Merck
  • Home
  • Search Results
  • First tests of a liquid ionization chamber to monitor intensity modulated radiation beams.

First tests of a liquid ionization chamber to monitor intensity modulated radiation beams.

Physics in medicine and biology (2003-12-05)
K Eberle, J Engler, G Hartmann, R Hofmann, J R Hörandel
ABSTRACT

First measurements with a prototype ionization chamber are described to be applied in online monitoring of modulated fields in radiation therapy. The liquids isooctane, isononane (TMP) and tetramethylsilane (TMS) are used in a high purity grade in order to realize high current signals for electronic read-out in parallel at frequencies exceeding 10 Hz. Signals of more than a factor 4 with respect to isooctane, analysis grade, are obtained. With an electrode structure of 400 pads, a uniformity in efficiency within 1.2% has been measured. The penumbra of a multileaf collimator could be resolved. Theoretical examination verifies that the free electrons in the liquids cause higher signals when the measured currents are compared with expectation for ion transport only.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Tetramethylsilane, ACS reagent, NMR grade, ≥99.9%
Sigma-Aldrich
Tetramethylsilane, electronic grade, ≥99.99% trace metals basis
Sigma-Aldrich
Tetramethylsilane, ≥99.0% (GC)
Supelco
Tetramethylsilane, analytical standard, for NMR spectroscopy, ACS reagent