Ten-year-old Ewan MacKerracher, from Coleraine, was diagnosed in 2010 with a tumour, which recurred in 2012.
His mother Kerrie said she was told he would need MRI scans every six months, and that the family was "living in fear" that Ewan's tumour would return.
Mrs MacKerracher said she was contacted by a surgeon on Monday following a BBC interview.
"We've just been through so much," Mrs MacKerracher told BBC Radio Foyle.
"We were told his surgeon was off on sabbatical at one stage. Ewan was then transferred from an adult waiting list to a children's waiting list.
"We were even told at one stage that his records were lost.
"It's been a series of errors and it's a shame I had to go to the press to get it sorted. I was always told he should be getting six-monthly scans.
"We got a call from a surgeon after the interview went out on BBC Radio Foyle and we now have a date for an MRI scan."
Mrs MacKerracher said Ewan was expected to have the scan next Monday.
"I'm really overjoyed," she said.
"To go from having no date for a scan to having a concrete date feels really good - it's an early Christmas present.
"Ewan isn't keen on getting scans but it is necessary and he is looking forward to knowing more about what's going on in his  head.
"He has been getting headaches recently. Hopefully we'll get an answer before Christmas."
The Belfast Health and Social Care Trust said the recommended interval for follow-up scans was 12-24 months, and it was "endeavouring to provide the best treatment and support" for Ewan.
A County Londonderry boy will now get a brain scan after a two-year wait, his mother has said.