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X-Ray; Types, Indications, Procedures, Adverse Effects

X-Ray is a form of electromagnetic radiation with very high frequency and energy. X-rays lie between ultraviolet radiation and gamma radiation on the electromagnetic spectrum. A bone x-ray uses a very small dose of ionizing radiation to produce pictures of any bone in the body. It is commonly used to diagnose fractured bones or joint dislocation. Bone x-rays are the fastest and easiest way for your doctor to view and assess bone fractures, injuries, and joint abnormalities.

Chest x-ray (frontal view)

Lateral CXR rarely indicated and should be discussed with a consultant
Pre-operative CXR NOT to be done routinely at any age.

Respiratory indications

Infection – to exclude pneumonia
Inhaled foreign body >most lodge in the intrathoracic tracheobronchial tree.
Need films in full inspiration and expiration to demonstrate air trapping or collapse.

Chest trauma

for an air leak, haemothorax or wide mediastinum.
Rib views rarely indicated.

Pneumothorax – full inspiratory films adequate

Asthma/ Bronchiolitis – Consider only if

diagnosis unclear
SEVERE attack – not responding to standard therapy
possible air leak.
NB. Focal signs +/- fever is most likely due to mucus plug and viral illness rather than pneumonia.

Cardiac indications

Clinical cardiomegaly or heart failure.

Large thymic shadow is normal under the age of 2 years.
Normal cardio-thoracic ratio 0.5 ( infants up to 0.6 )

Heart murmurs – If careful examination suggests innocent murmur, no need for urgent CXR – but arrange appropriate follow up.
Hypertension – CXR is seldom useful.

Neonates (<6wks)

Septic screen – CXR indicated unless clear focus elsewhere
Respiratory distress – to exclude congestive cardiac failure or cardiomegaly

Limb x-rays & other imaging modalities

Comparative and Stress Views – rarely necessary and should not be routinely taken. However may be useful for complex fractures (after consultation) if initial x-rays unclear (eg. elbow)

Specific Indications/Contraindications:

Trauma

Xray of the suspected fracture as well as the joints above and below if signs and symptoms suggest bone injury. If in doubt about the site of injury, seek senior help rather than x-raying the entire limb.

Follow up films after reduction of a displaced # should be done to assess the position.

If a fracture is clinically suspected but x-rays normal, discuss with the consultant and if in doubt treat as if fracture present.

Additional views are sometimes useful (eg. radial head views) and other fractures (eg. stress # or toddler #) might need Bone Scan or CT (these requests should be discussed with ED consultant & orthopedics and appropriate follow-up arranged).

Nonaccidental injury (to be seen by registrar or consultant)

If child > 2yr x-rays should be limited to sites of clinically suspected injury.
Complete Skeletal Survey if child < 3 years (not available after-hours unless urgent)
Bone Scan (if < 3yr) – can complement skeletal survey

Suspect NAI if:

metaphyseal
marked or unusual epiphyseal separation
of spine or ribs
unexplained skull intracranial- injury

Acutely painful hip

Plain xrays (AP and frog-leg lateral) will demonstrate slipped upper femoral epiphyses, Perthe’s and fractures.
USS/ bone scan may be indicated depending on clinical findings (discuss with specialty team or treating consultant).

Acutely swollen joint

Osteomyelitis

Early XR often shows no bony abnormality but may have deep soft tissue swelling.
Bone scan/MRI will demonstrate an abnormality earlier than XR (needs orthopedic team input)

Septic Arthritis

Normal XR or Bone scan does not exclude septic arthritis.
Ultrasound may be useful to demonstrate a joint effusion and soft tissue abnormality (discuss with orthopedic team or treating consultant)

Metabolic disorders

Rickets – XR of one wrist +/- one knee is most useful.
Osteogenesis Imperfecta – the very low threshold for an x-ray.

Pulled Elbow

If the injury mechanism and examination suggest radial head subluxation, an x-ray is unnecessary.

Abdominal x- rays

Suspected bowel obstruction/ perforation

A plain AXR will demonstrate most obstruction (dilated loops).
An erect AXR is indicated to exclude perforation

Suspected intussusception

A normal AXR does not exclude intussusception but is useful to exclude perforation or bowel obstruction in suspected intussusception.

Foreign Bodies

Ingested opaque FB requires a single survey AP film (mouth to anus).
Routine follow-up films are NOT indicated unless clinical symptoms develop.

Suspected Abdominal Mass

Initial investigation – plain AXR and ultrasound, then further as indicated

Blunt abdominal trauma

Needs early assessment by General Surgery.
CT scan is the best modality for diagnosing the intra-abdominal injury.

Unnecessary AXRs

If unsure whether AXR would be helpful – ask consultant or registrar for advice

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AXR not indicated for:

Vague central abdominal pain.
Gastroenteritis.
Haematemesis.
Pyloric stenosis.
Uncomplicated appendicitis.
Chronic constipation, encopresis or enuresis (in the Emerg. Dept setting )

Abdominal & pelvic ultrasounds

If an urgent ultrasound is necessary, the patient should be discussed with the surgeon &/or the treating consultant.

Specific indications

Suspected intussusception

Ultrasound by experienced operators is the diagnostic modality of choice for intussusception.
However these patients are potentially unstable and should only be sent for an ultrasound after appropriate resuscitation including an IV, and treatment as well as notifying the surgeons and the treating consultants

Suspected pyloric stenosis

Ultrasound is a very sensitive test for pyloric stenosis

Abdominal pain

or iliac or pelvic pain in the pubertal female with possible ovarian pathology (requires full bladder), or if potential renal tract obstruction, early ultrasound recommended.
Abdominal ultrasound is a useful tool for many other abdominal pain presentations however the urgency of the request should be proportional to the symptoms.

Urinary tract imaging

Bacteriologically proved first UTI usually requires renal tract US (particularly <4 years old) but only occasionally MCU

Intracranial and skull imaging

Specific Indications for Skull X-rays

Only indicated in well-appearing children

NAI

as part of the skeletal survey (more sensitive than Bone Scan for skull fracture)

Plagiocephaly

Craniosynostosis (prematurely fused sutures) accounts for the minority of abnormal skull shapes. An SXR is useful to evaluate sutures but is ideally done via outpatient follow-up (Craniofacial or neurosurgical unit- RCH Deformational head clinic)

There are no other routine indications for skull XRay and any such requests should be discussed with the treating consultant.

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Specific Indications for CT Brain

The treating consultant should discuss the need for all CT scans.
The Neurosurgical team should be involved before CT for the unwell or potentially unstable patient who may need urgent interventions.

Head Trauma

Useful for rapid diagnosis of suspected intracranial injuries and is the preferred investigation if clinical evidence of intracranial injury.
Clinical deterioration is usually an indication for repeat CT examination.

Depressed conscious level of unknown cause

CT scan is indicated after appropriate stabilizing treatment.

Headaches

Clinical evaluation is the most important factor in determining the need for imaging.

CT scan indications

Abnormal neurological signs.
Unexplained decrease in visual acuity.
Headaches with seizures.
Marked change in behavior.
Enlarging head
Symptoms of raised intracranial pressure.
The increasing frequency of unexplained headaches or new onset of a severe or persistent headache

Seizures

Persistent abnormal neurological signs/impaired conscious state.
Focal neurological signs or EEG findings.
Failure to respond to anticonvulsant therapy.
Neurocutaneous lesions.

Abnormal Size / Shape Of Skull

Clinical examination is usually sufficient to diagnose an abnormality of the skull.

Large head – rapidly enlarging head needs imaging-US or CT scan.
Small head – nearly always pathological secondary to abnormal brain growth. Evaluate with CT or MRI scan, which is usually best organized via the managing outpatient physician

Specific Indications for cranial ultrasound

Large head

Rapidly enlarging head with open fontanelle.

Neurological concerns in neonates/ infants

Clinical usefulness will vary depending on the size of fontanelle and indications and should be discussed with the radiologist.

Spinal imaging

Any investigations other than plain x- rays should be ordered in consultation with the treating consultant &/or the appropriate specialty team.

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NB. Down syndrome children have increased the risk of C1-2 instability.

Specific indications in Trauma:

Cervical spine

A normal Spinal Xray series or CT scan will not allow clearance of the neck in the unconscious or uncooperative patient

Thoraco-Lumbar Spine

Children poorly localize the level of the injury, therefore imaging the full length of thora columbar spine may be necessary (discuss with treating consultant).
If neurological signs present do a CT or MRI scan after consultation with Neurosurgery.