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spektrFluencePerAirKerma.m
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spektrFluencePerAirKerma.m
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function [ fluPerAirKerma ] = spektrFluencePerAirKerma( q )
%**************************************************************************
%% System name: SPEKTR
%% Module name: spektrFluencePerAirKerma.m
%% Version number: 3
%% Revision number: 00
%% Revision date: 19-Apr-2006
%%
%% 2016 (C) Copyright by Jeffrey H. Siewerdsen.
%% I-STAR Lab
%% Johns Hopkins University
%%
%% Usage: e = spektrFluencePerAirKerma(q)
%%
%% Inputs:
%% q - X-Ray Energy Spectrum (is a [150 x 1] matrix), generated from the
%% function spektrSpectrum(..,..). Each matrix element represents
%% the # of photons / mAs / mm^2 in an one keV energy bin (from 1-150 keV)
%%
%%
%% Outputs:
%% fluPerAirKerma = Fluence / Air Kerma (x-rays / mGy / mm^2)
%%
%% Description:
%% This function will generate the fluence per air kerma [x-rays / mGy / mm^2].
%%
%% Let:
%% u[E] = attenuation coefficient
%% p = density
%%
%% where (u[E]/p)en is the energy dependent mass energy absorption
%% coefficient of air -> UNITS are [cm^2/g]
%% where q[E] or q is the energy spectrum (x-ray)
%% where 114.5 is the conversion from in air exposure to air kerma
%%
%% Therefore;
%%
%% (photon fluence)/exposure [photons/mm^2 / mR] = (5.43x10^5)/((u[E]/p)en*E) * 114.5
%%
%%
%% Notes:
%%
%%*************************************************************************
%% References:
%%
%%*************************************************************************
%% Revision History
%% 3.000 2016 05 30 JGP Initial creation
%%*************************************************************************
%%
fluPerExpo = spektrFluencePerExposure(q);
fluPerAirKerma = fluPerExpo * 114.5;
end