Fwd: High Dose Fluoroscopy

[Ccja@aol.com]

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Forwarded message:
From:	nikos@GROVE.UFL.EDU (Nikolaos A. Gkanatsios)
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: 97-05-28 10:52:27 EDT

There was a lot of discussion about "high dose fluoroscopy" and high
fluoroscopic doses lately.  For those "concerned" out there, there is a paper
in the next issue of Radiology (June) by Gkanatsios, Huda, Peters, and
Freeman which analyses doses for more than 100 patients undergoing
neuroradiologic examinations.  The data have been collected using two PEMNET
dosimetry systems in a biplane setup.  I include the title and abstract of
the paper below.

Nikos Gkanatsios
University of Florida



EVALUATION OF AN ON-LINE EXPOSURE METER IN NEURORADIOLOGY
Gkanatsios NA, Huda W, Keith PR, Freeman J

PURPOSE: To assess the clinical performance and utility of an on-line patient
exposure meter installed on a neuroradiologic biplane imaging system.

MATERIAL AND METHODS: A commercial on-line patient exposure meter was
installed on each plane of a biplane neuroradiologic imaging system. The
meter computed skin exposures on the basis of selected technique factors (kV
and mAs) and information about patient location relative to the x-ray tube.
Simulations were performed to measure the system accuracy using an
angiographic anthropomorphic head phantom with the skin exposures measured by
an ionization chamber. Skin doses were computed  for 114 consecutive patients
who underwent diagnostic and interventional neuroradiologic procedures.

RESULTS: Agreement between measured and computed skin exposures in
fluoroscopy, cut film imaging and digital imaging was generally within 5%.
Median skin doses computed for patients undergoing neuroradiologic procedures
were 1.2 Gy  and 0.6 Gy for the frontal and lateral imaging planes,
respectively. In both planes, patient skin doses were primarily a result of
digital subtraction angiography acquisitions. About 25% of the patients
exceeded a skin dose measurement of 2.0 Gy but no radiation induced
deterministic effects were observed.

CONCLUSION: The dosimetry system provided accurate data on patient skin
exposures and was able to quantitatively document the contributions from
fluoroscopy and radiography. Neuroradiologic procedures resulted in patient
doses which could exceed threshold doses for the induction of deterministic
radiation effects in a significant number of patient examinations.