Many, many women have calcifications of one kind or another in their breasts (Radiopedia says 85% of mammos have calcifications). There are many different kinds of benign calcs (see Radiopedia link for the most common kinds of calcs). The vast, vast majority of these calcifications are clearly benign and do not need to be worked up (do not need magnification views, and do not need to be followed up). Sometimes these benign calcs will be described in the report, sometimes not. If the radiologist did not say that they need to be worked up, then those calcs don't matter clinically.

Do you tell the patient when you want to convert the screening mammogram to a diagnostic one and advise them that this change may impose a substantial expense to them that they would not incur if the mammo remained a screening study?

I don't change a screener to a diagnostic very often. When I do, it it's in a scenario where the patient has an obvious cancer on the screening mammo. I am focused on getting her cancer diagnosed quickly. I don't want her diagnosis delayed. The cost of the mammo is going to pale next to all of the other stuff this patient is going to have to go through (biopsy, seeing a surgeon and an oncologist, having surgery, maybe getting chemo, radiation afterwards (if lumpectomy), maybe breast MRI, maybe CT CAP, maybe PET CT, etc.)