International Journal of Radiation Oncology Biology Physics最新文献

Introduction: While technical advances have allowed for reduced radiation doses to the lungs and heart when treating esophageal cancer (EC), doses to these organs cannot yet be eliminated completely. We conducted a post hoc analysis of CALGB 80803 (Alliance) to evaluate whether the radiation doses delivered to the heart and lungs in a prospective study with robust quality assurance were associated with overall survival (OS), and we assessed the impact of intensity modulated radiation therapy (IMRT) on adherence with protocol-specified dose constraints.

Methods: Protocol-specified dose constraints were based on standard of care guidelines: total lung V10Gy ≤ 40%, V20Gy ≤ 20%, V30Gy ≤ 15%, V40Gy ≤ 10%; heart V30Gy ≤ 30%. Post hoc dose cutpoints were calculated that best differentiated OS.

Results: There were 225 patients who underwent induction chemotherapy, where radiation modality data were available for 209/225 (92.8%); 127/209 (60.9%) were treated with IMRT. Adherence rates were high for each of the protocol-specified dose constraints: 162/209 (77.5%), 179/209 (85.6%), 207/209 (99.0%), 208/209 (99.5%), and 158/209 (75.6%); total lung: V10Gy, V20Gy, V30Gy, V40Gy, and heart V30Gy, respectively. The heart V30Gy ≤ 21% (p = 0.016) was associated with improved OS. Among patients with heart V30Gy ≤ 21%, 8.5% and 32.3% received 3-dimensional conformal radiotherapy (3D-CRT) and IMRT, respectively (p< 0.001). Mean heart V30Gy was lower in the IMRT versus the 3D-CRT group (24.7 versus 35.6; p< 0.001). On multivariable analysis, lung V10Gy >42% (hazard ratio [HR]: 1.71; p = 0.017) and heart V30Gy > 21% (HR: 1.86; p = 0.013) were associated with worse OS.

Conclusion: Most patients on CALGB 80803 (Alliance) were treated with IMRT plans that met protocol-specified dose constraints for total lung and heart. Minimizing low dose volume to the lungs (V10Gy) and minimizing heart V30Gy were associated with a significant survival benefit. Total lung V10Gy ≤ 42% and heart V30Gy ≤ 21%, and utilization of IMRT over 3D-CRT, should be considered when designing radiation plans for EC patients.

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.