Wk 3 Flashcards
What is the error in this PA radiograph
The film is placed too posterior and does not have a clearance above the occlusal cusps of 2.5mm
What is dropped film corner and what angle technique is it most commonly seen in?
Dropped film corner is caused due to teh finger technqiue used by patients to hold the film in place during a bisecting angle technique
What is the error in this PA radiograph
Dropped film corner
What is the error in this PA radiograph
the film was placed too high causing a space of greater than 2.5mm above the cusps which can effect the capturing of the apical structures
What is the error in this PA radiograph
It is caused due to patient not biting onto the bite block resulting in a lack of capturing the apices
What is the error in this PA radiograph
Absence of the apical regions of the tooth
What is the error in this PA radiograph
Cone cutting
What is the error in this PA radiograph and what can it be caused from
It is an overlapping of the buccal and lingual cusps caused when the horizontal angle technique is not done correctly
What is the error in this PA radiograph and why can that lead too this image forming?
It is caused due to reversed conventional film resulting in the lead foil pointing towards the PID. The lead foil allows absorbing any unnecessary radiation exposure to the patient
What is the error in this PA radiograph
Digital film is placed towards PID
What is the error in this PA radiograph
This is due to a lowering in the angulation of the PID in bisecting angle technique causing a elongation in the image
What is the error in this PA radiograph
Increased angulation in the PID in bisecting angle technique causing a foreshortening in the image
What is the error in this PA radiograph
Blurring of image caused by patient movement
What is the error in this PA radiograph
Double exposure of the same film
What is the error in this PA radiograph
Cobalt chrome partial denture kept in patient mouth
What is the error in this PA radiograph
Thyroid shield
What is the error in this PA radiograph
Film bending
What is the error in this PA radiograph
Phalangioma
What is the error in this bitewing radiograph
Too posterior
What is the error in this bitewing radiograph
Too anterior
What is the error in this bitewing radiograph
Cone cutting
What is the error in this bitewing radiograph
Poor horizontal angulation
What is the error in this bitewing radiograph
Radiolucency of dentures
What is film density
Film density represents the darkness of the radiographic image
If the density of the image is too high what kind of image will we get?
Dark
If the density of the image is too low what kind of image will that give us
Bright
What are the 4 factors that may influence density of the film
- Patient size
- Exposure settings
- Object density
- Film fog
If a skinny patient is exposed with high KvP, mA, and exposure time how will this impact the density of the image vs a patient who is heavier is exposed with lower radiographic settings?
Skinny patient= high density in image
Larger patient= low density in image
How does object density effect film density
Higher object density reduces film density and vice versa
What is film fog caused from and how can it effect the density of the image
Film fog can be caused from scatter radiation, improper film storage, improper safe lighting, and using old films which can cause a high density in the film
What is contrast
Contrast refers to the differences in film densities between various regions of the radiograph
What is another name for high contrast images
Short gray scale
What are high contrast images in general
High contrast images represent shades off grey, light and dark surfaces
Help detect carious lesions
What are low contrast images?
Images that have a variation in shades of grey which is beneficial in detecting periodontal diseases
What 3 factors may influence the contrast of the image?
Exposure settings
Film processing and storage
Film fog
What is the speed of a film
Speed refers to the amount of radiation required for the film to produce a radiograph with appropriate density
What speed film has the greatest speed
F Speed Film
What is projection geometry
Is the relationship between the source, X-ray beam, and tooth being radiographed and the position of the film
What are 5 important situations that need to be considered to achieve an optimal radiograph?
Small focal spot
Target- tooth distance is large
Tooth-Film distance is short
Tooth and film are parallel
X ray beam passes perpendicular to the tooth and film
What is sharpness of an image?
Sharpness of an image is the measure of the details presented of an object in a radiograph
What are 6 Marion factors that influence sharpness
Small Focal spot
Target-tooth distance large
Tooth- film distance small
Film- small grains and double emulsion can reduce sharpness
Patient motion
Identifying screens
What is magnification
Is the increase in the size of the image
Do we get a smaller or larger magnification with the film being positioned close to the tooth
Larger image
Do we get a smaller or larger image when the PID is placed further away from the tooth
Smaller
What is distortion of an image
Distortion is referred to the change is the shape of an object
What 2 factors can lead to distortion of an image
- If film and tooth are not parallel to each other
- Poor vertical angulation or horizontal
What are the general steps in making radiation exposure to the patient
- PPE
- Seating the patient
Upright position
Place lead apron if required
Head rest perpendicular to the floor
Mid sagital plane pereipindicular to the floor
Occusal surface is to be parallel to the floor(mx. Told forwards md. Tilt back
Remove glasses and non fixed appliances
Discuss the procedure with patient
Check the X-ray unit settings
Place films into patient mouth
Position PID or head of tube
Expose patient with radiation
What are the indications for Periapical radiographs
- Developing periodontal diseases
- Monitoring periodontal health
- Endodontics
- Trauma
- Developmental anomalies
- Impacted teeth
- Implants
What are the two techniques used for taking a PA
Bisecting angle technqiue
Paralleling technique
Briefly describe bisecting angle technique
The bisecting angle technique is a technique in which the mean angle of the tooth and the mean angle of the film are not parallel to each other and the film is positioned close to the tooth to form a large magnification
Describe the head positioning of the patient in bisecting angle technique
- Mid sagital plane must be perpendicular to the floor
- If taking a maxillary radiograph patient must tilt their head down
- If taking a mandibular radiograph then patient is required to tilt their head back
- Placing the head rest perpendicular to the floor is critical
What are the two film holders used in bisecting angle technique
Snap a ray
Haemostat with rubber bite block
What is film #0 used for
In children
What is film #1 used for
Anterior PA for adults or bite wings in mixed dentition
What is number #2 film used for
Posterior teeth PA and bite wing
Occlusal radiographs for children
What is number 3 film used for
To capture greater number of teeth in a PA or bitewingPA especially in larger patients
What is a number 4 film used for
Occlusal radiographs in adults
What are the advantages of using bisecting angle technique
Easy and simple process
What are the disadvantages of dissecting angle technique
- Distortion of image
- Impossible to form reproducible images
- Vertical angulation may result in foreshortening or elongation
- Periodontal bone level may be poorly captured
- Cone cutting may occur
- Horizontal and vertical trenhqiues are very difficult to master therefore may increase errors
- Poor horizontal angle technique may result in overlapping image
Briefly explain paralleling technique?
Parallel technique requires the long axis of the film to be parallel with the long axis of the tooth which requires the film/bite block to be placed far away as possible to make sure the film and tooth are parallel
What two instruments used for parallel technique
Rinn-XCP
Kiki-bite
What is another name for parallel technique
Long cone
What are the advantages of parallel technique?
What are the disadvantages of parallel technique
Positing bite block may be challenging for inexperienced operators
anatomy of mouth may make the technique impossible
Positioning the holders in lower third molar may be difficult
What are the indicators of using bisecting angle technique
Shallow floor of the mouth and palate
Tori palatineus
Gaging patient
What are the advantages of parallel technique
