Technology the future of cancer treatment
To the untrained eye, the mess of squiggles and crude pictures on the whiteboard could appear as nothing other than child’s drawing.
Arrows that point to circles, surrounding dots next to a nonsensical schematic hardly looks like the stuff of medical breakthroughs.
But for medical physicist Ranjini Tolakanahalli and Dr. Ahbi Hallock, the head of radiation oncology at Niagara Health, those sketches are a map of the future.
The drawings tell the story of technology reshaping cancer treatment in Niagara, making it safer, more precise and more efficient.
In the past, oncologists were only able to be so accurate in using radiation to target cancerous tumours. Radiation therapy is very effective, but there was no way to avoid exposing healthy tissue and organs to doses of radiation that can lead to toxic side effects.
The phrase “the cure is worse than the disease,” often gets applied to cancer treatments because of the dramatic side effects of radiation therapy.
Now, using new technology called volumetric modulated arc radiotherapy, or VMAT, doctors can target tumours to within a few millimetres, sparing healthy tissue nearby.
Hallock said because VMAT is so precise it allows oncologists to attack tumours with higher doses of radiation in shorter treatment sessions that reduce the risk of side effects.
Tolakanahalli compares older methodology to traditional military bombing attack. The target gets destroyed, but there is a lot of collateral damage. In the metaphor, VMAT is a laser guided cruise missile, striking only what it is aimed at.
Part of the power of VMAT comes from three- dimensional mapping of a patient’s body, Tolakanahalli said.
Past scans, like x- rays, are twodimensional images that show slices of what is going on inside a patient. Tolakanahalli said doctors use multiple 2D scans taken from different angles target a tumour, but the inherent limitations in the scan mean pin- point accuracy isn’t possible. Gauging the exact volume and depth of a tumour is difficult.
“It’s not guesswork,” Tolakanahalli said of 2D methods, which are still commonly in use. “But there is a limitation in how much information you can get. And that means there is a limitation in your treatment plan.”
Hallock said using this method, oncologists develop a “target zone” — a box around a tumour to ensure the radiation dose is effective. That necessarily means healthy tissue also gets that dose.
VMAT uses accurate 3D scans of patient’s body, giving a vastly more accurate picture of the position, shape and volume of a tumour.
Combined with software that allows the radiation treatment machines to deliver doses exactly where the doctors want them, the scans allow the treatment to more precise than anything that came before it.
A typical patient will have as many as five straight days of treatments, and before each one, a new 3D scan is taken so doctors can track any changes in the tumour and the body, Tolakanahalli said.
The precision attack also allows for more intense, but shorter exposures for patients. It doesn’t just mean few side effects for patients, but better outcomes.
Hallock said the human body is constantly in motion. In the case of a prostate cancer patient, there is fluid moving through the bladder, the tumour is moving around and so is the prostate. The only way to accurately strike the tumour is to have a precise snapshot of the patient’s body on that day.
Treatment sessions last about a minute and half per treatment, meaning there isn’t time for something in the patient’s body to change drastically and reduce the effectiveness of the treatment, she said.
The treatment may be over in a flash for the patient, but Hallock and Tolakanahalli said each 1.5- minute session is preceded by up to 15 hours of preparation and pre- treatment quality control checks.
Tolakanahalli said preparation for modern radiation treatments are often compared to the kind of rigorous pre- flight checks used by the airline industry.
Niagara Health has only been using VMAT technology for about six months, and primarily only to treat prostate cancers. However, Hallock said VMAT will eventually be used to treat all tumours.
“I think that we can be as good or better as any other cancer centre,” she said. “I truly believe that.”
Tolakanahalli said VMAT is just the start for Niagara Health. There are other, hyper- precise cancerfighting methods being developed and the use of VMAT is creating “the foundation” to allow the hospital system to adopt those technologies in the future. glafleche@postmedia.com
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