{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"19cf4426ea4d4191c9cdfa8dbdd56f36b80eef6e4decab1802df383dfc0800f3","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["7076cbc43c307aa140efad6211c47c1fda6bf68320a8f771ccd82c872b9c28a8","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"4d527b5c228f96b977f181974ac16bd069083b549008d67d439334172c1df017","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"med.dosimetry.ion-beam-quality","kind":"well-posed","literature_status":"partially-resolved","n":"2","parents":[],"plain":"Converting a detector reading into dose in a particle beam needs the average energy spent to make one ion pair in air. Its uncertainty, especially for carbon ions, dominates the dose error.","posed_since":"1990","precise":"Reduce the uncertainty in the mean energy per ion pair in air $W_{\\mathrm{air}}$ and in the beam-quality correction factor $k_Q$ for carbon and other ions to the level needed for a total dosimetric uncertainty below $1.5\\%$. ICRU 90 values are $W_{\\mathrm{air}}$ of about $34.44\\,\\mathrm{eV}$ for protons (about $0.4\\%$ standard uncertainty) and $34.71\\,\\mathrm{eV}$ for carbon ions (about $1.5\\%$). An answer is a measured value set with reduced uncertainty.","problem_ref":"7076cbc43c307aa140efad6211c47c1fda6bf68320a8f771ccd82c872b9c28a8","references":"","settled_by":"Calorimetric determination of $W_{\\mathrm{air}}$ and $k_{Q}$ in clinical ion beams.","status_note":"IAEA TRS-398 Rev. 1 (2024) adopted the ICRU 90 data; for carbon ions the $W_{\\mathrm{air}}$ and $k_{Q}$ terms still keep the total uncertainty near 3 percent.","title":"Beam-quality factors and $W_{\\mathrm{air}}$ for ion dosimetry","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"37312f4ba4be4158da0c3127223d449e1dbf11cf2b35bb9300fb00194d72ea99","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"e574056d63015d62e902445f114dab3330c57d48092de9a1ae78846822358ef4","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"Sgl_LJ8EnHAuPLBUCypHZFYpsryDTSlOjgtNqGoCYZyT34pQOSH_5mf-spJja3jP--SGttMZc2R3i5LoDUacDg"},"schema":"pubphys.envelope/1"},"record_hash":"37312f4ba4be4158da0c3127223d449e1dbf11cf2b35bb9300fb00194d72ea99","leaf_index":3466}