Seems very similar to how maps work on the web these days, in particular protomap files [0]. I wonder if you could view the medical images in leaflet or another frontend map library with the addition of a shim layer? Cool work!
In 1970 a massive project crowdsourced thousands of photographs of everywhere in Paris (nearly every single grid square on each letter sized page, a rare few have no photos).
To see the photos, click on a map section to go to the subgrid page. Then find the square grid number that corresponds to where you want to see and click the corresponding numbered link from the list at the top.
Cool site, I especially appreciate the detailed about page [1] including the libraries used for the graphics (paperjs + GSAP) and the bloopers section [2], covering interesting glitches from development.
0: https://protomaps.com/