Remote dosimetric auditing for intensity modulated radiotherapy: A pilot study. (October 2017)

• Record Type: Journal Article
• Authors: Miri, Narges; Lehmann, Joerg; Legge, Kimberley; Zwan, Benjamin J.; Vial, Philip; Greer, Peter B.
• Is Part Of: Physics and imaging in radiation oncology. Volume 4(2017)
• Page Start: 26
• Page End: 31
• Publication Date: 2017-10
• Subjects: Radiotherapy -- Periodicals; Radiation dosimetry -- Periodicals; Cancer -- Imaging -- Periodicals; Oncology -- Periodicals; 615.842
• DOI: 10.1016/j.phro.2017.11.004
• Languages: English
• ISSNs: 2405-6316

Abstract

Abstract: Background and Purpose: Electronic portal imaging devices (EPIDs) can be used to reconstruct dose inside a virtual phantom. This work aims to study the feasibility of using this method for remote dosimetry auditing of clinical trials. Materials and Methods: Six centres participated in an intensity modulated radiotherapy (IMRT) pilot study of this new audit approach. Each centre produced a head and neck (HN) and post-prostatectomy (PP) trial plan and transferred the plans to virtual phantoms to calculate a reference dose distribution. They acquired in-air images of the treatment fields along with calibration images using their EPID. These data were sent to the central site where the images were converted to 2D field-by-field doses in a flat virtual water phantom and to 3D combined field doses in a cylindrical virtual phantom for comparison with corresponding reference dose distributions. Additional test images were used to assess the accuracy of the method when using different EPIDs. Results: Field-by-field 2D analysis yielded mean gamma pass-rates of 99.6% (±0.3%) and 99.6% (±0.6%) for HN and PP plans respectively (3%/3 mm, doses greater than 10% global max). 3D combined field analysis gave mean pass-rates of 97.9% (±2.6%) and 97.9% (±1.8%) for the HN and PP plans. Dosimetry tests revealed some field size limitations of the EPIDs. Conclusions: The remote auditing methodology using EPIDs is feasible and potentially an inexpensive method.