[Gate-users] SPECT without collimator, issue with source?

[Monika Kvassheim]

Dear all,

I have modelled a Siemens Symbia SPECT and obtain energy spectra consistent with experimental results with both a HE and a MELP collimator with a Ra-224 ion source. When I run the simulation without a collimator, the resulting energy spectrum matches the experimental result above 150 keV. The main peak at 80 keV however, disappears. Please see the attached plot.

I questioned whether the source was the issue and changed from an ion Ra-224 source to a userSpectrum. The result is also attached, I have a large 80 keV peak, but now the 240 keV peak is missing.

I am very confused and hope someone can help.

Best regards,
Monika Kvassheim


[cid:125f7980-a241-4550-bc3a-9e1924147ba1][cid:603bac32-05e7-476d-a0a7-4ab715315181]
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