Radiology Tutorial (including selection and perception) Flashcards
What are the three biological effects and risks of ionozing radition (3)
- Somatic Deterministic
- Genetic Stochastic effects
- Somatic Stochastic effects
Define Somatic Deterministic effects of radiation (4)
- Where there is a threshold dose, below which the effect will NOT occur
- E.g. Sun burn, cataract formation
- Severity is proportional to the dose
- Expect those effects with high radiation doses
Define Genetic Stochastic effects of radiation (3)
- Can occur spontaneously or be caused by radiation
- DNA damage in reproductive cells may lead to congenital abnormalities or mental retardation
- Hence why there is a maximum permissible dose for pregnant woman, but this is not relevant to dental radiographs
Define Somatic Stochastic effects of radiation (4)
- Stochastic effects are subject to the laws of chance
- E.g. induction of leukaemia
- ANY dose, large or small, may produce these effects i.e. there is no threshold dose
- Lower doses have lower chance but not no chance
What is the overall risk to the UK population from dental radiographs? (2)
- Low but accounts for 10 fatal malignancies per year
- Hence the need to keep all radiation exposures as low as reasonably achievable
Before taking a radiograph in CCDH what must you do? (4)
- Examine the patient before referring to radiology
- Check that there are not any previous images that could answer your question
- Provide sufficient clinical information to allow justification of your request
- Check hospital or department guidelines for imaging
What needs to be minimised in terms of radiographs for the patient? (4)
- Repeating exposures unnecessarily
- Undertaking those radiographs where the results are unlikely to affect patient management
- Doing the wrong investigation
- Over-investigating
What are the bitewing protocols for Screening for Caries? (3)
- High caries risk: 6 monthly bitewings until no new or active lesions are apparent
- Medium caries risk: annual bitewings until no new or active lesions are apparent
- Low caries risk: approx. 12-18month intervals in primary dentition then 2year intervals in the permanent dentition (longer intervals if there is explicit evidence of continuing low caries risk, be aware of changes which will affect caries risk in adults e.g. decreased manual dexterity, xerostomia and dietary changes)
What radiographs are required in periodontal disease? (3)
- Bitewings will show bone levels if bone loss is not too severe
- Periapical is required if a periodontal/endodontic lesion is suspected
- Panoramic/OPT of good quality may offer a dose advantage over a large no. of intra-oral radiographs and may be considered if available
What radiographs are recommended for endodontics? (4)
- A recent, good quality, periapical before starting
- Radiograph required to determine the working length
- A post-op radiograph is needed to act as a baseline for the assessment of subsequent bony healing
- Further post-op radiographs are taken annually for up to four years
In general what is the rule for differential diagnoses? (3)
- Shouldn’t have more than three
- Put them in order of relevance
- If you don’t know, give a general area for what it could be
If a fracture does not penetrate all the way through the bone, what is it called? Who is this common in? (2)
- Greenstick fracture
- Common in children
What are you looking for when describing a radiographic lesion? (4)
- Radiolucent/radiopaque
- Size
- Margins – corticated?
- Density
In a fracture what does radiolucency often imply? (1)
- Implies pathological fracture
Give a differential diagnosis for:
Patient cannot wear lower denture any longer as does not fit
Radiograph shows large radiolucency with ragged ill defined margins
Cortical plate thinned, jaw expanded
- Differential diagnosis – malignancy
- Answer: Metastatic deposit in jaw from 1⁰ kidney malignancy
Describe the typical appearance of a keratocyst on a radiograph (4)
- Oval
- Well defined
- Coricated margins
- Expansion to varying degrees
Describe the typical appearance of fibrous dysplasia on a radiograph, who does it usually manifest in and how does it look then? (2)
- Very radiolucent and expanded jaws
- Usually manifests in children, looks more radiolucent in children than adults
What does a sarcoma cause? (1)
- Causes bone cells to produce malignant cells
What is a giant cell lesion? (1)
- Benign lesion of the jaw
Where can malignancy start and how does this affect the radiograph? (2)
- Malignancy can start in overlying oral soft tissues and then penetrate into bone
- Bone destruction would taper as you go further from origin
What is a neurofibrosarcoma? (1)
- Nerve related malignancy
What is a lymphoma? (1,1+2,1)
- Malignant neoplasm arising from lymphocytes
- WHO classified lymphomas into three broad groups according to cell type:
- B, T, NK (natural killer)
- Plus less common groups e.g. Hodgkin Lymphoma - Blood related malignancy
Lymphomas affecting the oral cavity are mainly what type? (1)
- B-Cell Lymphoma
Who are Non-Hodgkin Lymphomas more common in? What are they often associated with? (2)
- More common in immunosuppression/HIV and autoimmune disease
- Often associated with Epstein-Barr Virus
Who do Hodgkin Lymphomas predominately affect? Often with history of? (5)
- Males predominately
- May have family history
- History of EBV
- Rarely history of HIV
- Rarely the prolonged use of growth hormone
Clinically, where to lymphomas usually present? And occasionally? (2)
- Pharynx or palate
- Occasionally tongue, gingivae or lips
What is a differential diagnosis of Lymphoma? (3)
- HL early stage disease: radiotherapy or chemotherapy
- HL later stage disease: combination chemotherapy alone
- NHL: combination of radiotherapy or chemotherapy, monoclonal antibodies, immunotherapy and haematological stem cell transplantation
What is the prognosis for lymphomas? (2)
- HL has a 90% five year survival
- NHL has a >50% five year survival
Where do most Metastatic Oral Neoplasm appear? Especially where? (2)
- Bone
- Especially the mandibular premolar or molar area or condyle
Where do most metastases originate from? (9)
Carcinomas of the:
- Breast
- Lung
- Kidney
- Thyroid
- Stomach
- Liver
- Colon
- Bone
- Prostate
How many metastatic oral neoplasms are the first manifestation of the original tumour? (1)
- One third
What are, often, the symptoms of metastatic oral neoplasms? (1)
- Asymptomatic
What symptoms can other metastatic oral neoplasms present with? (7)
- Pain
- Parasthesia or hypoesthesia
- Swelling
- Tooth mobility
- Non-healing extraction sockets
- Pathological fracture
- Radiolucency or radiopacity
What is the prognosis of metastatic oral neoplasms? (1)
- Grave. The time from diagnosis of the metastasis to death is often months.
What does a corticated margin imply about a lesion? (1)
- Slow growing
What is a residual cyst associated with? (1)
- Extracted tooth
What is a radicular cyst associated with? (1)
- Non vital tooth