ARRT review Image Production
Terms
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- Overall aomount of blackening on film?
- Density
- What is density rate regulated by?
- exposure rate or nmber of photons reaching the film
- To graphically illustrate the response of x ray film to amounts of exposure the densities can be plotted on a graph. What is this called?
- H&D Curve, sensitometric curve, or characteristic curve.
- Radiographic film base plus fog ranges around what numbers?
- .05-1.0
- What is the diagnostic useful range of density?
- .25-2.5
- The study of film emulsion to exposure is what?
- sensitometry
- What does the study of sensitometry require the use of?
- sensitometer, densitometer, and processor.
- Difference in density represent what?
- contrast
- Product of ma and time
- mAs
- Any combination of mA and time that will produce a given mAs will produce an identical density. This is know as what?
- reciprocity
- Is mAs a quatitative factor?
- yes
- What does mAs regulate?
-
beam intensity
exposure rate
quantity or # of x rays - Is MAS directly or indirectly proportional to denisty?
- directly
- What do you do that produces more high energy x-ray photons?
- Increase the kvp
-
KVP affects ___________ and ___________
of the film - quatity, quantity
- How are kvp and mAs related?
- directly but not proportionally
- When mAs manipulation is not possible, how can you double or half the density and what is the disadvantage of doing this?
- 15% rule, you change the scale of contrast
- The relationship between SID and density is governed by what law?
-
The inverse square law
I1 D2 squared
---=___________
I2 D1 squared - What is the distance maintenance formula?
-
mas1 (D1)2
____=_____
mas2 (D2)2 - If 25 mAs at 40 inches is necessary how much mAs should be used if 72 inches must be used?
- Distance Maintenance Formula
- What is the purpose of an intensifying screen?
- decrease patient dose and increase tube life
- As screen speed increases what will patient dose do?
- Decrease
- The flourescent light emitted by the phospors is responsible for what percentage of image density?
- 98-99%
- What is the purpose of a grid?
- improve contrast
- The primary purpose of a grid is to absorb _________ produced by what effect?
- scatter, compton
- The grid should be placed where?
- Between patient and film
- What should a patient measure for you to use a grid?
- 9-11 cm
- What are the types of grids?
-
Stationary- grid lines
Moving
Parallel
Focused
Cross hatch-prohibit tube angulation - What are the types of grid errors?
-
Off-level-loss of density
Off-center-loss of density
Off-focus-dark strip down middle
Upside down grid-dark strip down middle
"Moire" artifact-2 focused grids on top of each other. - What are the grid ratio conversions?
-
5:1 2
6:1 3
8:1 4
10:1 5
12:1 5
16:1 6 -
What is grid ratio?
Grid frequency? -
height/distance
# of lead strips per inch - Ordinary filtration of 2.5 mm Al has what effect on density?
- none
- What effect does beam restriction have on density?
- decreases (4x4 and lower, only manual settings)
- Does beam restriction have a greater effect on contrast or density?
- contrast increases
-
Under manual technique how would you compensate for most additive pathology?
What would you do with AEC? - increase 5-15%, nothing automatically adjust
- Is abscess additive or subtractive?
- additive
- Is edema additive or subtractive?
- additive
- Are tumors additive or subtractive?
- additive
- Is atealeactasis additive or subtractive?
- additive
- Is CHF additive or subtractive?
- additive
- Are pleural effusions additive or subtractive?
- additive
- Is pneumonia additive or subtractive?
- additive
- Is TB additive or subtractive?
- additive
- IS ascites additive or subtractive?
- additive
- Is cirrhosis additive or subtractive?
- additive
- Osteomyelitis is additive or subtractive?
- additive
- Is pagets's disease additive or subtractive?
- additive
- Is atrophy additive or subtractive?
- subtractive
- IS bowel obstruction additive or subtractive?
- subtractive
- is degenerative arthritis additive or subtractive?
- subtractive
- Is multiple myeloma additive or subtractive?
- subtractive
- Is osteomalacia additive or subtractive?
- subtractive
- Is osteoporosis additive or subtractive?
- subtractive
- Is emhysema additive or subtractive?
- subtractive
- emhysema
- subtractive
- Density
- Overall aomount of blackening on film