Step 1
Create a prompt page and add a prompt to it called pPages. Deselect the "Create a parametized filter" and don't link it to any queries - you just want it there to hold some static options. Make sure that multi-Select is set to yes.
Step 2
Add static choices to the prompt, with one option per page.
Now we need to create the variables that will control which pages a shown. Hover over "Conditional Explorer" in the central bar, then click on Variables. Drag a Boolean Variable into the Variables box, which will open a Report Expression dialogue. Click on the Parameters tab at the bottom, which should show you pPages. Drag it into the Expression Definition, then add "contains 'Summary' "
Click ok and give your new Boolean Variable a name...varSummary in this case.
Step 5
Now hover over the central bar again over Page Explorer and select Report Pages. Click on Summary, then in the Properties panel click on Render Variable. Click on the ellipsis and you should now see the list of boolean variables that you've just created. Select varSummary, which should now show you something like this:
As an aside, you can you a similar approach to have hidden pages in your report. This can be useful for keeping notes, descriptions, file locations, author names etc. All you'd need to do is to follow the same process, but in the expression for the boolean variable you'd put something like 2>1...which I generally name as "Always False"