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RE: shielding_CT scanner
I sent a seperate message to Mr. Skours wich included some spread sheets and a PDF of the draft shielding report, but thought I would post the coefficients here in case I gave him the wrong info, was hoping someone else on the list would correct any errors.
>From NCRP draft rewrite
Alpha Beta Gamma
kVp/120/140 120/140 120/140
lead 2.246/2.009 5.73/3.99 0.547/0.342
concrete 0.0383/0.0336 0.0142/0.0122 0.658/0.519
Also, draft report uses the CTDI Periphery value for a 10 mm beam and applies a scatter fraction of 9e-5 for the head phantom and 3e-4 for the body phantom to get the scatter at 1 meter.
Don
Donald E. Parry, CHP
Health Physicist
Michigan Department of Consumer & Industry Services
Radiation Safety Section
Phone : 517-241-1989 Fax: 517-241-1981
mailto:dparry@michigan.gov
www.michigan.gov/bhs
-----Original Message-----
From: thskouras [mailto:skouras@med.upatras.gr]
Sent: Wednesday, June 04, 2003 2:06 AM
To: radsafe@list.vanderbilt.edu
Subject: shielding_CT scanner
Dear Rad-safers,
I need an advice.
I am trying to find the appropriate shielding coefficients for CT
scanners(at 120,130 and 140kVp)for Archer equation (a,b and ? coefficients).
Is anybody familiar with the re-write NCRP 49 report? Does it includes these
kind of data?.
In addition, is it true that the same report uses scatter fractions
determined by CTDI's? and which CTDI (air or phantom)?. These CTDI's
fractions give the scatter air kerma in mGy/mAmin at 1m from the phantom?
I know that the published AAPM report 39 contains errors on table2 page9 for
a,b and ? coefficients, and that is why I am looking for NCRP re-writed
report49.
Thank you, in advance.
Theodoros Skouras
Medical Physicist
University Hospital of Patras, GREECE
e-mail:skouras@med.upatras.gr
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