<html> <head> <style> .hmmessage P { margin:0px; padding:0px } body.hmmessage { FONT-SIZE: 10pt; FONT-FAMILY:Tahoma } </style> </head> <body class='hmmessage'> Hi all, <BR>  <BR> I can get non-scattered and scattered photons from simulation output, but how can I evaluate the penetration effects of collimator? Primary and penetration are both not scattered. <BR>  <BR> Thanks, <BR>  <BR> Dan <BR><br /><hr />Get news, entertainment and everything you care about at Live.com. <a href='http://www.live.com/getstarted.aspx ' target='_new'>Check it out!</a></body> </html>