Re[2]: C_x and C_k

["Cummings, Frederick" <CUMMINFM@inel.gov>]

     The Cx and Ck values depend on the depth, beam geometry, phantom
     geometry and phantom composition (probably more than you wanted to
     know.)  As such it is tough to quote single values.  However, for the
     ICRU 4-element sphere, Dimbylow and Francis quote 1.02 rem/R at 7
     mg/cm2 and 0.991 rem/R at 1000 mg/cm2 ("A Calculation of the Photon
     Depth-Dose Distributions in the ICRU Sphere for a Broad Parallel Beam,
     A Point Source and an Isotropic Field, NRPB 92, National Radiological
     Protection Board, Harwell, England, 1979.)

     More recently, Chris Soares (NIST) has calculated that the Cx at
     7mg/cm2 is 1.038 rem/R (Ck = 1.18 Sv/Gy) and for 1000mg/cm2 the Cx is
     1.029 rem/R (Ck = 1.17 Sv/Gy).  Since these are based on Grosswendt's
     calculations, they are for broad monodirectional beams, PMMA (lucite)
     slab phantoms.  The conversions from Cx to Ck include a correction for
     bremmstrahlung of .996 (se draft standard ISO DP 9991).  Oh, yeah, as
     a PS, Grosswendt's #s only go to an MeV, so you will only be
     disappointed if you go to those references.  If you require further
     detail re: the calculations Chris did, he is on vacation for this
     month, but can be contacted later at  "csoares@enh.nist.gov".

     Rick Cummings              cumminfm@inel.gov

     Opinions expressed are only my own and may not reflect the views of my
     employer.
     "Shun advice at any price.
     Now, that's what I call good advice."   Piet Hein


______________________________ Reply Separator _________________________________
Subject: Re: C_x and C_k
Author:  RADSAFE (INELMAIL.RADSAFE) at _EMS
Date:    6/19/95 7:50 AM


     The ANSI N13.11-1983 and 1993 version does not include Co-60.

     The following is from Table 6C .. Dose Equivalent Conversion Factors
     and Angular Response Functions ... ICRU Tissue Sphere Phantom at 10 mm
     (ambient) and 0.07 mm (Directional) Depths for NIST Lightly Filtered,
     Specially Filtered Beams and Isotropic Sources..

     Co-60  Deep Ck (Sv/Gy) = 1.169             Shallow Ck (Sv/Gy) = 1.389

     compared to Cs-137 = 1.202                                     = 1.349

     Hope this helps



______________________________ Reply Separator _________________________________
Subject: C_x and C_k
Author:  radsafe@romulus.ehs.uiuc.edu at Internet-Mail
Date:    6/16/95 4:02 PM


     Dear RADSAFErs,

     What is C_x (per ANSI N13.11-1983) and C_k (per ANSI N13.11-1993) for
     Co-60 photons?  What is Co-60 C_x (1983) converted to C_k (1993)?

     Thank you in advance.
     Tosh Ushino
     ushinot@songs.sce.com