Getting bowels empty enough for RT

Great to have some advice on what seems quite difficult to get bowels empty enough for Radio Therapy (RT) treatment.  It took my OH 3 x CT planning sessions, even then his bowel was not empty using 3 sachets of Laxido a day and a Microlax mini-enema along with doing all the things needed to clear bowels e.g. prunes, chia seeds, fibre, fruit etc.  This is even though he thought he had emptied his bowels more than once in the morning.  He initially noticed a change in bowel movements as he started to get PCa symptoms which he was managing through diet and lactulose. The specialist nurse suggested Laxido was better suited.  At the third CT planning session his bowel was just within the tolerance they can use and we are now waiting for the RT plan sign off.  We want to get this right so that when the RT treatment sessions start his bowels are in the right state and realise after a couple of weeks of treatment the bowels will be less of a problem due to the reaction to the RT.  We have some questions: does the bowel need to be exactly in the same state as when the CT planning session was completed - is there any tolerance?  Would just using just a mini-enema be enough, the Laxido seems to be giving him wind.  Is it possible the RT treatment cannot be done daily if the bowel is not presented in the right state.  Just an indication of the worry we are going through while waiting - we may be overthinking all of this. 

PS thanks Decho for all your input on your RT treatment sessions, they have been really helpful. I can't thank you enough.

OH Diagnosed with locally advanced PCa in March 2023 G5+4, T3b N1 M0, initial PSA 290, which went down to PSA 23 after 4 months on Decapeptyl 6 month injections.  Declined Chemo and waiting for start of RT treatment.