Pub Date : 2026-02-04DOI: 10.1016/j.ijrobp.2025.12.031
Chang-Shiun Lin, Chenyang Shen, Thomas Banks, Rameshwar Prasad, Shahed Badiyan, Kenneth Westover, Yuanyuan Zhang, Andrew Godley, Arnold Pompos, Tu Dan, Aurelie Garant, Orhan Oz, David Sher, Robert Timmerman, Steve Jiang, Min Geon Choi, Bin Cai
Purpose: Biology-guided radiotherapy (BgRT), a novel treatment approach, integrates real-time PET imaging with external beam delivery to enable tumor-targeted dose modulation. Lung tumors, given their high FDG uptake and low background activity, are considered ideal candidates for BgRT. This study presents the first clinical experience of BgRT in lung cancer, evaluating treatment workflow, plan quality, PET signal characteristics, and delivery timing.
Materials and methods: A consecutive cohort of 27 patients with lung tumors were evaluated for biology-guided radiotherapy (BgRT) using the RefleXion X1 platform between December 2023 and January 2025. Of these, 14 patients received stereotactic body radiation therapy in five or fewer fractions. PET modeling and pre-treatment PET evaluation were performed to assess activity concentration (AC) and normalized target signal (NTS). Key metrics included treatment completion rate, plan quality parameters, temporal trends in FDG signal across fractions, and a timing analysis of treatment delivery encompassing imaging, planning, and delivery workflows.
Results: Among the 14 patients treated with BgRT, 12 completed all planned BgRT fractions. Two were transitioned to conventional IGRT due to insufficient PET signal and machine interlock, respectively. PET-based metrics demonstrated stable FDG avidity in most patients with gradual declines in AC and NTS that remained within clinically acceptable thresholds. BgRT plans met institutional dosimetric criteria, achieving median PTV V100% = 95.6% (range: 72.2-97.7%) and appropriate organ sparing. The median beam-on time was 29 minutes (range: 10-48 minutes), and median total procedure time was of 116 minutes (range: 91-136 minutes), supporting clinical feasibility.
Conclusions: BgRT using the RefleXion X1 system is clinically feasible, with preliminary indicators of short-term tolerability among evaluable fractions in lung cancer patients. This initial experience demonstrates reliable PET signal acquisition, consistent plan quality, and efficient delivery. These findings support the potential integration of BgRT into routine practice and justify further prospective studies in other disease sites.
{"title":"Feasibility, Workflow, Dosimetry and PET Signal Trends in Lung Cancer Treated with Biology-Guided Radiotherapy.","authors":"Chang-Shiun Lin, Chenyang Shen, Thomas Banks, Rameshwar Prasad, Shahed Badiyan, Kenneth Westover, Yuanyuan Zhang, Andrew Godley, Arnold Pompos, Tu Dan, Aurelie Garant, Orhan Oz, David Sher, Robert Timmerman, Steve Jiang, Min Geon Choi, Bin Cai","doi":"10.1016/j.ijrobp.2025.12.031","DOIUrl":"https://doi.org/10.1016/j.ijrobp.2025.12.031","url":null,"abstract":"<p><strong>Purpose: </strong>Biology-guided radiotherapy (BgRT), a novel treatment approach, integrates real-time PET imaging with external beam delivery to enable tumor-targeted dose modulation. Lung tumors, given their high FDG uptake and low background activity, are considered ideal candidates for BgRT. This study presents the first clinical experience of BgRT in lung cancer, evaluating treatment workflow, plan quality, PET signal characteristics, and delivery timing.</p><p><strong>Materials and methods: </strong>A consecutive cohort of 27 patients with lung tumors were evaluated for biology-guided radiotherapy (BgRT) using the RefleXion X1 platform between December 2023 and January 2025. Of these, 14 patients received stereotactic body radiation therapy in five or fewer fractions. PET modeling and pre-treatment PET evaluation were performed to assess activity concentration (AC) and normalized target signal (NTS). Key metrics included treatment completion rate, plan quality parameters, temporal trends in FDG signal across fractions, and a timing analysis of treatment delivery encompassing imaging, planning, and delivery workflows.</p><p><strong>Results: </strong>Among the 14 patients treated with BgRT, 12 completed all planned BgRT fractions. Two were transitioned to conventional IGRT due to insufficient PET signal and machine interlock, respectively. PET-based metrics demonstrated stable FDG avidity in most patients with gradual declines in AC and NTS that remained within clinically acceptable thresholds. BgRT plans met institutional dosimetric criteria, achieving median PTV V100% = 95.6% (range: 72.2-97.7%) and appropriate organ sparing. The median beam-on time was 29 minutes (range: 10-48 minutes), and median total procedure time was of 116 minutes (range: 91-136 minutes), supporting clinical feasibility.</p><p><strong>Conclusions: </strong>BgRT using the RefleXion X1 system is clinically feasible, with preliminary indicators of short-term tolerability among evaluable fractions in lung cancer patients. This initial experience demonstrates reliable PET signal acquisition, consistent plan quality, and efficient delivery. These findings support the potential integration of BgRT into routine practice and justify further prospective studies in other disease sites.</p>","PeriodicalId":14215,"journal":{"name":"International Journal of Radiation Oncology Biology Physics","volume":" ","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146131825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-03DOI: 10.1016/j.ijrobp.2025.11.018
Dominic H. Moon MD, David J. Sher MD, MPH
{"title":"In Reply to Wang et al","authors":"Dominic H. Moon MD, David J. Sher MD, MPH","doi":"10.1016/j.ijrobp.2025.11.018","DOIUrl":"10.1016/j.ijrobp.2025.11.018","url":null,"abstract":"","PeriodicalId":14215,"journal":{"name":"International Journal of Radiation Oncology Biology Physics","volume":"124 3","pages":"Page 873"},"PeriodicalIF":6.5,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146102405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-03DOI: 10.1016/j.ijrobp.2025.12.004
Christina Tsien MD, FRCP, FASTRO, Kevin Petrecca MD, PhD, FRSC
{"title":"Ahead of the Curve: Early Recognition and Effective Management of Radiation Necrosis","authors":"Christina Tsien MD, FRCP, FASTRO, Kevin Petrecca MD, PhD, FRSC","doi":"10.1016/j.ijrobp.2025.12.004","DOIUrl":"10.1016/j.ijrobp.2025.12.004","url":null,"abstract":"","PeriodicalId":14215,"journal":{"name":"International Journal of Radiation Oncology Biology Physics","volume":"124 3","pages":"Page 573"},"PeriodicalIF":6.5,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146102631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-03DOI: 10.1016/j.ijrobp.2025.12.002
Frank A. Giordano M.D.
{"title":"Heat or Healing? Dealing With “Something That Looks Like Progression” of Brain Metastases","authors":"Frank A. Giordano M.D.","doi":"10.1016/j.ijrobp.2025.12.002","DOIUrl":"10.1016/j.ijrobp.2025.12.002","url":null,"abstract":"","PeriodicalId":14215,"journal":{"name":"International Journal of Radiation Oncology Biology Physics","volume":"124 3","pages":"Page 572"},"PeriodicalIF":6.5,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146102654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-03DOI: 10.1016/j.ijrobp.2025.11.055
Christina C. Huang MD, Chris R. Kelsey MD
{"title":"In Reply to Oertel et al","authors":"Christina C. Huang MD, Chris R. Kelsey MD","doi":"10.1016/j.ijrobp.2025.11.055","DOIUrl":"10.1016/j.ijrobp.2025.11.055","url":null,"abstract":"","PeriodicalId":14215,"journal":{"name":"International Journal of Radiation Oncology Biology Physics","volume":"124 3","pages":"Pages 880-881"},"PeriodicalIF":6.5,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146102687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-03DOI: 10.1016/j.ijrobp.2025.11.014
Matthias May MD, PhD, Oscar R. Brouwer MD, PhD, Laura Elst MD, Maarten Albersen MD, PhD
{"title":"In Regard to Ka et al.","authors":"Matthias May MD, PhD, Oscar R. Brouwer MD, PhD, Laura Elst MD, Maarten Albersen MD, PhD","doi":"10.1016/j.ijrobp.2025.11.014","DOIUrl":"10.1016/j.ijrobp.2025.11.014","url":null,"abstract":"","PeriodicalId":14215,"journal":{"name":"International Journal of Radiation Oncology Biology Physics","volume":"124 3","pages":"Pages 868-869"},"PeriodicalIF":6.5,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146102404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-03DOI: 10.1016/j.ijrobp.2025.11.015
Pierre Loap MD, Youlia Kirova MD
{"title":"In Reply to Liu et al","authors":"Pierre Loap MD, Youlia Kirova MD","doi":"10.1016/j.ijrobp.2025.11.015","DOIUrl":"10.1016/j.ijrobp.2025.11.015","url":null,"abstract":"","PeriodicalId":14215,"journal":{"name":"International Journal of Radiation Oncology Biology Physics","volume":"124 3","pages":"Pages 877-878"},"PeriodicalIF":6.5,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146102526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-03DOI: 10.1016/j.ijrobp.2025.10.013
Maria Gebre-Medhin MD, PhD , Gabriel Adrian MD, PhD
{"title":"Circulating Tumor DNA in Human Papilloma Virus-Positive Oropharyngeal Squamous Cell Carcinoma—Are We Ready to Individualize Treatment?","authors":"Maria Gebre-Medhin MD, PhD , Gabriel Adrian MD, PhD","doi":"10.1016/j.ijrobp.2025.10.013","DOIUrl":"10.1016/j.ijrobp.2025.10.013","url":null,"abstract":"","PeriodicalId":14215,"journal":{"name":"International Journal of Radiation Oncology Biology Physics","volume":"124 3","pages":"Pages 686-691"},"PeriodicalIF":6.5,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146102652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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