"It was definitely my most successful season on the international stage," he said.
"Coming away with third at Pan Pacs was the first international medal that I had won - the first big one.
"I was starting to wonder if I was ever going to quite crack the top level but getting that result gave me the confidence that I definitely can get there and compete with those top guys."
Top swimmers from the United States, Canada, Australia and Japan attended the Pan Pacifics.
Radford explained that to qualify for the 2016 Rio Olympics he needed to finish in the top 10 at the world champs in Russia in July.
Despite having a second chance to qualify, Radford said his main goal was to finish in the top 10 at the world champs.
"The goal is to get that Olympic qualifying out of the way and not have it lagging in the background.
"And it will mean I can focus on medalling at the Olympics."
He said he felt he had progressed as an athlete since the last world champs in 2013, where he finished 18th in the 10km event.
"I think I have grown a lot mentally and have learned how to race the race.
"I think that is a massive part of open-water swimming - you can be as fit as you like but the fittest swimmer does not always finish at the front of the pack, it is the one who swims the smartest race."
Radford is back home in Rotorua but is based in Perth for most of the year, where he trains full-time.
He will race at the New Zealand Open Water Championships in Taupo this Saturday and hopes to defend his national 10km title.
If he wins the race he will make it five national titles in a row.
"You always want to win your national title. There is always prestige to be the national champ."
Radford trains with nine other swimmers in Perth under coach Paul Bruce.
Though the only open-water swimmer in the group, he said it was a great atmosphere for training.
