Absorption, attenuation, and grids Flashcards
1
Q
PEA results in complete
A
x-ray absorption
2
Q
compton causes
A
scatter
3
Q
attenuation
A
some penetrating x-rays are absorbed by tissues
4
Q
exponential attentuation
A
absorption depends on tissues thickness
5
Q
HVL measures x-ray
A
quality/penetrability
6
Q
HVL
A
thickness of absorbing material needed to reduce x-ray intensity by half
7
Q
types of filtering
A
- tungsten anode
- x-ray tube housing
- added filtration
8
Q
exposing body parts with unequal thickness
A
compensatory filter
9
Q
primary bean attenuated by 90%
A
tenth value layer (TVL)
10
Q
scatter intensity depends on..
A
kVp, beam field size, and patients thickness
11
Q
grid is a series of
A
lead strips –> cleans up scatter (up to 80%)
12
Q
grid ratio
A
R=h/D
13
Q
most frequent grid ratio used
A
8:1 to 10:1
14
Q
higher ratio grids
A
less scatter but more radiation exposure is needed
15
Q
paralleled grid flaw
A
grid cut-of artefact
