Re: Webster method

[Ryanchp@aol.com]

HELLO,

NEW YORK STATE HEALTH DEPARTMENT HAS ADOPTED THE "WEBSTER" EQUATION IN THEIR
REGULATIONS FOR PHYSICIANS ONLY, PERFORMING FLUOROSCOPY. (EDE=0.04xCOLLAR
BADGE READING + 1.5xUNDER APRON READING) HOWEVER THE AMERICAN NATIONAL
STANDARDS (HPS N13.41-1997) "CRITERIA FOR PERFORMING MULTIPLE DOSIMETRY" HAS
PROPOSED A DIFFERENT METHODOLOGY USING COMPARTMENT FACTORS. THE WEBSTER
EQUATION THEN BECOMES EDE=0.1xCOLLAR BADGE + 0.5xUNDER THE APRON BADGE. IT
ALSO IMPLIES THAT IF ONLY ONE BADGE IS WORN ON THE COLLAR (OUTSIDE THE Pb
APRON) THEN MULTIPLY BY THE COMPARTMENT FACTOR OF 0.5. I HAVE USED THE
WEBSTER METHOD FOR 3 YEARS. A COMPARISON WITH THE ANS EQUATION INDICATES THAT
THE ANS EQUATION PROVIDES A EDE ABOUT 30% HIGHER. BADGE VENDORS STILL PROVIDE
THE EDE AS THE COLLAR READING UNLESS DIRECTED OTHERWISE BY CUSTOMER.

ROBERT RYAN
RPI, DEPT OF ENVIR. & ENERGY ENG.
TROY, NY 12181