Heidelberg 2022 – scientific programme
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ST: Fachverband Strahlen- und Medizinphysik
ST 4: Radiation monitoring and dosimetry I
ST 4.3: Talk
Tuesday, March 22, 2022, 14:55–15:10, ST-H4
First study on energy resolution in proton radiography — •Marius Hötting, Kevin Kröninger, Isabelle Schilling, Jacqueline Schlingmann, Hendrik Speiser, and Jens Weingarten — TU Dortmund, department of physics
Proton radiography offers the possibility of real-time patient positioning before or during the treatment. Typically, pixelated silicon sensors are used in the implementation, which makes it possible to contour various structures of phantoms or patients from the pure evaluation of the proton hit position.
With the additional information of the deposited charge of each particle per pixel, the initial proton energy, the residual range and finally the water equivalent thickness (WET) can be calculated. This allows conclusions about the material traversed without an additional external energy detector and gives the opportunity for cross-check with the treatment plan.
The challenge is to determine the proton energy with the limited resolution in deposited charge and a low number of detected protons per pixel. The measurement of the WET of a phantom is therefore done in two steps, one without and one with an additional homogeneous absorber of known width. The energy difference in both images allows minimization of the systematic uncertainties. Finally, the conversion to the WET is done with a simulated calibration curve.
In this talk, we describe the currently investigated method for WET calculation with pixel sensors and first simulations with Allpix2 to determine depth-dependent uncertainties.