Sensory Placement & 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 - vertial
- PID/BID alignment
- sensor wire placement
Miscellaneous technique problems related ONLY to PSP & Film images:
- sensor bending
- sensor creasing
- double exposure
- reverse placement
Caused when patients finger is positioned infront of the sensor:
Phalangioma (look for finger bone)
Caused when patient or X-ray tube head moves during exposure:
Movement (causes blurry)
Lateral centered with open mesial contact:
Lateral incisor
Canine & 1st premolar centered with open contact:
Canine/premolar
Anterior receptor edge to middle of canine:
Maxillary/mandibular premolar
Anterior receptor edge to middle of 2nd premolar:
Maxillary/mandibular molar
For an anterior bitewing the anterior plate edge should be:
To middle of most anterior canine
For anterior bitewing, the receptor must be:
Parallel to the teeth of interest
For a vertical bitewing, the 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 small 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 & lingual planes; long axis
Anterior edge of receptor includes distal 1/2 of canine, the premolars & some of molars:
Maxillary premolar PA
For a maxillary premolar PA, the horizontal angle is directed through:
distal of canine/premolar, premolar/premolar & the second premolar/molar contacts
distal of canine/premolar, premolar/premolar & the second premolar/molar contacts
This is the horizontal angle for:
maxillary premolar PA
For a maxillary molar PA, the receptor parallels ___ of molars as well as _____ of molars
Buccal & 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 the receptor parallels _____ of premolars as well as _____ of premolars
Buccal & lingual planes; long axis
Anterior edge of receptor include 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 2nd premolar/1st molar contacts
distal of canine/premolar, premolars and 2nd premolar/1st molar contacts
This is the horizontal angle for:
Premolar bitewing
Where should a cotton role be correctly placed /
Between bite block & opposing teeth
(NOT bite block & imaged teeth)
What is the error seen in this image?
Cotton roll placement between bite block & 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/incisial edge
- patient not biting down
- insufficient vertical angulation paralleling
- sensor not positioned over the apical area in the mouth
- bite block not against occlusal/incisial edge
- patient not biting down
- insufficient vertical angulation paralleling
These may result in:
absence of apical structures
A dropped film corner=
tipping
What is the cause of tipping/dropped film corner?
sensor not placed parallel with occlusal/incisal surface of teeth
What can be seen in this image?
Tipping
For correct horizontal angulation, the central tray should be directed:
between 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 (Distal to mesial)
Is the incorrect horizontal angulation a result of (mesial to distal) or (distal to mesial)?
Mesial to distal
Is the incorrect horizontal angulation a result of (mesial to distal) or (distal to mesial)?
Mesial to distal
Incorrect vertical angulation results in:
- foreshortened images
- elongated images
Excessive vertical angulation results in:
foreshortened
X-ray is perpendicular to the image receptor, but the object is NOT parallel with the image receptor- what may occur?
Foreshortening or elongation
What error can be seen in the following images?
Excessive vertical angulation- foreshortening
What error can be seen in the following images?
Excessive vertical angulation- foreshortening
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 error can be seen in the following images?
Excessive vertical angulation- foreshortening
What error can be seen in the following images?
Excessive vertical angulation- foreshortening
Caused by insufficient vertical angulation:
Elongated images
What error can be seen in the following image?
Insufficient vertical angulation - elongation
What error can be seen in the following image?
Insufficient vertical angulation- elongation
Cone cuts occur with & without:
sensor holder
PID not properly aligned with the sensor holding device from either incorrect XCP assembly or poor alignment of PID with XCP:
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 the sensor holder?
PID not directed at center of film
Label which is an error caused by the thyroid collar & which is the cone cut:
Left- thyroid collar
Right- cone cut
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 & why:
1,2, 3 because post-exposure image processing by the software immediately corrects large exposure discrepancies
What exposure error can be corrected by post-exposure imaging processesing software?
- overexposure
- underexposure
- no exposure
What error can be seen in the following image?
Overexposure
(think over= dark out bc clouds are over the sun)
A high density image is:
overexposed
What factors contribute to an overexposed, high density image?
- increased time
- increased mA
- increased kV
What error can be seen in the image below?
Underexposure
What is the main cause of an underexposed image?
What else can contribute
Main cause: insufficient exposure time
kVp, mA, 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 can 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 the following image?
Post exposure image processing error- (+gain, gamma, -gain)
What error can be seen in the following 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 path of the primary X-ray beam
What error can be seen in the following image?
patient has glasses on
T/F: not removing jewelry risks masking disease
True
