Advanced Physics for Brachytherapy 2018

1. I need to be efficient, angular discretization

• discretization artifacts or “rays”: an artificial buildup of particle fluence along the finite number of directions used with high gradients of scatter fluence, at points where primary dose is small with N directions & voxel size at the expense of calculation time and potential volume averaging

10

10

10

8

8

8

224

360

528

6

6

6

4.5 %

4

4

4

3.5 %

2

2

2.5 %

2

1.5 %

0

0

0

0.5 %

Along, cm

-2

-2

-2

-0.5 %

-4

-4

-1.5 %

-4

-2.5 %

-6

-6

-6

-8

-8

-8

Figure from: Venselaar, Baltas, Meigooni, Hoskin (Eds), Comprehensive Brachytehrapy: physical and clinical aspects. CRC Press, Taylor & Francis, ©

-10

-10

-10

3 4 5 6 7 8 9 10 Away, cm

3 4 5 6 7 8 9 10 Away, cm

3 4 5 6 7 8 9 10 Away, cm