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</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal><span lang=PL>Hi Gaters and Uwe.<o:p></o:p></span></p><p class=MsoNormal><span lang=PL><o:p> </o:p></span></p><p class=MsoNormal>I have a question to Hits.dat ascii file produced in PET scanner simulation. Below is the image of the table taken from Hits.dat. In two last rows are data for photoelectric event in high density material like LSO with Lu atom.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><img width=1703 height=141 style='width:17.7395in;height:1.4687in' id="Picture_x0020_1" src="cid:image003.png@01D425BB.E6175D70"><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>You can see that stepLength for photoelectric event is 8.5 mm, which for a 63 keV photon in LSO is highly unlikely. <b>My question is what does step length associated with first hit in the crystal really correspond to?</b> Is it a path in the crystal until the photoelectric event, so the step length is counted only within crystal which is in my case a sensitive detector?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Regards<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=ES style='mso-fareast-language:EN-GB'>Marcin Balcerzyk, Ph.D.<br>Unidad Ciclotrón,<o:p></o:p></span></p><p class=MsoNormal><span lang=ES style='mso-fareast-language:EN-GB'>Centro Nacional de Aceleradores,<o:p></o:p></span></p><p class=MsoNormal><span lang=ES style='mso-fareast-language:EN-GB'>Universidad de Sevilla-CSIC-Junta de Andalucía,<o:p></o:p></span></p><p class=MsoNormal><span lang=ES style='mso-fareast-language:EN-GB'>Parque Tecnológico Cartuja 93, <o:p></o:p></span></p><p class=MsoNormal><span lang=ES style='mso-fareast-language:EN-GB'>c/Thomas Alva Edison Nº 7, <o:p></o:p></span></p><p class=MsoNormal><span lang=ES style='mso-fareast-language:EN-GB'>Tel.: (+34) 954 460 553 ext. 236, <br>Fax: (+34) 954 460 145,<br>mobile:(+34) 697 322 126<br>Skype: balcerzm<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>