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QUESTION regarding radiation theraopy using linear accelerator that produces a 6 MEV photon
I am forwarding this question for Michael Coogen. Please respond to
Michael directly at: michael_coogen@hq.dla.mil
I have a very dear friend whose wife has been diagnosed with
adenocarcinoma of the breast. The radiation therapist is using a
linear accelerator that produces a 6 MEV photon. Looking at Figure
5.3, page 129, in the RHH, June 84 edition, which is for water
absorption (it's the closest graph that is comparative for tissue),
and using the I=Ioe-(u/p)(p)(t) equation, I calculate that 0.8 of the
photons pass right on through the breast. So I ask why use such high
energy photons when most of them are not absorbed. Then looking at
the same graph for Compton scattering, at 6 MEV, the scattering
calculates to be only 7%. At 180 centigrays (rads/day), I conclude
that they need the very high energy photon to minimize compton
scattering to the rest of her body. I also suspect that the cone
created by the scattered photons is less as the energy goes up. Am I
right with these assumptions? Can anyone shed some light on the type
of therapy?
Michael Coogen
michael_coogen@hq.dla.mil
-------------------------------------------------
Sandy Perle
Director, Technical
ICN Worldwide Dosimetry Service
ICN Plaza, 3300 Hyland Avenue
Costa Mesa, CA 92626
Tel:(714) 545-0100 / (800) 548-5100 Extension 2306
Fax:(714) 668-3149
E-Mail: sandyfl@earthlink.net
E-Mail: sperle@icnpharm.com
Personal Website: http://sandy-travels.com
ICN Worldwide Dosimetry Website: http://www.dosimetry.com
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