|Message: Re: Problem of two peaks in the bragg peak||Not Logged In (login)|
Click on the Forum title, e.g. on the "Forums by Category" page, to read a sequence of postings to the Forum and its threads all in one page. If you are only interested in one thread or the thread following a specific posting, click the thread or the posting, which takes you to a smaller page, which contains only the part you are interested in and may be easier to navigate.
Messages are "chained" if there are only replies at the first level, i.e. 1/1.html, 1/1/1.html etc. In case of "chained" messages the message number is replaced by the icon and there is no indentation.
Inline: Display the subject line only or also the text of the posting(s); for the choice "All" the "Outline" choices are switched off.
|1||0||1||no text / full text of posting|
|2||1||All||text for level 1 only / text for All postings|
Outline: Choose the depth of the posting thread, successive toggle controls provide increasing detail.
|1||2||1||2 levels / 1 level (original posting)|
|2||3||2||3 levels / 2 levels|
|3||3||All||3 levels / all levels (all postings)|
the two peaks you see are due to the fact that probably you are using one of the macro files we have provided, where the beam traverse a specific beam line designed for proton beams at 62 MeV. In fact a brass collimator and a stopper of 7 mm are present, which are able to stop protons up to 70 MeV maximum. In your case, you are sending protons at higher energy and, therefore, they traverse the collimator and te stopper, loosing a part of their energy (and creating a second peak).
My suggestion is to modify the macro you are using in order to choose a suitable initial position of the beam: not the default one (-310 cm) but, for example, -0.1 cm (which means just 1 mm before the water phantom). In such a way you are "skipping" the passive beam line (specific for 62 MeV protons for ocular tumor treatment) and sending the beam just before the water phantom where the peak is acquired.
Hence, substitute the command:
/gps/pos/centre -310. 0. 0. cm
with the command
/gps/pos/centre -0.1 0. 0. cm
Hope this can help you.
|Inline Depth:||Outline Depth:||Add message:|