We use the BACE mode in our Bennett machine to image our patients with the standard breast. In this mode the unit automatically determines the exposure technique factors based on the thickness of the compressed breast. During normal clinical use, the breast compresses and the system provides accurate thickness readings and technique factors.
However, when we use this mode (as required by the regulations) for the weekly phantom test, we do not compress the phantom (to avoid damaging the paddle or the phantom) leading to inaccurate thickness readings. These inaccurate thickness readings may cause the unit to select inappropriate exposure technique factors. Can we manually adjust the scale to the thickness of the standard breast before we expose the phantom using the BACE mode? Given the situation described above, is it permissible to expose the phantom using the AEC (see Phantom Images Exposed in Fully Automatic Mode if that is the Clinically Used Technique), rather than the BACE mode?
You are permitted to manually adjust the scale to the thickness of the standard breast before exposing the phantom using the BACE mode. Because you do not use the AEC mode to image your patients with the standard breast, you may not use a different AEC mode to perform the weekly phantom test.