{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"58f88f0104ebb58be9b08f872d1f82fe0ff4fbfec2a59af5898c44dd4d51ed9a","created":"2026-10-03T07:18:07Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"47b64562739bcde3cb93f1108373acf534872fa3edaa6b83f31c2c59edb1cfd6","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"med.pcct.spectral-distortion","kind":"well-posed","literature_status":"partially-resolved","n":"1","parents":[],"plain":"When a photon lands between pixels, its charge splits and is counted twice at the wrong energies; when photons arrive too fast they are counted as one. Both corrupt the measured spectrum.","posed_since":"2010","precise":"Construct a detector response model giving the recorded energy spectrum from the incident one, including charge sharing between pixels of 200 to 500 micron pitch, K-escape of the sensor material, and pulse pileup at count rates of $10^{8}$ to $10^{9}$ counts per second per $\\mathrm{mm}^2$, accurate enough that material decomposition bias stays below 1 percent. An answer is a validated response matrix with its calibration procedure.","problem_ref":null,"references":"","settled_by":"Measurement of the detector response to monoenergetic beams across rate and position, reproduced by the model to within the stated bias.","status_note":"Clinical photon-counting CT systems since 2021 apply empirical corrections; a first-principles response model with sub-percent bias was not established.","title":"Forward model for charge sharing and pulse pileup","topic_ref":"26d23f25e437e5a24b43745dd4da6507964829094aa1ed73aeaafb9ea3f82278"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"30f5231b62427409c4d77ee23d01ca0b9b43a979c0198d42ee345685205dab00","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"5fb8a497ca1d154c3aa5a5dd8f9dd8b5aee15ec23468caa7206fe3b05a746834","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"6DszhaQeuyTaP1HuFnpgEU44OT7eAllXARuOiH532YbjPE9wq78f8L3BIeflIRmVYy-3s01t1pQbOUthhSm7AQ"},"schema":"pubphys.envelope/1"},"record_hash":"30f5231b62427409c4d77ee23d01ca0b9b43a979c0198d42ee345685205dab00","leaf_index":1712}