HS1-3 Introduction to Radiology

Question 1

How are X-rays obtained?

Answer 1

obtained using ionizing radiation passed through patient to expose a specialized detector

Question 2

What is the more technical term for “x-rays?”

Answer 2

plain film radiography

Question 3

What are the advantages of plain film radiography?

Answer 3

widely available
inexpensive
low radiation
excellent visualization of radiolucent/radiodense structures

Question 4

What are the disadvantages of plain film radiography?

Answer 4

limited anatomic detail of soft tissues and fluid

Question 5

How do radiodense structures appear on radiographs?

Answer 5

white

Question 6

Give three examples of radiodense structures.

Answer 6

metal
calcium
bone

Question 7

How do radiolucent structures appear on radiographs?

Answer 7

black

Question 8

Rank the five most common tissues/structures visualized in plain film radiography in terms of appearance.

Answer 8

air (black), fat (dark gray), soft tissue/organs/fluid (light gray), calcium (white), metal/contrast (super white)

Question 9

What are contrast agents?

Answer 9

radiodense suspesions (of iodine or barium) which are injected/instilled into the body during imaging to better visualize anatomic structures

Question 10

How does contrast appear in radiography?

Answer 10

white

Question 11

How is contrast administered? (2)

Answer 11

injected in vascular structures (intravenously or intra-arterially) OR orally

Question 12

How is injected intravascular contrast metabolized by the body?

Answer 12

filtered and excreted by the kidneys, which in turn allows for excellent visualization of the GI tract

Question 13

What does “CT” stand for?

Answer 13

computerized tomography

Question 14

How are CT scans obtained?

Answer 14

obtained using thin beam of ionizing radiation passed through patient to expose large bank of computerized detectors generating sequential cross-sectional tomograms

Question 15

In terms of patient position, how are CT scans obtained?

Answer 15

patient is supine such that scans are obtained in the axial plane

Question 16

What are the advantages of CT? (3)

Answer 16

fine anatomic detail of tissues
display in variable anatomic planes
eliminates superimposition of anatomic structures

Question 17

What are the disadvantages of CT? (4)

Answer 17

high radiation
must transport patient to scanner
expensive
contrast might be needed

Question 18

What is the density characterization by CT?

Answer 18

air (black)
fat (dark gray)
fluid (medium gray)
soft tissues (light gray)
bone (white)
metal/contrast (super white)

Question 19

How are ultrasounds obtained? (2)

Answer 19

by passing ultrasonic sound waves through the body; different tissues in the body absorb and reflect the sound waves differently

Question 20

What are the advantages of ultrasound? (5)

Answer 20

no radiation
safe
inexpensive
can image in any plane
exquisite detection of fluid

Question 21

What are the disadvantages of ultrasound? (3)

Answer 21

user dependent
cannot penetrate bone
cannot penetrate air

Question 22

How does fluid appear on an ultrasound?

Answer 22

appears black

Question 23

How does soft tissue appear on an ultrasound?

Answer 23

appears medium gray

Question 24

How are MRIs obtained? (2)

Answer 24

using strong magnetic fields and radiofrequency pulses to energize H+ ions in the body; energy released by H+ ions is used by computer to generate images

Question 25

What are advantages of MRI? (3)

Answer 25

no radiation relatively safe exquisite tissue detail, especially soft tissue

Question 26

What are two contraindications for MRI?

Answer 26

pacemakers | some implanted metallic devices

Question 27

What are two disadvantages of MRI?

Answer 27

claustrophobia | expensive

Question 28

What do the terms T1 and T2, in the context of MRI, refer to?

Answer 28

variable radiofrequency pulses used to create different appearing signals from the tissues

Question 29

How does fluid appear in T1 weighted images?

Answer 29

fluid is DARK

Question 30

How does fluid appear in T2 weighted images?

Answer 30

fluid is WHITE

Question 31

What is nuclear medicine/imaging?

Answer 31

targeted imaging by injecting radiolabelled drugs which are attracted to specific organs or tissues of interest

Question 32

In nuclear imaging, once a radiolabelled drug is uptaken by the target, what happens?

Answer 32

once uptaken by target organ, gamma radiation is emitted when is then imaged by a gamma camera

Question 33

What does SPECT stand for?

Answer 33

single photon emission computed tomography

Question 34

What is SPECT?

Answer 34

a method in which gamma cameras, measuring emitted gamma radiation, can be used to create multiple tomograms in different planes — similar to CT, except gamma radiation is used instead of x-rays

Question 35

What does PET stand for?

Answer 35

positron emission tomography

Question 36

What is PET?

Answer 36

a variant of nuclear imaging in which positron-emitting agents and positron-detecting cameras are used instead of gamma radiation/cameras

Question 37

What is an advantage of nuclear medicine?

Answer 37

evaluates function as well as structure

Question 38

What are two disadvantages of nuclear medicine?

Answer 38

less anatomic detail | moderate radiation dose

Question 39

How are angiograms obtained?

Answer 39

by rapidly injecting contrast agent into artery and taking rapid series of radiographs to allow for visualization of the arterial system

Question 40

What are the advantages of angiography? (2)

Answer 40

allows excellent visualization of arterial system | helps to guide arterial interventions/therapies

Question 41

What are four disadvantages of angiography?

Answer 41

invasive expensive high radiation dose contrast may be needed

Question 42

(T/F) Contrast is exclusively used in CT.

Answer 42

False, it is also used in angiography.

Question 43

Rank the radiographic imaging methods in terms of radiation dose, from least to highest.

Answer 43

ultrasound/MRI < radiography < nuclear medicine < CT < angiography

Question 44

Rank the radiographic imaging methods in terms of cost, from least to highest.

Answer 44

radiography < ultrasound < CT/nuclear medicine < MRI/angiography