Time resolution setting method and explanation

General Discussions
1

Dear Castor users,

(1) castor-GATERootToCastor -m LYSO.mac -s LYSO.root -TOF_reso 205.5 -vb 4 -src -o out2

(2) castor-GATERootToCastor -m LYSO.mac -s LYSO.root -vb 4 -src -o out2_v2

I reconstructed the image using the two commands above.

I measured the SNR after reconstruction.

(1) is the time value is set and (2) is the time value is not set, but the SNR value of 2 is better than the value of 1.

Why is that so?

Thanks for your help every time.

Best regards,

Suhwan Kim

2

Dear Kim,

It is not easy to answer without the reconstructed images and reconstruction parameters. The option -TOF_reso will set up the Time of flight options in the datafile and assume the CRT of your Gate simulated system is 205.5 ps.

You can potentially observe artifacts or noise increase if the TOF resolution does not match the actual resolution of the detectors. Additionnally, the convergence properties can change with time-of-flight (convergence is usually faster). This can lead to a worse SNR in the TOF reconstructed image than in the standard image for a same number of iterations, so it is worth to check SNR in image reconstructed with different number of iterations/subsets.

Best regards,
Thibaut

김수환 <ksh2454178@naver.com> a écrit :