{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"92cbe387c0760c1117b083d9dca25745195ab2effed367306ed877b5ab2010d6","created":"2026-10-03T07:18:06Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"86439f43a07e1f5ff6f095e7a37d4c5f200d98bf748cdbc6599b8104cbe4c785","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"med.ion-therapy.proton-rbe","kind":"phenomenon","literature_status":"contested","n":"1","parents":[],"plain":"Clinics assume protons are a fixed 10 percent more damaging than x-rays, but laboratory data show the factor rises near the end of the particle range. How much it rises in patients is unknown.","posed_since":"1990","precise":"Determine the proton relative biological effectiveness as a function of dose-averaged linear energy transfer $\\mathrm{LET}_{d}$ from $1 \\text{ to } 15\\,\\mathrm{keV}/\\mathrm{micron}$, dose per fraction from $100 \\text{ to } 1000\\,\\mathrm{rad}$, and tissue $\\alpha/\\beta$ from $200 \\text{ to } 1000\\,\\mathrm{rad}$, for clinically relevant normal-tissue endpoints. The clinical standard $\\mathrm{RBE} = 1.1$ is constant. An answer is a validated RBE model with uncertainty bands usable in treatment planning.","problem_ref":null,"references":"","settled_by":"Clinical outcome data correlating observed normal-tissue changes with planned $\\mathrm{LET}_{d}$ distributions, combined with in vivo endpoint measurements along a spread-out Bragg peak.","status_note":"Imaging-based evidence of elevated effect at the distal edge in brain accumulated through 2024, but no variable-RBE model had been clinically adopted.","title":"Variable biological effectiveness of proton beams","topic_ref":"783c95cea555c72f61498fd08fa3ced7be4a4b07d67abcd2e5bc27204e6bdab5"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"36b43a26a16b409cc0ec313f6a0af679c86f033453de7a4eda2e714c6e175783","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"c701437459974e9cb270ff0bec944daa083e023caed47eb8c9233f17311ea0e8","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"0IbM-fzXBs3pa1pNGM0hhuyKwKmQdmLOAMcMbJcERw8LN1Hj5nHWYsIuWf5orjicA6skS_Hbs8TaSO84Rf--Dg"},"schema":"pubphys.envelope/1"},"record_hash":"36b43a26a16b409cc0ec313f6a0af679c86f033453de7a4eda2e714c6e175783","leaf_index":1692}