Sensor Placement and Beam Positioning Problems: Flashcards
PSP:
Phosphor Storage Plate
CCD:
Charge Coupling Device
CMOS:
Complementary Metal Oxide Semiconductor
Shadow Casting Principles include:
- beam angulation
- Receptor placement
Miscellaneous technique problems include:
- phalangioma
- movement
- sensor placement
- beam angulation- horizontal
- beam angulation- vertical
- PID/BID alignment
- Sensor wire placement
Miscellaneous technique problems related ONLY to PSP and film images:
- Sensor bending
- Sensor creasing
- Double exposure
- Reversed placement
Caused when patients finger is positioned in front of the sensor:
Phalangioma (look for finger bone)
Caused when patients or X-ray tube head moves during exposure:
Movement (just kinda blurry)
Lateral centered with open mesial contact:
Lateral incisors
Canine and 1st PM centered with open contact:
Canine & premolar
Anterior receptor edge to middle of canine:
Maxillary premolar/Mandibular premolar
Anterior receptor edge to middle of second premolar:
Mandibular molar/ maxillary molar
For an anterior bitewing, the anterior plate edge should be:
middle of most anterior canine
For an anterior bitewing, the receptor must be:
Parallel to the teeth of interest
For a vertical bite wing, anterior receptor edge is at the:
mesial of mandibular first molar
Sensor placement is more critical with:
solid-state sensors
Why is sensor placement more critical with solid-state sensors?
There is a smaller active image capture area
What type of image is being shown?
bitewing
What type of image is being shown?
Periapical image
For a maxillary premolar PA: The receptor parallels ____ & ____ of premolars as well as the _____ of premolars
Buccal and Lingual planes; long axis
Anterior edge of receptor includes distal 1/2 of canine, the premolars and some of molars:
Maxillary Premolar PA
For a maxillary premolar PA, the horizontal angle is directed through:
distal of canine/premolar, premolar/premolar and the 2nd premolar/molar contacts
distal of canine/premolar, premolar/premolar and the 2nd premolar/molar contact
This is the horizontal angle for:
Maxillary Premolar PA
For a maxillary molar PA, the receptor parallels _____ of molars, as well as ___ or molars
Buccal and lingual planes; long axis
Anterior edge of receptor includes distal 1/2 of second premolar and as much of the molars as possible:
Maxillary molar PA
For a maxillary molar PA, the horizontal angle is directed through:
Distal of 2nd premolar/1st molar and the intermolar contacts
Distal of 2nd premolar/1st molar and the intermolar contacts
This is the horizontal angle for:
Maxillary Molar PA
For a premolar bitewing there receptor parallel _____ of premolars, as well as ____ of premolars
Buccal and lingual planes; long axis
Anterior edge of receptor includes mesial 1/2 of canine, the premolars and some of the molars:
Premolar bitewing
For a premolar bitewing, the horizontal angle is directed through:
distal of canine/premolar, premolars, and 2ndPM/ 1st molar contacts
distal of canine/premolar, premolars, and 2ndPM/ 1st molar contacts
This is the horizontal angle for:
Premolar bitewing
Where should a cotton role be correctly placed?
Between bite block and opposing teeth (Not bite block and imaged teeth)
What is the error seen in this image?
Cotton roll placement between bite block and Imaged teeth
What may cause the absence of apical structures?
- Sensor not positioned over the apical area in the mouth
- Bite block not against occlusal incisal edge
- Patient not biting down
- Insufficient vertical angulation paralleling
- Sensor not positioned over the apical area in the mouth
- Bite block not against occlusal incisal edge
- Patient not biting down
- Insufficient vertical angulation paralleling
These may cause:
abscence of apical structures
A dropped film corner=
tipping
What is the cause of tipping/dropped film corner?
Sensor not placed parallel with the occlusal/incisal surface of teeth
What can be seen in this image?
Tipping/ dropped film corner
For correct horizontal angulation, the central should be directed:
between the interproximal contacts of interest
For correct horizontal angulation, the central ray has to be projected:
perpendicular to the sensor
What error is seen in this image?
Central ray is not projected perpendicular to sensor (mesial to distal)
What error is seen in this image?
Central ray is not projected perpendicular to sensor (mesial to distal)
Is the incorrect horizontal angulation a result of (mesial to dista)l or (distal to mesial)?
Mesial to distal
Incorrect vertical angulation results in:
- foreshortened images
- Elongated images
Excessive vertical angulation results in:
Forshortened images
X-ray is perpendicular to the image but the object is not parallel with the image receptor. What may occur?
forshortening or elongation
What error can be seen in the following images?
excessive vertical angulation- forshortening
What is the issue with foreshortened images?
With smaller active area, parts of image are missed
What can be seen in the following images?
excessive vertical angulation- foreshortening
Caused by insufficient vertical angulation:
Elongated images
What can be seen in the following image?
Elongation- insufficient vertical angulation
Cone cuts occur with and without:
sensor holder
PID not properly aligned with the sensor holding device from either incorrect XCP assembly or poor alignment of PID with XCP results in:
Cone cuts with sensor holder
What error can be seen in the following image?
PID alignment problem- cone cut with sensor holder
Cone cuts =
PID alignment problem
What is the cause of cone cuts WITHOUT sensor holder?
PID not directed at center of film
Label which is the thyroid collar error and which is a cone-cut error:
Left Thyroid collar
Right Cone cut Error
What error can be seen in this image?
Sensor wire superimposition
Exposure problems include:
- overexposed
- underexposed
- no exposure
- sensor wire superimposition
- post exposure
- overexposed
- underexposed
- no exposure
- sensor wire superimposition
- post exposure
Out of these problems, which are less dramatic and why?
1,2,& 3 because post-exposure image processing by the software immediately corrects large exposure discrepancies
What exposures errors can be corrected by post exposure image processing software?
- overexposure
- underexposure
- no exposure
What error can be seen in the following image?
Overexposure
A high density image is:
over exposed
What factors contribute to an overexposure high density image?
- increased time
- increase mA
- Increased kV
What error can be seen in this image?
Underexposure
What is the MAIN cause of an under exposed image? What else can contribute?
Main cause: Insufficient exposure time
- kVp or mA, and excessive tube receptor distance (related to inverse square law)
- insufficient time
- insufficient mA
- insufficient kVp
These would result in what type of image?
underexposed
Sensor wire superimposition may be considered a ____ problem
exposure
What error can be seen in the following image?
Post-exposure image processing error (Calibration files)
What error can be seen in this image?
Post-exposure image processing error (+ gain, gamma, -gain)
What error can be seen in this image?
Post-exposure image processing error (+ gain, gamma, -gain)
The main patient preparation problem:
failure to remove a non-fixed item from patient that may be in the path of the primary x-ray beam
What error can be seen in the following image?
Patient glasses on
T/F: Not removing jewelry risks masking disease
true