Comparison of Intensity Modulated Radiotherapy Treatment Plans Between 1.5T MR-Linac and Conventional Linac

In this study, we assess the dosimetric qualities and usability of planning for 1.5 T MR-Linac based intensity modulated radiotherapy (MRL-IMRT) various clinical sites in comparison with IMRT plans using a conventional linac. total 30 patients disease brain, esophagus, lung, rectum vertebra were re-planned retrospectively simulated MRL-IMRT Elekta Unity dedicated treatment system (TPS) Monaco (v5.40.01). Currently, step-and-shoot (ss) is only delivery technique available on Unity. All treated an Versa HD TM dynamic multileaf collimator (dMLC) technique, designed v5.11. For comparison, same dMLC-IMRT plan was recalculated machine TPS but changing to step-and-shoot. The plans, be evaluated by Dose Volume Histograms (DVH) metrics, Homogeneity Index Conformality Index, compared plans. measured optimization time number Monitor Units (MUs). Comparing linac all created clinically equivalent current practice. However, had higher dose skin larger low region normal tissues. Furthermore, significantly reduced comparing MUs increased 23% ss-IMRT, no difference from dMLC-IMRT. conclusion, acceptable can achieved multiple tumor sites. Given differences characteristics, some minor quality found between practice should considered