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This in silico study explores Tikhonov-regularized anti-focus (AF) driving to improve transspinal focal quality when focusing with a 256-element, 400-kHz spine-specific array. Three focusing methods were simulated for 80 targets in an ex vivo human spine: (1) uncorrected (water-case) phases and amplitudes, (2) simulation-derived phases and inverse amplitude correction, and (3) AF-derived phases and amplitude shading. Simulation-derived correction reduced mean targeting error from 4.6\u2009\u00b1\u20092.1\u2009mm to 3.2\u2009\u00b1\u20093.1\u2009mm relative to the uncorrected case. AF-derived driving further reduced mean targeting error to 1.4\u2009\u00b1\u20090.9\u2009mm but decreased driving efficiency (maximum pressure normalized to driving amplitude) by 51%. Simulations were then extended to 304 targets in 4 human spines from an open-source CT dataset. Targeting error was reduced from 5.2\u2009\u00b1\u20092.8\u2009mm in the uncorrected case to 4.0\u2009\u00b1\u20093.2\u2009mm when using phase and inverse amplitude correction (23% decrease), whereas AF-derived driving reduced mean targeting error to 1.6\u2009\u00b1\u20091.4\u2009mm (69% decrease). In conclusion, AF-based driving greatly reduces targeting error in transspinal focused ultrasound simulations at a cost of reduced driving efficiency.<\/jats:p>","DOI":"10.1121\/10.0041763","type":"journal-article","created":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T12:05:27Z","timestamp":1779365127000},"page":"4524-4534","update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["A numerical analysis of anti-focus driving to improve focal quality in transvertebral focused ultrasound"],"prefix":"10.1121","volume":"159","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-7436-3157","authenticated-orcid":false,"given":"David","family":"Martin","sequence":"first","affiliation":[{"name":"Physical Sciences Platform, Sunnybrook Research Institute 1 , Toronto, Ontario M4N 3M5,","place":["Canada"]},{"name":"Department of Medical Biophysics, Temerty Faculty of Medicine, University of Toronto 2 , Toronto, Ontario M5G 2C4,","place":["Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1541-4110","authenticated-orcid":false,"given":"Ryan M.","family":"Jones","sequence":"additional","affiliation":[{"name":"Physical Sciences Platform, Sunnybrook Research Institute 1 , Toronto, Ontario M4N 3M5,","place":["Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2889-6614","authenticated-orcid":false,"given":"Meaghan A.","family":"O'Reilly","sequence":"additional","affiliation":[{"name":"Physical Sciences Platform, Sunnybrook Research Institute 1 , Toronto, Ontario M4N 3M5,","place":["Canada"]},{"name":"Department of Medical Biophysics, Temerty Faculty of Medicine, University of Toronto 2 , Toronto, Ontario M5G 2C4,","place":["Canada"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"231","published-online":{"date-parts":[[2026,5,21]]},"reference":[{"key":"2026060513261453600_c1","doi-asserted-by":"publisher","first-page":"640","DOI":"10.1148\/radiol.2202001804","article-title":"Noninvasive MR imaging-guided focal opening of the blood\u2013brain barrier in rabbits","volume":"220","year":"2001","journal-title":"Radiology"},{"key":"2026060513261453600_c2","doi-asserted-by":"publisher","first-page":"11","DOI":"10.1126\/scitranslmed.aaf6086","article-title":"Clinical trial of blood\u2013brain barrier disruption by pulsed ultrasound","volume":"8","year":"2016","journal-title":"Sci. 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