NEW DELHI: Gamma knife, a radiation therapy device used commonly to treat brain tumour, is now being deployed for treating cancerous tumours in the eye.
The device uses advanced imaging and computer software to deliver an intense radiation dose to the tumour while sparing the surrounding tissues unlike conventional treatment methods in which a small carrier containing radioactive “seeds” (known as a plaque) is placed on the outside of the eyeball over where the tumour to deliver radiation.
According to Dr Bhavna Chawla, professor of ophthalmology at AIIMS Delhi – where Gamma Knife has been used for radiation therapy in 15 patients suffering from Choroidal Melanoma already, the new methodology can help preserve vision while killing the cancer cells more effectively.
“Of the 15 patients who underwent radiation therapy using Gamma Knife at our hospital in the last two and a half years, vision could be preserved in 13 which is a big achievement,” she said.
Choroidal melanoma refers to cancerous tumour affecting the choroid which is a thin layer of tissue lying between the sclera or white outer layer of the eye and the retina. According to Dr Chawla, conventionally treatment for this rare type of cancer involves plaque therapy which is an invasive procedure.
“We must conduct a small surgery to place the plaque, a small carrier containing radioactive “seeds”, on the outside of the eyeball over where the tumour is and after the radiation dose is administered another surgery is needed to remove the plaques. It poses a high risk of damage to the surrounding tissues and the optic nerve and, therefore, the chances of preserving vision. The use of the Gamma knife device is likely to improve the outcome,” the AIIMS doctor said.
AIIMS Delhi has been using the Gamma Knife device to treat tumours and lesions involving the brain since late 1990s, Dr Deepak Agrawal, professor of neurosurgery at the premier medical institute said. “Recently, we have started to explore its usage for cancerous tumour of the eye. The results have been encouraging,” he said. AIIMS is charging Rs 75,000 for radiation therapy using the Gamma Knife device as well as follow-up MRIs.