Re: to ListMembers in medical field.

["Duncan Howe" <HOWE@dcsmserver.med.sc.edu>]

We have no formal guidelines which have been proceduralized for 
minimizing patient and worker dose from the scatter emitted 
from patients receiving portable X-ray examinations.  Portable 
shielding may occasionally be available for protection of the tech 
administering the exam.  However, instead of developing expensive and 
awkward shieilding systems in the ICU wards, the techs who conduct 
the examinations rely primarily on the distance portion 
of the time-distance-shielding formulation for reducing personnel 
dose.  If you look at Table B-2 in NCRP 49 you will find that the 
ratio of scattered to incident exposure at one meter, for X-ray 
kVp settings below 125 kV, is less than 0.0025 for scatter angles 
from 30 to 135 degrees.  If the entrance skin exposure for a chest 
exam at 40 inches SID were 50 mR, the exposure to another patient or 
a technologist located at one meter from the center of the field 
of view would be less than 1 mR.
  If you need to formalize guidelines for minimizing patient and 
worker dose from scatter in this portable environment, you may want 
to consider preferentially establishing requirements for minimum 
distances from the patient when the exposure is taken.