....

RenderTarget2D renderTarget;

....

renderTarget = new RenderTarget2D(Game.GraphicsDevice, Width, Heigth, 1, SurfaceFormat.Color);

....

RenderTarget cTarget = Game.GraphicsDevice.GetRenderTarget(0);
Game.GraphicsDevice.SetRenderTarget(1, renderTarget);

... all my draw code ...

Game.GraphicsDevice.SetRenderTarget(0, cTarget as RenderTarget2D);

 {
            Game.GraphicsDevice.SetRenderTarget(0, renderTarget);

            Game.GraphicsDevice.VertexDeclaration = Game.GraphicsDevice.VertexDeclaration = new VertexDeclaration(Game.GraphicsDevice, VertexPositionColor.VertexElements);
            Game.GraphicsDevice.Vertices[0].SetSource(vertexBuffer, 0, VertexPositionColor.SizeInBytes);
            
            lineEffect.Begin();
            foreach (EffectPass pass in lineEffect.CurrentTechnique.Passes)
            {
                pass.Begin();

                lineEffect.Parameters["worldViewProj"].SetValue(view * projection);

                renderTarget.GraphicsDevice.DrawPrimitives(PrimitiveType.LineList, 0, 11);

                pass.End();
            }
            lineEffect.End();

            Game.GraphicsDevice.SetRenderTarget(0, null);

            spriteBatch.Begin();

            spriteBatch.Draw(renderTarget.GetTexture(), new Vector2(50, 50), Color.White);

            spriteBatch.End();

            base.Draw(gameTime);

        }