In 2017, Sunway Medical Centre treated their first patient with the newly acquired Gamma Knife Icon, the latest iteration of the Gamma Knife (6th generation) and the first unit installed in the South East Asian region. The Gamma Knife is a dedicated radiosurgery device specifically designed for the treatment of intracranial lesions. It is a means of effectively treating intracranial tumours including brain metastases and other benign brain lesions such as acoustic neuromas, gliomas, and meningiomas, without surgical incisions or the need for a craniotomy.
Developed in the 1968 by Lars Leksell, a Swedish neurosurgeon, the Gamma Knife is the most extensively researched and published radiosurgery device with more than a million cases treated till date, and more than 2500 number of peer-reviewed publications to its name. It has stood the test of time and established itself as a precise and reliable treatment modality for lesions in critical and sensitive locations inside the cranial cavity.
At the core of this device, is a large helmet-like structure which houses up to 192 radially-placed sources of Cobalt-60 with precise beams converging on a single focal point at the centre of the helmet-shaped structure. This is akin to focusing the beams of sunlight with a magnifying glass on a central target, for example, on the centre of a piece of paper, while unaffecting anything outside the target focal point. Utilising sophisticated algorithms and powerful imaging technologies, the focal hotspot can be shaped and placed to cover the volume of most targets measuring under 3cm with sub-milimetre accuracy in the brain.
The device enables the delivery of a high dose of radio-therapeutic radiation to these targets, with an extremely sharp dose fall-off outside of the target. As such, it even enables doctors to treat, for example, small lesions within the brain stem effectively and safely. This has revolutionised the ability to treat complex and difficult lesions which would otherwise necessitate long arduous sojourns attended with significant risks when treated with conventional brain surgery.
With the Gamma Knife, patients can be treated on a daycare basis with little or no pain. In the prior iterations of the Gamma Knife, a simple frame fixation was necessary for treatment. In the latest iteration, the Gamma Knife Icon, mask-based therapies have become possible with the addition of a cone-based CT scanner to the existing model.
Additionally, with the Gamma Knife Icon, therefore, the standard 2.5 centimetre limit for most lesions have been expanded to be able to treat larger lesions safely by the use of fractionation, i.e. with the intended dose delivered over 3 to 5 sessions. It has now become possible to treat large brain metastasis, for example in the posterior fossa of the brain, without inducing excessive oedema (related to the treatment) and thus obviating the need for surgical excision, reducing both financial costs, risks and unnecessary hospital time, particularly for patients with cancer. The latest data coming out from other Gamma Knife Icon centres around the world are proving the effectiveness of fractionated and staged treatment for large cerebral metastases. This is once again a game-changer in patient therapy.
With the advent of the Gamma Knife Icon, the presence of multiple brain metastases is no longer an end-point for the cessation of treatment, or in other words, a ‘death sentence’. Whole brain radiotherapy which carries significant risks of cognitive decline can also be avoided. Patients with cancer, who have good control of their primary disease, can have their brain metastases treated with a very high success rate. They are then followed-up over 3-6 months periods with MRI scans. In the event that new metastasis occur, they are re-treated (“picked away at”) by the Gamma Knife once again. Thus, the cognitive functioning of these patients are maintained and a good quality of life is afforded. Function and quality of life is preserved. Life expectancy is however determined by the primary disease status.
In the pre-Gamma Knife era, lesions such as arterio-venous malformations (AVMs), skull-based tumours, and large recurrent pituitary tumours, had to be treated surgically with high attendant risks. With the Gamma Knife and specifically with the improved treatment plans, these lesions can now be treated literally on a daycare basis with very low attendant risks and high control rate. As such, more and more indications are being switched over from open brain surgery to the Gamma Knife.
Treatments with the Gamma Knife are not limited to the treatment of tumours, but are also currently being applied to functional disorders such as trigeminal neuralgia. Trigeminal neuralgia can now be treated with Gamma Knife with low risk and high control rates. The Gamma Knife has also been used for the treatment of movement disorders such as tremor-predominant Parkinson’s disease, essential tremor, and obsessive-compulsive disorders.
Open brain surgery will always remain the mainstay of treatment for large rapidly growing lesions in symptomatic patients with short histories. That being said, the paradigm continues to shift in favour of less invasive and more accurate and effective therapies such as the Gamma Knife. From being a complementary tool in the surgical armamentarium of neurosurgeons, this latest iteration of the Gamma Knife, namely the Gamma Knife Icon, is pushing at the envelope and replacing surgery in many of the traditional indications.
We owe this technology to the pioneering work of the Professor Lars Leksell of the Karolinska Institute in Stockholm, Sweden. In 1968, the first Gamma Knife was born using Cobalt-60 as the energy source. The term “stereotactic radiosurgery” was coined by Professor Leksell. The prototype unit used for 12 years was primarily used for functional disorders (pain and movement disorders). The product evolution of this nascent technology is the Icon. It is the most precise radiosurgery device in the market with micro-radiosurgical capability providing treatment with ultra high precision. The prospect of having “brain surgery” and going home on the same day without a surgical cut on one’s head is mind-bending. We wait with bated breath on what lies ahead in this paradigm-shifting landscape. Watch this space!
For more information about treatment with the Gamma Knife Icon, contact Sunway Medical Clinic at +62811 8 1614 86