Fwd: Fluoroscopic abdomen phantom

[Ccja@aol.com]

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Forwarded message:
Subj:    Re: Fluoroscopic abdomen phantom
Date:    97-09-23 15:39:15 EDT
From:    Ccja
To:      MEDPHYS@lists.wayne.edu

There are two abdominal phantoms described in AAPM Report 31, "Standardized
Methods for Measuring Diagnostic Xray Exposures". One is a CDRH creation, the
other a modified ANSI phantom. I haven't time to give you the specs here, but
you can obtain a copy of the Report from the American Institute of Physics:
(800)445-6638. The CDRH version has been clinically verified; the Report
includes an intercomparison of readings obtained with it, and with the
modified ANSI model.

Your question is a timely one, since the CDRH (FDA) will probably promulgate
regs in the near future to require that fluoroscopes (at least, those for
interventional use) be equipped with instruments to display and record, in
real time, air kerma at the point where the patient's skin would be. The only
device, that I know of, capable of doing this (the PEMNET), can also be
calibrated to estimate tissue kerma, or roentgens. Tissue (skin) kerma is, of
course, what the CDRH is really concerned about. Can anyone think of a reason
why that shouldn't be permissible, as well? Actually, I would think that even
an estimate of roentgens delivered would be closer in numerical value to that
of the skin kerma, than air kerma would be, if one included the backscatter
from deeper tissues. I shall hover here, and await the anti-aircraft guns.

chris alston
ccja@aol.com