Bruce Johnson, senior vice-president at the Houston, Texas offices of internationally-recognised HKS Architects, examines the considerable physical challenge of accommodating sizeable proton external beam radiation therapy equipment into hospitals, drawing on work undertaken by the practice to date in designing hospitals to cater for such sizeable machinery.
Proton therapy has actually been used on patients since 1957, when the patient was required to come to the cyclotron labs for treatment. At the time there were only three labs capable of administering the treatment in the world – at Uppsala University in Sweden; Berkeley University in California, and Harvard University in Boston. Results were promising, but the inability of imaging technology of that era to accurately locate tumours, or to direct protons to sites deep within the body, meant that only a few patients were appropriate candidates for the treatment. The first hospital-based proton treatment centre in the United States was built in 1990 at Loma Linda University Medical Center in Loma Linda, California, closely followed by the completion of a centre at Massachusetts General Hospital in Boston. In the following years, various manufacturers have researched and improved the properties of particle physics and, in the process, created new technologies to deliver the promise of heavy ion radiation in the treatment of cancer. Today there are nearly 30 proton therapy treatment centres worldwide. Proton therapy centres are an integration of particle physics technology, supporting engineering requirements, and the architecture that holds this equipment, creating a “human space”. In simple terms, a proton centre involves four main spaces:
• Creation of the proton beam in a single cyclotron room, creating proton particles 1,800 times the mass of photons (used in linear accelerators), which travel at two-thirds of the speed of light.
• An energy selection system to reduce and shape the beam energy required.
• Transportation of the proton beam up to 300 ft in a horizontal vacuum tube, guided by electromagnets into designated treatment rooms.
• Delivery of the radioactive beam in a massive three-storey treatment space, with the patient lying on a movable “couch” in the centre area or treatment floor. A 10 m high, 100 ton motorised steel frame gantry spins 360 degrees around the patient to attack tumours from the most effective angle.
Accelerators: cyclotrons and synchrotrons
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