$vid = 'hospitals';
$terms = Drupal::entityTypeManager()->getStorage('taxonomy_term')->loadTree($vid);
foreach ($terms as $term) {
  $term_data[] = [
    'tid' => $term->tid,
    'tname' => $term->name,
    'image' => ...???..,    // image field
    'contact' => ...???..,  // text field
  ];
}