<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <style type="text/css" style="display:none"></style> </head> <body dir="ltr" style="font-size:12pt;color:#000000;background-color:#FFFFFF;font-family:Calibri,Arial,Helvetica,sans-serif;"> Dear all, I'm running simulations on a gamma camera with two different collimator materials: Tungsten and Lead. As I had some strange results, I run a simulation for each material putting a collimator without holes in order to see how much counts I have in the detector; with a collimator 1 cm thicker I had quite the same counts in the detector instead of having less in Tungsten as I expected. The material database has the right value of density. I'm using the Singles output for my analysis. Did anyone had the same problem as mine or knows where I'm wrong? Thanks, Barbara The Institute of Cancer Research: Royal Cancer Hospital, a charitable Company Limited by Guarantee, Registered in England under Company No. 534147 with its Registered Office at 123 Old Brompton Road, London SW7 3RP. This e-mail message is confidential and for use by the addressee only. If the message is received by anyone other than the addressee, please return the message to the sender by replying to it and then delete the message from your computer and network. </body> </html>