{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,26]],"date-time":"2026-07-26T22:36:15Z","timestamp":1785105375648,"version":"3.55.0"},"reference-count":38,"publisher":"Wiley","issue":"9","license":[{"start":{"date-parts":[[2024,6,4]],"date-time":"2024-06-04T00:00:00Z","timestamp":1717459200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["aapm.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["J Applied Clin Med Phys"],"published-print":{"date-parts":[[2024,9]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Purpose<\/jats:title><jats:p>CT Hounsfield Units (HUs) are converted to electron density using a calibration curve obtained from physical measurements of an electron density phantom. HU values assigned to an MRI\u2010derived synthetic computed tomography (sCT) may present a different relationship with electron density compared to CT HU. Correct assignment of sCT HU values is critical for accurate dose calculation and delivery. The goals of this work were to develop a sCT calibration curve using patient data acquired on a clinically commissioned CT scanner and assess for CyberKnife\u2010 and volumetric modulated arc therapy (VMAT)\u2010based MR\u2010only treatment planning of prostate SBRT.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Same\u2010day CT and MRI simulation in the treatment position were performed on 10 patients treated with SBRT to the prostate. Dixon in\u2010phase and out\u2010of\u2010phase MRIs were acquired on a 3T scanner using a 3D T1\u2010weighted gradient\u2010echo sequence to generate sCTs using a commercial sCT algorithm. CT and sCT datasets were co\u2010registered and HU values compared using mean absolute error (MAE). An optimized HU\u2010to\u2010density calibration curve was created based on average HU values across an institutional patient database for each of the four sCT tissue types. Clinical CyberKnife and VMAT treatment plans were generated on each patient CT and recomputed onto corresponding sCTs. Dose distributions computed using CT and sCT were compared using gamma criteria and dose\u2010volume\u2010histograms.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>For the optimized calibration curve, HU values were \u221296, 37, 204, and 1170 and relative electron densities were 0.95, 1.04, 1.1, and 1.7 for adipose, soft tissue, inner bone, and outer bone, respectively. The proposed sCT protocol produced total MAE of 94\u00a0\u00b1\u00a020HU. Gamma values mean\u00a0\u00b1\u00a0std (min\u2010max) were 98.9%\u00a0\u00b1\u00a00.9% (97.1%\u2013100%) and 97.7%\u00a0\u00b1\u00a01.3% (95.3%\u201399.3%) for VMAT and CyberKnife plans, respectively.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>MRI\u2010derived sCT using the proposed approach shows excellent dosimetric agreement with conventional CT simulation, demonstrating the feasibility of MRI\u2010derived sCT for prostate SBRT treatment planning.<\/jats:p><\/jats:sec>","DOI":"10.1002\/acm2.14411","type":"journal-article","created":{"date-parts":[[2024,6,5]],"date-time":"2024-06-05T05:39:48Z","timestamp":1717565988000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Linac\u2010 and CyberKnife\u2010based MRI\u2010only treatment planning of prostate SBRT using an optimized synthetic CT calibration curve"],"prefix":"10.1002","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8822-7861","authenticated-orcid":false,"given":"Jessica","family":"Scholey","sequence":"first","affiliation":[{"name":"Department of Radiation Oncology University of California San Francisco  San Francisco California USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1112-9905","authenticated-orcid":false,"given":"Tomi","family":"Nano","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology University of California San Francisco  San Francisco California USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3408-9587","authenticated-orcid":false,"given":"Kamal","family":"Singhrao","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology University of California San Francisco  San Francisco California 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