Gamma 3D in CERR

[osman...@gmail.com]

Dear CERR Development Team, I have a question about the 3D Gamma Calculation GUI that I hope you can clarify. OBSERVATION: When I configured gamma analysis with 2% dose difference and 10% low-dose threshold, the resulting gamma dose was labelled "Gamma_1.3715%_2mm_BODY". I notice the stored dose difference (1.3715%) differs from my input (2%). QUESTION: Is the low-dose threshold intended to modify the dose difference criterion? I observe: - Max Reference Dose: 68.57 Gy - 10% threshold = 6.857 Gy absolute - Stored value: 2% × (6.857 / 10) = 1.3715% Could you explain how the low-dose threshold interacts with the dose difference parameter? Understanding this would help me interpret results correctly, especially when comparing across multiple analyses with different thresholds. Thank you for your help.

Best wishes

Sarah

[Aditya Apte]

Voxels below the low dose threshold (68.57*0.1=6.875Gy in your case) are ignored from calculation(the dose is too small for meaningful gamma calculation). The dose difference criteria used for gamma in your case is 68.57*0.02=3.1715Gy.

Thanks,

Aditya

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[osman...@gmail.com]

Thank you so much Aditya for the quick clarification - that's very helpful! 

One small observation: the gamma map label shows "1.3715%" in this case - I initially found this a bit confusing since it's actually an absolute dose (1.37 Gy) rather than a percentage. Would it make sense to consider labelling it as "1.37Gy" in future versions? Just a thought that might help other users avoid the same confusion. 

Thanks again for maintaining this excellent tool. 

Best regards,

Sarah

[Aditya Apte]

Yes, thanks for the feedback. We will fix this.

-Aditya

To view this discussion visit https://groups.google.com/d/msgid/cerr-forum/54fd39bf-0abd-4038-b0a3-4f0b28aad140n%40googlegroups.com.