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Idea Re: RE: Uniform distribution of a radioactive source in body phantom 

Forum: Medical Applications
Re: Question Uniform distribution of a radioactive source in body phantom (Sunil Kumar)
Re: None RE: Uniform distribution of a radioactive source in body phantom (Susanna)
Re: None Re: RE: Uniform distribution of a radioactive source in body phantom (Sunil Kumar)
Re: None Re: RE: Uniform distribution of a radioactive source in body phantom (michel maire)
Re: None Re: RE: Uniform distribution of a radioactive source in body phantom (Sunil Kumar)
Date: 10 Aug, 2018
From: Michael H. Kelsey <Michael H. Kelsey>

On Fri, 10 Aug 2018 11:31:54 GMT, Sunil Kumar wrote:
> I saw the example as you told. It is for a symmetric shape but I want to
> perform it for an irregular shape(body phantom)

For an irregular shape, you'll need to use an accept-reject method. Given an arbitrary G4VSolid, get the "bounding box" (x,y and z minimum and maximum coordinates) for the solid in its local coordinate system (in 10.3, the Extent() function was introduced to do this in one call).

Throw a random point in that box, and call G4VSolid::Inside() to ask whether the point is contained or not. If it is not, try again. Once you have a suitable local point, transform it from the local coordinate system to global coordinates (for this you need the G4Touchable corresponding to your placement volume).

This works best for bulky, roughly rectangular objects, and worst for thin objects with non-xyz projections, or with lots of interior holes (e.g., a thin spherical shell). Your body phantom shape should be fine.

  -- Michael Kelsey

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