A New Technology for Fast Two-Dimensional Detection of Proton Therapy Beams

Figure 15

Ionization signal from the Micromegas chamber using the uniform-scanned proton delivery technique in which a relatively large Gaussian spot is magnetically scanned to produce a large, uniform fluence behind a collimating aperture. The aperture was 5 mm × 4.5 mm. The beam was on for 21 seconds and 65 pairs of pulse sets were collected in that time. All 65 sets are plotted here by shifting the phase of each set by 0.32112 s.