Gate里的scatter记录

The phantomSD plays a crucial role in GATE simulations, as it is used to detect and count Compton and Rayleigh interactions taking place in the scanner FOV. This information is then used to estimate whether a photon reaching a detector is a direct or a Compton-scattered photon. Thus, in PET, the phantomSD is currently the only way to discriminate scattered from true coincidences. To simulate low energy X-ray acquisitions (for example mammography acquisitions from 7 to 28 keV), information concerning Rayleigh interactions is significant.

Using this type of sensitive detector, it's possible to retrieve two types of information considering the hits:

• The number of Compton and Rayleigh interactions occuring in all the volumes attached to the phantomSD: this information is stored in the data output variables nPhantomCompton and nPhantomRayleigh.

Note: This information is also available for the crystalSD with the variables nCrystalCompton and nCrystalRayleigh.

• The last volume attached to the phantomSD in which a Compton or aRayleigh interaction occured: the data output variables used are named compVolName and RayleighVolName.

Attachment of the phantomSD

• One first needs to define a dummy, air-filled volume covering the whole field-of-view of the scanner.
• Then, all the source volumes should be offsprings (direct or indirect) of this volume.
• Last, all these volumes (FOV and sources) should be attached to the phantomSD using the command attachPhantomSD.