Technical Note: The first live treatment on a 1.0 Tesla inline MRI-linac



Publication Details

Liney, G. P., Jelen, U., Byrne, H., Dong, B., Roberts, T. L., Kuncic, Z. & Keall, P. (2019). Technical Note: The first live treatment on a 1.0 Tesla inline MRI-linac. Medical Physics, 46 (7), 3254-3258.


Purpose:This work describes the first live imaging and radiation delivery performed on a prototype1.0 T inline MRI-Linac system in a rat brain tumor model, which was conducted on 29 January2019.Methods:A human scale 1.0 T MRI-Linac was adapted to be suitable for animal studies via a spe-cially constructed open 6-channel receiver radiofrequency (RF) coil. A Fischer rat injected with 9Lglioma cells in the right hemisphere was imaged and irradiated at day 11 post surgery as part of a lar-ger cohort survival study. The rat was anesthetized and positioned at the iscocenter of the MRI-Linac.Imaging was used to localize the brain and confirm the presence of a tumor following the administra-tion of a gadolinium nanoparticle contrast agent. A single dose of 10 Gy was delivered using a2.25 cm92.90 cm radiation field covering the whole brain and verified with radiosensitive filmin situ. Real-time imaging was used throughout the irradiation period to monitor the animal and tar-get position.Results:The signal-to-noise ratio (SNR) measured in the rat brain was 38. Postcontrast imaging wasable to demonstrate a tumor of 5 mm diameter in the upper right hemisphere of the brain approxi-mately 45 min after administration of the nanoparticles. The radiation beam had no impact on SNRand images at the rate of 2 Hz were effective in monitoring both respiration and intrafractionalmotion. In vivo film dosimetry confirmed the intended dose delivery. The total procedure time was35 min.Conclusions:We have successfully used MRI guidance to localize and subsequently deliver a radia-tion field to the whole brain of a rat with a right hemispheric tumor. Real-time imaging during beamon was of sufficient quality to monitor breathing and perform exception gating of the treatment. Thisrepresents the first live use of a high field inline MRI-Linac

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