Dosimetric Concepts 1 Flashcards
1
Q
Beam quality
A
The penetrating power of the beam
Higher beam energy has higher penetrating ability
2
Q
Monoenergetic beams
A
Electrons and gamma rays
12MeV
3
Q
Heterogeneous beams
A
X-ray
4MV, 18MV
4
Q
Effective energy
A
Type of X-ray beam is always heterogeneous in RT, but X-ray can have an equivalent energy of a mono energetic that have equivalent HVL
Can be estimated as 1/3 the max electron potential
4MeV/3=1.33 MeV effective energy
5
Q
Supervoltage
A
50-150kVp
HVL 1-8 mm Al
Treatment distance 15-30cm
90%dose at 5mm depth
6
Q
Ortho
A
150-500 kVp
HVL 1-4 mm Cu
59-70cm SSD
90% dose at 2xm depth
7
Q
Primary radiation
A
That which passes directly from the source through the collimating system and to the point of measurement/patient
8
Q
Secondary radiation
A
Patient scatter
Collimator scatter
Leakage radiation
