I can produce galleries for all the images that mention a particular page with
{{#dpl: | debug=1 | namespace=File | linksto={{PAGENAME}} | suppresserrors=false | allowcachedresults = false | mode=userformat | format = «gallery hideaddbutton="true"»,%PAGE%\n,\n,«/gallery» }}
And I can extract the text from a section of the image page with
{{#dpl: | debug=1 | namespace=File | linksto={{PAGENAME}} | ordermethod=sortkey | suppresserrors=true | distinct=false | allowcachedresults = false | include=#Source }}
But I can't find a way of combining the two, so I get a gallery of images which picks up both the image name, and its caption from part the page. Ideally I'd look for a variable like %INCLUDE% which provided the included text, but it doesn't seem to exist.