Sue Wigmore says getting a diagnosis early for her father made it less frightening.
Families have told ITV News they are relieved that a scanner to diagnose early and complex forms of dementia will soon be available for health boards across Wales.
The PET (positron emission tomography) scanner was originally designed for cancer patients, but a pioneering study found it is able to identify signs of dementia that can otherwise be difficult to diagnose.
Dementia treatment in Wales has previously lagged behind the rest of the UK, with around half of those with the condition not getting a diagnosis, according to Alzheimer's UK.
88-year-old Mike Runnalls recently had the PET scan and was later diagnosed with Alzheimer's disease.
His daughter, Sue Wigmore, said the early diagnosis has enabled the family to prepare.
"It's frightening because you don't know how it's going to progress, but actually deciding that knowing and being able to plan and think about what's ahead has made it less frightening," she said.
Sue's mother also suffered from dementia before passing away a year ago. Her father is receiving treatment for the incurable disease.
Sue added: "Dad might not necessarily go down the same path mum did, but we're prepared, which I think is the most important thing".
Having taken care of his wife, Mike was keen to get an early diagnosis for himself.
Describing his experience of the disease, he said: "It's very hard to know where the disabilities are coming from.
"I am aware most obviously of the bad memory, I forget things completely. Not all the time though, it fluctuates.
"I write copious notes so I know what's going on."
The announcement of the service being expanded comes during Dementia Awareness Week.
It also follows the Welsh Government's £10m annual funding investment in a Dementia Action Plan, first announced in 2018.
The successful pilot involved teams at Aneurin Bevan University Health Board, Cardiff University researchers at the University Hospital of Wales and the Royal College of Psychiatrists in Wales.
The technology at University Hospital of Wales will scan around 2,000 people a year.
The Royal College of Psychiatrists said the roll out will help improve the accuracy of diagnosis and reduce waiting lists that have increased during the coronavirus pandemic.
Dr Chineze Ivenso, chair of the Old Age Faculty, said: "This is a proud moment for everyone involved in this ground-breaking project from the start. It really is fantastic news for my patients as well as their families.
"Living with dementia is not easy but an early diagnosis helps in managing the condition. Getting people, the help they need, quickly.
"For a long time, Wales was behind the curve when it came to diagnosing dementia. Now we're leading the way."