TWIN FALLS — If you have no idea what a certified medical dosimetrist does, you’re not alone.

It’s a behind-the-scenes job that often goes under the radar. But it’s a crucial one: designing and mapping out radiation treatment plans for patients, especially those who have cancer.

St. Luke’s Mountain States Tumor Institute in Twin Falls has two medical dosimetrists: Jake Osen and Randy Tibbetts.

After a radiation oncologist prescribes a dose of radiation for a patient, dosimetrists develop a treatment plan to make sure the radiation is administered in a safe, effective manner, Tibbetts said.

It allows a patient to receive treatment to a certain area of their body — such as where their tumor is — while seeking to minimize damage to the surrounding normal tissues and organs.

“If we can avoid some of those critical structures, we can avoid some of the side effects,” Osen said.

Unlike diagnostic radiology — which revolves around figuring out what’s wrong with a patient — dosimetrists are part of the treatment process. They currently have 35 patients on radiation treatment.

Osen said they’re trying to provide hope for patients or buy them more time to spend with their families. And it’s humbling when a patient tells them “thank you,” he added.

People often think it would be depressing working with cancer patients, Tibbetts said, but that’s not true. “The patients actually lift you up a lot here.”

At MTSI in Twin Falls, there’s a room that looks much like a computer lab. After patients undergo a CT scan, Osen and Tibbetts import the images into a treatment planning computer. The doctor shows them where the tumor is.

A doctor talks with the patient to find out how aggressive they want to be with their treatment. That plays a role in creating a plan.

Sometimes, dosimetrists have just 20 minutes to create an emergency plan. Or it can take more like six to eight hours if it’s a really involved plan.

When dosimetrists create a plan for a lung cancer patient, for example, they use historical data to dictate the decision-making process. “There are certain types of lung cancer that need a certain dose,” Tibbetts said.

There are computer shortcuts, “but every single patient is different,” he said.

Dosimetrists review completed treatment plans with doctors to make sure they’re safe, and a medical physicist double checks their work, too. They also make sure a radiation therapist can decipher it.

The stakes are high.

“If it’s not done right, you can do a lot of harm with radiation,” Tibbetts said, and it can kill people. But Osen said they know so much about radiation, and there are a lot of checks and balances in place to ensure it’s safe.

Also, radiation is a localized treatment affecting one area of the body — unlike chemotherapy, which affects the whole body.

People tend to have a lot of fears about radiation, though, Tibbetts said. “When people think about radiation, they tend to think of Chernobyl or something like that.”

Radiation therapy isn’t used exclusively for cancer. It can also be used to treat other conditions, such as bone growths on a patient’s hips.

Interested in becoming a certified medical dosimetrist? Working in radiologic technology is a good place to start, followed by becoming a radiation therapist.

To become a dosimetrist, it’s typically a master’s degree-level university program, with a heavy emphasis on math, physics, and anatomy and physiology.

Working as a dosimetrist includes communicating with patients, using a simulator for treatment planning and computer work.

Osen has been at St. Luke’s Magic Valley Medical Center for 17 years and as a dosimetrist for five of those. He knew he wanted to work in the health care field, but he didn’t want to be a nurse.

He’d never heard of dosimetry when he began his career in medicine. He went to school a few times as his career progressed: Idaho State University for radiologic technology, Weber State University for radiation therapy and University of Wisconsin-La Crosse for medical dosimetry.

For Tibbetts, he worked in radiologic technology and therapy previously, and received on-the-job training in medical dosimetry at a teaching hospital before taking the certification exam. He has been in dosimetry for about 20 years.

“For me, I felt it was just a further progression in my career to go this route,” he said.

Tibbetts is originally from New England and ended up in the Magic Valley on a 13-week assignment. That was nine years ago. He ended up staying.

There was talk of opening a new hospital in Twin Falls, which happened in 2011, and new opportunities and computer programs.

“It seemed like a good fit,” he said.