The Tribune Democrat, Johnstown, PA

Breast Cancer

October 1, 2012

Challenges remain for radiation therapy

Pinpoint accuracy required

JOHNSTOWN — The challenge with radiation therapy is the same as it was when X-rays were first pointed at a tumor nearly a century ago.

“It might be a trite statement, but you want to put the radiation where the cancer is,” Dr. David F. Stefanik, radiation oncologist, said at the John P. Murtha Regional Cancer Center in Johnstown.

But exposing cancer to the optimum dose of radiation – while limiting exposure of surrounding, healthy tissue and organs – involves meticulous measurements and controls using equipment costing several million dollars.

The first step is determining if the patient is a candidate for radiation therapy, Stefanik said.

The decision is made through consultations with the breast surgeon and medical oncologist.

Breast cancer patients opting for lumpectomies almost always receive therapeutic radiation, while mastectomy patients normally don’t, Stefanik said.

A patient referred for radiation therapy first comes in for a consultation and planning session. She is positioned on the Murtha Center’s combination positron emission tomography/computed tomography imaging machine, commonly called a PET/CT scanner.

PET images show the body’s metabolic activity, while CT images show body structures. The two images are digitally overlaid.

“It helps us to hone in on the tumor,” Stefanik said. “We get a better picture on what we are dealing with. The scope and extent of the disease is certainly better appreciated with that technology.”

Once Stefanik identifies the area to be treated, he works with the treatment planning team to develop a strategy. The team includes certified dosimetrists Barb Garland and Jane Williams and physicist Chandrakant Pujara.

Garland and Williams entered the relatively new field of dosimetry after working directly with patients as radiation therapists.

“We will create a visual image in three dimensions of a body model,” Williams said. “We put in critical structures that need to be spared the radiation as well as structures that need the radiation.”

Stefanik can then identify the area to receive radiation, including the tumor and nearby tissue at risk for cancer, Williams said.

The model directs positioning of the X-ray-producing linear accelerator on an identical exam table in the next room.

“We plan that down to the millimeter,” Stefanik said. “They use their background in therapy to be sure once those patients are on the treatment machine, it’s the same.”

Pujara then measures the linear accelerator’s field and dosage. The field is contoured to the shape of the tumor.

“We do a phantom simulation before the patient ever gets treatment,” Pujara said. “What we plan is verified first. Several factors go into the calculation. All the calculations of the field are checked three times or four times.”

Safety is a major focus, Garland said. For breast cancer patients, foam body molds are customized to help position them in the same position each time they get on the table.

“We are very careful that everything is exactly the same as they were here on the setup day,” Garland said.

Each treatment only takes about 15 minutes from the time the patient enters the treatment room, Williams said.

Most radiation therapy regimens last seven weeks, but some patients whose breast cancer is caught in the earliest stages can have theirs wrapped up in five days with technology that introduces radiation from inside the breaast.

Breast brachytherapy available at Indiana Regional Medical Center’s Herbert L. Hanna Center for Oncology Care allow radiologist Ali M. Tunio to introduce radioactive pellets into the cavity left after the lumpectomy.

The therapy is only available to patients whose small tumors had not spread to any lymph nodes.

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