{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"cc3027c809c990565421a6c9b114c7045e47903dd152df458837024556fc5ea6","created":"2026-10-03T07:18:06Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"cd24fd0052cbc608d033282c5805e8cc6ddb69ba3a4979712a49c197a37002ce","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"med.ion-therapy.stopping-power","kind":"well-posed","literature_status":"partially-resolved","n":"1","parents":[],"plain":"The plan converts a CT scan into a map of how fast particles slow down. Converting image numbers into that map introduces an error of a few percent, which becomes a few millimetres of range error.","posed_since":"1996","precise":"Determine the stopping power of patient tissues relative to water from imaging to better than 1 percent root-mean-square, including tissue mean excitation energies relative to water and tissue-composition variability. Candidate routes: dual-energy CT, photon-counting spectral CT, proton CT. An answer is a validated conversion with a stated uncertainty budget.","problem_ref":null,"references":"","settled_by":"Direct proton-beam measurement of stopping power in tissue samples and phantoms compared against the imaging-derived map.","status_note":"Dual-energy CT lowered relative stopping-power errors to roughly 1 percent by 2023; tissue I-values and tissue-composition variability remain the dominant residual terms.","title":"Patient stopping-power accuracy below one percent","topic_ref":"783c95cea555c72f61498fd08fa3ced7be4a4b07d67abcd2e5bc27204e6bdab5"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"a22354c180e8fbc6c1d75512c16d788ed379a8f5cb6bc266153c39ca43612c0f","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"675b8fbbc6b431d82a428c1a95190e1712e64a9998cf0884722988ab118faadb","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"8qEU4mtbCTpJOPqAX9TGklMOUivfv4v-R2DXIzD6WUBepvfJf7I8OXeLT93ShVVvQrRAPwaq5UfmcKLQmVkPDQ"},"schema":"pubphys.envelope/1"},"record_hash":"a22354c180e8fbc6c1d75512c16d788ed379a8f5cb6bc266153c39ca43612c0f","leaf_index":1694}