RECOMBINATION CHAMBERS-DO THE OLD IDEAS REMAIN USEFUL?

Recombination methods were invented almost contemporaneously with the introduction of the ICRU/ICRP concept of a radiation quality factor expressed in terms of linear energy transfer. Since then, recombination chambers and related methodologies have been extensively developed, along with new concepts of dosimetry and radiation protection. This article briefly presents the main features of recombination chambers and their possible applications in practical systems for measuring dosimetric quantities.

INVESTIGATION OF SECONDARY MIXED RADIATION FIELD AROUND A MEDICAL LINEAR ACCELERATOR.

The aim of this study is to investigate secondary mixed radiation field around linac, as the first part of an overall assessment of out-of-field contribution of neutron dose for new advanced radiation dose delivery techniques. All measurements were performed around Varian Clinic 2300 C/D accelerator at Maria Sklodowska-Curie Memorial, Cancer Center and Institute of Oncology, Krakow Branch. Recombination chambers REM-2 and GW2 were used for recombination index of radiation quality Q4 determination (as an estimate of quality factor Q), measurement of total tissue dose Dt and calculation of gamma and neutron components to Dt.

Uncertainties in determination of 131I activity in thyroid gland.

The values of the iodine 131I uptake determined from the measurements with a NaI scintillation counter might be significantly influenced by the thyroid position in the human neck. It is shown that the ratio of the counting rate in the energy peak of 364 keV to the counting rate in the Compton scattering band can be used for the determination of the effective depth of the thyroid. The uncertainties of the standard method are discussed basing on results of calibration measurements.

Standard fields of old neutron sources--parameters and traceability.

Standard neutron fields of isotope neutron sources, established in the Institute of Atomic Energy, Poland, have been examined for nearly 20 y. The neutron dose equivalent and gamma dose rates were measured, applying various techniques. The neutron emission of standard neutron sources of 241Am-Be and 252Cf has been originally determined in primary standard laboratory, then checked, making use of transfer instrument calibrated in primary laboratory.