Glaser on

In an article on Cerenkov fluorescence published today by, Dartmouth PhD candidate Adam Glaser explains how the light imaging technique can be used to measure an imparted dose from an X-ray photon linac beam.

The technique developed by Glaser and his Dartmouth colleagues has been verified through a series of experiments using a clinical linac from Varian Medical Systems. The first step in the process is to fill a water tank with tap water and dissolve the fluorophore (quinine sulphate) to a concentration of 1.0 g/l. Then, a standard commercial CMOS camera is positioned at a given distance from the water tank, perpendicular to the incident beam, and focused to the beam’s isocentre.

When the beam is turned on, a 2D projection image is captured using a 10 s exposure time, and an equivalent image with the beam off is recorded and subtracted to isolate the Cerenkov-excited fluorescence for direct correlation to the deposited dose.

“Each image is immediately downloaded from the camera to a computer and can be viewed in real time,” explained Glaser. “Our experiments in this proof-of-concept study show that the strength of the fluorescence signal equates near-linearly to the dose imparted in the water. We believe this is the first demonstration of using Cerenkov light to indirectly determine the spatial distribution of a charged particle’s energy deposition within a medium.”

For more on Glaser’s research, read the article on

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