| Zugriffsnummer | 33733 |
| Dokumenttyp | Zeitschriftenartikel |
| Sprache | Englisch |
| Titel | W values and radial dose distributions for protons in TE-gas and air at energies up to 500 MeV |
| Autor(in); Institution |
Großwendt, Bernd; 6.24, Strahlungstransportgrößen, PTB-Braunschweig
Baek, Woon Yong; 6.24, Strahlungstransportgrößen, PTB-Braunschweig
|
| Quelle/Jahr | Physics in Medicine and Biology: 43 (1998), 2, 325 - 337 |
| ISSN | 0031-9155 (PRINT) ; 1361-6560 (ONLINE) |
| DOI | |
| Verlag | Bristol: IOP Publ. |
| Klassifikationscode | PACS: 87.53.Bn ; PACS: 87.56.Da |
| Freie Schlagworte | medical physics |
| Zusammenfassung | The dosimetry of charged-particle beams is frequently performed by measuring the ionization yield produced in gas-filled ionization chambers and converting it into absorbed dose using the mean energy W expended in a gas per ion pair formed, or its differential value ω for the filling gas. Because of the increasing importance of proton therapy and the lack of accurate values of W and ω at high proton energies in particular, we investigated the ionization yield formation by protons in air and methane-based tissue-equivalent gas in the energy range up to 500 MeV. For this purpose, we analysed the available experimental values of W and ω and, in a second step, investigated the ionization-yield formation by protons as a function of their initial energy using an analytical method based on the Spencer-Fano equation in the framework of the continuous-slowing-down approximation. To estimate possible ionization losses which can be expected if the ionometric method is applied in the case of an incomplete secondary-electron equilibrium, a new analytical model has been developed which can be used to calculate the radial distribution of the ionization yield produced by secondary electrons around high-energy proton tracks. |
