A new HK$20 million radiotherapy machine at Pamela Youde Nethersole Eastern Hospital is set to slash therapy time while offering better treatment, the hospital has said. Radiotherapy, one of the main ways of treating cancer, uses high-energy radiation to kill cancer cells. It can take up to 20 minutes per session. The new instrument, known as RapidArc, can complete a session in as little as three minutes. The shorter time meant that the hospital - which uses radiotherapy on 1,000 cancer sufferers a year - might treat 20 per cent more patients, said Anne Lee Wing-mui, chief of the clinical oncology department. The machine cuts treatment time by continuously rotating around the patient to apply radiation, unlike the current intensity-modulated radiotherapy, which administers a complex sequence of fixed radiation beams from multiple angles. The constant rotation also reduces discomfort and exposure to radiation, according to the hospital. RapidArc was also tipped to provide more focused therapy by changing the shape of the radiation beam as it rotated around the patient, targeting only the cancerous tumour while avoiding the surrounding healthy cells, the hospital said. This would be especially critical in treating head and neck cancers because of the proximity of vital organs, it said. Of three patients who had undergone such treatment since doctors began using it early this week, one suffered from head and neck cancer, the hospital said. Patients would not need to pay more for the new technology, Dr Lee said. The RapidArc instrument is a gift to the hospital by an anonymous donor. There are only 15 others in regular service across the world.