@hopeful33250 this is exactly the question I asked my team after the first treatment so I understand how you are feeling as there is always initial apprehension that the treatment is not effective. I was told that the gold standard to assess the effectiveness of the full PRRT treatment is 3 months after the last treatment as the impact after each treatment really takes a full three months to show up. I think I could have pushed for a PET scan after the second treatment but after the second treatment my attitude changed somewhat and I started to feel that it was best to wait for the full picture rather than view pieces of the puzzle ad hoc. Also after the second treatment my blood work started to show significant signs of decreased tumour activity and this has been encouraging, although blood work i keep being told is not the gold standard as to the effectiveness of treatment ( but it certainly helps to see the numbers go down!) I do have a standard CAT scan the morning after each treatment so my team can see how the radiation has settled ( and look at my other major organs to ensure they are unscathed I guess) but it also shows ( in less detail of course than a PET) how the tumours are shrinking from the prior treatments. The morning after the first treatment I could not observe a change in tumours with the less detailed CAT scan, just that their darkness suggested they had absorbed a big hit of radiation, which felt like a victory in and of itself. However after my latest CAT scan, after my final treatment this week, I have noticed my largest tumour looks about 1/3 of its original size, which is certainly giving me hope. My team agreed and we all felt positive but let’s see what the PET shows. I think it’s important to trust your team and go with what is recommended. That said I am certainly now very eager to see the results of my PET scan scheduled for October and hope and pray that the 4 PRRT sessions have given me my old life back for a period of time, hopefully a long time but it’s all a win. Keep the faith Ron.