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A review of why the depth at which a proton beam stops cannot be predicted exactly, and how much margin centres add for it. One common recipe, 3.5 per cent of the range plus 1 millimetre, overshoots by about 8 millimetres for a beam reaching 20 centimetres into soft tissue.
Paganetti reviewed the sources of range uncertainty in proton therapy (imaging, patient set-up, beam delivery and dose calculation) and the role of Monte Carlo simulation in reducing it. The full text sets out the margin recipes in use: 3.5 per cent of the range plus 1 mm at the Massachusetts General Hospital, 3.5 per cent plus 3 mm at MD Anderson, Loma Linda and the University of Pennsylvania, and 2.5 per cent plus 1.5 mm at the University of Florida. The MGH recipe originated at the Harvard Cyclotron Laboratory from estimates of CT uncertainty in the early 1980s. The abstract concludes that in complex geometries Monte Carlo techniques might reduce the range uncertainty by several millimetres.
The millimetres added for range uncertainty are healthy tissue irradiated to protect the target, and they are a large part of why the theoretical advantage of protons over photons is smaller in practice.
Shares Proton range uncertainty and the range margin, Pencil-beam scanning and intensity-modulated proton therapy, Proton therapy and the tags precision, radiation.
Shares the tags precision, radiation.
Shares the tags precision, radiation.
Shares the tags precision, radiation.
Shares the tags precision, radiation.
Shares the tags precision, radiation.
Shares the tags precision, radiation.
Shares the tags precision, radiation.
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