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

Corey Clift, Andrew Thomas, John Adamovics, Zheng Chang, Indra Das, Mark Oldham

Research output: Contribution to journalArticle

46 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1279-1293
Number of pages15
JournalPhysics in Medicine and Biology
Issue number5
StatePublished - 2010

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging

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