Bibliographic Details
| Title: |
Single-Isocenter Linac-Based Radiosurgery for Brain Metastases with Coplanar Arcs: A Dosimetric and Clinical Analysis. |
| Authors: |
Faccenda, Valeria1 (AUTHOR) valeria.faccenda@irccs-sangerardo.it, Panizza, Denis1,2 (AUTHOR) denis.panizza@irccs-sangerardo.it, Pisoni, Valerio3 (AUTHOR) valerio.pisoni@irccs-sangerardo.it, Trivellato, Sara1 (AUTHOR) sara.trivellato@irccs-sangerardo.it, Daniotti, Martina Camilla1 (AUTHOR) martina.daniotti@unimi.it, Bianchi, Sofia Paola2 (AUTHOR), De Ponti, Elena1,2 (AUTHOR) elena.deponti@irccs-sangerardo.it, Arcangeli, Stefano2,3 (AUTHOR) stefano.arcangeli@unimib.it |
| Source: |
Cancers. Sep2023, Vol. 15 Issue 18, p4496. 13p. |
| Subject Terms: |
*METASTASIS, *STEREOTAXIC techniques, *MAGNETIC resonance imaging, *BRAIN tumors, *TREATMENT effectiveness, *DESCRIPTIVE statistics, *KAPLAN-Meier estimator, *RADIATION doses, *RADIOSURGERY, *LOGISTIC regression analysis, *RADIATION dosimetry, *EVALUATION |
| Abstract: |
Simple Summary: Stereotactic radiosurgery (SRS) and fractionated SRS (fSRS) for brain metastases (BM) have become the standard of care for patients with up to 10 BM, yielding similar survival but a lower risk of long-term neurocognitive decline than whole-brain radiotherapy (WBRT). New technologies have allowed the accurate delivery of these high doses to the target using linac-based frameless techniques, and single-isocenter multiple-target (SIMT) approaches have recently been adopted for the simultaneous treatment of all BM. However, residual setup errors combined with intrafraction head motion may result in non-negligible compromised target coverage. While many groups have evaluated the efficacy of linac-based treatments using multiple and non-coplanar arcs, to our knowledge, only a few studies have presented clinical experience with coplanar arcs. Therefore, the present study aims to report our institutional investigation about the accuracy and outcomes of single-isocenter VMAT SRS treatments for both single and multiple BM delivered using only coplanar arcs and kV-CBCT as an IGRT system. The efficacy of linac-based SRS/fSRS treatments using the single-isocenter coplanar FFF-VMAT technique for both single and multiple BM was investigated. Seventy patients (129 BM) treated with 15–21 Gy in 1 (n = 59) or 27 Gy in 3 (n = 11) fractions were analyzed. For each fraction, plans involving the intra-fractional errors measured by post-treatment CBCT were recalculated. The relationships of BM size, distance-to-isocenter, and barycenter shift with the difference in target coverage were evaluated. Clinical outcomes were assessed using logistic regression and Kaplan-Meier analysis. The median delivery time was 3.78 min (range, 1.83–9.25). The median post-treatment 3D error was 0.5 mm (range, 0.1–2.7) and the maximum rotational error was 0.3° (range, 0.0–1.3). In single BM patients, the GTV D95% was never reduced by >5%, whereas PTV D95% reductions >1% occurred in only 11 cases (29%). In multiple BM patients, dose deficits >5% and >1% occurred in 2 GTV (2%) and 34 PTV (37%), respectively. The differences in target coverage showed a moderate-to-strong correlation only with barycenter shift. Local failure of at least one treated BM occurred in 13 (21%) patients and the 1-year and 2-year local control rates for all lesions were 94% and 90%, respectively. The implemented workflow ensured that the degradation of target and brain dose metrics in delivered treatments was negligible. Along with encouraging clinical outcomes, these findings warrant a reduction in the PTV margins at our institution. [ABSTRACT FROM AUTHOR] |
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