RAD: Exposure Test 1

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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


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