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L O Mattsson

Publications and source records attributed to L O Mattsson.

5 recordsLinked to original sources
PubMed1984

Charge build-up effects in insulating phantom materials.

When a medium is irradiated with electrons, electric charges are injected into the medium. If this is an electric insulator and its extension in the beam direction is larger than the electron range, the electrons are trapped inside the medium. In this work the influence on the ionization chamber dosimetry of the charge trapping in insulating phantom materials, such as polystyrene and polymethylmethacrylate (PMMA), has been investigated. It has been shown that the electron fluence inside a cylindric ionization chamber used in these materials increases when the number of electrons trapped in the phantom increases. The influence of various parameters, such as electron energy, accumulated absorbed dose, type and purity of the phantom material, radiation induced conductivity and ionization chamber construction are discussed. The effect can cause errors of several per cent in the dosimetry. We conclude, in agreement with the conclusion of GALBRAITH et coll., that insulating phantom materials should therefore be avoided in electron beam dosimetry.

Electricity↗
PubMed1982

Dosimetric intercomparison at the Scandinavian radiation therapy centres. I. Absorbed dose intercomparison.

A dosimetric intercomparison was carried out at all the centres in Denmark, Norway and Sweden. All the beam qualities (except conventional roentgen rays) used in radiation therapy were investigated. The ratio of the absorbed dose measured by us to that stated by the centre was determined. The mean ratio and standard deviation with the reference field-size were for 60Co gamma beams 1.001 +/- 0.014, for roentgen ray beams (4-45 MV) 1.017 +/- 0.023, electron beams with energy E0 less than 10 MeV 0.989 +/- 0.027, and electron beams with energy E0 greater than or equal to 10 MeV 0.996 +/- 0.034. The difference between the highest and lowest ratios was 17.8 per cent. A systematic difference due to the application of different protocols (NACP 1972 and 1980) was found.

Denmark↗
PubMed1982

Ferrous sulphate dosimeter for control of ionization chamber dosimetry of electron and 60Co gamma beams.

A check of the dosimetry using ionization chambers and applying the procedures described in the Nordic dosimetry protocols (NACP 1980, 1981) was carried out using the ferrous sulphate dosimeter as reference. Measurements have been carried out in electron beams in the energy range 2.8 to 27.5 MeV and in 60Co gamma beams. Consistent results were obtained with the two systems within about one per cent. Larger differences were only observed in electron beams containing a large proportion of scattered low energy electrons and contaminating roentgen rays which were not corrected for in the ionization chamber method.

Cobalt Radioisotopes↗
PubMed1981

Calibration and use of plane-parallel ionization chambers for the determination of absorbed dose in electron beams.

The dosimetry procedures to be used at electron energies, E0, below 15 MeV in order to determine absorbed dose to water with an ionization chamber have been investigated. The performance of different types of plane parallel ionization chambers was tested. A chamber suitable for use in accordance with the Nordic dosimetry recommendations was designed. Correction factors to be applied in order to use solid phantom materials instead of water were determined.

Electrons↗