<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:10pt"><div><span style="font-weight: bold;">Dear GATE users,</span></div><div style="color: rgb(0, 0, 0); font-size: 13px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><span><br></span></div><div style="color: rgb(0, 0, 0); font-size: 13px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><span>I have modeled a trapezoid as the collimator in my SPECT simulation. </span></div><div style="color: rgb(0, 0, 0); font-size: 13px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><span>Everything seems to be right,
but, I have faced an unexpected problem: an extra volume exists inside the trapezoid (as shown in attached figure).</span></div><div style="color: rgb(0, 0, 0); font-size: 13px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><span><br></span></div><div style="color: rgb(0, 0, 0); font-size: 13px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;">Here are the commands used to define aforementioned trapezoid:</div><div style="color: rgb(0, 0, 0); font-size: 13px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><br></div><div style="background-color: transparent;"># Collimator (Trapezoidal Collimator)</div><div style="background-color:
transparent;">/gate/world/daughters/name collimator</div><div style="background-color: transparent;">/gate/world/daughters/insert trpd</div><div style="background-color: transparent;">/gate/collimator/geometry/setX1Length 10 cm</div><div style="background-color: transparent;">/gate/collimator/geometry/setY1Length 5 cm</div><div style="background-color: transparent;">/gate/collimator/geometry/setX2Length 10 cm</div><div style="background-color: transparent;">/gate/collimator/geometry/setY2Length 1 cm</div><div style="background-color: transparent;">/gate/collimator/geometry/setZLength 3.0 cm</div><div style="background-color: transparent;">/gate/collimator/setMaterial Lead</div><div style="background-color: transparent;">/gate/collimator/vis/setColor red</div><div style="background-color: transparent;">/gate/collimator/vis/forceWireframe</div><div style="color: rgb(0, 0, 0); font-size: 13px; font-family: HelveticaNeue, 'Helvetica Neue',
Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><span><br></span></div><div style="color: rgb(0, 0, 0); font-size: 13px; font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; background-color: transparent; font-style: normal;"><span>Any suggestion or idea would be appreciated; thank you in advance.<br></span></div><div></div><div> </div><div><br></div><div><font size="2" face="arial, helvetica, sans-serif"><b>Hojjat Mahani, </b></font></div><div><font size="2" face="arial, helvetica, sans-serif">PhD Candidate of Medical Radiation Engineering.</font></div><div><br></div><div><br></div></div></body></html>