ESTRO 2022 - Abstract Book

S1306

Abstract book

ESTRO 2022

Conclusion We created a virtual HexaMotion platform to quantify the time-resolved performance of MRI-guided MLC-tracking in 3D using a Delta4 on Unity.

PO-1525 Radioluminesence imaging for CyberKnife® dosimetry and quality assurance

A. Spinelli 1 , Z. Shakarami 1 , S. Broggi 2 , A. del Vecchio 2 , C. Fiorino 2

1 San Raffaele Scientific Institute, Experimental Imaging Center, Milan, Italy; 2 San Raffaele Scientific Institute, Medical Physics, Milan, Italy Purpose or Objective To investigate the applicability of radioluminescence imaging (RLI) as a novel 2D quality assurance (QA) dosimetry system for CyberKnife®. Materials and Methods We developed a real time dose measurement system based on a commercial complementary metal oxide semiconductor (CMOS) camera facing a radioluminescence screen located at the isocenter (Figure.1). The radioluminescence light collected by a lens was used to measure 2D dose distributions. An image transformation procedure, based on two reference phantoms (square and star), was developed to correct for projective distortion due to the angle (15 degrees) between the optical and the radiation beam main axis. Dose profiles were measured for field sizes ranging from 10 mm to 60 mm using fixed circular and Iris™ collimators and compared against gafchromic film (GC). The corresponding full width at half maximum (FWHM) was measured using the RLI and benchmarked against GC film. Small shift of the isocenter position were introduced on purpose to test the sensitivity of the RLI system to field size variations.

Figure 1: RLI acquisition setup. The radiation beam (yellow) impinged on the scintillation screen, which then emits light collected by the camera (orange).

Results The FWHM measurements using the RLI system indicated strong agreement with GC film with maximum absolute difference equal to 0.131 mm for fixed collimators and 0.049 mm for the Iris (Table.1). A 2D analysis of RLI with respect to GC film