Contrast

Question 1

what is radiolucent

Answer 1

when x-rays can pass through

Question 2

what is radio-opaque

Answer 2

when x-rays pass through at a lower extent

Question 3

what property is similar for soft tissues

Answer 3

absorption

Question 4

what absorbs more bone or soft tissue

Answer 4

bone

Question 5

what are the two types of contrast

Answer 5

+ and -

Question 6

describe negative contrast

Answer 6

• not used
• radiolucent (x-rays pass through)
• less dense than soft tissues
• absorbs less radiation than ST
• structure becomes dark

Question 7

describe positive contrast

Answer 7

• absorbs more x-rays than ST
• more dense than ST
• radio-opaque
• structures are white
• used in RT

Question 8

what contrast is barium sulphate

Answer 8

it is a positive agent which is found as a suspension used for the GI tract

Question 9

what happens if the blood brain barrier is crossed

Answer 9

increased chance of substances passing through. the active section of the tumour has a high metabolic rate which has a faster uptake of contrast

Question 10

what type of contrast is iodine based agents

Answer 10

positive

Question 11

describe iodine based agents

Answer 11

• liquid form
• used in GI tract, kidneys and head and neck
• can be ingested, injected or used in the body cavities
• used for localisation

Question 12

are ionic agents used in RT

Answer 12

no they have a higher osmolar contrast which dissociate into positive and negative ions

Question 13

what are iso-osmolar agents

Answer 13

non ionic, which have no osmosis occur due to the concentration being relative to plasma.

Question 14

an example of iso-osmolar

Answer 14

omni-opaque 300

Question 15

describe non ionic agents

Answer 15

they contain a side chain which dissolves in water. It is a low osmolar media so the osmolarity side effects are reduced

Question 16

what is the criteria for contrast

Answer 16

• little/no side effects
• concentrated in the area of interest
• easily administered
• stable
• appropriate storage
• appropriate viscosity
• non toxic/carcinogenic
• rapidly eliminated by the body

Question 17

what are the risk factors

Answer 17

• extremities of age
• previous reactions
• allergies or asthma
• cardiovascular disease
• diabetes
• dehydration
• anxiety
• blood disorders

Question 18

what are the minor complications (no risk)

Answer 18

• anxiety
• local pain
• nausea
• flushing
• uritiaria or itching

Question 19

what are the intermediate complications (medical attention)

Answer 19

• more severe minor complications
• mild bronchospasm
• mild hypotension

Question 20

what are the severe complications (urgent)

Answer 20

• severe minor complications
• respiratory collapse
• cardiovascular collapse
• convulsions
• unconsciousness
• cardiac arrest
• laryngeal oedema
• cardiac dysrhythmia

Question 21

what are the pre cautions

Answer 21

• no previous reaction
• emergency drugs close by
• monitor patient closely
• must stay within the department for 30 minutes afterwards