physics bunker design

Question 1

definition of transmission

Answer 1

xray photons that pass thru patient unchanged

Question 2

definition of Absorption

Answer 2

xray photons that transfer their energy into patient

Question 3

definition of scatter

Answer 3

radiation that changes direction while passing thru patient (may decrease energy)

Question 4

definition of attenuation

Answer 4

when radiation losers power when travelling thru matter.

can be scatter or absorption or both

Question 5

definition of quality

Answer 5

measurement of penetrating power of beam.

-when quality increases, the proportion of high energy photons increases

Question 6

Effective Dose Equivalent

Answer 6

H = ∑i Ei Wi

E=Equivalent dose
W=tissue weighting factor
unit=Sv

Question 7

what does effective dose equivalent take into account

Answer 7

relative radio-sensitivities of different organs

Question 8

dose limits for public-
for lens of eye-
skin averaged over any area of 1 cm2-

Answer 8

1mSv in 12 month period
15mSv
50mSv

Question 9

• dose limits for occupational exposure
• lens of the eye
• skin
• hands, forearms, feet and ankles
• pregnant

Answer 9

• 20mSv per 12 month
• 20mSv
• 500mSv within 12 mths
• ’’
• 1mSv for the remainder of the term

Question 10

what is TVL

Answer 10

amount of material needed to reduce intensity of beam to one tenth of its orginal

Question 11

TVL depends on two things

Answer 11

energy of beam

material

Question 12

how does TVL depend on energy of beam

Answer 12

higher energy beam needs more attenuation and therefore larger TVL

Question 13

how does TVL depend on material

Answer 13

more dense material attenuates more and therefore TVL smaller