[Gate-users] Z-grid spacing problem

[kangh at mskcc.org]

Hello Kris,

I am having a problem with z grid spacing for using STIR.  I read
through STIR-user messages but it is not clear to me what I have to
change to make my current interfile work for STIR.  When I tried to run
STIR with my current .hv file I have gotten the following message

WARNING: 
WARNING: BinNormalisationFromAttenuationImage:
        attenuation image data are supposed to be in units cm^-1
        Reference: water has mu .096 cm^-1
        Max in attenuation image: 0.096

ERROR: DataSymmetriesForBins_PET_CartesianGrid can currently only
support z-grid spacing equal to the ring spacing of the scanner divided
by an integer. Sorry


I found out that the cause of the error is incorrect scaling factor for
the z direction.  
The following lines are from my .hv file.

!matrix size [3] := 21
scaling factor (mm/pixel) [3] := 1.27999

I was told that changing the value of scaling factor (mm/pixel) [3] from
1.27999 to 4.25 should work. I tried and actually I did not get the
error message.  I was going to recalculate the matrix size to be 6 or 7
to make scaling factor to be 4.25 (21*1.27999/4.25). However, there
seems to be certain ways to assign those parameters according to the
messages about z-grid in the user message instead of simply fixing the
value of scaling factor (mm/pixel) [3] to be 4.25.  

Could you clarify this?

Thank you in advance,

Hyejoo

 
     =====================================================================
     
     Please note that this e-mail and any files transmitted with it may be 
     privileged, confidential, and protected from disclosure under 
     applicable law. If the reader of this message is not the intended 
     recipient, or an employee or agent responsible for delivering this 
     message to the intended recipient, you are hereby notified that any 
     reading, dissemination, distribution, copying, or other use of this 
     communication or any of its attachments is strictly prohibited.  If 
     you have received this communication in error, please notify the 
     sender immediately by replying to this message and deleting this 
     message, any attachments, and all copies and backups from your 
     computer.