Plan comparison and data analysis
PD
Following the Fast‐Forward trial's protocol requirement, the clinical TrueBeam and Halcyon APBI plans were compared for target coverage and dose achieved to adjacent OAR. Additionally, delivery efficiency and accuracy were recorded for both platforms. Total number of monitor units (MU) per fraction, beam modulation factor (MF): ratio of total number of MU per fraction to the prescription dose in cGy, and total beam‐on time (BOT) were recorded during portal dosimetry QA measurement at the machine. Dosimetric verification of treatment delivery accuracy on both platforms was performed using a portal dosimetry (PD) VMAT QA procedure,