Ben,

Each page of a document is stored as its own tif image.  So for example a five page document will actually have five different tif images associated with it.  In your example the filename '000005A7.tif' could actually represent just one page of a multi-page document, not the entire document (unless it is a single page document). 

That being said, here is a SQL statement that will return the path of the image if you supply the hex filename for the tif image;

SELECT dbo.vol.fixpath + '\' +
SUBSTRING(CONVERT(VARCHAR(8),CONVERT(VARBINARY(4), dbo.doc.storeid),2),1,2) + '\' + 
SUBSTRING(CONVERT(VARCHAR(8),CONVERT(VARBINARY(4), dbo.doc.storeid),2),3,2) + '\' +
SUBSTRING(CONVERT(VARCHAR(8),CONVERT(VARBINARY(4), dbo.doc.storeid),2),5,2) + '\' +
CONVERT(VARCHAR(8),CONVERT(VARBINARY(4), dbo.doc.storeid),2) + '.TIF' AS FullPathAndFilename
FROM dbo.doc  
LEFT JOIN dbo.toc ON dbo.doc.tocid = dbo.toc.tocid
LEFT JOIN dbo.vol ON dbo.toc.vol_id = dbo.vol.vol_id
WHERE CONVERT(VARCHAR(8),CONVERT(VARBINARY(4), doc.storeid),2) = '000005A7'

(edit the value in the WHERE clause to look for different images);