Radiology 2 Flashcards by Hannah McKinnon

What view is this?

Intra-oral: Peri-apical

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What view is this?

Intra-oral: Bitewing (horizontal)

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What view is this?

Intra-oral: Bitewing (vertical)

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What view is this?

Intra-oral: Occlusal (maxilla)

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What view is this?

Intra-oral: Occlusal (mandible)

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What view is this?

Extra-oral: DPT (dental panoramic tomogram) - can be called OPT/OPG

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What view is this?

Extra-oral: Lateral cephalogram

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What view is this?

Extra-oral: Postero-anterior mandible

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What view is this?

Extra-oral: Lateral oblique mandible

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What view is this?

Extra-oral: Occipital-mental views of facial bones

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Why might you take a peri-apical radiograph?

+ Detecting apical inflammation/infection
+ Assess periodontal issues
+ Trauma-fractures to tooth and/or surrounding bone.

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What is the exposure time on a DPT?

X-ray tube rotates round the patient’s head with a constant long exposure of 14 seconds forming a panoramic image of the patient’s teeth and supporting structures.

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When would you take a lateral cephalogram?

+ Used extensively in orthodontics to assess the relationship of the teeth to the jaws and the mandible to rest of the facial skeleton.
+ Used in surgical planning of the nose and lips.

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When would you take a postero-anterior mandible ?

+ Used for showing a mandible fracture
+ Requested in conjunction with a DPT

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When would you take a lateral oblique mandible?

+ Commonly done for children that cannot tolerate a bitewing radiograph.
+ Can be used for adults with mandible fracture when DPT is not available.

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When would you take Occipital-mental views of facial bones?

+ Commonly done in the first instance when a patient reports to A&E following facial trauma.
+ Shows fractures of the orbits, maxilla and zygomatic arches.

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How many views are taken for the Occipital-mental views of facial bones?

+ Two views are taken, the first with the beam angled at 10 degrees and the second with the beam angled at 30 degrees.
+ Take the films erect (patient stood up) as this can help demonstrate fluid levels in the antra.

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The closer the object is to the receptor, the better the…

detail on the image.

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What document would help decide which radiograph was most appropriate?

FGDP Selection Criteria for Dental Radiography

Two main intra-oral techniques

+ Paralleling technique
+ Bisected angle technique

Paralleling technique

Standard intra-oral technique
+ Uses holders to facilitate positioning
+ Receptor parallel to tooth
+ Accurate/reproducible image

Bisected angle

When patient can’t tolerate a holder in their mouth (can also be used during endodontic procedures).
+ Can be done without a holder
+ Operator dependent
+ Non reproducible

What are holders made up of?

+ A bite-block (retains the receptor)
+ An indicator arm/rod (fits into the bite-block)
+ An aiming ring-slides onto the arm to establish alignment of collimator with receptor

Anterior holder

Posterior holder

What is the receptor?

Describe the receptor-tooth relationship

+ The vertical plan of the film should be positioned so that it is parallel to the long axis of the tooth/teeth. + The horizontal plane of the film must be parallel to the dental arch under examination.

What can vertical angulation (downwards) result in?

Vertical angulation is incorrect positioning of the X-ray tube and result in elongation of the of the tooth structures

What can vertical angulation (upwards) result in?

Vertical angulation is incorrect positioning of the X-ray tube and result in fore-shortening of the of the tooth structures.

What can horizontal angulation of the X-ray tube result in?

Blurring of the tooth structure

What are the two main factors that effect image size?

+ X-ray source (focal spot) to receptor distance. + Object (tooth) to receptor distance

How does X-ray source (focal spot) to receptor distance affect image size?

Object to film to source distances?

Short object to film distance, and a long source to object distance.

Image receptor orientation for posterior teeth

Horizontal (landscape)

Image receptor orientation for anterior teeth

Vertical (portrait)

Why is this a poor x-ray?

Vertical angulation of the beam has foreshortened the teeth and separated the cusps.

Why is this a poor x-ray?

Horizontal overlap of the teeth caused by horizontal angulation of either the receptor or the beam.

Why is this a poor x-ray?

Vertical angulation of the be a, and also an appearance called cone cutting. This is caused when the corners of the collimator have not been touching the guiding ring and absorbed the radiation preventing the receptor from being exposed and forming the image.

Which x-ray is poor and why?