New scanner tracks tumors
Katherine Lee monitors a PET scan at HealthCenter Northwest in Kalispell. The PET scanner tracks radioactive isotopes injected into patients to track tumors and other diseases. Karen Nichols/Daily Inter Lake
Idell Johnson, 82, just napped through the procedure.
It involved 40 minutes of letting a sugar-coated radioactive fluid wander through her body, then 25 minutes of that fluid emitting positrons through her skin to be caught by a big ring circling her.
The Whitefish woman had to keep perfectly still through both segments.
This is HealthCenter Northwest's new PET scan machinery, present at the hospital since November.
PET stands for positron emission tomography.
It's a way -combined with a computed axial tomography, or CT, scan that is essentially a three-dimensional X-ray - to track tumors and diseases.
In Johnson's case, the target is cancer in her left breast: Her first clue was a lump in late September.
HealthCenter Northwest in Kalispell used to have a PET scan tractor-trailer truck from Alliance Imaging Inc. visit weekly to do PET scans. The facility already had CT scanning equipment.
But HealthCenter Northwest needed the PET scan rig twice a week on Tuesdays and Fridays. So it bought its own equipment for $1.7 million.
The new PET scan equipment is inside a new CT scan ring -with only minuscule differences from just a CT scanner apparent from the outside.
Essentially, the PET scan tracks the radioactive isotopes as they flow and clump in Johnson's body.
Manufactured in Spokane, this particular isotope has a half life of 118 minutes -meaning it loses half of its radioactivity each 118 minutes.
The fluid also contains a type of sugar. Some tissues inside the body, and organs such as the brain, suck in any sugary fluids.
Cancer tumors are another sugar-absorbing biological tissue. "Cancer loves sugar," said HealthCenter Northwest CT supervisor Katherine Lee.
These radioactive isotopes are persnickety.
The timing has to be precise with the isotopes in a lead container leaving Spokane at a specific time, then injected into a patient in Kalispell at a specific time so the radioactivity has decayed to a specific level.
After being injected with the radioactive fluids, Johnson had to stay perfectly still for 40 minutes.
She could not even watch television because her eye movements would be enough to disrupt the flow of the radioisotopes as they went through her bloodstream and were absorbed by her body.
"I just close my eyes and take a nap," Johnson said.
Then Johnson was gently wheeled to a stretcher-like bed next to the PET-CT scanning machinery. The bed was then slowly eased into the circular scanning device.
X-rays and positrons then did their thing.
A three-dimensional cross-section of Johnson's body slowly materialized on a computer screen, while the positrons mapped the dimensions of the tumor on the same images.
A radiologist would later interpret the images and compare them with a previous set of scans to track the cancer.
Johnson was matter-of-fact about the cancer and the procedure.
"You face it and do the best you can," she said.
Reporter John Stang may be reached at 758-4429 or by e-mail at jstang@dailyinterlake.com