OSCE book - Radiology Flashcards
This 16 year old girl is missing her upper left canine. Radiographs are required to determine whether the tooth is impacted/unerupted.
Please seat the patient in the chair and set up the machine ready to take a radiograph of the appropriate area. (N.B you do not have access to a OPT or CBCT)
Props
- PA films
- Occlusal films
- Film holders
- CW rolls
- Gloves
- X ray machine
Radiographs that can be taken are upper PA or upper occlusal view.
PA view has two techniqes, Paralleling technique or bisecting angle technique.
Paralleling technique
1. Allow film holder to sit parallel to the tooth and aim x ray tube head at 90 degree to teh film
2. As it is anterior tooth use blue film holder and smaller sized film (1)
3. Sit patient up straight with head against the head rest and occlusal plane is horizontal
4. Get them to remove anything insde mouth
3. Place film so long axis of film is behind long axis of tooth
4. Patient then bites gently on the film holder to hold it in place
5. Position the ring against the patients skin
6. Align the cone with the film holder ring
7. Select the correct exposure
Bisecting angle technique
- Same set up as parallel
- However film is held against the palatal surface of the tooth with patients finger. Then angle the cone of x ray to 50degrees to the horizontal so that the beam is at 90 degrees to the angle between the tooth and the film packet. The beam must be positioned in the vertical plane to allow the whole of the tooth to be visualised in the film
- Select correct exposure
How do you take a standard upper occlusal view?
When the radiograph of the 16 year old with the missing 23 is developed it is apparent that she has an unerupted permenant canine.
You need to determine the exact position of the tooth. What further radiographs could you take?
Please set up the machine to take this view. When the radiograph is developed, how will you determine whether the tooth is buccally or lingually placed?
Using parallax technique
Can be done on the horizontal plane with
- 2 PA’s
- 2 Occlusal views
Or it can be done on the vertical plane with
- An occlusal and PA
- OPT and a PA/occlusal
Using accroynm PAL. Palatal and lingual comes with us or SLOB (same lingual, opposite buccal)
For example if canine is palatal on the second PA the tooth will move in the same direction as the tube.
The following radiographs have been taken by you in practice.
What is the problem with the images, why has it happened and how can it be avoided?
Image is too dark
Caused by over exposure
Avoid this by checking the exposure is correct
The following radiographs have been taken by you in practice.
What is the problem with the images, why has it happened and how can it be avoided?
Lower canine PA, teeth are elongated and missing the apices
Cause - too shallow beam
To avoid this - correct bisecting angle, increasing the occlusal plane/tub-head angle; correct use of film holder.
The following radiographs have been taken by you in practice.
What is the problem with the images, why has it happened and how can it be avoided?
Bitewings showing severe overlap of the contact points, required teeth also not shown with the premolars missing.
This has happened as the film is too far back in the mouth and the horizontal angle angle is greater or less than 90.
This can be avoided by lining up the film correctly parallel with the mesial surface of the canine and align beam to 90 degrees to arch
This is a radiograph taken of Mr John Smith, DOB 14/2/88 on the 27/3/13
A - What radiographic view is this and how is it taken
B - Please describe this radiograph.
A - This is a posterior anterior view of the mandible. It is taken by positioning the patient so that the line from the outer canthus of the eye to the external auditory meatus is horizontal, and their forehead and tip of the nose touch the film. The tube head is positioned horizontally. The beam is centred on the cervical spine so as to pass between the rami of the mandible
B - This is a posterior - anterior view of the mandible (PA mandible)
- It is acceptable
- Taken of 27/3/13 of Mr John Smith aged 25
- Pt is full dentate
- It shows the whole of the mandible and mid face.
- Clearly visible is a displacement fracture of the right mandibular condyle with significant shortening of ramus height. The ffractured segement is minimallly angulated. Another fracture is visible in the right parasympyseal region.
A - What radiographic view is this?
This is a 30 degree Occiptal mental radiograph (OM)
B - How would you go about describing this radiograph?
C - What interesting features can you see on this view?
This radiograph shows evidence of a previous fracture left zygoma.
The fracture has been reduced but there is still a visible step in the lateral wall of the left maxillary antrum. There are no steps visible in the fronto-zygomatic region or the ZT region. There is a mini bone plate present on the elft anterior maxillary wall. The maxillary antra are clear with no evidence of fluid level.
Please label this ceph.
- Sella turcica
- Maxillary antrum
- Anterior nasal spine
- Posterior nasal spine
- Nasion
- External auditory meatus
- Condyle
- Gonion
- Gnathion
- Frontal sinus
- Infra-orbital rim
- Menton
- Pogonion
A - What view is this
B - Please label this radiograph
A - OPT
You have been appointed radiation protection supervisor in your practice.
What are your responsibilites and what information must your written set of local rules include.
A
A - OPT
B
When describing a lesion on a radiograph. It is usual to cover the following points.
* Radiodensity
* Site
* Size
* Shape
* Outline
* Adjacent structures
With regard to this lesion there is a radiolucent lesion at the angle of the mandible on the RHS, extending from the apex of the lower second premolar right up to the sigmoid notch area. It is multi-locular and has a well corticated margin. It has not resorbed the roots of the adjacent teeth and it is not possible to evaluate its relation to the inferior dental nerve. The lesion is not a normal anatomical structure and is not due to an artefact, hence it is likely to be pathology
C
Common radiolucent lesions in the mandible include.
* Cysts
* Tumours
* Giant cell lesions
* Infections
* Traumatic lesions
* Idiopathic lesions
Common multilocular radiolucent lesions in the mandible inlude:
* Cysts - keratocysts
* Odontogenic tumours - ameloblastomas, Pindborgs tumour (calcifyinf epithelial odontogenic tumour), odontogenic fibroma, odontogenic myxoma
* Central giant cell lesions
A definative diagnosis is only possible after a biopsy
Look at the radiographs below and suggest a differential diagnosis for the appearance in each one
When describing a lesion on a radiograph. It is usual to cover the following points.
* Radiodensity
* Site
* Size
* Shape
* Outline
* Adjacent structures
A
* Radiodensity - radiopaque (same density as root)
* Site - maxillary antrum
* Size - small
* Shape - conical
* Outline -
* Adjacent structures - discontinuity of antrum floor
Likely diagnosis is a displaced root in maxillary antrum with evidence of OAC
B
* Radiodensity - radiopaque (may be surrounded by a thin radiolucent line - but not abvious in this image)
* Site - apex of lower right first molar
* Size - 1cm
* Shape - round lesion appears attached to root
* Outline - well defined
* Adjacent structures - Attached to root, which is obscured.
The likely diagnosis for a well defined radio-opaque lesion at apex of the lower right first molar is benign cementoblastoma (true cementoma). The differential diagnosis is cemental dysplasia usually lower incisor teeth, radiolucent in early stage but radiopaque in later stage.
A - Describe the rating of radiographs
B - Rate the following radiographs
A - Describe the rating of radiographs
B - Rate the following radiographs
A - Describe the rating of radiographs
B - Rate the following radiographs
