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P Wootton

Publications and source records attributed to P Wootton.

31 records · Page 2Linked to original sources
PubMedDate not supplied

Measurement of photon dose fraction in a neutron radiotherapy beam.

Photon dose fractions (PDFs) have been measured in and around a neutron radiotherapy beam with a tissue-equivalent proportional counter (TEPC) and with paired ion chambers. The PDFs were found to increase linearly with increasing field size and width depth in phantom. PDFs were shown to decrease with decreasing phantom size and to be larger in the shielded region of the phantom than in the direct beam. Uncertainties in the PDF values were estimated to be 10%-15% for the TEPC measurements but about 50% for the measurement made with ion chambers.

Elementary Particles↗
PubMedDate not supplied

Dosimetric properties of neutrons from 21-MeV deuteron bombardment of a deuterium gas target.

Spectra, yields, average energies, and kerma rates in tissue of neutrons from 21-MeV deuteron bombardment of deuterium gas targets have been calculated for target thicknesses of 1, 3.5, and 5 MeV. A high pressure gas cell was constructed and was filled with 33 atm of D2 gas (equivalent to an energy loss of 3.5 MeV for 21-MeV deuterons); dose rate, dose buildup, and depth-dose properties of neutrons produced by the D(d,n) reaction were measured. Dosimetric properties of these neutrons are superior to those of neutrons from a thick Be target bombarded by a deuteron beam of the same energy.

Fast Neutrons↗
PubMedDate not supplied

Uniformity in dosimetry protocols for therapeutic applications of fast neutron beams.

In this supplement to both the American and the European protocols for clinical neutron dosimetry, new recommendations are given with respect to the basic physical parameters and experimental techniques employed. For neutron dosimetry, the air kerma or exposure calibration in a photon beam is the most suitable method for the calibration of tissue-equivalent ionization chambers until calibration in a standard neutron field becomes available. More recent data are recommended for the physical parameters required for the photon calibration as well as for the measurements in the neutron beam. Water is recommended as the reference phantom material due to its similarity in absorption and scattering properties to muscle. The resulting overall change in absorbed dose calculated according to this supplement, compared with the original protocols, will be smaller than about +/- 2% due to differences in the basic physical parameters. An additional change of several percent occurs at depth in a phantom as a result of the difference between water and the muscle-equivalent liquid formerly recommended as the reference phantom material.

Fast Neutrons↗