density?