Attenuation Image and Coefficients in PET List-mode Recon


When reconstructing PET list-mode data with attenuation correction, CASToR requires an attenuation correction factor for each event in the input *.cdf file. Also, if the attenuation correction flag is on, an attenuation image needs to be passed to CASToR which, as far as I understand, is used during normalization.

I am wondering why CASToR doesn’t use the input attenuation image to calculate an attenuation correction factor for each event automatically?

Thank you all,


Hi Reza,

This is a good point but we did not have time yet to implement it. This feature will be provided in the next release.




To add to Simon answer, if you have an attenuation image, there is no need to compute acf for each event in list-mode reconstruction. Attenuation correction will be computed from the attenuation image during the sensitivity image generation.

Also, in the event of the dimensions of reconstructed image do not match those of the atn image, make sure that the whole atn image is contained in the reconstruction FOV, as the atn image will be interpolated to the reconstruction dimensions before generating the sensitivity image.



Hi Reza,

I will backtrack from my previous mail. Contrary to what I previously stated, YES, for the moment you have to provide both an attenuation image and acf for each events for list-mode attenuation correction in the release version of CASToR… This will no longer be the case in the next release.

Sorry for any confusion :slight_smile: