review

Question 1

what is the changing directions of electrons that produces radiation

Answer 1

bremstrolong

Question 2

what causes x rays to be produced by the cathode giving electrons to the anode because it got heat up

Answer 2

thermionic emission

Question 3

interaction between x ray and matter most responsible for image contrast

(determined by z number)

Answer 3

photoelectric effect

Question 4

target metal in x ray tube

Answer 4

tungston

Question 5

how does dexa bone scan work

Answer 5

duel energy x rays and comparing attenuation

Question 6

what are the mammo kVp ranges

Answer 6

LOW kvp (want the least amount of grey values as possible, higher contrast)

Question 7

what in an x ray absorbs scattered radiation

what do they do

Answer 7

grids

allow primary photons through

Question 8

what type of digital receptor does not use a scintillator (which makes photons that aer then transmitted into electrical signals)

they convert x rays inot electrical signals, not into light THEN into sighansl

Answer 8

direct conversion detector

Question 9

what happens when a photon ejects an inner shell electron

Answer 9

photolectic effect

Question 10

what is complete absorption of an x ray photon and transfers that energy to an electron

Answer 10

photoelectric effect

Question 11

where does the photoelectric effect occur in

what happens

does this reach the detector and why or why not

Answer 11

in the patients tissue

an x ray beam PHOTON hits an inner shell electron and produces a PHOTOelectron that is absorbed within the patient

It is absorbed so it does not reach the detector and shows up as back (happens in bone)

Question 12

where does characteristic radiation and bremstolong occur and between what

Answer 12

in the tube, happens with the tungsten atoms

Question 13

what happens when photons scatter off loosely bound outer shell electrons (like a cheap shot)

Answer 13

common scatter, theyre cheap in Compton

Question 15

what happens when photons wiggle atoms and bounce off unchanged, but still cause scatter

Answer 15

reighlegh, she jiggles

Question 16

why is CT scanner radiation output

Answer 16

CTDI

Question 17

what is when CTDI is corrected for table movement and averaged across the scan volume

Answer 17

CTDIvol

think about this as geometrically taking into account the length of the table, hence volume

NOT a measurement of radiation obtained by the patine t

Question 18

aritfact caused when x rays pass through highly attenuated materials and cause streaks

why

Answer 18

beam hardening

low energy photons are trapped within the material and one the harder ones are able to pass

Question 19

important property of a good radio tracer

primary
secondary

Answer 19

biological specificity

short half life

Question 20

what is the units for 2 photons in a PET scan

Answer 20

511 KILLI eVOLTS

Question 21

occupational annual radiation dose

normal

Answer 21

5000 MILLI rem (think milli is already 1000, so those are your units)

100 MILLI rem (down one factor of 10)

Question 22

what is the rotating cameras

what is the donut

Answer 22

SPECT

PET

Question 23

thyroid

diagnostic

therapuric

Answer 23

i123

i131

Question 24

3 principles of alarm

Answer 24

time
distance
shielding

Question 25

when you increase kVp, what happens to dose what happens to contrast

Answer 25

increase dose decrease contrast

Question 26

what is the primary way x rays are produced in the x ray tube

Answer 26

bremstrallung

Question 27

when though you have a higher kVp (which gives you higher dose when mAs is left alone), what will ensure that you dose is lower

Answer 27

automated exposure control

Question 28

the higher the Z, the more ____ ____ effect

Answer 28

photoelectric (why bones are white, they are completely absorbed)

Question 29

who discovered x rays

Answer 29

rotogen 1

Question 30

does scatter influence contrast

Answer 30

yes

Question 31

does mAs affect contrast does current affect contrast

Answer 31

no no

Question 32

thickness of material where half of incident photons are attenuated

Answer 32

half value layer

Question 33

what does a grid do what does a filter do what does a collimator do

Answer 33

reduce scatter by only letting in primary removes low energy radiation shapes beam

Question 34

besides beam hardening, what else does a filter do

Answer 34

better spatial resolution

Question 35

et placement x ray

Answer 35

portable AP

Question 36

low kVp and low dose x ray is for what

Answer 36

mammo

Question 37

when you image is under penetrated and not diagnostic, what should you do

Answer 37

add a grid (to reduce scatter) increase the mAs change the kVp

Question 38

from window, what comes after (downwards)

Answer 38

widow filter collimator

Question 39

what imaging is for minimally invasive procedures

Answer 39

IR

Question 40

what is for real time x ray imaging

Answer 40

fluoroscopy

Question 41

why does the anode rotate

Answer 41

improves heat dissipation (gets hit a ton and gets pitted)

Question 42

difference between CTDI and DLP

Answer 42

CTDI is the dose intensity within a scanned slice DLP is that ^ but accounts for the entire length of the scan, and estimates overall patient radiation (SCDI x scan length)

Question 43

if cardiac gating is required, what does it maman to take images dirge a specific period of the heart

Answer 43

prospective gating (guessing when to do it)

Question 44

why non con for renal stones

Answer 44

better contrast bc stones calcified

Question 45

what is it when you scan ROI and scanner attenuates in real time, then stops at HU what is it when you allow the contrast to sit for a bit then guess when toimahe

Answer 45

automatic triggering delayed phase (kindeys)

Question 46

2 instances where bolus timing is needed trigger vs delay

Answer 46

trigger - arterial for tumor (they only need blood, none coming back to heart) kindly study delayed dont want to excrete contrast

Question 47

3 factors that effect SNR in CT to increase it

Answer 47

increase mAs with more photons increase slice thickness so more photons per slice increase FOV with same metric size so each pixel has more data

Question 48

what's the only emission based thing we've covered so far

Answer 48

nuc med

Question 49

what is higher res, PET or SPECT

Answer 49

PET

Question 50

what are the 4 steps of FBP

Answer 50

cdetectors collect data organized into a sinogram passed though filter for noise and blue projected back into image space

Question 51

from bottom to top

Answer 51

radiation collimators scintilaltino crystals photomultipliers