Radiology Flashcards
How do CT scanners damage cells
The radiation from them creates ions and free radicals which have enough energy to break the covalent bonds between DNA strands.
The cell will try and repair this but may be unsuccessful leading to a mutation which is passed onto daughter cells
Why are children more at risk from CT scanners than adults
Children are more sensitive to radiation as they are still growing and have a higher cell production rate
They also have a longer life expectancy than adults, resulting in a larger window of opportunity for expressing radiation damage
May end up receiving a higher dose if the machine is not adjusted to a smaller body
How can we minimise CT radiation exposure in children
Only perform CTs when absolutely necessary
Use non-radiating methods like US or MRI where possible
Adjust machine to minimise dose - child size, organ system and target area
Exposure to ionising radiation as a child increases the risk of brain tumours - true or false
True
Approximately 3 times the risk
Gliomas, schwannomas, meningioma
Exposure to ionising radiation as a child increases the risk of leukaemia - true or false
True
Which neuroimaging procedures are considered safe in children
Cranial US
EEG
MRI (unless they have metal implants or need GA)
What is the main contraindication of X-ray in children
Must consider pregnancy in girls post menarche
Otherwise a relatively low dose of radiation
List conditions which could cause altered consciousness in a child
Sepsis Raised ICP Trauma Hypoglycemia Post-convulsive state DKA Shock Meningitis or encephalitis
What is the first line neuroimaging technique in children with altered consciousness
CT head
Especially in acute setting
Which conditions require neuroimaging in children
New-onset blackouts
History or signs of head trauma / haemorrhage
Acute clinical brain injuries
Raised Intracranial pressure
Intracranial abscess
Altered consciousness of unknown origin
What is the investigation of choice for seizures when EEG/clinical presentation is not diagnostic
MRI scan
MRI scans should be carried out in which children presenting with seizure
Diagnosed with epilepsy before 2 years of age
With a history/EEG suggestive of focal onset
In whom seizures persist following first-line therapy
Which underlying patholgies causing a seizure may be picked up on MRI
Brain haemorrhage - usually a few days post event (consider NAI)
Infection - meningeal enhancement may be seen in meningitis
Tumours - can cause focal seizures
How can CT scans be used in the investigation of seizures
In acute setting it can be used to determine if a seizure has been caused by an acute neurological lesion or illness
Can be used to find underlying pathology if MRI unavailable or contraindicated
CT scans can be useful if the child or young person would require general anaesthetic or sedation for an MRI but not for CT.
What is the primary investigation for head trauma in children
CT
MRI can be added after if more information about the injury is required
Which children should be sent for a CT head within 1hr of presentation
Suspicion of NAI
Post-traumatic seizure, but no history of epilepsy
GCS <14, or for children under 1 year GCS (paediatric) < 15 · At 2 hours after the injury GCS < 15
Suspected open or depressed skull injury or tense fontanelle
Any sign of basal skull fracture (haemotympanum ‘panda’ eyes, cerebrospinal fluid leakage from the ear or nose, Battle’s sign). ·
Focal neurological deficit ·
For children under 1 year, presence of bruise, swelling or laceration of more than 5 cm on the head
Children who do not require an urgent CT within 1hr but have a risk factor present should be monitored for how long
At least 4 hours post head injury
Then considered for CT or discharge depending on how they are
There are a second set of risk factors following head injury and if a child has more than one, they need a CT - what are they
Witnessed loss of consciousness > 5 minutes
Abnormal drowsiness
3 or more discrete episodes of vomiting
Dangerous mechanism of injury (high-speed road traffic accident either as a pedestrian, cyclist or vehicle occupant, fall from height of > 3 metres, high speed injury from an object
Amnesia (antegrade or retrograde) lasting > 5 minutes
Should be sent for CT within an hour of the risk factors being identified
When a child is being monitored post-head injury, which factors would make them eligible for a head CT
If during this observation period they experience further episodes of vomiting or abnormal drowsiness or their GCS drops below 15
What is the one condition that would require a head CT in a child with a head injury even if they didnt have any of the risk factors
If they are on anticoagulant therapy due to hemorrhage risk
All kids on these therapies should get a head CT within 8 hours of injury
When would a child get a skeletal survey
If there was suspected NAI
Which factors can pre-dispose a child to cervical spine injury
Trisomy 21, osteogenesis imperfecta, achondroplasia, and other rheumatological, congenital, metabolic or genetic conditions or previous cervical spine surgery
What are the criteria for X-ray in suspected C-spine injury
Unable safely assess range of movement
(cervical tenderness/intoxication/not alert)
Unable actively rotate neck 45 degrees
GCS 14-15
Dangerous mechanism injury:
