Using SPOTBEAM to create radiotherapy field

Source Definition
1

Dear Fluka experts,
I am trying to use the SPOTBEAM source to create a 5 cm^2 x 5 cm^2 radiotherapy field size. The interval is 2 mm among the beam spots. I want to know how I can define accurate the field size using SPOTBEAM source. Thanks in advance!
Cheers,
Xiaoman

2

Dear Xiaoman,

it is not completely clear, that you want a 5x5 cm^2 beam with one SPOTBEAM card, our you want to use many small beams to cover the area.

However, in both cases, you can set the shape of the beam in the X-Y plane using the SPOTPOS card’s Shape(X) and Shape(Y) options. It is also possible to rotate the beam into an arbitrary direction using the SPOTDIR card.

Cheers,
David

3

Dear David,
Indeed, I want to use many small beams to cover the area. If the mono-energy beam has a 8 mm FWHM and the interval is 2 mm among the beam spots, I need add 25 beam spots using SPOTBEAM to cover 5x5 cm^2 area. Is it right? The 25 beams have same direction in Z-axis.
Cheers,
Xiaoman

4

Dear Xiaoman,

if you want a beam every 2 mm, then you would need 25 * 25 = 625 spots in total to cover the 50 * 50 mm^2 area.

Cheers,
David

5

Dear David,
Thanks a lot. Is it not necessary to consider the beam characteristic in calculating the number of beam spots. The beam itself has size. By the way, is there simple methods to add so many beam spots to flair? Thanks again.
Cheers,
Xiaoman

6

Dear Xiaoman,

The easiest way to add that many card would be to generate and write them to a separate file with an external script (bash, python, etc).
Then you could include this file into the Flair input with the #include directive card.

Cheers,
David

7

Dear David，
I used SPOTTRAN card and combined with ROT-Defi card to replicate the spot beamnewtest1.flair (685 Bytes) , but it cann’t realize. What should I do to transform those spot beam? Thanks a lot.
Cheers,
Xiaoman

8

Dear Xiaoman,

the attached flair project is empty.

SPOTTRANS cards are not necessary to use, the beam direction can be set up using the SPOTDIR cards. Please take a look at this lecture starting at slide 25, and especially slide 34:

Cheers,
David

9

Dear David,
Thanks for your advice. I have got it. Thanks again.

Cheers,
Xiaoman