{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,7]],"date-time":"2025-11-07T11:28:56Z","timestamp":1762514936901,"version":"build-2065373602"},"reference-count":49,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2025,3,19]],"date-time":"2025-03-19T00:00:00Z","timestamp":1742342400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000289","name":"Cancer Research UK","doi-asserted-by":"publisher","award":["A26234","C33589\/A28284"],"award-info":[{"award-number":["A26234","C33589\/A28284"]}],"id":[{"id":"10.13039\/501100000289","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Magnetic Resonance in Med"],"published-print":{"date-parts":[[2025,7]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>To measure the gradient system transfer function (GSTF) of an MR\u2010Linac (Elekta Unity, Stockholm, Sweden) using an accessible phantom\u2010based method and to apply trajectory corrections for UTE image reconstruction in the context of MR\u2010guided radiotherapy of lung cancer.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>The first\u2010order GSTF of a 1.5\u2009T, split gradient Elekta Unity MR\u2010Linac was measured using a thin\u2010slice technique to characterize gradient system imperfections for each physical gradient axis (X, Y, Z). Repeatability measurements of the GSTF were performed 48\u2009h apart. The GSTF was applied to trajectory correction in multi\u2010echo UTE image reconstruction (TEs\u2009=\u20090.176, 1.85, 3.52\u2009ms) to allow for UTE\u2010Dixon inputs in the generation of synthetic CT. Images were acquired in an anthropomorphic phantom and in two free\u2010breathing lung cancer patients. For patient scans, respiratory\u2010correlated 4D\u2010MR images were reconstructed using self\u2010navigation and an iterative compressed\u2010sensing algorithm.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      The GSTF magnitude was similar across the X\/Y\/Z axes up to \u02dc6\u2009kHz. The GSTF phase was similar between the X\/Y\/Z components up to \u02dc3\u2009kHz. Repeatability measurements demonstrated minimal variations corresponding to a system delay difference of 0.06\u2009\u03bcs. Corrected UTE trajectory spokes are shifted approximately 1\u2009m\n                      <jats:sup>\u22121<\/jats:sup>\n                      compared to the nominal\n                      <jats:italic>k<\/jats:italic>\n                      \u2010space location. Corrected phantom and patient UTE images exhibited improved signal uniformity and contrast and reduced halo and signal loss artifacts. Trajectory correction for the later TE images did not improve overall image quality.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>The proposed GSTF measurement method using standard MR\u2010Linac hardware enables successful trajectory correction in UTE imaging reconstruction, with applications to lung synthetic CT generation for MR\u2010guided radiotherapy.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1002\/mrm.30505","type":"journal-article","created":{"date-parts":[[2025,3,19]],"date-time":"2025-03-19T16:30:09Z","timestamp":1742401809000},"page":"28-40","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Gradient system characterization of a 1.\n                    <scp>5\u2009T MR<\/scp>\n                    \u2010Linac with application to\n                    <scp>4D UTE<\/scp>\n                    imaging for adaptive\n                    <scp>MR<\/scp>\n                    \u2010guided radiotherapy of lung cancer"],"prefix":"10.1002","volume":"94","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5109-4738","authenticated-orcid":false,"given":"Rosie","family":"Goodburn","sequence":"first","affiliation":[{"name":"Joint Department of Physics Institute of Cancer Research and Royal Marsden NHS Foundation Trust   London United Kingdom"},{"name":"The Royal Marsden NHS Foundation Trust  Sutton United Kingdom"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tom","family":"Bruijnen","sequence":"additional","affiliation":[{"name":"Department of Radiotherapy University Medical Center Utrecht  Utrecht The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bastien","family":"Lecoeur","sequence":"additional","affiliation":[{"name":"Joint Department of Physics Institute of Cancer Research and Royal Marsden NHS Foundation Trust   London United Kingdom"},{"name":"Department of Computing Imperial College London  London United Kingdom"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Prashant","family":"Nair","sequence":"additional","affiliation":[{"name":"Joint Department of Physics Institute of Cancer Research and Royal Marsden NHS Foundation Trust   London United Kingdom"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Merina","family":"Ahmed","sequence":"additional","affiliation":[{"name":"The Royal Marsden NHS Foundation Trust  Sutton United Kingdom"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Helen","family":"Barnes","sequence":"additional","affiliation":[{"name":"The Royal Marsden NHS Foundation Trust  Sutton United Kingdom"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Uwe","family":"Oelfke","sequence":"additional","affiliation":[{"name":"Joint Department of Physics Institute of Cancer Research and Royal Marsden NHS Foundation Trust   London United Kingdom"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4799-2193","authenticated-orcid":false,"given":"Andreas","family":"Wetscherek","sequence":"additional","affiliation":[{"name":"Joint Department of Physics Institute of Cancer Research and Royal Marsden NHS Foundation Trust   London United Kingdom"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2025,3,19]]},"reference":[{"key":"e_1_2_8_2_1","doi-asserted-by":"publisher","DOI":"10.1002\/cmr.a.21297"},{"key":"e_1_2_8_3_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.13574"},{"key":"e_1_2_8_4_1","doi-asserted-by":"publisher","DOI":"10.1109\/TMI.2019.2935916"},{"key":"e_1_2_8_5_1","doi-asserted-by":"publisher","DOI":"10.1148\/radiol.230052"},{"key":"e_1_2_8_6_1","doi-asserted-by":"publisher","DOI":"10.1088\/1361-6560\/ab0dbb"},{"key":"e_1_2_8_7_1","doi-asserted-by":"publisher","DOI":"10.1002\/jmri.24713"},{"key":"e_1_2_8_8_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.22016"},{"key":"e_1_2_8_9_1","doi-asserted-by":"publisher","DOI":"10.1002\/mrm.24263"},{"key":"e_1_2_8_10_1","unstructured":"KronthalerS RahmerJ B\u00f6rnertP KarampinosD.Trajectory correction for ultrashort echo\u2010time (UTE) imaging based on the measurement of the gradient impulse response function (GIRF) with a thin\u2010slice method. 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