ESTRO course Dose Modelling and Verification 2017

Head scatter fluence calculation - integration over extended sources

Scatter source

Main steps in the OOPS (Object Oriented Pixel Shadowing) back projection algorithm for head scatter geometry integrations:

Collimator

Can not be seen through the collimators

Can be seen through the collimators

Calculation point

I. Cover scattering surface by a pixel matrix. II. Set all pixels as scattering. III. Illuminate the matrix by a light source place in the calculation point. IV. Construct the shadow cast on the matrix from each collimating element (collimator, MLC, block,…). V. Combine all shadows (reset shadowed pixels).

Only visible pixels remains set !

36