Dose distribution of oblique incidence electron beam
- VernacularTitle:电子线斜入射对剂量分布影响的分析
- Author:
Zhihua LI
- Publication Type:Journal Article
- Keywords:
Electron beam;
Oblique incidence;
Dose distribution
- From:
Chinese Journal of Radiation Oncology
1992;0(01):-
- CountryChina
- Language:Chinese
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Abstract:
ObjectiveTo analyze the dose distribution of oblique incidence electron beam. MethodsIn water phantom,the relative dose values were measured along the central axis of electron beam. The slope angles of 80% and 50% isodose lines were measured in the penumbra area. All these measured data were compared with those without oblique angle. Results1. When the oblique incidence angle of electron beam increased,the depth of the maximal dose and the isodose lines of 90%,80%,50% and 10% decreased. 2.The higher the beam energy ,the greater the depth of maximal dose and the isodose lines of 90%,80%,50% and 10%. 3.The effect of oblique incidence was also related to field size. When the beam size increased,the depth of maximal dose and the isodose lines of 90%,80%,50% and 10% decreased. 4. For the same oblique incidence angle,the effect of electron energy is more obvious than that of beam size. 5. Because of the oblique incidence of electron beam,the 80% and 50% isodose lines in the penumbral area would slope up to the direction with air gap and the slope angle was wider than the oblique incidence angle of the electron beam. Conclusions The oblique incidence of electron beam not only reduces the depth of maximum ionization,but also weakens the transmissive ability of electron beam. The weakening extent of the transmissive ability is related to electron energy and field size. In the oblique incidence,the movement of 80% and 50% isodose lines in horizontal direction should be noted,otherwise the dose of some tumor will be very low.
