Introduction to Radiology and Imaging

Question 1

What is radiology?

Answer 1

Medical discipline using imaging to diagnose and treat disease

Question 2

Modalities used

Answer 2

X-ray
Ultrasound
Computed tomography (CT)
Magnetic resonance imaging  
Nuclear medicine

Question 3

Which modalities use ionising radiation?

Imaging type ?

Answer 3

Plain x-ray - single projection
CT - cross sectional
Fluoroscopy - dynamic
Nuclear medicine - varied

Question 4

Which modality uses high frequency sound waves?

Answer 4

Ultrasound - dynamic

Question 5

What does MRI use?

Answer 5

High strength magnetic field and radio frequency waves

Cross-sectional

Question 6

X-ray and CT images

Answer 6

Air
Lung
Fat 
Water
Soft tissue
Bone
Metal

Question 7

Different planes for brain CT scan

Answer 7

Axial
Sagittal
Coronal

Question 8

Ultrasound

Answer 8

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

Question 9

Contrast

Answer 9

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

Question 10

Benefits of plain x-ray

Answer 10

Quick and cheap
Good for initial examination for lungs and bones
Low radiation dose

Question 11

Negatives of plain x-ray

Answer 11

Ionising radiation
Limited spatial information
Poor examination for soft tissue pathology

Question 12

Ct benefits

Answer 12

Relatively quick scanning of large areas of the body
Good anatomical info in multiple planes
Appropriate for assessment of most acute clinical problems

Question 13

Negatives of CT

Answer 13

Can involve large amounts of ionising radiation
Risk of allergy to iodine content
Poor at assessing the spinal cord and reproductive organs

Question 14

Fluoroscopy benefits

Answer 14

Dynamic real time anatomical assessment
Good for interventional procedures
Low radiation dose

Question 15

Negatives of fluoroscopy

Answer 15

Doses for complex IR can be large
Always need contrast agent
Poor soft tissue assessment and overlapping of anatomy

Question 16

MRI benefits

Answer 16

No ionising radiation
Excellent anatomical detail
Multiple phases enable some functional assessment of tissues

Question 17

Negative MRI

Answer 17

Time consuming and expensive
Safety issues regarding metallic implants
Claustrophobic

Question 18

Ultrasound benefits

Answer 18

Dynamic study - real time assessment
Does not involve ionising radiation
Good for paediatric and antenatal imaging

Question 19

Negatives of ultrasound

Answer 19

Poor assessment of air filled structures and bone
More heavily operator/patient dependent
Attenuation of sound waves limits scan depth

Question 20

Nuclear medicine benefits

Answer 20

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

Question 21

Negatives of nuclear medicine

Answer 21

Scan acquisition is time consuming
Poor resolution compared to alternative cross-sectional imaging
Radiation exposure continues after termination of examination

Question 22

Future ?

Answer 22

Artificial intelligence
Advancing interventional radiology
Molecular imaging and genomics

Question 23

Risks from ionising radiation

Answer 23

Damage to tissue - direct, or indirect from free radicals

Can cause cataracts and hair loss -> severe malignancy and hereditary effects