Introduction to Radiology and Imaging Flashcards
What is radiology?
Medical discipline using imaging to diagnose and treat disease
Modalities used
X-ray Ultrasound Computed tomography (CT) Magnetic resonance imaging Nuclear medicine
Which modalities use ionising radiation?
Imaging type ?
Plain x-ray - single projection
CT - cross sectional
Fluoroscopy - dynamic
Nuclear medicine - varied
Which modality uses high frequency sound waves?
Ultrasound - dynamic
What does MRI use?
High strength magnetic field and radio frequency waves
Cross-sectional
X-ray and CT images
Air Lung Fat Water Soft tissue Bone Metal
Different planes for brain CT scan
Axial
Sagittal
Coronal
Ultrasound
High frequency sound waves are emitted via an ultrasound transducer
‘Echoes’ are reflected back and a representative image is displayed in real time
Sound waves are attenuated and reflected according to tissue type, frequency and distance travelled
Soft tissue, fat and fluid filled structures are particularly well visualised
Flow through vessels can be assessed through the Doppler effect
Contrast
Delineate anatomy and improve detection of pathology
Can be used in any modality according to clinical question
Administered intravenously, orally, rectally or via tubes/drains
Benefits of plain x-ray
Quick and cheap
Good for initial examination for lungs and bones
Low radiation dose
Negatives of plain x-ray
Ionising radiation
Limited spatial information
Poor examination for soft tissue pathology
Ct benefits
Relatively quick scanning of large areas of the body
Good anatomical info in multiple planes
Appropriate for assessment of most acute clinical problems
Negatives of CT
Can involve large amounts of ionising radiation
Risk of allergy to iodine content
Poor at assessing the spinal cord and reproductive organs
Fluoroscopy benefits
Dynamic real time anatomical assessment
Good for interventional procedures
Low radiation dose
Negatives of fluoroscopy
Doses for complex IR can be large
Always need contrast agent
Poor soft tissue assessment and overlapping of anatomy
MRI benefits
No ionising radiation
Excellent anatomical detail
Multiple phases enable some functional assessment of tissues
Negative MRI
Time consuming and expensive
Safety issues regarding metallic implants
Claustrophobic
Ultrasound benefits
Dynamic study - real time assessment
Does not involve ionising radiation
Good for paediatric and antenatal imaging
Negatives of ultrasound
Poor assessment of air filled structures and bone
More heavily operator/patient dependent
Attenuation of sound waves limits scan depth
Nuclear medicine benefits
Large number of tracers available to assess different tissues
Provides anatomical and functional info
Usually allows more definitive assessment of pathology identified over other modalities
Negatives of nuclear medicine
Scan acquisition is time consuming
Poor resolution compared to alternative cross-sectional imaging
Radiation exposure continues after termination of examination
Future ?
Artificial intelligence
Advancing interventional radiology
Molecular imaging and genomics
Risks from ionising radiation
Damage to tissue - direct, or indirect from free radicals
Can cause cataracts and hair loss -> severe malignancy and hereditary effects
