{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,5]],"date-time":"2026-05-05T01:39:57Z","timestamp":1777945197981,"version":"3.51.4"},"reference-count":28,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2025,1,25]],"date-time":"2025-01-25T00:00:00Z","timestamp":1737763200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"},{"start":{"date-parts":[[2025,1,25]],"date-time":"2025-01-25T00:00:00Z","timestamp":1737763200000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["aapm.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Medical Physics"],"published-print":{"date-parts":[[2025,5]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>The use of iodinated contrast\u2010enhancing agents in computed tomography (CT) improves the visualization of relevant structures for radiotherapy treatment planning (RTP). However, it can lead to dose calculation errors by incorrectly converting a CT number to electron density.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>This study aimed to propose an algorithm for deriving virtual non\u2010contrast (VNC) electron density from dual\u2010energy CT (DECT) data. This algorithm was developed by extending the formula previously developed by Saito, which enables the calculation of the electron density of human tissue through weighted subtraction of CT numbers acquired from DECT scans.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>To investigate the feasibility of the proposed VNC algorithm, we performed analytical DECT image simulations at 90 and 150\u00a0kV\/Sn on virtual phantoms consisting of various tissue\/iodine surrogates with known mass densities and elemental compositions. Two different shapes of phantoms made of water\u2010mimicking surrogates were generated as inputs: a circular phantom (33\u00a0cm diameter) for calibration and an elliptical phantom (33\u00a0cm width and 28\u00a0cm height) for validation. The circular phantom was equipped with inserts of human\u2010tissue\u2010mimicking substitutes, pure water, and iodine\u2010enhanced soft\u2010tissue substitutes (2, 5, 10, and 15\u00a0mg\/mL iodine). The elliptical phantom contained inserts of reference human tissues, iodine\u2010enhanced soft\u2010tissue substitutes (2, 2.5, 5, 7.5, 10, 15, and 20\u00a0mg\/mL iodine), and a 10\u2010mm\u2010diameter core of 4\u00a0mg\/mL iodine surrounded by a blood\u2010mimicking base material. The performance of the proposed algorithm was evaluated by comparing the accuracy of VNC electron densities with those of non\u2010contrast (NC) base materials (water\u2010 or blood\u2010mimicking surrogates).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>The derived algorithm enabled the calculation of VNC electron density in a manner similar to that of unenhanced human tissues by adapting a VNC\u2010specific weighting factor, thereby eliminating the intermediate step of converting CT numbers to electron density. The simulated results showed that the VNC algorithm could almost completely remove the contrast in the electron density image between iodine\u2010enhanced and base materials. The relative deviations of simulated VNC electron density values from the corresponding pre\u2010contrast value were within\u00a0\u00b1\u00a00.4% for all tested materials, with a root\u2010mean\u2010square error (RMSE) of 0.2%.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Within the limits of the analytical DECT image simulation used in this study, the simple VNC algorithm could effectively provide accurate VNC electron densities for iodine\u2010enhanced materials. This may allow the contrast agent to be used for CT scans during RTP without compromising dose calculation accuracy.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/mp.17648","type":"journal-article","created":{"date-parts":[[2025,1,25]],"date-time":"2025-01-25T06:50:12Z","timestamp":1737787812000},"page":"3107-3116","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["A simple algorithm to derive virtual non\u2010contrast electron density from dual\u2010energy computed tomography data for radiotherapy treatment planning"],"prefix":"10.1002","volume":"52","author":[{"given":"Masatoshi","family":"Saito","sequence":"first","affiliation":[{"name":"Department of Radiological Technology, School of Health Sciences, Faculty of Medicine Niigata University  Niigata Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tatsuki","family":"Saito","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Faculty of Science Hokkaido University  Sapporo Hokkaido Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2025,1,25]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031\u20109155\/24\/4\/011"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejrad.2018.05.007"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1148\/rg.2016150220"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1186\/1748\u2010717X\u20109\u2010168"},{"key":"e_1_2_8_6_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.14702"},{"key":"e_1_2_8_7_1","doi-asserted-by":"publisher","DOI":"10.1002\/acm2.13468"},{"key":"e_1_2_8_8_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.acra.2013.01.010"},{"key":"e_1_2_8_9_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.meddos.2021.03.006"},{"key":"e_1_2_8_10_1","doi-asserted-by":"publisher","DOI":"10.1259\/bjr.20200170"},{"key":"e_1_2_8_11_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.12934"},{"key":"e_1_2_8_12_1","doi-asserted-by":"publisher","DOI":"10.1088\/1361\u20106560\/ab1af1"},{"key":"e_1_2_8_13_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.14204"},{"key":"e_1_2_8_14_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.3694111"},{"key":"e_1_2_8_15_1","doi-asserted-by":"publisher","DOI":"10.1088\/1361\u20106560\/acabfa"},{"key":"e_1_2_8_16_1","doi-asserted-by":"publisher","DOI":"10.1259\/0007\u20101285\u201059\u2010708\u20101209"},{"key":"e_1_2_8_17_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.3584200"},{"key":"e_1_2_8_18_1","volume-title":"Catalog of diagnostic x\u2010ray spectra and other data (IPEM Report No. 78)","author":"Cranley K","year":"1997"},{"key":"e_1_2_8_19_1","unstructured":"ICRU.Photon electron proton and neutron interaction data for body tissues ICRU Report No 46 ICRU;1992."},{"key":"e_1_2_8_20_1","doi-asserted-by":"crossref","unstructured":"BergerMJ HubbellJH.XCOM: photon cross sections on a personal computer. 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