Sensor Placement Beam Align

Question 1

MISCELLANEOUS TECHNIQUE
PROBLEMS
(11)

Answer 1

1. Phalangioma
2. Movement
3. Sensor placement
4. Beam angulation - Horizontal
5. Beam angulation - Vertical
6. PID/BID alignment
7. Sensor wire placement
8. Sensor bending
9. Sensor Creasing
10. Double exposure
11. Reversed placement

Question 2

8. Sensor bending
9. Sensor Creasing
10. Double exposure
11. Reversed placement
    #8 - #11 relate to (2) images

Answer 2

PSP and film

Question 3

1. Phalangioma
   – Cause:

Answer 3

Patient’s finger positioned in front of the sensor

Question 4

2. Movement
   – Cause:

Answer 4

Patient or x-
ray tube head moves
during exposure

Question 5

Sensor placement is MORE critical with

Answer 5

solid-state sensors
There is a smaller active image capture area

Question 6

Maxillary Premolar PA
(4)

Answer 6

• Receptor parallels B and Li planes
  of premolars
• Receptor parallels long axis of
  premolars
• Anterior edge of receptor includes
  distal ½ of canine, the premolars
  and some of molars
• Horizontal angle directed through
  distal of canine/premolar,
  premolar/premolar and the 2nd
  premolar/ molar contacts

Question 7

Maxillary Molar PA
(4)

Answer 7

• Receptor parallels B and Li planes of molars
• Receptor parallels long axis of molars
• Anterior edge of receptor includes distal ½ of 2nd
  premolar and as much of the molars as possible
• Horizontal angle directed through distal of 2nd
  premolar/1st molar and the intermolar contacts

Question 8

Premolar Bitewing (BW)
(4)

Answer 8

• Receptor parallels B and Li planes of premolars
• Receptor parallels long axis of premolars
• Anterior edge of receptor includes mesial ½ of canine, the premolars and some of molars
• Horizontal angle directed through distal of canine/premolar, premolars and the 2nd premolar/ 1st molar contacts

Question 9

Incorrect Placement
*Cotton roll placement

Answer 9

Between biteblock and opposing teeth;
NOT between biteblock and imaged teeth

Question 10

Incorrect Sensor Placement
Absence of apical structures
(2)

Answer 10

– Cause: Sensor not positioned over the apical
area in the mouth
– Bite block not against occlusal/incisal edge;
OR patient not biting down

Question 11

ncorrect Sensor Placement
“Tipping”
i.e., Dropped film corner
– Cause:

Answer 11

Sensor not
placed parallel with the
occlusal / incisal
surface of teeth

Question 12

Set the Horizontal Angle
* The Central Ray should
be directed

Answer 12

between
the interproximal
contacts of interest

Question 13

4. Horizontal Angulation
   * Central ray has to
   be projected

Answer 13

perpendicular to
sensor

Question 14

Incorrect Horizontal
Angulation
* Cause:

Answer 14

Central ray
is not projected
perpendicular to
sensor

Question 15

Incorrect Vertical Angulation
Foreshortened images
(2)

Answer 15

– Cause: Excessive
vertical angulation
– Beam is
perpendicular to the
sensor

Question 16

Incorrect Vertical Angulation
Foreshortened images
– With smaller active area,

Answer 16

parts of image are missed

Question 17

Incorrect Vertical Angulation
Elongated images
(2)

Answer 17

– Cause: Insufficient
vertical angulation
– Beam is
perpendicular to the
tooth/teeth

Question 18

6. PID ALIGNMENT
   PROBLEMS
   Cone cuts with sensor holder
   – Cause:

Answer 18

PID not properly aligned
with the sensor holding device
from;
- incorrect XCP Assembly
- poor alignment of PID with XCP

Question 19

6. PID ALIGNMENT PROBLEMS
   * Cone cuts without
   sensor holder
   – Cause:

Answer 19

PID not
directed at center of
film

Question 20

II. EXPOSURE PROBLEMS
(5)

Answer 20

1. Overexposed
2. Underexposed
3. No exposure
4. Sensor wire superimposition
5. Post exposure

Question 21

1. Overexposed
2. Underexposed
3. No exposure
4. Sensor wire superimposition
5. Post exposure

PROBLEMS 1, 2, & 3 are less dramatic
because

Answer 21

post-exposure image processing by
the software immediately corrects large
exposure discrepancies.

Question 22

HIGH DENSITY Image
1. Overexposed
(3)

Answer 22

a. Increased time
b. Increased mA
c. Increased kV

Question 23

EXPOSURE PROBLEMS
Overexposed images
– Cause:

Answer 23

Excessive
exposure to x-
radiation from
excess time, kVp,
mA, or any
combination of
these

Question 24

TIME AND EXPOSURE FACTOR
PROBLEMS
* Underexposed image
(2)

Answer 24

– Cause: Insufficient
exposure time, kVp, mA,
or any combination of
these;
– in SoD Radiology Clinic,
time is the main cause

Question 25

Underexposed (3)

Answer 25

* Insufficient time * Insufficient mA * Insufficient kVp

Question 26

* Excessive tube-receptor distance; related to

Answer 26

inverse square law

Question 27

I. EXPOSURE PROBLEMS 5. Post Exposure Image Processing (2)

Answer 27

Faulty program software image settings: calibration files Faulty program software image settings: + gain, gamma, - gain

Question 28

III. Patient Preparation PROBLEMS (2)

Answer 28

Failure to remove a non-fixed item from patient that may be in path of the primary x-ray beam examples: gum, candy, piercings, eyeglass frames, et cetera

Question 29

I. MISCELLANEOUS TECHNIQUE PROBLEMS 8. Sensor Bending – Cause:

Answer 29

Sensor is bending toward source because of impingement against palate

Question 30

I. MISCELLANEOUS TECHNIQUE PROBLEMS 8. Sensor Creasing/scratch marks – Cause:

Answer 30

damage to storage phosphors so there is no signal to the area with damaged pixels

Question 31

. MISCELLANEOUS TECHNIQUE PROBLEMS 10. Double exposure (2)

Answer 31

– Cause: Sensor is accidentally exposed twice – Not possible with contemporary CMOS capture software

Question 32

I. MISCELLANEOUS TECHNIQUE PROBLEMS 11. Reversed Placement – Cause:

Answer 32

Sensor is placed back to front in sensor holder

Question 33

. MISCELLANEOUS TECHNIQUE PROBLEMS 11. Reversed Placement – Not possible with contemporary CMOS sensors because of

Answer 33

poor unstable fit in biteblock