Change the layout of drupal radio button

Copy and paste the below code in your template.tpl.php file in theme folder

function theme_radio($variables) {
  $element = $variables['element'];
  $element['#attributes']['type'] = 'radio';
  element_set_attributes($element, array('id', 'name', '#return_value' => 'value'));

  if (isset($element['#return_value']) && $element['#value'] !== FALSE && $element['#value'] == $element['#return_value']) {
    $element['#attributes']['checked'] = 'checked';
  }
  _form_set_class($element, array('form-radio'));

  return '<input' . drupal_attributes($element['#attributes']) . ' />';
}

Change theme_checkbox with your theme-name for example your theme name is prohcj then change it to prohcj_checkbox

and add your html structure inside return value. Example need to add before checkbox follow below code.

return '<span><input' . drupal_attributes($element['#attributes']) . ' /></span>';