Commissioning and quality assurance for Mlc-Based IMRT

Cheng B. Saw, Komanduri M. Avyangar, Weining Zhen, Robert B. Thompson, Charles A. Enke

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

The commissioning and quality assurance (QA) associated with the implementation of linear accelerator multileaf collimator (MLC)-based intensity-modulated radiation therapy (IMRT) at the University of Nebraska Medical Center are described. Our MLC-based IMRT is implemented using the PRIMUS linear accelerator interface through the IMPAC record and verification system to the CORVUS treatment planning system. The 'step-and-shoot' technique is used for this MLC-based IMRT.Commissioning process requires the verification of predefined parameters available on the CORVUS and the collection of some machine data. The machine data required are output factor in air and output factor in phantom, and percent depth dose for a number of field sizes. In addition, inplane and crossplane dose profiles of 4 × 4 cm and 20 × 20 cm field sizes and diagonal dose profiles of a large field size have to be measured. Validation of connectivity and dose model includes the use of uniform intensity bar strips, triangular-shaped nonuniform intensity bar strip, and N-shaped target.QA procedure follows the recommendation of the AAPM Task Group No. 40 report. In addition, the leaf position accuracy and reproducibility of the MLC should be checked at regular intervals. The dose validation is implemented through the hybrid plan where the patient beam parameters are applied to a flat phantom. Independent dose calculation method is used to confirm the dose delivery plan and data input to the CORVUS.

Original languageEnglish (US)
Pages (from-to)125-133
Number of pages9
JournalMedical Dosimetry
Volume26
Issue number2
DOIs
StatePublished - 2001

Keywords

  • Commissioning
  • IMRT
  • Intensity
  • MLC
  • Photon beam
  • Quality assurance
  • modulation

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Oncology
  • Radiology Nuclear Medicine and imaging

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