Ambient dose equivalent H(10) (ICRU 39)

[Michael McNaughton <mcnaught@lanl.gov>]

Dear RadSafers

Could anyone help me to understand the physical basis for Figure 3 in ICRU39.
This is the conversion of exposure (roentgen) to ambient dose equivalent
(cSv).
Why is it not equal to the ratio of the mass attenuation coefficients for
tissue and air? For example, near 80 keV, Figure 3 shows about 1.7, whereas
the ratio of the mass attenuation coefficients is about 1.1. What is the
physical basis used to obtain Figure 3?

Thank you, mike

************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html