SEDL / STP / STP1228-EB / STP15157S

Energy and Spatial Distribution of the Photoneutron Flux from a Radiotherapy Electron Accelerator

Agosteo, S
Research scientist, Politecnico di Milano, Milano,

Foglio Para, A
Associate Professor, Politecnico di Milano, Milano,

Pages: 10    Published: Jan 1994

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Abstract

An analytical method accurately describing the energy and the spatial distribution of the photoneutron flux in a radiotherapy room is reviewed by taking into account the influence both of different materials and thicknesses of the accelerator shield and of the composition of the walls of the radiotherapy room. This dependence is investigated by means of Monte Carlo simulations which also provides a validation of the method. The resulting formulas are employed to estimate the neutron production yield from flux measurements by means of activation detectors. The results of the measurements performed around some linear accelerators of the present generation have shown that the mean emission rate is of the order of 10¹¹ neutrons per second.