Definition of an X-ray Cabinet

[james.g.barnes@att.net]

Good afternoon,

Need some thoughts regarding the interpretation of an FDA 
regulation regarding cabinet X-ray systems.

Following is the definition of a cabinet X-ray system 
from 21 CFR 1020.40:

"(3) Cabinet x-ray system means an x-ray system with the 
x-ray tube installed in an enclosure (hereinafter
termed cabinet) which, independently of existing 
architectural structures except the floor on which it may 
be placed, is intended to contain at least that portion 
of a material being irradiated, provide radiation 
attenuation, and exclude personnel from its interior
during generation of x radiation. Included are all x-ray 
systems designed primarily for the inspection of carry-on
baggage at airline, railroad, and bus terminals, and in 
similar facilities."

My question regards the interpretation of the phrase 
"independently of existing architectural structures 
except the floor."  There are cabinets that are table-top 
devices, or "free standing" walk-in units that sit on the 
floor, but are not really attached to the building 
structure (i.e, not intended to be part of a building's 
structure, clearly separate from the rest of the 
building's structure; not considered a "room" in the 
building, etc.).  These clearly exist independently of 
the building structures, and would be considered 
cabinets.

However, there are situations where one has built an 
x-ray cell where the room is permanently built into a 
facility (i.e., permanently anchored to the floor, not 
amenable to dismantlment and movement, considered a 
"room" in the building, etc.), but doesn't structurally 
"attach" itself to the walls or ceiling of the 
overall facility (for example, a permanent two-story tall 
x-ray cell in a four-story warehouse).  I have recently 
heard it argued that this type of cell construction (as 
it uses a "stand alone" construction style supported only 
by the floor) is a "cabinet" under the definition above, 
and that the construction or modification such a facility 
would fall under 21 CFR 1020-40.

This sounds like a very strained interpretation of the 
regulations.  Does anyone know of further materials that 
would clarify the intent of the definition?


Thanks,

Jim Barnes, CHP
Radiation Safety Officer
Rocketdyne/Boeing
james.g.barnes@boeing.com
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