PubMed Health⌕ Search

Biomedical subjects

J Booz

Publications and source records attributed to J Booz.

34 records · Page 2Linked to original sources
PubMed1981

Microdosimetric investigations on collimated fast neutron beams for radiation therapy: II. The problem of radiation quality and RBE.

The correlation between radiation quality and cellular RBE of a mixed n-gamma field produced by a collimated fast-neutron beam produced by the bombardment of 14 MeV deuterons on Be in a water phantom is investigated. The microdosimetric parameters yF and YD are used for a physical description of the local distribution of radiation components. On the basis of the dose fractions of these components, the dependence of RBE on depth is calculated and is compared with experimental RBE data. Outside the beam centre, it is shown that the microdosimetric parameter y can be used for estimates of local changes of RBE, if particular conditions for the absorbed dose and for the range of neutron energies are met. The spatial distributions of y for the mixed radiation changes in RBE for equal absorbed doses of 1 Gy are at maximum 10% and thus perhaps negligible.

Cells, Cultured↗
PubMed1978

Local distribution of energy deposition in and around the follicles of a 125I contaminated thyroid.

Iodine-125, which is used for the clinical diagnosis of the thyroid gland, has a high probability of decay by K-capture followed by the emission of low-energy electrons having ranges of up to 23 micrometer. Thus one has high local concentrations of energy deposition comparable in size to that of the smaller follicles. In this paper the local distribution of energy deposition inside and outside the follicles of the human thyroid gland is calculated for follicle sizes of 20--400 micrometer. Also the local dose rate at the position of the nuclei of the follicle cells is determined as a function of the follicle size. Possible dosimetric approaches to the problem of radiobiological effectiveness are discussed, at first in general and then for the example of the inactivation of follicle cells due to the incorporation of 125I.

Electrons↗
PubMed1976

The influence of the counter wall and the counter shape on the spectral energy deposition in small volumes by 60Co gamma-rays and 200 kV x-rays.

The spectral energy deposition in small volumes by 60Co gamma-rays and by 200 kV X-rays was measured with a walled spherical counter, a walled cylindrical counter and a wall-less cylindrical counter. The simulated volumes had dimensions of 0.1--3 mum. By comparing the spectra of the spherical and cylindrical walled counters the influence of the counter shape is derived. The wall effect is discussed by comparing the spectra and the mean lineal energy measured with the walled and the wall-less cylindrical counters. The influence of the counter size and of radiation quality on the energy deposition spectra is also analysed.

Cobalt Radioisotopes↗
PubMed1975

Neutron scattering and energy deposition spectra.

The influence of neutron scattering in the wall of a spherical proportional counter on the energy deposition spectra and the absorbed dose is investigated. Event probabilities, and frequency and dose-averaged deposited energies are calculated with and without scattering contribution and compared. The change of absorbed dose due to attenuation of the primary neutron flux is also evaluated.

Neutrons↗