The screen-film contact and uniformity of screen speed tests must be performed on new cassettes prior to clinical use. 21 C.F.R. 900.12(e)(10) Because the screen-film contact test is a semi-annual QC test, the QC technologist may perform this test. The uniformity of screen speed test, including the screen artifact test, is part of the annual physicist’s survey and, in that context, must be performed by the medical physicist. 21 C.F.R. 900.12(e)(5)(viii), (e)(9). However, in the context of cassettes being added during the course of the year (between annual physics surveys), the QC technologist (or someone with adequate training designated by the QC technologist) can perform this test in consultation with the medical physicist. However, in all cases where the newly acquired cassette(s) are nominally of a different speed from the existing group of cassettes [e.g., speed class 100 (regular) for the new cassettes vs. 150 (fast) for the existing cassettes], the medical physicist should provide oversight. If these new cassettes are used to image the standard breast. and require higher technique factors such that the dose could reasonably exceed 300 mrad (3.0 mGy), a mean glandular dose measurement must be performed for the new group of cassette(s). In such a case, the medical physicist must perform this dose measurement test before this group of cassettes is used on patients. 21 C.F.R. 900.12(e)(10).