Trial Information

Exclusive Hypofractionated Stereotactic Radiotherapy in Non-resectable Single Brain Metastasis: Prospective Study

For the planning, patients will undergo magnetic resonance imaging (MRI) 1.5 to 3 Tesla,
with contrast and volumetric reconstruction of 1 mm and can be used MRI from the diagnosis
of metastasis, if it is compatible with the planning system. Then, there will be
individualized mask Mask Set for One Patient 41100 (BrainLAB AG, Heimstetten, Germany) for
each patient. Patients will undergo computed tomography (CT) without contrast with 1-mm
slices with tracking and stereotactic fixation. The images of MRI and CT are fused in the
planning system IPLAN version 4.1 (BrainLAB AG, Heimstetten, Germany), where the plan will
be implemented. The clinical target volume (CTV) is the macroscopic disease (GTV) displayed
on the sign of T1 contrast. The planning target volume (PTV) is the CTV with 3-mm margin in
all directions. Can be used multiple dynamic arcs, static conformal multiple fields,
multiple static fields modulated and multiple static arcs. The dose-fractionation scheme
will be 4 fractions of 7 Gy at the periphery of the PTV, a once daily on 4 consecutive
working days. The dose to the PTV encompassing areas of the brainstem or optic tract will be
reduced by 20%. The plans will be standardized at the isocenter. The isodose prescription
will be the largest isodose that meets the following criteria: isodose covering at least 95%
of the PTV with the prescription dose (V100 ≥ 95%) and 95% of prescription dose covering at
least 99% of the PTV (V95 ≥ 99%) (36). The maximum dose should be less than 35 Gy. The dose
constraint reported by Ernst-Stecken et al will be respected at the expense of prescription
isodose, where the normal brain volume (total brain volume less volume PTV) of 20 cc will
not receive a dose of 4 Gy per fraction or larger, there is no maximum size limit of
metastasis to be included in the study. Use as an index of compliance reported by the
Paddick et al and Radiation Therapy Oncology Group (RTOG). Tests will be done for collision
safety tests and quality control to ensure the alignment of isocenters radiation, mechanical
and coincidence of lasers (Winston-Lutz test). After all, the patients are treated with
6-MeV photons in the linear accelerator Varian Clinac 600 CD (Varian Medical Systems, Palo
Alto, CA, USA) with a system of "micromultileaf" m3 (BrainLAB AG, Heimstetten, Germany).