RE: shielding_CT scanner

["Gary Isenhower" <garyi@trinityphysics.com>]

Is anyone using the published CT scatter transmission data from D. 

Simpkin?  Or are the alpha beta gamma values a curve fit based on 

Simpkin's work?



Thanks,

Gary Isenhower

garyi@trinityphysics.com



Subject:        	RE: shielding_CT scanner

Date sent:      	Wed, 4 Jun 2003 09:34:37 -0400

From:           	"Parry, Don  (CIS)" <dparry@michigan.gov>

To:             	<radsafe@list.vanderbilt.edu>

Send reply to:  	"Parry, Don  (CIS)" <dparry@michigan.gov>



> 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

> 

************************************************************************

You are currently subscribed to the Radsafe mailing list. To unsubscribe,

send an e-mail to Majordomo@list.vanderbilt.edu  Put the text "unsubscribe

radsafe" (no quote marks) in the body of the e-mail, with no subject line.

You can view the Radsafe archives at http://www.vanderbilt.edu/radsafe/