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arXiv · 0707.4144

The grid-dose-spreading algorithm for dose distribution calculation in heavy charged particle radiotherapy

Nobuyuki Kanematsu·Shunsuke Yonai·Azusa Ishizaki
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Abstract

A new variant of the pencil-beam (PB) algorithm for dose distribution calculation for radiotherapy with protons and heavier ions, the grid-dose spreading (GDS) algorithm, is proposed. The GDS algorithm is intrinsically faster than conventional PB algorithms due to approximations in convolution integral, where physical calculations are decoupled from simple grid-to-grid energy transfer. It was effortlessly implemented to a carbon-ion radiotherapy treatment planning system to enable realistic beam blurring in the field, which was absent with the broad-beam (BB) algorithm. For a typical prostate treatment, the slowing factor of the GDS algorithm relative to the BB algorithm was 1.4, which is a great improvement over the conventional PB algorithms with a typical slowing factor of several tens. The GDS algorithm is mathematically equivalent to the PB algorithm for horizontal and vertical coplanar beams commonly used in carbon-ion radiotherapy while dose deformation within the size of the pristine spread occurs for angled beams, which was within 3 mm for a single proton pencil beam of $30^\circ$ incidence, and needs to be assessed against the clinical requirements and tolerances in practical situations.

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Nobuyuki Kanematsu, Shunsuke Yonai, Azusa Ishizaki. 2007-07-27. The grid-dose-spreading algorithm for dose distribution calculation in heavy charged particle radiotherapy. https://doi.org/10.1118/1.2829878

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