ch 13 ct safety

Question 1

skin dose in CT is (more/less) than in x-ray/fluoro

Answer 1

less

Question 2

dose distribution in CT is (more/less) uniform

Answer 2

more

Question 3

shielding in CT is no more effective than ___________

Answer 3

collimators

Question 4

AEC for CT is _____________________

Answer 4

tube current modulation

Question 5

tube current modulation uses ___________ to vary the mA during scan

Answer 5

scout image

Question 6

tube current modulation is more effective than ______________

Answer 6

older bismuth shielding

Question 7

with angular based modulation, anterior side mA will ______________; posterior side mA will __________

Answer 7

decrease, increase

Question 8

iterative reconstruction is better than filtered back projection (could be done _____); iterative reconstruction can be done ________________

Answer 8

once, over and over

Question 9

iterative reconstruction reduces radiation exposure ____% compared to filtered back projection

Answer 9

25-40%

Question 10

increasing kVp in CT will (increase/decrease) patient dose

Answer 10

increase

Question 11

reducing tube potential from 100 to 80 kVp will reduce patient dose ____

Answer 11

1.5x

Question 12

CTDI is determined by _________________

Answer 12

an ionization chamber with a phantom

Question 13

what does CTDI stand for?

Answer 13

Computed tomography dose index

Question 14

CTDIW (weighted) is the __________________________

Answer 14

average of 2 measured CTDI volumes

Question 15

CTDIVOL = _____________

Answer 15

CTDIW/Pitch

Question 16

with CT effective dose, there is ________________ risk of cancer or early death _________ effective dose

Answer 16

no increased, <100 mSv

Question 17

typical effective dose
Abdomen
Pelvis
Coronary angiography

Answer 17

Abdomen 5-8 mSv
Pelvis 3-6 mSv
Coronary angiography 1-18 mSv

Question 18

typical effective dose
Head
Chest

Answer 18

Head 1-2 mSv
Chest 2-6 mSv

Question 19

Effective mAs = mAs = _________

Answer 19

mAs/Pitch

Question 20

_____________ is older than ___________ in CT cardiac imaging

Answer 20

Prospective gating, ECG gated imaging