{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"40aa50cf97116e37639222943dc2a6d50c3f239d8e20e813f6f1d99e7f656cff","created":"2026-10-03T07:18:07Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"65fdea8044f201373ab939cd59220262f55bb62b9a16d39e04d18a78161d4ba3","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"med.pet.timing-limit","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Today the best clinical scanners time the two photons to about two hundred trillionths of a second (picoseconds). Getting to ten would place each emission directly, with no image reconstruction.","posed_since":"2017","precise":"Determine whether a coincidence time resolution of 10 ps full width at half maximum is attainable in a detector of sufficient stopping power for 511 keV photons, which corresponds to a position uncertainty of about 1.5 mm along the line of response. Required chain: photon production statistics and rise time, light transport, photodetector transit-time spread, and electronics jitter. An answer is a demonstrated detector pair or a proof that a chain element forbids it.","problem_ref":null,"references":"","settled_by":"A bench measurement of 10 ps coincidence resolution between two detectors with 511 keV efficiency comparable to clinical crystals.","status_note":"Laboratory detector pairs reached the tens of ps range by the mid 2020s; clinical systems were at about 180 to 230 ps.","title":"Is 10 ps coincidence time resolution reachable","topic_ref":"82c46a639f6fd1f2c6c4e5f93efaf610a76f3cc0784379dd43df49391264c57d"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"b9ac9f44652a99795b9547ff2d404bfa7120d276ceb5cc641d745b4bcd729558","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"59eb85b6dfac2da339a8970938b61fdded810cfaad6ea37e56d1274d3215a332","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"5FoLCaRdKNUkz_2_R4xIrnYabAfTMTGDfgT6bY5r8y-LATTIPx77xJ00SAxm65YnIeVnYF-Q830TNL6wgmkLBg"},"schema":"pubphys.envelope/1"},"record_hash":"b9ac9f44652a99795b9547ff2d404bfa7120d276ceb5cc641d745b4bcd729558","leaf_index":1716}