composites
A patient table that radiation has to pass through: why the couch tops of radiotherapy and imaging systems are carbon fibre sandwich panels, and what the material still costs in dose.
About: Radiotherapy and imaging couch tops · Carbon-fibre-reinforced polymer · Composite sandwich panel
A radiotherapy couch top must hold the patient still and rigid while treatment beams, and the imaging used to aim them, pass through it. Carbon fibre is described as the material of choice: strong, stiff and light, and more transparent to radiation than the hardboard, copolyester or PMMA used before.[1]
The top is itself a sandwich panel — two carbon fibre plies held apart by a light filler, which is what makes it stiff — and newer tops built for image-guided treatment have dropped the metal side bars that earlier designs relied on for rigidity.[1,2]
Transparent is not invisible. For one imaging couch top, two treatment planning systems predicted that the couch absorbed between 2 and 9.5 per cent of the beam, and that it raised the dose to the patient’s skin by roughly half to nearly double; the authors recommend modelling the couch in every treatment plan in which beams pass through it.[1]
Often said
“A carbon fibre treatment table has no effect on the radiation dose.”
What the evidence supports
Carbon fibre is far more radio-translucent than older table materials, but it still attenuates the beam by a few per cent and markedly raises skin dose, so the couch must be included in treatment planning.
Supporting records: radiotherapy-and-imaging-couch-tops-dose-trade-off
Bracketed references link to the structured entity records whose claims support each paragraph. Last updated 2026-10-30.