{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,3]],"date-time":"2026-10-03T20:32:44Z","timestamp":1791059564032,"version":"4.1.0"},"reference-count":36,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2011,2,24]],"date-time":"2011-02-24T00:00:00Z","timestamp":1298505600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["2R44021794"],"award-info":[{"award-number":["2R44021794"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000097","name":"National Center for Research Resources","doi-asserted-by":"publisher","award":["2R44021794"],"award-info":[{"award-number":["2R44021794"]}],"id":[{"id":"10.13039\/100000097","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Medical Physics"],"published-print":{"date-parts":[[2011,3]]},"abstract":"<jats:sec>\n                    <jats:title>Purpose:<\/jats:title>\n                    <jats:p>The objective of the study was to demonstrate that, in x\u2010ray computed tomography (CT), more than two types of materials can be effectively separated with the use of an energy resolved photon\u2010counting detector and classification methodology. Specifically, this applies to the case when contrast agents that contain K\u2010absorption edges in the energy range of interest are present in the object. This separation is enabled via the use of recently developed energy resolved photon\u2010counting detectors with multiple thresholds, which allow simultaneous measurements of the x\u2010ray attenuation at multiple energies.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods:<\/jats:title>\n                    <jats:p>To demonstrate this capability, we performed simulations and physical experiments using a six\u2010threshold energy resolved photon\u2010counting detector. We imaged mouse\u2010sized cylindrical phantoms filled with several soft\u2010tissue\u2010like and bone\u2010like materials and with iodine\u2010based and gadolinium\u2010based contrast agents. The linear attenuation coefficients were reconstructed for each material in each energy window and were visualized as scatter plots between pairs of energy windows. For comparison, a dual\u2010kVp CT was also simulated using the same phantom materials. In this case, the linear attenuation coefficients at the lower kVp were plotted against those at the higher kVp.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results:<\/jats:title>\n                    <jats:p>In both the simulations and the physical experiments, the contrast agents were easily separable from other soft\u2010tissue\u2010like and bone\u2010like materials, thanks to the availability of the attenuation coefficient measurements at more than two energies provided by the energy resolved photon\u2010counting detector. In the simulations, the amount of separation was observed to be proportional to the concentration of the contrast agents; however, this was not observed in the physical experiments due to limitations of the real detector system. We used the angle between pairs of attenuation coefficient vectors in either the 5\u2010D space (for non\u2010contrast\u2010agent materials using energy resolved photon\u2010counting acquisition) or a 2\u2010D space (for contrast agents using energy resolved photon\u2010counting acquisition and all materials using dual\u2010kVp acquisition) as a measure of the degree of separation. Compared to dual\u2010kVp techniques, an energy resolved detector provided a larger separation and the ability to separate different target materials using measurements acquired in different energy window pairs with a single x\u2010ray exposure.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions:<\/jats:title>\n                    <jats:p>We concluded that x\u2010ray CT with an energy resolved photon\u2010counting detector with more than two energy windows allows the separation of more than two types of materials, e.g., soft\u2010tissue\u2010like, bone\u2010like, and one or more materials with K\u2010edges in the energy range of interest. Separating material types using energy resolved photon\u2010counting detectors has a number of advantages over dual\u2010kVp CT in terms of the degree of separation and the number of materials that can be separated simultaneously.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1118\/1.3553401","type":"journal-article","created":{"date-parts":[[2011,3,4]],"date-time":"2011-03-04T09:55:04Z","timestamp":1299232504000},"page":"1534-1546","source":"Crossref","is-referenced-by-count":177,"title":["Material separation in x\u2010ray CT with energy resolved photon\u2010counting detectors"],"prefix":"10.1002","volume":"38","author":[{"given":"Xiaolan","family":"Wang","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dirk","family":"Meier","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Katsuyuki","family":"Taguchi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Douglas J.","family":"Wagenaar","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bradley E.","family":"Patt","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eric C.","family":"Frey","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2011,2,24]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.595958"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1097\/00004728\u2010198408000\u201000029"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1148\/radiology.140.2.7255718"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00330\u2010005\u20102919\u20102"},{"key":"e_1_2_8_6_1","doi-asserted-by":"publisher","DOI":"10.1117\/12.844859"},{"key":"e_1_2_8_7_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.1645679"},{"key":"e_1_2_8_8_1","doi-asserted-by":"publisher","DOI":"10.1148\/126.1.255"},{"key":"e_1_2_8_9_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.594672"},{"key":"e_1_2_8_10_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.598982"},{"key":"e_1_2_8_11_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.acra.2009.01.002"},{"key":"e_1_2_8_12_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.3083567"},{"key":"e_1_2_8_13_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.3157098"},{"key":"e_1_2_8_14_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031\u20109155\/53\/15\/002"},{"key":"e_1_2_8_15_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031\u20109155\/51\/17\/010"},{"key":"e_1_2_8_16_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0168\u20109002(97)01309\u20100"},{"key":"e_1_2_8_17_1","doi-asserted-by":"publisher","DOI":"10.1109\/23.737664"},{"key":"e_1_2_8_18_1","unstructured":"T. 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