Fwd: Mammography with two casette/screen systems

[Ccja@aol.com]

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Forwarded message:
From:	RJHZULU@AOL.COM
Sender:	medphys@LISTS.WAYNE.EDU (Medical Physics Listserver)
Reply-to:	MEDPHYS@LISTS.WAYNE.EDU (Medical Physics Mailing List)
To:	MEDPHYS@LISTS.WAYNE.EDU (Multiple recipients of list MEDPHYS)
Date: 97-03-11 16:17:01 EST

I would like to get some feedback to the following occurrence.  A hospital
 that I serve started using a new cassette/screen (about two months ago)
along with their old ones (film remained unchanged) without informing me. The
FDA inspector came to make an inspection and was given the choice of using
either cassette, they did
 not conceal the fact that they were using both types of cassettes
/screens, he judged their performance acceptable. I came in the following
week to  perform the annual medical physicist inspection. I discovered what
had happened and determined that the performance of the two cassette/screen
systems both gave acceptable
 densities 1.35 vs. 1.55 under the same conditions (DMR using the CNT mode of
operation), I suggested however that I thought that using the two systems
interchanegeably was not desirable and that they should use only one
of the two cassette/screen systems. Questions  - am I being to picky and
should I be concerned that the FDA inspector did not make note of what I
thought was an undesirable
 practice. Note - each system individually would meet the requirements as
would both systems together however the average density of the two system
would be different by 0.2. I don't know that it happened but I suppose that
it is possible that a given patient could have had left and right breasts
imaged with different systems.