{"entity":{"id":"paper-paganetti-range-uncertainties-pmb-2012","kind":"paper","name":"Range uncertainties in proton therapy and the role of Monte Carlo simulations","aka":[],"tldr":"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.","summary":"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.","asOf":"2026-10-20","links":[{"label":"Physics in Medicine and Biology 2012","url":"https://doi.org/10.1088/0031-9155/57/11/R99"},{"label":"PubMed 22571913","url":"https://pubmed.ncbi.nlm.nih.gov/22571913/"},{"label":"Full text in PubMed Central","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC3374500/"}],"tags":["precision","radiation"],"related":[],"cancers":[],"sections":["radiation"],"technologies":["proton-therapy","intensity-modulated-proton-therapy"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["proton-range-uncertainty","bragg-peak"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"journal":"Physics in Medicine and Biology","year":2012,"doi":"10.1088/0031-9155/57/11/R99","pmid":"22571913","authors":"Paganetti H.","paperType":"review","findings":["Margin recipes in use: 3.5 per cent + 1 mm (MGH), 3.5 per cent + 3 mm (MD Anderson, Loma Linda, Pennsylvania), 2.5 per cent + 1.5 mm (Florida).","The 3.5 per cent + 1 mm recipe gives a deliberate overshoot of 8 mm for a 20 cm range field in soft tissue.","Monte Carlo dose calculation might reduce range uncertainty by several millimetres in complex geometries."],"whatItMeans":"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.","caveats":["A 2012 review; centres have since adopted robust optimisation and, in places, Monte Carlo dose calculation, and current recipes may differ.","The recipes are institutional choices, not trial-derived values."]},"route":"/key-papers/paper-paganetti-range-uncertainties-pmb-2012/","neighbours":{"section":[{"id":"radiation","kind":"section","name":"Radiation Therapy","route":"/fronts/radiation/"}],"technology":[{"id":"intensity-modulated-proton-therapy","kind":"technology","name":"Pencil-beam scanning and intensity-modulated proton therapy","route":"/technologies/intensity-modulated-proton-therapy/"},{"id":"proton-therapy","kind":"technology","name":"Proton therapy","route":"/technologies/proton-therapy/"}],"term":[{"id":"bragg-peak","kind":"term","name":"Bragg peak","route":"/terms/bragg-peak/"},{"id":"proton-range-uncertainty","kind":"term","name":"Proton range uncertainty and the range margin","route":"/terms/proton-range-uncertainty/"}]}}