Dosimetry Flashcards
1
Q
Absorbed dose
A
D
Amount of energy absorbed from a beam of radiation per unit mass of tissue
Gray (Gy) (1 Joule/kg)
2
Q
Equivalent dose
A
H
Allows potential harm from different types of R to be considered
Sievert (Sv)
H = D x Wr (Wr = 0 for xray and gamma)
3
Q
Effective dose
A
E
Allows doses from different investigations of different body parts to be compared
E = H x Wt (tissue weighting factor)
Sievert
4
Q
Collective dose
A
CD
Considers total effective dose to population
CD = E x population
Mann- sievert
5
Q
Entrance surface dose
A
ESD
Represents max dose to tissues
mGy
6
Q
Dose-area product
A
DAP
mGycm-2
7
Q
Practical dose reduction
A
Controlled area: Operator 2m away from patient and tube Greater 70kV = 1.5m sets Less 70kV = 1m sets Distance: inverse square law intensity reduces to 1/4 as distance is doubled
8
Q
Best film speed/ set up
A
70kV F Rectangular collimation 0.001
9
Q
Multiplication factors
A
30yrs = 1
10
Q
When are personal dosimeters used
A
In practice if weekly > 100 IO or 50 pano
