Intro to radiography

Question 1

Clinical context of radiography

Answer 1

state of patient
relevant previous history
other investigations

Question 2

Diagnostic context of radiography

Answer 2

differential diagnosis?
what questions are we trying to answer?
why is there doubt?- another test if 1st test is normal

Question 3

x rays densities

Answer 3

black- air
dark grey- fat
light grey- soft tissue
white- bone/ metal

Question 4

pros of radiography

Answer 4

quick, cheap, easy, universal, well understood

Question 5

cons of radiography

Answer 5

2D, artefact, radiation

Question 6

abnormality during x ray

Answer 6

loss of silhouette sign - cannot see border

Question 7

common uses of radiography

Answer 7

fracture, failure vs pneumonia, bowel obstruction

Question 8

CT

Answer 8

x ray source
exposure at different angles generating 2D- multiply to make 3D 
same 4 densities 
IV and oral contrast 
toxic, can damage kidneys

Question 9

modern CT

Answer 9

volume of data for reconstruction, fast- can track contrast and recreate image with structure with most contrast (isolate)

Question 10

Stroke

Answer 10

urgent CT to decide on thrombolysis- clot busting drug 
if haemorrhage (white on CT) no thrombolysis because can bleed to death

Question 11

CT windowing

Answer 11

4000 shades of grey but eye can only see 50 so you can window to select part to display

Question 12

CT common uses

Answer 12

trauma, cancer staging, abdominal sepsis

Question 13

CT pros

Answer 13

quick, good spatial detail, reconstructions

Question 14

CT cons

Answer 14

poor tissue contrast (better with contrast media)

high radiation dose (often needed repeated exams)

Question 15

Fluoroscopy

Answer 15

continuous screening of patients with x ray with some contrast
inject or drink barium
dynamic assessment

Question 16

fluoroscopy common uses

Answer 16

upper GI, angiography, renal tract imaging

Question 17

fluoroscopy pros

Answer 17

adaptable

structure and function

Question 18

fluoroscopy cons

Answer 18

high radiation dose (repeats)
invasive
planar imaging

Question 19

Ultrasound

Answer 19

piezoelectric crystals to produce US wave
work out depth of structure
electric signals to sound then reflects back- electric current

Question 20

US common uses

Answer 20

abdominal pain
renal tract imaging
musculoskeletal

Question 21

US doppler effect

Answer 21

to measure blood flow

find tumours as lots of blood flow is there, when sound comes towards you the waves compress

Question 22

US pros

Answer 22

very safe
cheap
portable
good for superficial vessels

Question 23

US cons

Answer 23

variable
artefact
limited info

Question 24

MRI

Answer 24

magnet to align protons
radiowaves sent to excite them, let them relax (relaxes at different rates)
collect emitted energy

Question 25

other applications of MRI

Answer 25

time delays to see how mobile protons are- diffusion weighted
find direction and map- diffusion tensor
analyse chemical signature

Question 26

MRI common uses

Answer 26

brain and spine imaging
MSK
tumour characterisation

Question 27

MRI pros

Answer 27

structure and function

no ionising radiation

Question 28

MRI cons

Answer 28

time consuming
claustrophobia
artefact
magnets

Question 29

Nuclear medicine

Answer 29

not good for structure
can repeat image
large areas/ specific organs

Question 30

Nuclear medicine and CT

Answer 30

PET-CT- extra dose

SPECT- volume imaging like normal CT but with isotope

Question 31

Nuclear and CT common uses

Answer 31

TUMOURS 
bone imaging
lungs
renal function
thyroid

Question 32

nuclear and CT pros

Answer 32

structure and function

relatively specific- narrow Dx

Question 33

nuclear and ct cons

Answer 33

ionising radiation
time consuming
poor spatial resolution

Question 34

interventional radiology

Answer 34

new field- using imaging to guide therapy- often angiography and US

Question 35

image guided surgery

Answer 35

neuronavigation

virtual training

Question 36

risks of radiography

Answer 36

radiation
contrast media nephrotoxic 
invasive procedures
artefact- misdiagnosis, false reassurance, further tests 
incidental findings

Question 37

what can we do

Answer 37

sensible referrals
optimise techniques
ALARA as low as reasonably achievable
conscientious vetting- ‘scan if you must’

Question 38

radiology and law

Answer 38

ionising radiation (medical exposure regulations) 2000 
concerned with patient dose and radiology staff 

referrer required to provide sufficient clinical info in order that the practitioner can make a decision about justifying the medical exposure