Isodose Charts

Question 1

What is an isodose distribution?

Answer 1

2D representation of absorbed dose.
Lines that receive equal amounts of dose.
It measures how deep dmax is at depth and u times it by 4 to find energy.
Line or X shows dmax

Question 2

When considering what isodose curves correlate with which machine we need to take in 4 factors?

Answer 2

Shape
Roundness
Pnumbra
Dmax location

Question 3

Explain an electron isodose look like?

Answer 3

Dmax is under skin surface
Lines at packed together as electrons are not very penetrating so it drops off with dose.
Electrons are light so a lot of pnumbra

Question 4

Explain a KV isodose curve

Answer 4

Dmax skin surface
Sideways scatter so pnumbra
Round isodose lines due to no beam flattening

Question 5

Colbalt isodose lines

Answer 5

D max is under skin surface
Round isodose due to no beam flattening
Little scatter no pnumbra

Question 6

MV isodose curve lines

Answer 6

Dmax under skin surface
Isodose lines are flat so beam flattening filter
Minimal scatter so little pnumbra
Energy|4 equals dmax