What advantage does multi spectral analysis hold over the x ray machine

Seeing that your question is listed under art, I will try to answer it within that context. Multispectral analysis in essence images a specimen at multiple wavelengths. The technique has been applied on ancient papyri where the ink and paper are able to reflect infrared light but do not noticeably reflect visible light. In paintings, different frequencies show different pigments of paint, which can inform conservation techniques. This kind of analysis can also sometimes reveal layers of a painting that are covered up and in detail not possible with a standard radiograph (x-ray).