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PMC gets new cancer treatment system

POCATELLO — New cancer treatment at Portneuf Medical Center delivers radiation therapy continuously as a machine rotates around a patient’s targeted location.

Dr. Michael Callaghan, the Portneuf Medical Center Cancer Center radiation oncologist, said the treatment was first conducted at PMC recently on a prostate cancer patient.

The new therapy, known as Volumetric Modulated Arc Therapy, has been in the works since last August, about the time the Cancer Center moved into its new location on Hospital Way. The VMAT is a significant technological advancement over the former stationary intensity modulated radiation therapy.

“Traditional radiation throws a really good fastball, we’re actually able to shape the radiation in a way that is kind of like throwing a curveball so you can actually curve the dose around critical structures,” Callaghan said. “It’s made the toxicity of the treatment less.”

Callaghan said the treatment can be used on prostate cancer, head, neck and brain tumors.

The treatment includes three phases, the initial CAT scan, planning and treatment delivery.

This new technology works like a stencil by targeting treatment to a mapped out location and shielding the areas that don’t need to be exposed to the radiation.

The patient received two CAT scans, one with a detailed image and one prior to treatment and the images are aligned for the treatment area. The image that is generated is translated into moving “blocks.” The moving blocks create a fluid hole that the radiation passes through to the treatment area.

“This provides us the ability to exclude as much normal tissue as possible and treat the areas that have potential cancer or cancer in it,” Callaghan said. “The other advantage of this is it actually cuts the treatment times by about half to a third and that’s important because if you have a patient laying on a table, things move. ... The faster time you have to deliver it the more accuracy you have.”

Bruce Broswick, the PMC Cancer Center director, said technology has change since he and Callaghan first started delivering radiation cancer treatment. He said four stationary blocks were used to deliver the treatment for a standard prostate cancer patient, that technology was succeeded by a multileaf collimator device or MLC, which still delivered treatment in four stationary areas. IMRT allowed between 4-8 fields of treatment. The VMAT delivers continuous treatment.

“The beam is on all the time that it goes around. The cloud of radiation around the tumor is really customized to the shape of the tumor,” Broswick said. “If we can decrease the treatment times it is much safer and much quicker. They smile when they walk out of the room now.”

Callaghan said the next procedure that will be available at the PMC Cancer Center will be stereotactic body radiotherapy, which is slated to be up and running in the late summer or early fall.

Dr. Mike Callaghan sits by a video of the new cancer treatment system at the Portneuf Medical Center in Pocatello. The Volumetric Modulated Arc Therapy system more precisely targets radiation to tumors. For video from this story, see