Evaluation of water equivalent thicknesses using the IEM-CSIC scanner prototype

Abstract

Proton imaging has been proposed as an alternative low-dose imaging technique for acquiring relative stopping power (RSP) maps and for patient positioning. In proton therapy and hadrontherapy, the water equivalent thickness (WET) of a material represents its radiological thickness, however, its calculation requires computationally intensive methods or approximate solutions. At IEM-CSIC, we have developed a scanner prototype for imaging with protons composed of two double-sided silicon strip detectors (DSSSD) and fast scintillators with high energy resolution, detectors that are commonly used in Experimental Nuclear Physics. Two custom-made samples of aluminum, air, and polymethyl methacrylate (PMMA) were imaged and their proton radiography images (pRads) are presented in terms of WET. Pattern reproduction, spatial resolution, and sensitivity to di↵erent materials were studied. We present pRads of our samples obtained using a rather traditional approach to compute WET values. All three materials of the studied samples, aluminum, PMMA, and air, were well distinguished; the resulting WET values were in good agreement between samples.