{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"60f1036833b546031538a225c701b40dca1fe559ffeb0d512294018d7fd53640","created":"2026-10-03T07:18:06Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"a69604a0ae681302e96e497d6530914259b25ca1fcde33ebf8d6910c8221d0ba","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":"1","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 $1.5\\,\\mathrm{percent}$. ICRU 90 values are $W_{\\mathrm{air}}$ of about $34.44\\,\\mathrm{eV}$ for protons (about $0.4\\,\\mathrm{percent}$ standard uncertainty) and $34.71\\,\\mathrm{eV}$ for carbon ions (about $1.5\\,\\mathrm{percent}$). An answer is a measured value set with reduced uncertainty.","problem_ref":null,"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":"be2989252171f9f987d92f4b562e96075370f97879f879218827602913f7731c"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"7076cbc43c307aa140efad6211c47c1fda6bf68320a8f771ccd82c872b9c28a8","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"bfa8a43200053f4c5303397dd72de02b30e8d6f8831f863cfcc02876ef3e7389","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"1l1Mf-EdYtbefTM6qFqlPailSdhqIFer9L4A0Y7LX0YG6Sk9UDcJUmrUuvsz8j2I6qX0t-n9tAqKrppSxRCkCw"},"schema":"pubphys.envelope/1"},"record_hash":"7076cbc43c307aa140efad6211c47c1fda6bf68320a8f771ccd82c872b9c28a8","leaf_index":1673}