{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T09:34:27Z","timestamp":1789724067133,"version":"4.0.1"},"reference-count":26,"publisher":"Wiley","issue":"6","license":[{"start":{"date-parts":[[2025,4,9]],"date-time":"2025-04-09T00:00:00Z","timestamp":1744156800000},"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":[[2025,6]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Purpose<\/jats:title><jats:p>An evaluation of the accuracy, safety, and efficiency of the Halcyon ring delivery system (RDS) for stereotactic radiosurgery (SRS) treatment to relatively small (1\u20133\u00a0cm) brain lesions.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>After completing the extensive in\u2010house quality assurance checks including Winston\u2013Lutz test and independent dose verification via MD Anderson IROC SRS head phantom irradiation on Halcyon, fifteen brain SRS patients previously treated with a single dose of 20\u00a0Gy on TrueBeam (6MV\u2010FFF) with HyperArc geometry were retrospectively replanned on Halcyon (6MV\u2010FFF). Plan quality metrics including conformity index (CI), gradient index (GI), gradient distance (GD), PTV coverage, gross tumor volume (GTV) dose, heterogeneity index (HI), and doses to organs\u2010at\u2010risk (OAR) including normal brain dose were evaluated. Patient\u2010specific quality assurance (PSQA) and independent dose verification via in\u2010house Monte Carlo (MC) 2nd checks were performed.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>The Halcyon was able to provide highly conformal brain SRS plans. When compared to TrueBeam, CI, planning target volume (PTV) coverage, GTV dose (mean and minimum), HI, and doses to brainstem, optic pathway, and cochlea were statistically insignificant. Statistically significant increases in GI (3.76\u00a0vs. 3.25, <jats:italic>p<\/jats:italic>\u00a0&lt;\u00a00.001), GD (0.56\u00a0cm vs. 0.48\u00a0cm, <jats:italic>p<\/jats:italic>\u00a0=\u00a00.001), and V<jats:sub>12Gy<\/jats:sub> (5.5 cc vs. 4.6 cc, <jats:italic>p<\/jats:italic>\u00a0=\u00a00.014), on average using Halcyon versus TrueBeam was found, albeit clinically acceptable values for the majority of brain SRS cases. Halcyon plans provided statistically insignificant maximum dose to most adjacent OARs, though there was a statistically significant decrease in the maximum dose to the spinal cord (0.1\u00a0Gy vs. 0.4\u00a0Gy, <jats:italic>p<\/jats:italic>\u00a0=\u00a00.009). Halcyon beam\u2010on time increases by a factor of \u223c2 (<jats:italic>p<\/jats:italic>\u00a0&lt;\u00a00.001). However, the faster patient setup on Halcyon results in a comparable estimated overall treatment time for both platforms. Plan deliverability and accuracy was ensured with PSQA\u00a0(&gt;\u00a095% pass rate for 2%\/2\u00a0mm clinical gamma criteria) results and MC 2nd check agreement within\u00a0\u00b1\u00a05.0%.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>Halcyon brain SRS plans provided a similar plan quality compared to HyperArc plans, although it demonstrated an inferior intermediate dose fall off thus slightly higher V<jats:sub>12Gy<\/jats:sub>. This study suggests that Halcyon provides acceptable treatment for solitary relatively small brain lesions of 1\u20133\u00a0cm in diameter. Treatment of select patients on Halcyon will be started at our clinic and it is recommended that other clinics complete an end\u2010to\u2010end test, validate, and implement Halcyon SRS treatments at their practices, especially community cancer centers to provide high\u2010quality service to an underserved patient cohort.<\/jats:p><\/jats:sec>","DOI":"10.1002\/acm2.70105","type":"journal-article","created":{"date-parts":[[2025,4,10]],"date-time":"2025-04-10T00:10:42Z","timestamp":1744243842000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["An investigation into the feasibility and efficacy of stereotactic radiosurgery for 1\u20133\u00a0cm single brain lesions on the ring\u2010mounted Halcyon LINAC"],"prefix":"10.1002","volume":"26","author":[{"given":"Kate","family":"Hazelwood","sequence":"first","affiliation":[{"name":"Medical Physics Graduate Program Department of Radiation Medicine University of Kentucky  Lexington Kentucky USA"},{"name":"Rhodes College Physics, Biochemistry and Molecular Biology  Memphis Tennessee USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-9300-4857","authenticated-orcid":false,"given":"Shane","family":"McCarthy","sequence":"additional","affiliation":[{"name":"Medical Physics Graduate Program Department of Radiation Medicine University of Kentucky  Lexington Kentucky USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-8084-0438","authenticated-orcid":false,"given":"Josh","family":"Misa","sequence":"additional","affiliation":[{"name":"Medical Physics Graduate Program Department of Radiation Medicine University of Kentucky  Lexington Kentucky USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David","family":"Castelvetere","sequence":"additional","affiliation":[{"name":"Medical Physics Graduate Program Department of Radiation Medicine University of Kentucky  Lexington Kentucky USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"William","family":"St. Clair","sequence":"additional","affiliation":[{"name":"Medical Physics Graduate Program Department of Radiation Medicine University of Kentucky  Lexington Kentucky USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2694-1047","authenticated-orcid":false,"given":"Damodar","family":"Pokhrel","sequence":"additional","affiliation":[{"name":"Medical Physics Graduate Program Department of Radiation Medicine University of Kentucky  Lexington Kentucky USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2025,4,9]]},"reference":[{"key":"e_1_2_10_2_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.prro.2011.12.004"},{"issue":"1","key":"e_1_2_10_3_1","first-page":"333","article-title":"Radiosurgery with 20\u00a0Gy provides better local control of 1\u20133 brain metastases from breast cancer than with lower doses","volume":"35","author":"Rades D","year":"2015","journal-title":"Anticancer Res"},{"key":"e_1_2_10_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijrobp.2009.06.006"},{"key":"e_1_2_10_5_1","doi-asserted-by":"publisher","DOI":"10.1002\/acm2.13877"},{"key":"e_1_2_10_6_1","unstructured":"Varian Medical Systems.Halcyon Physics Manual 2.0 2019:183(Palo Alto CA)."},{"key":"e_1_2_10_7_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejmp.2019.11.015"},{"key":"e_1_2_10_8_1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.13396"},{"key":"e_1_2_10_9_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.meddos.2023.03.005"},{"key":"e_1_2_10_10_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.3438081"},{"key":"e_1_2_10_11_1","doi-asserted-by":"publisher","DOI":"10.1002\/acm2.14281"},{"key":"e_1_2_10_12_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.adro.2020.01.003"},{"key":"e_1_2_10_13_1","doi-asserted-by":"publisher","DOI":"10.3389\/fonc.2019.00007"},{"key":"e_1_2_10_14_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.prro.2011.06.014"},{"key":"e_1_2_10_15_1","unstructured":"Clinical Trials (Alliance brain SRT\/SRS trial). 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