SU-E-T-167: Comprehensive Evaluation of EPID Image Acquisition for Integrating and Temporal Dosimetry of Fixed-Gantry IMRT and ArcIMRT

Medical Physics
Inhwan Jason YeoBaldev Patyal

Abstract

To evaluate EPID for dosimetry applications of arc and static-gantry IMRT with sliding window (SW) and/or step-and-shoot (SS) deliveries Methods: IMRT beams (SW & SS) were designed that generate beam hold-offs and dose rate modulation due to MLC motion under 10 × 10 cm jaw. An arcIMRT beam was designed by adding gantry movement to the SW field. A 10 cm × 10 cm open beam was also used. Despite differences in delivered dose rates/pulse characteristics, the four beams should deliver the same total dose. For each beam, various MUs with 6 MV beam at 300MU/min were irradiated on EPID which operated in image acquisition of integration mode (IM), continuous scanning mode with synchronization (CMs) and without (CMn) to beam pulses. Acquired images were evaluated in repeatability, dose linearity, and reproducibility (reproduce open beam output in IM). In IM, repeatability, dose linearity, and reproducibility were within 1% for all dose levels and beams. In CMs, they were within 1-2% if dose rate was maintained steady (1) for SW beam (needed a minimum 1.3 MU/cm MLC motion) and (2) arcIMRT beam (needed a minimum 1 MU/degree and 2.8 MU/cm MLC motion) and (3) if a minimum of 38-40 MU per shoot was used for SS beam. Nonlinearity was observed ...Continue Reading

Related Concepts

Related Feeds

Buruli Ulcer

Buruli ulcer is a progressive disease of subcutaneous tissues caused by mycobacterium ulcerans. Here is the latest research.