added photo

content/ra_quantity.html

@@ -141,6 +141,14 @@ in multi-centre studies
 (<a href="https://doi.org/10.1007/s00259-015-3165-8">Kuhnert et al., 2016</a>).</p>
 
 
+<div class="images">
+  <a href="./pic/quadra.jpg">
+  <img src="./pic/quadra_600x416.jpg" alt="Vision Quadra"
+       style="padding:10px 10px 10px 10px; height:416px; width:600px;" />
+  </a>
+</div>
+
+
 <br>
 
 <h2>See also:</h2>