The LS detector prototype with the coordinate system used throughout this work.
(a) A sample of the images of proton spots acquired with the CCD camera. Each frame represents a different proton spot of a nominal range in water of 10.5 cm delivered in 1 cm increments along the x-axis (crossline) (b) Depth profiles of the spots shown in (a) and (c) lateral profiles of the spots shown in (a).
Measured pixel size of the LSD system; (a) pixel size as a function of the distance between the image plane and the CCD (i.e., along the y-axis), the solid line represents a linear fit; (b) pixel size as a function of the lateral position on the image (i.e., along the x-axis), the solid line represents an exponential fit.
Measured proton ranges using different reference points. Plus sign (+) represents the average position between the Bragg peak and the distal 30%, black circle represent the distal 80%, open circle the distal 70%, and open square the distal 90%.
(a) Scintillation light profile of three proton spots with different lateral position (−5.6 cm, 0 cm, and +5.6 cm). All spots are drawn centered on their peak; (b) relative difference in the intensity of two spots (−5.6 cm and +5.6 cm) relative to the central spot (x = 0 cm).
Comparison of measured proton beam range in the LS detector system with expected range.
Relative intensity measurements of proton spots along the x-axis. The pair of horizontal dotted lines represents ±2%.
Summary of the optical and physical phenomena that alter the measured light distribution.
Comparison between expected and measured lateral position of the proton spot along the x-axis.
Measured spot position and width (FWHM) differences from a spot on the central axis as a function of its distance in the direction parallel to the camera’s axis (y-axis).
Measured proton spot intensity. The measured value at 5 MU is not shown because it is used as a reference.
Differences in proton intensity as a function of position along the y-axis. The second column show the deviation in % from the light intensity of the spot at y = 0 cm after correction of the varying distances between the spot and the CCD camera. The third column further correct for the attenuation inside the LS.
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