Precise and powerful CyberKnife robot destroys inoperable tumours

By Caitlin Renneson

Patients don’t need to have a metal halo screwed into their skull when they receive radiation treatment with CyberKnife. That was one of the appealing factors for neurosurgeon Dr. John Sinclair to bring the radiosurgery robot to The Ottawa Hospital.

With previous radiosurgery, a patient with brain tumours had to have their head immobilized during treatment. A metal frame or ‘halo’ was screwed into their skull and then fastened to the table they’d lie on for treatment. However, a patient does not need to be rigidly immobilized when receiving CyberKnife radiosurgery. The robot uses X-rays and complex precision software to accurately track the tumour, and deliver a high dose of radiation to the precise location of the brain tumour while the patient lies on the table fitted with a custom-made plastic mask.

“CyberKnife has an advantage over regular radiation because it is so much more accurate; precision is less than a millimetre,” says Dr. John Sinclair, Director of Cerebrovascular Surgery at The Ottawa Hospital. “You can give very high doses of radiation right to the lesion and get almost no spill over to normal tissue. And as a result, we see much more improved responses to this type of treatment compared to traditional radiation.”

Dr. Sinclair was first introduced to CyberKnife when he did a fellowship at Stanford Medical Center in California. CyberKnife was invented at Stanford, so the neurosurgeon was one of the first to see the benefits of this frameless radiosurgery treatment.

When Dr. Sinclair was recruited to The Ottawa Hospital in 2005, he hoped to bring this novel technology to patients here. At the time, it was a technology that wasn’t approved by Health Canada. So, Dr. Sinclair and his team made a case for robotic radiosurgery, presenting scientific data that validated its success. The Ottawa Hospital was eventually one of two health research centres in Ontario allowed to test the CyberKnife. However, there was no government funding available to purchase the machine. The hospital appealed to the community, which pulled together and generously raised the entire $4 million to purchase it. CyberKnife began treating patients in September 2010.

“Because it’s delivering a high dose, it’s considered similar to surgery without using a scalpel, so no blood loss, no pain, no ICU stay, or recovery time,” says radiation oncologist Dr. Vimoj Nair, one of the radiation oncologists trained to prescribe CyberKnife treatment. “So CyberKnife radiosurgery does provide an option where people can be treated with outpatient techniques,” says Dr. Nair.

With conventional radiation, the daily doses were lower, and patients were required to come to the clinic for more radiation treatments overall. Conventional radiation treatment could range from five to six weeks. With CyberKnife, radiation is focused precisely to the tumour allowing for larger doses to be delivered daily and, therefore, the total treatment can be delivered in one to six days. The hospital’s CyberKnife has gained a reputation for improving treatment of various tumours. And Dr. Nair says because it is only one of three in Canada, patients occasionally are referred to The Ottawa Hospital for treatment from British Columbia to the Maritimes.

“At first, we would treat one tumour. Now, we treat five or six individual tumours at a time and spare the rest of the brain. We’re only delivering radiation to those metastatic tumours,” says Dr. Sinclair. “There is a proportion of patients who develop cognitive problems a few months after whole brain radiation. But with radiosurgery, because we only give the radiation –a higher dosage– to the actual tumours, patients have improved outcomes, and so quality of life is better.”

Radiation therapist Julie Gratton says this has meant an increase in the number of patients having multiple tumours treated in the same session. “Treating several tumours at once helps keep the patient’s clinic visits to a minimum while targeting individual tumours rather than treating the whole organ helps spare healthy tissues and reduce side-effects,” says Julie who has worked on CyberKnife since it was installed at The Ottawa Hospital.

Up until 2017, 1,825 patients had been treated on CyberKnife. In 2018, 359 patients have already received 1,824 CyberKnife treatments. Julie says that because more tumours are being treated at once in each patient, the number of treatments delivered per year has increased as expected.

Although 90 percent of CyberKnife treatments are for malignant or benign brain tumours, CyberKnife is also being used to treat tumours outside the head. As it doesn’t require a frame to rigidly immobilize the area receiving radiation, CyberKnife’s image guidance system is used to treat organs that move constantly, such as the lungs, kidneys, liver, prostate gland and lymph nodes. CyberKnife can precisely align the radiation beam to the tumour even when it moves. The method of tracking tumours in organs and soft tissue has been improved by research at The Ottawa Hospital.

Caitlin Renneson is the Communications Coordinator at The Ottawa Hospital.