"No X-ray facility for under 2's - we didn't know..."

We've used the minor injuries dept before with great success with our elder boys. Unfortunately this evening we needed to use it for our 15 month old daughter who had shut her fingers in a door -just like one of our sons had in precious years. we thought to go to the MIU as we knew it was a minor injury but when we got there were told that we'd have to go to A&E as they don't X-ray under 2 year olds. I was very surprised at this and in a very stressful situation (blood all over daughter and she was very distressed, husband parking car with 3 other children) did not appreciate having to travel another 30 mins in rush hour traffic through Wycombe. I don't understand why under 2's can't be X-rayed? Please can parents be made aware of this? I searched for information regarding this when I got home but I found nothing on any website and the information leaflet really indicates that X-raying small children would be possible. Many thanks.