TITLE:
Technical Note: The Uses of I’mRT MatriXX in Electron Beams
AUTHORS:
Mutian Zhang, Sicong Li, Hua Deng, Sumin Zhou
KEYWORDS:
Electron Beam; MatriXX; Dosimetry; Quality Assurance
JOURNAL NAME:
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology,
Vol.2 No.1,
February
26,
2013
ABSTRACT: Purpose: The objective of this study is
to investigate the properties of I’mRT MatriXX device in electron beams, and to
validate MatriXX in electron dosimetry and quality assurance (QA). Methods: The measurements were
conducted using MatriXX in electron and photon beams from Siemens linacs. The
MatriXX was placed horizontally on the linac tabletop. Solid Water layers were
used for buildup. For all the measurements, the linac gantry angle was 0?, and
the source-to-surface distance was100 cmfrom the Solid Water surface. The electron cone factors, cutout factors, and
beam profiles were measured and compared with thimble ionization chamber
results. Results: The effective
water equivalent depth of MatriXX measurement point is larger than4 mm. When measuring at the respective depths
of maximum dose, MatriXX has different responses to different beam energies.
The cone factors measured by MatriXX are nearly identical or close to those
derived by ionization chambers. Beam profiles (flatness and symmetry) can be easily
determined using MatriXX and are comparable to water tank results. The planar
dose map of electron cutout blocks can be visually observed, and the cutout
factors can be conveniently measured. Conclusions: The MatriXX needs separate dose calibration factors for electron and photon
beams. MatriXX can be used to measure electron cutout factors and beam
profiles, thus has the potentials in electron beam dosimetry and routine linac
and patient-specific QA tests.