RAD: Exposure Test 1
The average focal spot size range from _____ to_____ .
0.1mm/3.0mm
What percentage of the film is exposed directly by x-rays?
1%
What are the steps of radiographic film/screen formation?
1. x-ray releases electrons 2. electron move to sensitivity center 3. atomic (metallic) silver is formed at sensitivity center 4. process repeats many times 5. silver builds up at sensitivity center 6. chemical processing converts remaining halide to metallic silver 7. resulting silver grain creates radiographic image
In a PA projection of the chest being used for cardiac evaluation, the heart measures 15.2 cm between its widest points. If the magnification factor is known to be 1.3 cm, what is the actual diameter of the heart?
15.2 / 1.3 = 11.7cm
A radiograph is taken using 15 mAs at 40", if the radiograph is repeated using an SID of 50", what mAs should be used to maintain density?
15mAs/x = (50/40)^2 =23.4mAs
Automatic processing reduces development time to ____.
22 sec.
Using a 48-in. SID, how much OID must be introduced to magnify an object two times?
24-in. OID
The radiation intensity is 4 mR 6 ft. from the source. What will the intensity be if the distance from the source is decreased 5 ft.?
4mR/x =( 5/6)^2 =5.8mR
Manual processing of radiographs took about ____?
60 min.
A patient received a dose of 100 mR at a 180 cm SID. If the SID is doubled with no other changes made, the dose will be reduced by:
75%
What 3 projections use the anode-heel effect:
AP thoracic spine AP femur AP axial foot
What are 2 formulas for determining the magnification factor?
MF=SID/SOD
If a heart measures 12.5 cm at its maximum width and its image measures 14.7 cm, what is the MF?
MF=SID/SOD MF=14.7/12.5 MF=1.176
What is the degree of magnification for an examination with an SID of 40in. and an SOD of 38in.?
MF=SID/SOD MF=40/38 MF=1.05
SID is equal to:
OID + SOD
Sharpness of detail can be improved by increasing ____.
SID
What has the greatest effect on radiographic density?
SID
How is distortion controlled?
SID and OID
A stable black metallic silver atom is formed when.
a positive silver ion obtains an electron
The ______ focal spot is the area of target actually being bombarded by electrons.
actual
Foreshortening is caused by a _____.
angled body part when the beam is perpendicular to the IR
The anode side has less density than the cathode side because some of these x-rays are partially absorbed by the anode itself (25% fewer photons). This statement explains what concept?
anode-heel effect
How is SID related to exposure rate and radiographic density?
as SID increases, exposure rate decreases and radiographic density decreases
Radiographic film should be stored:
at a temp. below 68 degrees F in 30 to 60 percent humidity on end
Of the following groups of technical factors, which will produce the greatest radiographic density? a. 5mAs, 85 kVp, 40-in. SID b. 10mAs, 74 kVp, 36-in SID c. 5mAs, 85 kVp, 48-in. SID d. 10 mAs, 74 kVp, 44-in SID
b. 10mAs, 74 kVp, 36-in SID
The two basic components of radiographic film are the ___ and the___.
base, emulsion
What is the reason for angeling the anode?
better heat dissipation better detail on image
Give some examples of VOLUNTARY motion. What is the best way to avoid it?
breathing not holding still during exposure can be avoided with good communication
Silver halide crystals are mainly comprised of silver _____.
bromide
Which of the following sets of exposure factors would best control involuntary motion? a. 300 mA , 30 ms b. 200 mA, 0.045 sec c. 500 mA, 18 ms d. 100 mA, 0.09 sec
c. 500 mA, 18 sec
Which set of factors would produce the least patient dose? Which set of factors would produce the most density? a. 25mAs, 40 SID b. 45mAs, 30 SID c. 5mAs, 60 SID d. 100mAs, 50 SID
c. 5mAs, 60" SID, would produce the least patient dose b. 45mAs. 30" SID, would produce the most density
The small focal spot will provide a ____. a. higher quality x-rays beam b. greater quantity of x-rays c. finer detail of the image
c. finer detail of the image
What is the best way to reduce magnification distortion?
decrease the OID
As film speed increases, sharpness of detail:
decreases
As the SID increases, magnification:
decreases
An image becomes visible during?
development
According to the Gurney-Mott theory, the incident photon interacts with one of the halide crystals and ejects a:
electron
Types of shape distortion include:
elongation and foreshortening
What information, located on each box of film, is important to note and has a direct relationship to film quality?
expiration date
As crystal size increases, film speed decreases True or False
false
Dryer system air temp. ranges from 200 to 250 degrees F. True or False
false
The pass box is used to pass:
film cassettes
What are the 4 components affecting image noise?
film graininess structure mottle quantum mottle scatter radiation
What is in the second tank in an automatic processor?
fixer
The undeveloped silver is removed from the emulsion during _____.
fixing
Name 2 things that effect the geometric properties of recorded detail:
focal spot size distance
Give some examples of INVOLUNTARY motion. What is the best way to avoid it?
heart beat tremors from Parkinson's disease control it by reducing exposure time immobilization devices
Classified as the random fluctuation in the optical density of the image. ( image densities that contain no information).
image noise radiographic noise
As emulsion thickness increases, speed:
increases
As the SID increases, the x-ray field size:
increases
focal spot blur _____ as focal spot size increases.
increases
What does the image represent?
inverse square law
Define distortion:
is a misrepresentation of the shape of an object
Define magnification:
is a misrepresentation of the size of an object
The unseen change in the atomic structure of the crystal lattice in the emulsion is called the ____ image.
latent
The primary purpose of radiographic processing is to convert the ___ image into the ____ image.
latent, visible
The principle that states the effective focal spot (what is projected onto the patient and IR) is smaller than the actual focal spot when the target angle is less than 45 degrees, it is foreshortened. This is a statement of the ______.
line focus principle
What is the unit for expressing recorded detail?
line pairs per millimeter (lp/mm)
Name 3 geometric factors affecting detail:
magnification distortion focal-spot blur
The worst enemy of image detail is _______.
motion
Name 3 factors that affect distortion:
object thickness object position object shape
The area of unsharpness around a radiographic image is termed:
penumbra
What is the term for the unsharp edges in an image?
penumbra
Intensifying screens are used to:
reduce patient radiation dose produce light photons amplify the incoming x-ray beam
What is not considered a primary step of automatic processing?
ripening
When all other factors remain the same, a change in the SID will effect:
sharpness of detail
According to the line-focus principle, the effective focal-spot size is controlled by 2 things. What are they?
size of actual focal spot anode target angle
What 2 things affect the EFFECTIVE focal spot size?
size of actual focal spot anode target angle
The anode-heel effect is most noticeable when:
smaller focal spots large film sizes short SID (40 inches)
When using the anode-heel effect, which part of the body to you place under the cathode end of the tube?
thickest
Focal-spot blur is greatest
toward the cathode end of the x-ray beam
As the emulsion layer increases, the film speed increases. True or False
true
Film latitude is the "forgiving" characteristic in the emulsion that gives you leeway in your technical factors. True or False
true
Mismatching of film and screen often increases patient dose. True or False
true
Most darkrooms are equipped with a dark-red filter safelight. True or False
true
The recovery system is used to remove silver from the fixer solution. True or False
true
The usual storage time for radiographic film is 5 to 7 yrs. True or False
true
