{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"1737b92dd5c681d5f5e3ac08537d649c2982f6a80d987094836f80a8617b23fa","created":"2026-10-03T07:18:06Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"d03eafc3213d46985a6b617d29cf76b4a7e65326aa4c72df44785f773563471c","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"classification","assisted_by":[],"external_id":"med.ion-therapy.optimal-ion","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Beyond protons, beams of helium, carbon, oxygen and neon are possible, each with a different balance of sharpness, biological effect and unwanted fragments. Which one is best for which tumour is unsettled.","posed_since":"1975","precise":"Rank ion species by atomic number Z from 1 to 10 against the combined criteria of lateral and distal penumbra, dose-averaged LET in target versus normal tissue, fragmentation tail dose beyond the Bragg peak, and oxygen enhancement ratio in hypoxic targets. An answer is a classification of tumour and site classes to the preferred ion, with the physics criteria that decide each case.","problem_ref":null,"references":"","settled_by":"Comparative planning plus measured fragmentation yields and in vivo effectiveness for each species on a common endpoint set.","status_note":"Helium returned to clinical use at HIT Heidelberg in 2021, after the Berkeley helium programme of 1957 to 1992; oxygen and multi-ion schemes were under study in 2025 without a settled ranking.","title":"Which ion species is optimal for therapy","topic_ref":"783c95cea555c72f61498fd08fa3ced7be4a4b07d67abcd2e5bc27204e6bdab5"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"8923634a80ac2c692e25b4672531dbb73514b1b18f2d33f0880b53eff3a4dcc5","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"bbb3667feda655cbef47763ff9d68f50c4685bec1f615bde1e69f76fa4b7a079","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"mPG4yW7w6jFFDof7093y6ymIyFh1jX0Yd9lgVzeVBu35uFhUlYF42BQrXkmM9vtZg00ZO5IZS6YIOlZ1MJ_aBQ"},"schema":"pubphys.envelope/1"},"record_hash":"8923634a80ac2c692e25b4672531dbb73514b1b18f2d33f0880b53eff3a4dcc5","leaf_index":1691}