Dose level in CST

[Mariam950-wp]

Dear Friends.

In cst struct of TG119 phantom of matrad test data, there are some treatment planing parameters defined, one of which is a level of dose. I wonder how the level dose is related to an actual dose in Gray. So how it is defines that target should get a specific dose?

[wahln]

The Standard objectives are of type "squared overdosing" and "squared deviation".

The reference level for squared deviation is the total dose (summed over all fractions) and means that the optimizer will minimze the least squares to this parameter.

For squared overdosing, the parameter is a lower limit, in the sense that the square of positive difference will be minimized.

For somewhat historical reasons we stick with the convention that the prescriptions are given as total dose, while the dose that is by default displayed in matRad is the fraction dose. This is sometimes confusing, but when setting "60" as a dose parameter in the target and setting number of fractions to "30", you will consequently see target doses of 2 Gy / fraction in matRad.

[Mariam950-wp]

Thanks for your answer 🙂 and I have n emore question. I know that matrad is based on interpolations and it is not monte-carlo simulation but how can I guess how many protons were simulated in a fraction if it is possible. I see defauls number of particles for a ray in documentation, but not actual one. Thanks

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________________________________ From: Niklas Wahl ***@***.***> Sent: 10 October 2024 23:46 To: e0404/matRad ***@***.***> Cc: Mariam Abuladze ***@***.***>; Author ***@***.***> Subject: Re: [e0404/matRad] Dose level in CST (Discussion #777) The Standard objectives are of type "squared overdosing" and "squared deviation". The reference level for squared deviation is the total dose (summed over all fractions) and means that the optimizer will minimze the least squares to this parameter. For squared overdosing, the parameter is a lower limit, in the sense that the square of positive difference will be minimized. For somewhat historical reasons we stick with the convention that the prescriptions are given as total dose, while the dose that is by default displayed in matRad is the fraction dose. This is sometimes confusing, but when setting "60" as a dose parameter in the target and setting number of fractions to "30", you will consequently see target doses of 2 Gy / fraction in matRad. — Reply to this email directly, view it on GitHub<#777 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ASBXGRBZ4LXMAYOLU6DURHTZ23KRBAVCNFSM6AAAAABPXEFOQWVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTAOJQHAYTINA>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[wahln]

Our dose kernels in the particle machine data is normalized to 1e6 primaries / weight. That means a value of 1 in the weight vector after optimization is 1e6 particles (for a fraction).
This means nParticles = 1e6 * sum(resultGUI.w)