Corrugated Fiberboard as a Positioning Insert for Patients Undergoing Radiotherapy

Triple-wall corrugated fiberboard/Carbon-fiber base plate/Patient-positioning insert/Body immobilization device. We have developed a new body fixation system for single patient use, which consists of a vacuum cush ion, a thermoplastic fixation sheet which is used to suppress involuntary and voluntary patient movement, and a triple-wall corrugated fiberboard base pl ate to which both the vacuum cushion and the thermoplastic sheet are affixed. To evaluate the characteristi cs of the fiberboard as a patient-positioning insert, the photon beam attenuation of a fiberboard base plate, a carbon-fiber base plate, and a vacuum–formed cushion were compared. The strength of the fiberboard was also evaluated. The attenuation for the carbonfiber base plate was 3.7% and 2.6% in 4 MV and 10 MV photon beams, respectively, while the results we re less for the fiberboard base plate, i.e. 1.9% and 1.6%. The vacuum–formed cushion had a minimal effect on transmission. None of the materials subsided under the weight loading of 20 g/cm 2 . There was no difference between the thicknesses of the fiberboard before and after a 50 times daily load with the 60 kg weight of a volunteer. Corrugated fiberboard is a robust and low attenuating material that functions well as a patient-positioning insert.