I just started to learn fluka recently. I want to use fluka to simulate the scattering effect of X-ray with different energy levels in the phantom and the ray distribution after penetrating the phantom.
I built a simple X-ray generation and filtration model and a simple thigh model.Using 110kev electron beams bombarded tungsten targets to generate bremsstrahring radiation to produce X-rays of different energies, which were filtered through the aluminum plate and passed through the phantom.But my model still lacks a component to show the distribution of rays after passing through the phantom.
1、So my first question , is there any way to show the distribution of rays as they pass through the mode?
On the other hand, I used usrbin score for the entire cone beam to simulate the scattering line results inside the thigh model.However, I think the results obtained are not ideal, as shown in the figure below, with large errors and little effective data for reference.I used 1*E5 primaries,Spawn=5,10 Cycles,the total number of particles is 5 *E6.
2、So, the number of particles should not be the cause of this error, I don’t know if my conjecture is correct?And I want to know how to reduce these errors?
3、Finally, I heard that biasing can be applied to my models, is that true？
The number of primaries does not correspond to the number of x-rays reaching the thigh but it is the number of electrons. These have to undergo bremsstrahlung to generate the x-rays and that comes with a given efficiency. In order to reduce the uncertainties, you have to increase the number of primaries.
For biasing, you can have a look at the biasing lecture from the last course. Unfortunately for you, biasing in air is not a good thing in MC simulations (search on this forum about this, since it has already been discussed) therefore, I don’t think it fits your problem.
1、I will continue to study the course on usrbdx cards.
2、I can’t agree with you more, I know that Bremsstrahring happens and only a small fraction of the X-rays are produced. According to you, in my model, five million particles is still not enough?And I have to keep increasing the number of primaries, right?
3、I will search and read the related posts you mentioned
Finally, this is my first post, I am honored to receive your reply, it is very helpful to me,thank you
amario
The number of primaries is enough when it allows you to reduce the statistical uncertainty down to a level that it good for you. It is only for you to judge when you have achieved a results that is statistically good enough.
