(*-*) EXPOSURE LIMITIS, SHIELDING, QA

Question 1

which barrier is where the useful beam hits?

Answer 1

primary

Question 2

which barrier is where the scatter and leakage hits?

Answer 2

secondary barrier

Question 3

restricted/controlled areas (like control room) are limited to ____ msv/wk or ____ msv/yr

Answer 3

.5 msv/wk
or 5 msv/yr

Question 4

unrestricted/uncontrolled areas (like waiting room) are limited to ____ msv/wk or ___ msv/yr

Answer 4

.02 msv/wk or 1 msv/yr

Question 5

who keeps the personnel dosimetry records?

Answer 5

RSO (radiation safety officer)

Question 6

“monitored if expected to receive __% or more of effective dose”

Answer 6

10% or more of effective dose

Question 7

label which is the PRIMARY BARRIER and which is the SECONDARY barrier

Answer 7

Question 8

what interlocks are checked daily?

Answer 8

-door
- EPID collision
-safety lights
-audio/visual
-radiation output
-laser alignment
-ODI
-collimator indicator agreement
-imaging QA
-CT water phantom tests (noise and CT numbers/HU)

Question 9

what interlocks are checked monthly?

Answer 9

-gantry collision
-emergency off buttons
-flatness and symmetry
-light and radiation field agreement

Question 10

what interlocks are checked annually?

Answer 10

-electron cones
-gantry (mechanical iso)
-collimator (mechanical iso)
-radiation isocenter

Question 11

what does a “functional” tolerance mean?

Answer 11

means it works, or it does not work - if it does not work, we cannot treat

Question 12

safety lights, audio/visual, and emergency off buttons have what tolerance?

Answer 12

functional tolerance

Question 13

safety lights for a LINAC say what? for HDR say what?

Answer 13

LINAC - beam is ON
HDR - source is exposed

Question 14

what is most common malfunction of safety lights not turning on?

Answer 14

light bulb being out

Question 15

if emergency off button fails to turn beam off, what is next step?

Answer 15

circuit breaker switch

Question 16

each LINAC should have at least how many visuals? and a what kind of audio?

Answer 16

2
and a two-way audio system

Question 17

with cameras, we have what kind of visual of LINAC treatment room. Whereas a CT room has what kind of visual?

Answer 17

an indirect visual

a CT room has a direct visual since kv source is low enough

Question 18

what interlocks are checked weekly?

Answer 18

-MLC performance (picket fence test)

Question 19

the “star pattern test” tests for what?

Answer 19

Radiation Isocenter – checks gantry, collimator, and couch

Question 20

LEVEL 1 requires what?

Answer 20

can still trt but inspect

Question 21

LEVEL 2 requires what?

Answer 21

can still trt but schedule maintenance ASAP

Question 22

LEVEL 3 requires what?

Answer 22

do not trt - immediate action needed

Question 23

1 TVL = ____ HVL

Answer 23

3.3

Question 24

how much lead is in lead apron?

Answer 24

.5 mm

Question 25

flattening filter is used for photons or electrons? and is in shape of what?

Answer 25

photons and is in shape of cone
- made of high Z material

Question 26

high Z material = _________

Answer 26

absorption

Question 27

intention of flattening filter is what?

Answer 27

to create a flat, even, dose distribution

Question 28

intention of scattering foil is what? what is the material?

Answer 28

spread e- beam out
-copper or lead

Question 29

primary collimators are __moveable/stationary__

Answer 29

stationary

Question 30

secondary collimators are __moveable/stationary__

Answer 30

moveable & asymm

Question 31

field size ranges from __x__ to __x___ of secondary collimators

Answer 31

0x0 to 40x40

Question 32

MLCs can transmit <__% of beam

Answer 32

<2%

Question 33

ODI is located __within/outside__ treatment head

Answer 33

outside treatment… but on it … ODI projects our numbers

Question 34

you can or cannot adjust primary collimators?

Answer 34

cannot!

Question 35

collimating jaws and mlcs are made of what?

Answer 35

tungsten