AW: Unusual increase in the background dose

From: Sommerer, Florian <>
Date: Wed, 17 Mar 2010 10:52:11 +0100

 Dear Dulitha,

Your lateral scoring is too narrow. Since the beam broadens with depth
the plateau in the entrance appears raised. You can easily understand
the effect if you score for example laterally from -1 to 1 cm with 100
bins and plot the result in 2D (xz or yz plots).

Cheers, Florian

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Gesendet: Montag, 15. M=E4rz 2010 23:17
Betreff: Unusual increase in the background dose

Dear experts,

To check absorbed energy from proton beams, I used following coding
(please see the attachment #1). My USRBINs are
0.5*0.5*0.1 cm^3 in X, Y, Z respectively. I'm using an annular beam,
where radius is 0.3cm. If I used 108MeV/p proton beams, I'm getting a
nice Bragg peak. But, if I use 158MeV/p, I'm getting an unusual
increase in the background dose before the Bragg Peak. (Attachment #2).
Also I reduced the radius up to 0.15cm, in that case I got a higher
absorbed dose, where as I should get a lower dose than the previous case
(attachment #3). Could you please explain this to me?

Thank you,

Received on Wed Mar 17 2010 - 11:49:16 CET

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