方法如下：
{
xtype: 'radiogroup',
items: [
{ boxLabel: "<img src='xyz1.gif'/>radio1", name: 'radio', inputValue: 'radio1', checked: true },
{ boxLabel: "<img src='xyz2.gif'/>radio2", name: 'radio', inputValue: 'radio2' },
{ boxLabel: "<img src='xyz3.gif'/>radio3", name: 'radio', inputValue: 'radio3' },
]
}