{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"840ffb91b726ae54a77bf391a825bc7ddd2daef2cec53a1efe2ba2f6d1cd4dd4","created":"2026-10-03T07:18:07Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"1b28be20964e97863ae2ddccbc83b992cbc1cb79286a364eace164aeaa1851e1","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"med.pcct.k-edge-sensitivity","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Elements like iodine and gadolinium absorb x-rays sharply above one energy, which lets a spectral scanner tell them apart. How little of an element can be detected is not pinned down.","posed_since":"2008","precise":"Determine the minimum detectable concentration of K-edge elements (iodine at 33.2 keV, gadolinium at 50.2 keV, and higher-Z labels such as tantalum, gold and bismuth) in a 30 cm diameter water phantom at clinical dose, as a function of detector energy resolution, bin count and photon flux. An answer is a detection-limit formula in mg per cm^3 with its dependence on these quantities.","problem_ref":null,"references":"","settled_by":"Phantom measurements across concentration and dose compared against a task-based detectability calculation using the measured detector response.","status_note":"","title":"Detection limit for K-edge contrast agents","topic_ref":"26d23f25e437e5a24b43745dd4da6507964829094aa1ed73aeaafb9ea3f82278"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"930874c36a968325068f34df74a2c7b9308fb8335791479d0f0816a4a8ac6a4e","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"85bbed3c3fc558df28cb1ea4dabca8463040969350bb746e1be39c402beb091a","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"htEibjPxa86Ia6zxUA1ZZxoYQ1ZJlG-79TAOCytmvM6Aq4U6IHmfNKjD5Sc4rftdbWy6SWBxA7sjZ8YexlQ5Ag"},"schema":"pubphys.envelope/1"},"record_hash":"930874c36a968325068f34df74a2c7b9308fb8335791479d0f0816a4a8ac6a4e","leaf_index":1711}