Hold your breath for 30 seconds.
It's a simple task that could help women protect their heart as they undergo radiation treatment for breast cancer.
The first patient to use the deep inspiration breath hold method just graduated from Sharp Chula Vista's Barnhart Cancer Center.
Radiation oncologist Dr. Phillip Zentner said DIBH could protect a woman's heart from radiation that could lead to heart disease or other forms of cancer later in life.
Celina Lopez, 36, was the first patient to complete the treatment. She discovered a lump in her left breast late last year.
"That shouldn't be there, my body doesn't feel like that," she remembered telling herself.
The preschool teacher underwent chemotherapy and lost her thick curly hair. Then came radiation, where doctors historically zap the cancerous tumor with radiation, even though the lump may be dangerously close to the heart.
That's where DIBH came in.
Doctors had Lopez hold her breath for 30 seconds at a time.
"If women take a deep breath," explained Zentner, "the heart moves down and back and away from the chest."
The separation creates enough space to protect the heart from the radiation.
Lopez repeated the process for more than 30 days, and Zentner said her prognosis looks good.
On Tuesday, Lopez rang a bell in the hallway at the Barnhart Cancer Center to celebrate her final treatment.
Zentner said the process hinges on whether a patient's lump is on the left side and if patients can hold their breath for at least 30 seconds.
Zentner estimated the DIBH process should be effective on 75 percent of breast cancer patients.