<div dir="ltr"><div><div><div><div>Hi Wei,<br><br>Few questions:<br><br></div><div>1. What version of Gate are you using ?<br></div><div><br>2. What navigator are you using ?<br></div><br> Typically if regularMatrix, be careful with the skipVoxelBoundaries flag (try to turn it off).<br>
</div> If fictitiousVoxelMap, are you forcing the fictitious energy, or the gamma-discard energy ?<br><br></div>3. Could you give the numbers ? is it a big difference ?<br><br>Also, happy new year to all !<br><br></div>Cheers,<br>
Simon<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Dec 16, 2013 at 4:47 AM, Wei ZHAO <span dir="ltr"><<a href="mailto:zhihuaigu@163.com" target="_blank">zhihuaigu@163.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="line-height:1.7;font-size:14px;font-family:arial"><div style="line-height:1.7;font-size:14px;font-family:arial">
<div style="line-height:1.7;font-size:14px;font-family:arial"><div> </div><div>Dear GATE user,</div><div> </div><div>I have imported a thorax 3D data set using voxelized phantom format and want to investigate influence of the phantom downsampling on the extracted scatter signal. The scatter events were extracted with <strong>VOXELPHANTOMSD.</strong> The voxelized phantoms are 32x32x16, 64x64x16,128x128x16,256x256x16 grids with 8.8x8.8x11.2mm^3, 4.4x4.4x11.2mm^3,2.2x2.2x11.2mm^3,1.1x1.1x11.2mm^3 voxel size respectively. Since the phantom size is the same (with different voxel size), the extract scatter shouldn't change significantly. However, the final scatter have dramatic change. This may related to <strong>HOW GATE RETRIEVAL SCATTER USING VOXELPHANTOMSD? Does this dependent on voxel size? I have used the ROOT output.</strong></div>
<div> </div><div>I have used the below command to record scatter events.</div><div> /gate/thorax_phantom/attachVoxelPhantomSD </div><div><strong>the result is the smaller voxel size is, the smaller scatter signal I got.</strong></div>
<div> Can anyone help me sort this out? Any suggestion will be appreciated.</div><div> </div><div>Thank you very much!</div><div>Best regards</div><div>Wei</div><div> </div><div>below is my interfile for 64x64x16 and 32x32x16 voxelized phantom :</div>
<div>--------------------------64x64x16------------------------------------------------------------</div><div>!number of images/energy window := 16<br>!process status := Reconstructed<br>!matrix size [1] := 64<br>!matrix size [2] := 64<br>
!number format := unsigned integer<br>!number of bytes per pixel := 2<br>scaling factor (mm/pixel) [1] := +4.400000e+00<br>scaling factor (mm/pixel) [2] := +4.400000e+00<br>!number of projections := 16<br>!extent of rotation := <br>
!time per projection (sec) := 0<br>study duration (sec) := 0<br>!maximum pixel count := +2.000000e+02<br>patient orientation := head_in<br>patient rotation := supine<br>;<br>!SPECT STUDY (reconstructed data) :=<br>method of reconstruction := Unknown<br>
!number of slices := 16<br>number of reference frame := 0<br>slice orientation := Transverse<br>slice thickness (pixels) := +11.200000e+00<br>centre-centre slice separation (pixels) := +11.200000e+00<br>filter name := Unknown<br>
filter parameters := Cutoff<br>method of attenuation correction := measured<br>scatter corrected := N<br>oblique reconstruction := N<br>!END OF INTERFILE :=</div><div>------------------------------------------------------------------------------------------------------</div>
</div>---------------------------------------32x32x16--------------------------------------------------<br>!number of images/energy window := 16<br>!process status := Reconstructed<br>!matrix size [1] := 32<br>!matrix size [2] := 32<br>
!number format := unsigned integer<br>!number of bytes per pixel := 2<br>scaling factor (mm/pixel) [1] := +8.800000e+00<br>scaling factor (mm/pixel) [2] := +8.800000e+00<br>!number of projections := 16<br>!extent of rotation := <br>
!time per projection (sec) := 0<br>study duration (sec) := 0<br>!maximum pixel count := +2.000000e+02<br>patient orientation := head_in<br>patient rotation := supine<br>;<br>!SPECT STUDY (reconstructed data) :=<br>method of reconstruction := Unknown<br>
!number of slices := 16<br>number of reference frame := 0<br>slice orientation := Transverse<br>slice thickness (pixels) := +11.200000e+00<br>centre-centre slice separation (pixels) := +11.200000e+00<br>filter name := Unknown<br>
filter parameters := Cutoff<br>method of attenuation correction := measured<br>scatter corrected := N<br>oblique reconstruction := N<br>!END OF INTERFILE :=<br><span title="neteasefooter"><span>-------------------------------------------------------------------------------------------------------------------------</span></span></div>
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