WPF Image显示图片，文件被占用异常

imageControl.Source = this.GetBitmapImage(imagePath);//imageControl为WPF Image控件

　　

public BitmapImage GetBitmapImage(string imagePath)
{
            BitmapImage bitmap = new BitmapImage();
            bitmap.BeginInit();
            bitmap.CacheOption = BitmapCacheOption.OnLoad;
            bitmap.UriSource = new Uri(imagePath);
            bitmap.EndInit();
            return bitmap.Clone();
}