Safety

Question 1

What are the types of radiation damage and what do they mean?

Answer 1

Deterministic - dose dependent, exceeding dose will harm (think like UV, tanning, sunburn)

Stochastic - no dose associated, singular exposure can harm (think of The Hulk)

Question 2

tell me 4 tissues with particular sensitivity to radiation?

Answer 2

testes/ovaries, lymphoid tissue, bone marrow, intestine

Question 3

what are the Canadian limits on radiation exposure?

Answer 3

annual: 50 mSv
5 yr: 100 mSv
(if preggers, 5 yr = 4 mSv)

Question 4

What does ALARA mean? explain it in more detail

Answer 4

As Low As Reasonably Achievable

reduce time (retakes, mAs), increase distance (inverse square law), increasing shielding

Question 5

How do we monitor radiation exposure?

Answer 5

radiation dosimeters

Question 6

shielding (gloves, gowns, thyroid protectors, leaded glasses) protects you from what?

Answer 6

scatter

Question 7

How do you decrease time exposed to radiation?

Answer 7

decrease mAs, minimize retakes, rotate technical staff

Question 8

how do you increase your distance from radiation exposure?

Answer 8

minimize contact restraint, maximize distance (exit room for ex), positioning devices and sedation

Question 9

what information goes on the radiographic log?

Answer 9

owner/patient info, technique used, measurements of animal (where applicable), # of images produced

Question 10

what information goes on the actual radiograph?

Answer 10

date, patient record number/other patient ID

Question 11

With ultrasound, there is a loss of _____ during its path through tissue.

Answer 11

signal intensity

Question 12

what factors affect image during ultrasound?

Answer 12

tissue density
frequency of probe
depth of tissue
focus
gain (TGS)
frequency
depth

Question 13

define these terms:
hyperechoic
hypoechoic
anechoic
isoechoic

*remember that these are relative terms, except for anechoic

Answer 13

hyperechoic: brighter
hypoechoic: darker
anechoic: black
isoechoic: same as adjacent tissues

Question 14

Computed tomography (CT)… what is it?

Answer 14

ionizing radiation like radiographs, rotating gantry with both generator and detector. xrays pass thru subject over full circumference, detector measures attenuation, computer produces a volume of voxels –> 3D image produced

Question 15

tell me the advantages and disadvantages of CT scans.

Answer 15

Advantages:
- superior contrast resolution
- eliminate superimposition
- multiplanar reconstruction

disadvantages:
- anesthesia
- greater exposure to radiation
- expensive
- lots of data

Question 16

Magnetic resonance imaging (MRI)…. what is it?

Answer 16

no radiation - uses strong magnets
magnets lines hydrogen up, radio frequency pulses cause disruption in alignment, realignment is measured (depends on amount of H+ in tissue type)

Question 17

tell me about the advantages and disadvantages of MRI

Answer 17

advantages:
- superior contrast resolution
- eliminate superimposition
- multiplanar reconstruction
- no ionizing radiation
- better than CT for soft tissue - brain, spinal cord
- better than CT - can see bone edema

disadvantages:
- anesthesia
- time
- subject to artifacts from implants
- expensive
- lots o’ data
- CT is better for bone margins and lytic lesions

Question 18

What is nuclear scintigraphy?

Answer 18

using Technetium 99 that emits gamma radiation, collects at areas of increased metabolism or bone turnover (inflammation) - gamma camera detects release of radiation from patient

poor spatial resolution, labour intensive (requires isolation), acquisition time is lon g