True or False     Detail or slow speed screen should be used when imaging the abdomen of a dog, in order to decrease motion artifact on the finished  radiograph.

False

True or False   Gloves and aprons with .5 mm lead             provide complete protection from                                                                        both primary and secondary radiation.

False

True or False    

                 A stationary anode dissipates heat best.

False

True or False   

As the thickness of the area of the patient being examined is increased, the  amount of secondary radiation is increased.

True

True or False

               A radiograph is synonymous with x-rays.

False

True or False

High speed screens allow for a more detailed radiographic image than slow                                                         speed screens.

False

True or False

Due to the heel effect, the x-ray beam has a higher intensity on the anode side                                                                of the tube.

False

True or False

            A somatic effect occurs during one’s lifetime.

True

Fill in the Blank

Silver halide crystals are located in the ______

of the x-ray film.

Emulsion

Short Answer

Clearly defined what white artifacts on a finished radiograph can be caused by

Foreign film material trapped between the film and screen 

Short Answer

The heel effect is caused by

Steep target angles creating unequal distribution of x-ray beam intensity

Short Answer

Intensifying screens are used in veterinary radiography because they

Do not require as much radiation as direct exposure film in order to produce the same amount of radiograhpic density.

Short Answer

The developer functions to

Convert silver halide crystals in the flim emulsion into black metallic silver

Short Answer

When does a latent image occur in relation to exposure and development?

After exposure and before developement

Short Answer

When do static artifacts occur?

In low humidity conditions

Short Answer

When is it necessary to use a grid?

When we have increased scatter and the area of interest is greater than 10 cm.

Short Answer

What must be done to mAs and kVp to lengthen scale of constrast but maintain radiographic density?

Increase kVp by 20% and halve the mAs

Short Answer

When increasing FFD, what must be done to the mAs to maintain radiographic density?

If double FFD, quadruple mAs

Short Answer

List the subject densitry from lowest to highest x-ray absorption

Air

Fat

Muscle

Bone

Metal

Essay

List four basic identification items that must be legally included on a finished/developed flat film

Date, patient name, owner name, clinic name

Either/Or

Hight speed screens have (large/small) crystals compared to slow speed screens

Large

Either/Or

Overexposure is caused by too much (mAs/kVp)

mAs

Either/Or

A radiograph produced with a higher kVp will have a (longer/shorter) scale of latitude, which will produce (more/less) variation in shades of gray. 

Longer, more

Either/Or

Penumbra can be decreased by (increasing/decreasing) focal spot size (FSS)

Decreasing

Short Answer

Why should the patient area of interest be as close to the film as possible?

To decrease penumbra and magnification

Short Answer

With regard to penumbra, what is the practical application of a small focal spot size? (Why is a small focal spot size desirable?)

It decreases penumbra which increases radiographic detail and image resolution.

Short Answer

In relation to image geometry, what is the importance of centering directly over the patient area of interest?

To decrease the possibility of false narrowing.

Short Answer

With regard to subject density, what two patient factors affect the x-ray beam's ability to pentrate?

Average atomic number

Subject thickness

Short Answer

What specific type of image disortion is caused by increasing the object film distance (OFD)?

Magnification

Short Answer

What causes foreshortening?

Subject area not being parallel to the recording surface (film).

Short Answer

How can the Inverse Square Law be helpful in producing good quality radiographs?

It prevents the operator from increasing the mAs to a level that is dangerous to patient and personnel. It also keeps exposure times short to reduce motion of film.

It decreases penumbra, increases detail, increases safety, all with the same density.

Short Answer

Describe the appearance of an image containing high radiographic contrast.

Black and white a predominant, increased % of difference between black and white.

Short Answer

Describe the appearance of an image containing low radiographic contrast.

Fewer blacks and whites, decrease % of difference between lack and whites= more grays.

What does a long scale of contrast mean?

Many shades of gray with few blacks and whites.

What does a short scale of contrast mean?

Few shades of gray with more blacks and whites.

Increasing kVp results in (increase/decrease) of penetration and (increase/decrease) in the scale of contrast.

Increase, increase.

What is the exposure latitude and how it relates to scale of contrast?

Range of exposures that allow some flexibility in technique choices while still producing diagnostic images... increased exposure latitude with increased kVp levels.

What is the difference between radiographic density and radiographic detail?

Density= degree of blackness on the film.

Detail= degree of crispness/sharpness of the film.

Increasing mAs (increases/decreases) radiographic density, producing (high/low) overall contrast radiograph.

Increases, high

How is the scale of contrast affected by increasing the mAs? By decreasing the mAs?

Scale of contrast is not affected by mAs.

What is penumbra and how does it affect radiographic detail?

Blurring and loss of detail between tissue interfaces at edges of collimated image.

Decreases radiographic detail.

Name 3 ways to decrease the penumbra effect

1) Decrease FSS as much as practical

2) Increase FFD to 36-40 inch range

3) Decrease OFD to a minimum

What type of film is preferred for most general radiography?

Long latitude, long scale film.

Define film fogging, what are it's causes?

Overal "grayed out" dull radiographic appearance, loss of detail, lack of serosal surface definition

Caused by: light leaks in darkroom or cassette, heat humidity, scatter radiation, pressure, expired/old film

How can false narrowing be prevented when imaging the cervical vertebral region?

Pad under the sagging areas (mid cervical, nose) and make the vertebral column parallel to the recording surface (film).

List the subject densities from least dense to most dense and whether they appear white, light, dark or black on a radiograph.

Air (black)

Fat (dark gray)

Water/muscle ( medium gray)

Bone (light white)

Metal (white)

What % of energy is released as heat during x-ray production?

99% heat

1% x-rays

Where is the electron cloud produced, the Anode or the Cathode?

Cathode.

What is the purpose of the aluminum filter that is placed across the window?

To absorb the low energy (soft) x-rays.

Is the anode maintained at a positive or negative potential during an exposure?

Positive. 

What type of machine utilizes stationary anodes?

Low output/portable. 

List 2 advantages of using a rotating anode over a stationary anode.

1) Better heat dissipation

2) Larger target area

Name 4 ways x-ray machines are rectified

1) Single phase, half-wave rectification

2) Single phase, full-wave rectification

3) 3 phase rectification

4) Self rectification

What is the purpose of a tube rating chart?

It prolongs the life of the x-ray tube by helping the operator to determine the max/min exposure characteristics that allow safe operation of the machine.

List and explain two types of damage that may occur from an improperly set exposure technique.

1) Tube overload- combined kVp and mAs are too high for the machine. Too much heat is created causing the anode to crack.

2) Tube saturation- not enough positive potential (voltage) between the cathode and anode to pull all the electrons across the tube. The extra electrons build up on the glass envelope. The envelope cracks and is destroyed. 

Does kVp control the quantity or quality of the x-ray beam?

Quality.

What effect does a high kVp have on the electrons?

Makes them move faste=shorter wavelength= more penetrating power

What is the reason for Tungsten being used as the target metal?

It has a high melting point for better heat dissipation.

Increasing kVp (increases/decreases) the proportion of short wavelength x-rays and (increases/decreases) the penetrating power of the beam. 

Increases, increases.

What is the heel effect?

Unequal distribution of the x-ray beam intensity emitted from the x-ray tube.

Does the mAs control the number of x-rays produced or the penetration power?

Number of x-rays produced (quantity).

Why should the effective focal spot be as small as possible?

To increase detail to the radiographic image.

What is the difference between half wave rectified, full wave rectified, and three phase generators?

Half wave is the standard potential where only 1/2 the current is usable.

Full wave inverts the negative part of the wave to make it more usable.

3-phase inverts the negative part of the wave, but also overlaps them so more of it is usable. 

Describe a few examples of somatic effects caused by exposure to ionizing radiation (6)

Radiodermatitis

Thyroid malfunction

Cataracts

Anemia

Decreased immunity

infertility

Which body systems are most senstive to radiation?

All rapidly reproducing cell systems including embryonic and fetal tissues.

Why should we be as far away from the primary beam as possible?

To decrease exposure to primary and secondary radiation. 

What are the purpose of the film badges that we wear?

Measure the cumulative dose of radiation during ones lifetime. 

Who should wear film badges and where on the body should they be placed?

All personnel working with radiation equipment. 

They should be worn at the level of the thyroid on the outside of lead PPE... additional fetal badges should be worn at baby level under lead PPE.

What is the recommended thickness of lead to be contained in lead gloves, aprons and thyroid shields?

0.5 mm

Describe the proper way to care for lead apparel and why it is important to do so.

Hang gowns and thyroid shields over specially designed hangers draping them flat so as not to crack the lead.

Place cans or PVC pipe inside gloves to prevent cracks or tears in the lead. 

Why would proper radiographic and darkroom techniques be considered radiation safety devices?

It decreases the number of retakes, increases the efficiency of the team, and decreases radiation exposure.

What is ALARA and how does it apply to veterinary radiography?

As Low As Reasonably Attainable- this is the practical approach to radiation safety to keep you well below the 5 REM/year limit in the work environment.

How is lead protective apparel inspected for damage? How often should the inspections be done?

Gloves- every 6 months using 5-30 mAs, 80 kVp and a rapid cassette on the tabletop. 

Thyroid shields- every 12 months using 5 mAs, 80 kVp and a rapid cassette on the table top.

Gowns-  radiographed in sections using 5 mAs, 80 kVp and a rapid cassette on tabletop or observed with fluoroscopy at least yearly.

Any damaged items are removed from use and replaced.

Name the 3 speeds of x-ray film, which one requires the highest/longest exposure time? Which one is most commonly used in veterinary practice?

High speed- fast

Average speed-par (most commonly used in vet practice)

Slow speed- detail (requires highest/longest exposure)

Why are some brands of non-screen film not suitable for automatic processors?

The emulsion is too thick and the film will be damaged by the rollers in the processor. It could also get stuck in the processor.

How should unexposed film be stored?

In a cool, dry area

Away from temperature extremes, light shources, moisture, and chemical fumes.

Stored on end(upright) inside the film boxes or film bin.

What is the latent image and how is it produced?

The image on the film after exposure but before processing. It is invisble until processed.

It is produced by exposing the silver halide crystals in the emulsion to x-rays or light.

When does the film contain black metallic silver in relation to exposure and development?

After exposure and after development.

What is one method of increasing film speed?

Increase the emulsion thickness, increase crystal size.

What % of film exposure is due to light from the screen? What % is due to x-rays?

95% from fluorescence (light) 

5% from x-rays

High speed screens have (large/small) crystals compared to slow speed screens.

Large

What is the advantage to using rare-earth screens?

Increased efficiency of converting x-rays photons into light energy to expose film.

Permits significant reduction of mAs and kVp thus exposure to personnel and patient.

How do intensifying screens expose the film?

Each x-ray phon produces 1000 light photons. The light photons then expose the film in addition to the x-rays that reach the film. Intensifying screens amplify the photographic effects of x-rays which increases fluorescence. 

Name one disadvantage of high speed screens.

Less detailed image, more grainy appearance. 

What can be done to the phosphor layer to obtain more detail?

Add dyes, decrease thickness of the phosphor layer, decrease the crystal size.

What should intensifying screens be cleaned with?

Antistatic solutions specifically recommended by the manufacturer and a lint free cloth (i.e. 4x4 gauze).

Do secondary x-ray photons have a longer or shorter wavelength than those of the primary beam?

Longer

Why are we concerned about scatter (secondary) radiation?

More easily absorbed by tissues causing increased cell damage.

Is more scatter produced during exposures with high kVp or low kVp? Why?

High

Due to increased speed and forces of electrons against target. 

How does collimation help control scatter radiation?

Confines the primary beam to just the area being imaged. 

Where is the grid positioned in relation to the patient and the film?

Between the patient and the film.

What occurs when the tube head is not properly aligned with the grid? How will the finished radiograph appear if the tube is not properly aligned with the grid?

Grid cut-off or lateral decentering

Decreases detail and density, makes an overly white/light image and visible grid lines if no Bucky.

When is it necessary to use a grid?

When the area of interest measures >9-10 cm.

What is the purpose of a moving grid?

To blur the visible grid lines from the lead strips in the grid that show up on the radiograph. 

Why are more mAs required when using a grid?

Grids contain lead strips that absorb some of the x-rays from the primary beam which decreases density; more x-rays are needed to compensate for this. 

Which grid is more effective at filtering scatter radiation: one with a grid ratio of 8:1 or one with a grid ratio of 16:1? Why?

16:1 is more efficient. Increased abilty to absorb scatter radiation due to the increased lead ratio in the grid. 

What 3 things can radiation energy do once it enters the patient's body or objects?

a) pass through to reach the film

b) be absorved (stay in the body)

c) produce scatter radiation

List some disadvantages of scatter radiation.

Hazard to patient and personnel, decreases diagnostic quality of the images (increased fog on film).

When utilizing a Potter Bucky mechanism, list 3 possible causes that visible grid lines may still appear on a finished radiograph. 

1) Bucky moves before or after the exposure

2) Bucky moves irregularly

3) Grid misaligned with Bucky

4) No bucky movement (malfucntion or turned off

Which grid is more efficient at controlling scatter radiation?

a) 8:1 ratio with 102 lines per inch

b) 5:1 ratio with 80 lines per inch

c) 10:1 ratio with 80 lines per inch

d) 10:1 lines with 102 lines per inch

10:1 ratio with 102 lines per inch

Where are the silver halide crystals located in the x-ray film?

In the emulsion.

Scatter radiation:

a) improves density on a finished radiograph

b) decreases penumbra on periphery of radiograph

c) is lessl ikely to be absorbed by the tissues

d) has a longer wavelength than the primary beam

D

As a general rule, grids are used when imaging areas measuring greater than:

a) 40 cm

b) 72 in

c) 10 cm

d) 11 degrees

C. 10 cm

Which of the following is the most efficient grid?

a) parallel

b) focused

A) Parallel

When does tube overload occur?

mAs and kVp are too high

When does tube saturation occur?

kVp too low

What is the anode heel effect?

Which side of the tube with lower target angles have a distrubtion of x-ray beam intesnity that decreases on that side?

The unequal distribution of x-ray beam intensity emitted from the x-ray tube. 

Anode side

When is the anode heel effect an advantage?

When radiographing areas of unequal thickeness, such as the thorax or abdomen.

What are the 3 basic x-ray machine controls and what do they control?

1) kVp- controls the quality of the x-ray beam: the higher, the more potential is applied 

2) mA- affect the quantity of x-rays

3) exposure time- control quantity of x-rays

What is radiographic contrast?

The differences in radiographic density between adjacent areas on a radiographic image. 

The amount of radiographic contrast depends on what 4 factors?

1) subject densitry

2) kVp level

3) Film contrast

4) Film fogging

What is radiographic detail? 

What factors affect this?

Good radiographic detail has sharp tissue and organ interfaces. 

Patient motion and penumbra effect. 

What are the 3 ways to decrease penumbra effect?

1) Decrease the focal spot size

2) Increase the focal film distance

3) Decrease the object film distance

4 types of beam limiting devices that decrease scatter radiation.

1) Cones- restricts primary beam to size of cone used.

2) Diaphragms- sheets of lead fitting on tube near tube window, limit the size of primary beam to size of diaphragm being used.

3) Collimators- lead shutters in the tube head. Adjustable and allow visualization of the actual size of the primary beam field. 

4) Filters- thin sheets of aluminum paced over the tube window, absorb the less penetrating (soft) x-rays as they leave the tube head.