Radiographic Technique 1 Flashcards
What are the three kinds of intra-oral radiographs?
Peri-apical
Bite-wings = horizontal or vertical
Occlusal = maxilla and mandible
What are the six kinds of extra-oral radiographs?
Dental Panoramic Tomogram - DPT Lateral Cephalogram Postero-anterior Mandible Reverse Townes Lateral Oblique Mandible Occipito-mental Views of Facial Bones
Why would you take a peri-apical? (8 points)
Detect apical inflammation/infection to include cystic changes Assess periodontal problems Trauma-fractures to tooth and/or surrounding bone Tooth Morphology pre extraction Presence/position of unerupted teeth Endodontics Pre/post apical surgery Evaluation of implants
What two techniques are there for taking a peri-apical?
Paralleling techniue
Bisected angle technique
What are the three differences between paralleling and bisected angle technique?
PARALLELING BISECTED ANGLE
Uses holders to facilitate Can be done without a holder
positioning
Film parallel to tooth Operator dependent
Accurate/reproducible Not reproducible
image
Name the 8 points describing Paralleling Technique.
- Uses holders to facilitate positioning
- Allows accurate geometry of image
- Film parallel to tooth
- X-ray beam perpendicular to tooth/film
- Minimises magnification
- Accurate reproducible image
- Holders are bulky and may not be tolerated by patient. Can reduce dose to patient by reducing repeats and does not expose patients fingers (see bisected angle)
- This is the technique of choice
What are the holders made up of?
A bite block - retains the film packet
An indicator arm/rod - fits into the bite block
An aiming ring - slides into the arm to establish alignment of cone with film.
What are the two types of holders?
Anterior and posterior
What are the two types of receptor?
Film or digital
Describe the film/tooth relationship.
The vertical plane of the film should be positioned so that is is parallel to the long axis of the tooth.
The horizontal plane of the film must be parallel to the horizontal plane of the tooth under examination.
The x-ray beam should be at which position to the tooth/film?
Right angles, 90 degrees
What two things affect the image size?
The x-ray source (focal point) to the film distance.
The object to the film distance.
How can magnification be reduced?
The use of long source to film distances and the distance from the x-ray source to the tooth should be as long as possible.
Use of short object to film distance minimises magnification as well as decreasing the distance between the film and the tooth.
Difference between a well taken and a badly taken image?
A well taken image will give you accurate information - think technique, positioning, exposure, processing
A badly taken image will give you reduced information or no information at all - remember this when viewing all your patients images.
What are the barriers to good positioning?
Mouth size, gag reflex, film size and digital sensor size and shape.
