PSI

Paediatric anaesthesia for proton radiation therapy at the Paul Scherrer Institute

Background

In an interdisciplinary collaboration between the University Children`s Hospital and the Paul Scherrer Institute, small children with solid tumours, mainly brain tumours are treated with proton radiation therapy under anaesthesia / sedation since summer 2004.

Proton radiation therapy is a modern therapy option for brain tumours - but also other solid tumours of children. Brain tumours are relatively common in children and account for about 20 – 25% of cancer diseases in children. They are known to occur even in neonates. The first step of the therapy consists of as complete excision of the tumuor as possible. Depending on the histology of the tumuor and the localisation, additional chemotherapy and/or radiotherapy may be necessary.

Proton radiation therapy is a gentle technique where the radiation doses can be focused exactly on the tumour alone, thereby saving the adjacent normal tissue from radiation damage. Besides reducing a long-term squeal caused by radiation, the risk of developing a second tumour is also diminished.

In order to achieve a successful result of proton radiation therapy in the region of brain and neck, absolute immobilization as well as reproducible and precise positioning of the head is mandatory. Therefore the head is fixed either by a mask or by a bite-block. The bite-block is prepared for each individual patient as a mould of the hard palate and upper teeth. This is done under general anaesthesia with tracheal intubation. Afterwards the bite-block holds at the hard palate by means of vacuum which is established through a small channel in the middle of the mould. With this technology a daily reproducible accuracy of head positioning of about 0.2mm can be achieved. An average of about 30 radiation sessions over a period of 6 – 7 weeks are necessary.

Awake proton radiation therapy can be offered only to older children and adults because children younger than 5 years of age do not tolerate head positioning with a bite-block or a mask and are not able to lie absolutely still without anaesthesia. Proton radiation therapy has become an available option for small children only because of the establishment of a separate paediatric anaesthesia unit in the Paul Scherrer Institute by the Department of Anaesthesia at the University Children`s Hospital Zuerich.