Density Flashcards
Define exposure factors
The factors that influence and determine the quantity and quality of x-radiation to which the patient is exposed.
Radiation quantity refers to
Radiation intensity
Units: mR or mR/mAs
Radiation quality refers to
X-Ray beam penetrability
Best measured in half-value layer
Beam penetrability and quality is controlled by
kVp
KVP helps to determines the number of x-rays in the….
Image forming beam.
mA determines the number of….
X-Rays produced
Short exposure time does what?
Reduces motion blur
What factors affect density?
Kvp MAS Part thickness Field size Grid Filters Distance
Distance has no effect on?
Radiation quality
If you increase SID, you also need to increase?
mAs
Result of direct square law
3 patient factors
Thickness
Composition
Pathology
If the patient is thicker, what is required?
More radiation is required to penetrate the patient to expose the image receptor.
When only soft tissue is being imaged, what techniques?
Low kVp and high mAs
With an extremity, which consists of soft tissue and bone, what technique is adjusted
Low kVp
Exposure to IR is called—- in film screen and—–in digital system
Density
Brightness
4 Radiographic Qualities
- Density/brightness
- Contrast
- Detail/Spatial Resolution
- Distortion
Factors that impact exposure to the IR, of both F/S and Digital
- Scatter
- kVp
- mAs
- SID
- Collimation
- Thickness
- Grids
- Filters
- Nature of part
What does nature of part mean?
Tissue type
Presence or absence of pathology: additive or destructive
Controlling factor of density in F/S
mAs
3 factors that impact density in F/S
Emulsion characteristics
Intensity Screen characteristics
Chemical Processing
What controls contrast/brightness is digital
kVp
mAs controls the ? of radiation reaching the film
Quantity
Define density
The degree of blackness or opacity of an area in a radiograph due to the accumulation of black metallic silver following exposure and processing of a film.
Brightness define
The measurement of the luminance of a monitor calibrated in units of candela (cd) per square meter on a monitor or soft copy. Density on a hard copy is the same as film.
Equation for density
Log incident light intensity/transmitted light intensity
State the Reciprocity Law
The same Radiographic density or exposure to IR, will result from different mA and time combinations, as long as the mAs totals are equal.
ARRT
American Registry of Radiologic Technologists
Log 10/1 equals
Density of 1
Focal spot is the same as
mA
As screen speed increases, the exposure factors must ? In order to maintain original film density
Decrease
When SID is doubled, how much do we increase mAs to maintain same density
4 times
If the exposure number is in green but High end of DEI, you need to
Cut the mAs in half
⬆️quantity of X-ray reaching IR will
⬆️ density
Go from 200 mA to 400mA will
⬆️ density
If you go from .5 sec to .25sec
Decrease density
