Optical imaging provides quality assurance for small radiotherapy beams

Physics World

October 22, 2019

"Optical scintillation imaging is proving feasible as a quality assurance (QA) tool for small static beams and for pre-treatment verification of radiosurgery and volumetric-modulated arc therapy (VMAT) plans," reports Physics World. "Researchers at Dartmouth have shown that the technique can perform QA for each control point within five dynamic VMAT plans. Moreover, the approach is sensitive to small errors in gantry angle and multileaf collimator (MLC) leaf position (Med. Phys. 10.1002/mp.13797).

"Recently, Brian Pogue and colleagues at Thayer School of Engineering successfully used Cherenkov imaging as a QA tool for broad beams from an MR-linac. They demonstrated good agreement between optical images acquired from an intensified CCD camera and simulated dose distributions from the treatment planning system (TPS), but were not able to image small beamlets reliably due to a low signal-to-noise ratio.

"'While the detection principle is the same as Cherenkov imaging, in scintillation imaging, an organic phosphor is used to boost the signal, allowing the recording of the smallest, dynamic beams with high fidelity,' explains co-author Petra Bruza.'"

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