SAD Dose Function

Question 1

Attenuation

Answer 1

As radiation beam passes through matter it undergoes a gradual reduction of the number of photons per area

Photons May be absorbed or scattered

Question 2

TAR

Answer 2

=absorbed dose in tissue at depth/absorbed dose in air (=Dd/Dfs)

Used for SAD treatments for energies less than 4MV like cobalt

Question 3

BSF

Answer 3

=dose in tissue at Dmax/dose in air

We use this when field size changes

Question 4

SAR

Answer 4

Scatter air ratio
Primary radiation won’t change, just scatter
Used for energies over 3Mv

Question 5

TPR

Answer 5

Tissue phantom ratio
=Dd/Dref
Useful in beam energies over 4MV

Question 6

TPR

Answer 6

Tissue phantom ratio

=Dd/Dmax