Impact of PTV margin reduction (2 mm to 0 mm) on pseudoprogression in stereotactic radiotherapy of solitary brain metastases

Technical Innovations & Patient Support in Radiation Oncology

Mirjam Mast¹  Jan-Huib Franssen²  Anna Petoukhova³  Ruud Wiggenraad³  Justine Badloe³  Elyas Ghariq⁴  Noëlle van der Voort van Zijp⁵ 

[1] Department of Radiation Oncology, Haga Hospital, The Hague, the Netherlands;Department of Medical Physics, Haaglanden Medical Center, The Hague, the Netherlands;Department of Radiation Oncology, Haaglanden Medical Center, The Hague, the Netherlands;Department of Radiation Oncology, Haga Hospital, The Hague, the Netherlands;Department of Radiology, Haaglanden Medical Center, The Hague, the Netherlands;

关键词: Brain metastases;    Stereotactic radiotherapy;    Margins;    Pseudoprogression;   

DOI  :  

来源: DOAJ

【 摘 要 】

Purpose: To determine the influence of PTV-margin (0 mm versus 2 mm) on the incidence of pseudoprogression (PP) and local tumour control (LC) in patients treated with stereotactic radiotherapy (SRT) for solitary brain metastases. Methods: Patients were treated on Novalis LINAC. Three dose schedules were used depending on the PTV-size. The PTV-margin was 2-mm prior to 2015 and 0-mm thereafter. MRI-scans were made every three months including a perfusion MRI-scan when pseudoprogression was suspected. We examined the relation of pseudoprogression and local control with the size of PTV-margin. Besides this, the association of dose-volume data of the whole brain (minus GTV) and pseudoprogression was investigated. Results: 121 patients were analyzed (2-mm margin in 84 patients; 0-mm margin in 37 patients). There was no difference in GTV (7.6 cc versus 9.1 cc p = 0.2). At 24 months there was no difference in incidence of pseudoprogression (49% and versus 33%, p = 0.5) and local control in the 2-mm and 0-mm group (82% and versus 79%, p = 1.0). The size of PTV-margin was not associated with PP. Both margin and volume of brain receiving 12 Gy (V12) were not associated with pseudoprogression in patients treated with single fraction. Conclusions: PTV-margin reduction did not reduce the incidence of pseudoprogression in LINAC-based-SRT for single brain metastases. We did not find a significant association of GTV-PTV margin or V12Gy with the incidence of pseudoprogression in solitary metastases treated with a single fraction. LC rates were similar, indicating margin reduction seems to be safe.

【 授权许可】

Unknown