Toward acquiring comprehensive radiosurgery field commissioning data using the PRESAGE/optical-CT 3D dosimetry system.

Published

Journal Article

Achieving accurate small field dosimetry is challenging. This study investigates the utility of a radiochromic plastic PRESAGE read with optical-CT for the acquisition of radiosurgery field commissioning data from a Novalis Tx system with a high-definition multileaf collimator (HDMLC). Total scatter factors (Sc, p), beam profiles, and penumbrae were measured for five different radiosurgery fields (5, 10, 20, 30 and 40 mm) using a commercially available optical-CT scanner (OCTOPUS, MGS Research). The percent depth dose (PDD), beam profile and penumbra of the 10 mm field were also measured using a higher resolution in-house prototype CCD-based scanner. Gafchromic EBT film was used for independent verification. Measurements of Sc, p made with PRESAGE and film agreed with mini-ion chamber commissioning data to within 4% for every field (range 0.2-3.6% for PRESAGE, and 1.6-3.6% for EBT). PDD, beam profile and penumbra measurements made with the two PRESAGE/optical-CT systems and film showed good agreement with the high-resolution diode commissioning measurements with a competitive resolution (0.5 mm pixels). The in-house prototype optical-CT scanner allowed much finer resolution compared with previous applications of PRESAGE. The advantages of the PRESAGE system for small field dosimetry include 3D measurements, negligible volume averaging, directional insensitivity, an absence of beam perturbations, energy and dose rate independence.

Full Text

Duke Authors

Cited Authors

  • Clift, C; Thomas, A; Adamovics, J; Chang, Z; Das, I; Oldham, M

Published Date

  • March 7, 2010

Published In

Volume / Issue

  • 55 / 5

Start / End Page

  • 1279 - 1293

PubMed ID

  • 20134082

Pubmed Central ID

  • 20134082

Electronic International Standard Serial Number (EISSN)

  • 1361-6560

Digital Object Identifier (DOI)

  • 10.1088/0031-9155/55/5/002

Language

  • eng

Conference Location

  • England