Author: Andrew Groll, Ayan Mitra, PhD, Manoj Narayanan, Sanchit Sharma, Ray Yang, Timothy Pok Chi Yeung 👨🔬
Affiliation: Reflexion Medical Inc,, RefleXion Medical 🌍
Purpose: To develop a versatile QA tool enabling dose recalculation of a patient’s plan sinogram redeployed onto arbitrary replacement phantom geometry, and extract computed dose along detector planes to compare against measurement.
Methods: An automation pipeline was developed enabling the optimized plan sinogram of clinical patients to be extracted from the RefleXion treatment planning system database and aligned with any replacement CT reference image. Leveraging the product dose calculation engine and site-specific beam model, the resulting recalculated 3D dose distribution can be previewed, and setup shifts adjusted to intersect the detector plane over regions subtending dose variations of interest. Calculated dose to the detector plane can be exported as a baseline.
Results: Considering a case study of a clinical head-and-neck patient, redeployed onto a QA cheese phantom, the plan was delivered to ion chamber and calibrated film intersecting the target. The ion chamber measured 153.8cGy, compared with 154.4cGy recalculated in the phantom (within 0.4%). Across the film plane, sandwiched vertically between hemispheres, 94.57% of points passed a 3%/2mm gamma criteria, exhibiting excellent qualitative agreement in high dose regions.
Conclusion: Decoupling between plan sinogram and its underlying CT enables substitution of patient geometry with an arbitrary phantom for flexible QA measurements on the RefleXion X1 system.