Helping mum

Hi there. I'm new to this forum. My mum has been on quite a cancer journey. She discovered she had small cell lung cancer in February 2024 on holiday in Brisbane Australia. They diagnosed her quick and offered to treat her under the reciprical arrangement with the UK. After 3 weeks from initial detection, her first Chemo was administered. Roll on to now. She had 4 cycles of chemo and 35 treatments of radiotherapy on Oz. They were great, but the regime was hard on her. She's now back in the UK and has connected with the UK NHS lung cancer section at the BRI in Bristol. Here's the rub. Mum had excellent care in Oz, and scans that showed the areas of cancer to zap. Now in the UK, she's had her first CT scans. They can't tell what areas of her right lung were treated / where her 2 areas of shrunk/ dead cancer are, nor the 4mm nodule that her Oz oncologist asked her to keep an eye on. Not even a comparison of Oz CT scans has helped. 'Too much scar tissue to spot the reference points. So we go from certainty in Oz to complete uncertainty in the UK. It's dispairing. So mum has taken the decision to have a privately funded PET CT scan. The UK oncologist would be not order one on cost effectiveness grounds. Somehow, the light needs to be shined onto this darkness. I welcome any experiences like this and whether scarring from previous treatment has also got in the way of knowing if things are stable or the big C is on the move. And if the PET CT scan will help.