Single-isocenter stereotactic non-coplanar arc treatment of 200 patients with brain metastases: multileaf collimator size and setup uncertainties.
Strahlenther Onkol
; 198(5): 436-447, 2022 05.
Article
en En
| MEDLINE
| ID: mdl-34528112
ABSTRACT
PURPOSE:
The purpose of this study was to evaluate our 2 years' experience with single-isocenter, non-coplanar, volumetric modulated arc therapy (VMAT) for brain metastasis (BM) stereotactic radiosurgery (SRS).METHODS:
A total of 202 patients treated with the VMAT SRS solution were analyzed retrospectively. Plan quality was assessed for 5â¯mm (120) and 2.5â¯mm (high-definition, HD) central leaf width multileaf collimators (MLCs). For BMs at varying distances from the plan isocenter, the geometric offset from the ideal position for two image-guided radiotherapy workflows was calculated. In the workflow with ExacTrac (BrainLAB, München, Germany; WET), patient positioning errors were corrected at each couch rotation. In the workflow without ExacTrac (W-noET), only the initial patient setup correction was considered. The dose variation due to rotational errors was simulated for multiple-BM plans with the HD-MLC.RESULTS:
Plan conformity and quality assurance were equivalent for plans delivered with the two MLCs while the HD-MLC plans provided better healthy brain tissue (BmP) sparing. 95% of the BMs had residual intrafractional setup errors ≤â¯2â¯mm for WET and 68% for WnoET. For small BM (≤1â¯cc) situated >3â¯cm from the plan isocenter, the dose received by 95% of the BM decreased in median (interquartile range) by 6.3% (2.8-8.8%) for a 1-degree rotational error.CONCLUSION:
This study indicates that the HD-MLC is advantageous compared to the 120-MLC for sparing healthy brain tissue. When a 2-mm margin is applied, WnoET is sufficient to ensure coverage of BM situated ≤â¯3â¯cm of the plan isocenter, while for BM further away, WET is recommended.Palabras clave
Texto completo:
1
Bases de datos:
MEDLINE
Asunto principal:
Neoplasias Encefálicas
/
Radioterapia de Intensidad Modulada
Tipo de estudio:
Observational_studies
Límite:
Humans
Idioma:
En
Revista:
Strahlenther Onkol
Asunto de la revista:
NEOPLASIAS
/
RADIOTERAPIA
Año:
2022
Tipo del documento:
Article
País de afiliación:
Dinamarca