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Radiology > March 3- Radiographic Errors Finals > Flashcards

March 3- Radiographic Errors Finals Flashcards

1
Q

What are the characteristics of a perfect radiograph.

A
  1. Detail, Definition, Density, Contrast.
  2. No placement, handling or processing errors
  3. Area of interest and landmarks visible (with correct size and contour)
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2
Q

What are the two factors affecting detail

A
  1. KVP
  2. Developing
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3
Q

4 Factors affecting definition

A
  1. Distance factors
  2. Focal spot size
  3. Receptor type
  4. Motion
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4
Q

4 Factors affecting density

A
  1. Kvp
  2. mAmp
  3. Exposure time
  4. Processing
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5
Q

4 Factors affecting contrast

A
  1. Kvp
  2. Receptor type
  3. Processing
  4. Subject contrast
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6
Q

When a radiograph isn’t perfect like we want it to be what are some things we need take into account.

A
  • Is the error minor?
  • Is the error major necessitating a retake?
  • What caused the error?

• How can I ensure that the error will not occur on the retake film?

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7
Q

Give some examples of Patient Preparation Errors?

A
  • Forgetting to:
    • Remove glasses
    • Remove dentures
    • Remove piercings (Tongue and Nose rings
  • Thyroid collar/ lead apron placed incorrectly/ BID not taking into account the thyroid collar/lead apron
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8
Q

What are some examples of Patient Errors?

A

Image is unsharp and blurred due to
• Patient movement
• Receptor movement
• BID movement/drifting

  • Patient not biting down on bite block.
    • leads to incorrect orientation of XCP holder.
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9
Q

what would cause a blurry image like this?

A

The patient moving as X-ray is taken

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10
Q

What is caused this image error?

A

Patient not biting down on bite block

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11
Q

What are some examples of receptor errors?

A

Improper placement of adhesive bite block on receptor

Putting PSP plate or film in backwards

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12
Q

What happens if the adhesive biteblock isn’t placed properly on the biteblock?

A

You could miss the apices of the teeth you are looking at OR you could miss the incisal edges

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13
Q

How are adhesive bite blocks properly attached to receptors/plates?

A
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14
Q

How is an adhesive bite block properly attached to a direct receptor?

A

For direct sensors the edge of the adhesive biteblock for anterior periapicals should be placed where the dots start-(about 3 mm above the edge of the sensor)- otherwise incisal edge will be missing on image.

If placed too down you’ll miss apices

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15
Q

How can you tell if film has been placed backwards in the mouth?

A

You will get the trade mark “tire treads” or “cobblestone” markings

OR

You could get an error an Dot Artifact from Dot in the Slot film holder. (you want the dot to be superimposed away from root apices)

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16
Q

How can you tell if a PSP plate has been put in the mouth backwards?

A

You will see a radiopaque circle on the radiograph.

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17
Q

What happens as a result of holder assembly error.

A

the most common problem with holder receptor errors is cone cutting.

ALWAYS MAKE SURE THE RECEPTOR IS IN THE MIDDLE OF THE HOLDER OR ITS NOT ASSEMBLED PROPERLY

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18
Q

Receptor placement error can result in missing apices.
How can this be avoided/corrected?

A
  • Position receptor in highest part of palate/deepest part of lingual sulcus
  • Use steeper vertical angulation
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19
Q

Incorrect receptor placement can result in you missing the specific area of interest being missed. How can this be avoided/corrected?

A
  • Adhere to performance criteria for a full mouth series. (on moodle )
  • If an isolated tooth required: place tooth of interest in center of image.
20
Q

It is often difficult to position a direct sensor in a person with a small mouth or shallow palate. How can this be fixed?

A

• Easier with a PSP plate or film as thinner and can be brought more anterior to capture the distal of the canine

21
Q

If sensor/plate/film is not placed correctly or if the BID isn’t oriented properly it can cause contacts to be overlapping.

A

Position the BID so that the X-ray beams pass through the contacts. This can be done by orienting the plate PARALLEL to the LINGUAL SURFACE OF THE TEETH and ensuring BID is perpendicular to the plate.

22
Q

How should horizontal bitewings with tabs be positioned to avoid overlapping contacts?

A

Like this:

23
Q

Sometimes if receptor/patient aren’t positioned properly it can result in a tipped occlusal plane. How can this be avoided?

A
  • Solution:
  • Ensure patient’s occlusal plane is parallel to floor.
  • Ensure the edge of the receptor is placed parallel to the occlusal surface of the teeth.
24
Q

Receptor placement error can cause foreshortening of the teeth on the radiograph. Why does this happen?

A
  • Paralleling technique-

Receptor not parallel to long axis of tooth.

  • BA technique-

Too great a vertical angulation of BID.

25
Q

Receptor placement error can also cause Elongation.
What causes this?

A

Causes:

• Paralleling technique- Receptor not parallel to long axis of tooth

• BA technique-
Not enough vertical angulation of BID.

• Excessive film/psp plate bending

26
Q

Beam alignment errors can result in cone cutting because only part of the receptor recieves radiation, how can this be resolved?

A

Solutions:

  • Carefully align collimator and ring notches
  • Ensure XCP holder is correctly assembled
  • Correct size and orientation of collimator
27
Q

how can the collimator and ring indicator be used to avoid beam alignment errors?

A

By lining up the notches on both the collimator and the ring indicator.

and making sure the ring indicator and the BID are parallel with equal spacing on each side.

28
Q

Why are collimators used and what is one potential downside?

A

They increase the likelihood of a cone cut but reduce the radiation exposure five-fold compared to a circular collimator.

29
Q

When should you NOT use a rectangular collimator?

A
  • Don’t use a collimator for occlusal views, bitewings with tabs, bisecting angle periapical technique.
30
Q

How can cone cuts be avoided when doing bisecting angle radiographs?

A

Solution

Ensure blue line on Snap-R-Ray holder is just within the BID

Your index finger can help you do this by being positioned at the blue line on the bite block can aid the ant/post positioning of the BID

31
Q

How can cone cuts be avoided when using bisecting angle technique?

A

Follow these rules for the Mandibular and reverse them for the maxillary

32
Q

Double Images occur when:

• Already exposed film or plate is exposed again. Not possible with a direct sensor

A

Solutions:

  • Use clearly marked containers for unexposed and exposed films.
  • Ensure “erase” function on psp scanner is activated
33
Q

Blank film can occur for a number of reasons including the following:

A

Machine not turned on
No X-rays hit the film

Expose button not fully pressed down

Film not exposed/ another film double exposed.

Not arming computer beforehand (for direct sensors)- wait for audible prompt before exposing

34
Q

Why do images come out looking too pale?

A

Causes:

  1. Insufficient Radiation (underexposed)
    check: exposure factors-Kvp/ mA, locator ring to far from skin, exposure setting too low, exposure button not held for full “beep” 2.Processing error (Film) (underdevelopment)

check: dark room process. 3.Excessive thickness of patient tissues

35
Q

Why do images come out looking too dark?

A

Causes

• Too high a radiation exposure

check mA, kVp, source film distance, exposure time.

  • Dark room Factors (film) overdevelopment
  • Thin patient tissues
36
Q

What are causes of low contrast?

A

Causes:
• Processing error

• Film fogging

37
Q

Receptor handling error can create a number of artifacts which can make radiographs harder to interpret. What are some some potential handling errors which occur with film?

A
  • Pressure marks from Nails, teeth, pen
  • Moisture Contamination
  • Saliva / Cavicide spray
  • Paper remnants

• Bend Marks

38
Q

What is this an receptor handling error an example of?

A

Pressure marks from nails, teeth and pens.

39
Q

What is handling error an example of?

A

bending the film

40
Q

what happened to this solid state receptor?

A

This solid state receptor was dropped.

41
Q

what happened to this psp plate?

A

this PSP plate was scratched.

42
Q

What happened with this direct sensor radiograph?

A

The cable from the sensor is superimposed in the radiograph

43
Q

What are some direct sensor do’s and dont’s

A
44
Q

What are some other receptor do’s and dont’s?

A
45
Q
A

Radiology (13 decks)

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