Dose 2016

Pencil beam kernel parameterization - 2

Double exponential, incl. depth parameterization, solely based on TPR 20,10 (extracted from photon beam database) T Nyholm, et al (2006) Radiother Oncol 78 , 347-51.

A/a

B/b

4.E-03

1.E-03

6 MV

From photon beam database

3.E-03

From TPR(20/10)

9.E-04

/cm 2 g -1

/cm 2 g -1

Corresponds to primary dose ( R = ∞ )

2.E-03

6.E-04

Corresponds to scatter dose ( R = ∞ )

1.E-03

3.E-04

0.E+00

0.E+00

0

10

20

30

40

50

60

0

10 20 30 40 50 60 Depth /cm

Depth /cm

b

a

0.16

20

(98%)=ln(0.02)/b

R

If one assumes that lateral equilibrium is established when one gets 98% of the total dose on axis from a field with infinite field size

scatter

~ 33 cm

0.12

15

(98%)=ln(0.02)/a

R

/cm -1

0.08

/cm -1

10

primary

~ 1.3 cm

From photon beam database

0.04

5

From TPR(20/10)

0

0

0

10

20

30

40

50

60

0

20

40

60

Depth /cm

Depth /cm