我不太确定我是否正确理解了您的问题，但您想要的是将边界半径添加到您添加的Image.network中，
你可以用ClipRRect或ClipOval Package 图像小部件。下面是当Image用ClipRRect和ClipOval Package 时捕获的图像，下面的代码是我如何做到的。
希望这个有用。

StaggeredGrid.count(
        crossAxisCount: 15,
        mainAxisSpacing: 10,
        crossAxisSpacing: 10,
        children: [
          StaggeredGridTile.count(
            crossAxisCellCount: 5, //
            mainAxisCellCount: 6, //
            child: ClipRRect(
              borderRadius: BorderRadius.circular(20),
              child: Image.network(
                'https://i.pinimg.com/564x/cf/bc/6d/cfbc6d2dd13c9dc0977986847cb8c385.jpg',
                fit: BoxFit.cover,
                alignment: Alignment.center,
              ),
            ),
          ),
          StaggeredGridTile.count(
            crossAxisCellCount: 5,
            mainAxisCellCount: 4,
            child: ClipOval(
              child: SizedBox.fromSize(
                size: const Size.fromRadius(50),
                child: Image.network(
                  'https://i.pinimg.com/564x/fe/96/29/fe96299107f1b0b94fa434b6558d6568.jpg',
                  //height: 60.0,
                  fit: BoxFit.cover,
                  alignment: Alignment.center,
                ),
              ),
            ),
          ),
          StaggeredGridTile.count(
            crossAxisCellCount: 5,
            mainAxisCellCount: 9,
            child: ClipOval(
              child: SizedBox.fromSize(
                  size: const Size.fromHeight(50),
                  child: Image.network(
                    'https://i.pinimg.com/564x/71/84/7b/71847bcc4d8e4ab580c87dc6008cafb0.jpg',
                    //height: 60.0,
                    fit: BoxFit.cover,
                    alignment: Alignment.center,
                  )),
            ),
          ),
          StaggeredGridTile.count(
            crossAxisCellCount: 5,
            mainAxisCellCount: 5,
            child: ClipOval(
              child: SizedBox.fromSize(
                  size: const Size.fromWidth(50),
                  child: Image.network(
                    'https://i.pinimg.com/564x/45/de/d4/45ded4dd846a4d994ae3afaf3345fb8e.jpg',
                    fit: BoxFit.cover,
                    alignment: Alignment.center,
                  )),
            ),
          ),
          StaggeredGridTile.count(
            crossAxisCellCount: 5,
            mainAxisCellCount: 3,
            child: ClipRRect(
                borderRadius: BorderRadius.circular(20),
                child: Image.network(
                  'https://i.pinimg.com/750x/a5/75/1e/a5751ed87fdbab76af299df228cb78ab.jpg',
                  fit: BoxFit.cover,
                  alignment: Alignment.center,
                )),
          ),
        ],
      )