A group of mourning parents are sharing their stories about treatment at a Metro Vancouver hospital, saying they hope their warnings will prevent it from happening again.

Speaking exclusively to CTV Vancouver, the parents say their children weren't given tests at Delta Hospital that may have saved their lives.

Nona Gallagher said her 21-year-old daughter, Erin, had always been healthy. But in October 2011 something was wrong.

"She said that she felt dizzy. Her head was just so bad. She felt nauseous," Nona recalled.

"She would drink water and vomit."

Erin went to the emergency room at Delta Hospital, and kept going back. She was admitted four or five times in about 2 ½ months, Nona said.

Initially, doctors thought the young woman simply caught a cold or a flu.

"Delta never offered a CAT scan, even though they had a brand new one… It was right there," Nona said.

On January 18, 2012, she went in again, and was discharged. Hours later, her mother found her passed out in her room.

An ambulance rushed her back to the hospital and a scan was performed.

"They found a huge mass, a spindle cell tumour, in the frontal part of her brain," Nona said. The benign tumour hemorrhaged, and Erin died the next day.

"She just wanted to have fun and hang out with animals… She was my best friend."

Denise Turner's daughter Nicole was also having debilitating headaches.

"I would tell them that she was disoriented. I just said, there's something wrong with her," Denise recalled.

Nicole was 26 and eight weeks pregnant. Her mother took her to the Delta ER four times before a CT scan was performed in October 2010.

The scan uncovered a brain tumour, and she was transferred to Royal Columbian Hospital where she died hours later.

"I just wish they had done the CAT scan," Denise said.

In Nicole's medical records, one Royal Columbian staff member wrote that the "severity of the illness seemed downplayed by sending MD," and that they would "look into management at Delta Hospital."

Denise says she still struggles with her daughter's death. During the last hospital visit, Nicole asked whether she was mad.

"I said, 'No, just scared,' because I didn't know what was going on."

Denise and Nona reached out to CTV News after 14-year-old Kyle Losse died of a brain injury in January. He died just hours after he too was released from Delta Hospital without a CT scan.

Fraser Health says headaches are one of the most common complaints at the Delta ER, and admitted that CT scans are easy to order, but that the majority of patients aren't offered the option.

"We know that CT scans have radiation associated with them, and it's a genuine risk," said Dr. Neil Barclay, regional medical director of emergency medicine for Fraser Health.

"Some of the studies have shown that radiation can impair a child's ability to graduate high school."

But Denise and Nona both wish they'd been given the choice.

"The point of the matter is, if anybody goes for help they should get it automatically," Nona said.

Fraser Health is encouraging both mothers to file formal complaints to help prevent more tragedies. Both said they planned to do so.

"I don't want anybody else to go through this," Denise said.

With a report from CTV Vancouver's Breanna Karstens-Smith