Mapping 3D doses in water with a cable robot equipped with plastic scintillator

Abstract

This work presents the first use of a cable robot for 3D dosimetry. Its design was optimized to operate in water and offer five degrees of freedom. It was equipped with a plastic scintillation detector. The cables and the end effector were made of plastic, thus making all components inside the phantom water equivalent. Feasibility and reproducibility was demonstrated using a 6MV beam. The cable robot prototype had a usable workspace of 40 cm in each direction and could rotate over 90 degrees in both the polar and azimuthal directions. It was tested at speeds of up to 120.8 mm/s. Position precision was within 2.5 mm for translation and within 1.1 mm for rotations about a fixed point. This new robotic dosimetry system is more versatile and can address limitations of current water phantoms that are constrained to only 3 translation axes.