"I was less scared in the ocean," said Hallett.
Georgetown University doctors are using the CyberKnife -- a more targeted approach -- to kill Fred's prostate cancer.
Four gold seeds are placed in the patient's prostate. Beams of radiation then target the seeds. If the prostate moves, the radiation beams move with it so other organs are not damaged.
Other radiation treatments take much longer. Internal seed therapy takes three months. External radiation lasts 40 days. The CyberKnife cuts treatment down to five days.
"Prostate cancer is a cancer of 10 or 20 years, so we won't know how good the results are for that long, but we're not willing to wait because we have the best radiation technology in the world, and I'm not willing to wait 20 years to give this opportunity to men," said Dr. Sean Collins.
A PSA blood test can detect your risk of the disease. A score of 4 or higher could mean prostate cancer.
As for Fred, his PSA score is down from 9.3 to 2 and he's ready to get back to his adventures at sea.
Prime candidates are patients whose cancer is confined to the prostate and those with a PSA of 20 or less.
Side effects are the same as any form of radiation treatment, which include urinary frequency, but experts say CyberKnife patients usually experience less side effects.
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