AI- rCM

Question 1

what is attenuation a combination of

Answer 1

absorption and scatter

Question 2

what does att depend on

Answer 2

density/atomic number/thickness of tissue

Question 3

define what RCM’s do ?

Answer 3

RCM’s artificially adjust the density and atomic number of the structure to increase /decrease x-ray absorption

Question 4

define more radiolucent (see through image easier) ?

Answer 4

decreasing density and atomic number

Question 5

define more radiopaque

Answer 5

increasing density and atomic number

Question 6

requirements for RCM ?

Answer 6

• Easy to administer
• Easily visualised on imaging
• Tolerated by the patient
• Non-toxic
• Rapidly eliminated when necessary
• Cost effective
• Stable compound
• Non-carcinogenic

Question 7

how can a rcm be administered ? (5 ways)

Answer 7

Orally- gastro-intestinal
(GI) tract

Intravascularly- blood vessel (vein/artery)

Intrathecally- spinal canal

Rectally- rectum

body cavity or joint- uterus, ovarian tube etc

Question 8

name 3 types of RCM ?

Answer 8

Negative Contrast Media

Barium Sulphate (BaSO4)

Iodinated

Question 9

what is negative contrast media usually used for ?

Answer 9

Gases used for
GI tract and Bladder imaging

Question 10

what is barium sulphate used for

Answer 10

usually used for GI tract examinations

Question 11

what can iodinated be used for

Answer 11

versatile in multiple modalities

(Fluoro, angiography, X-ray and CT)

visibility of organs and blood vessels in medical images, such as X-rays and CT scans

Question 12

give 2 negative contrast medias

Answer 12

air

co2

Question 13

give the major facts regarding negative contrast media ?

Answer 13

• All negative contrast agents are
  gases
• Radiolucent with low atomic
  number
• Low density
• Attenuate less X-rays than
  surrounding tissue, appears
  darker on the resultant image

Question 14

how is air used as an RCM

Answer 14

• inspired or pumped in manually eg- double contrast barium enemma

Question 15

how is oxygen used an rcm

Answer 15

• introduced into body cavities

Question 16

how is carbon dioxide used as a rcm

Answer 16

• pumped in during a barium
  enema, injected into the colon after the barium liquid to improve the quality of the X-ray

-during angiography
(alternative to iodinated
contrast)

Question 17

give two examples of positive contrast media

Answer 17

• barium sulpahte iodine- based

Question 18

main facts regarding positive contrast media

Answer 18

• Radiopaque with higher atomic
  number (than body tissues)
• High density
• Attenuate more X-rays than
  surrounding tissue, appears bright on
  the resultant image
• E.g.
• Barium Sulphate
• Iodine

Question 19

properties of barium sulphate

Answer 19

• Predominantly used in Fluoroscopy for GI
  tract examinations
• White, crystalline compound
• Radiopaque
• Excellent coating properties
• Insoluble – forms suspension in water
• Orally or rectally administered
• Stable

Question 20

what is double contrast media

Answer 20

• Uses positive AND
  negative contrast media
  together

Question 21

iodine rcm properties;

Answer 21

• Iodine based (a.k.a iodinated RCM)
• Colourless liquid
• Radiopaque
• Soluble in water
• Excreted via the kidneys in urine

Question 22

how can iodine based contrast be administered ? (all 5)

Answer 22

• Oral
• Intravascular (artery or vein)
• Intracavital
• Rectal
• Intrathecal

Question 23

what is special about iodinated contrast media ?

Answer 23

can be either ionic or non ionic

Question 24

what differentiates different types of iodinated contrast media

Answer 24

• Physical and chemical characteristics
• Osmolality
• Viscosity
• Iodine Content

Question 25

why are different types of iodinated contrast media used ?

Answer 25

* Different types used for different body systems and examinations

Question 26

state some facts regarding iodinated contrast media (ionic) ?

Answer 26

* Breaks apart (dissociates) when placed in fluid creating charged particles (ions) * This increases the number of particles in the vascular system **BUT...** * Ions that are created can destroy electrical charges associated with the brain and heart * Disruption is called neurotoxicity * Considerably toxic * Higher incidence of patient experiencing adverse reactions

Question 27

state some facts regarding iodinated contrast media (non ionic) ?

Answer 27

-Nothing happens when placed in fluid (no charged particles) * Low osmolality * Comparatively less toxic * Lower incidence of patient experiencing adverse reactions (3%)

Question 28

define hypertonic

Answer 28

Solution has HIGHER osmolality (little water) than the cell, this is called Hypertonic, water moves from cell to solution

Question 30

how can viscosity affect RCM ?

Answer 30

The viscosity of an RCM can affect the time it takes to inject

Question 31

difference between positive and negative contrast media ?

Answer 31

Negative contrast media: Less opaque than body tissues, and absorbs less radiation than surrounding tissues. Negative contrast media appears darker grey or black than its surroundings on an image.(air,eg) Positive contrast media: More opaque than body tissues, and absorbs more radiation than surrounding tissues. Positive contrast media appears white on an image. (barium, iodine)