Are you sure that the x-ray you are being sent for isnt an HSG?
An hsg (hysterosalpingogram) is an X-ray of the uterus and fallopian tubes which allows visualization of the inside of the uterus and tubes.It entails the injection of a radio-opaque material into the cervical canal and usually fluoroscopy. The picture will reveal any abnormalities of the uterus as well as tubal problems such as blockage and dilation (hydrosalpinx). If sterilization reversal is planned, the point at which the tubes are blocked can be seen. This helps to plan the reconstructive procedure.... what kind of xray were you to ask for when booking it?
Maybe just a regular x-ray will find the location of the clips just fine, although i havent heard of it done that way... but combined with a transvaginal u/s, maybe that's all you need.
The dr you are seeing is way up there at the UBC fertility Clinic, I beleive he is a Faculty head, so I wouldnt worry. I am very sure he knows exactly what he is doing.

I understand your worry, and i know you just want to make sure you are doing everything necessary, but i can guarantee you the he is right on the mark. It will all be fine. MAke sure you update us after your test on tuesday and let us know how it went.