The study of mechanical movement displacement for three amorphous silicon electronic portal imaging devices
10.3760/cma.j.issn.1004-4221.2013.01.023
- VernacularTitle:电子射野影像装置机械运动的位置误差研究
- Author:
Guanghua JIN
;
Junhan ZHU
;
Hailei LIN
;
Xiaowu DENG
;
Lixin CHEN
- Publication Type:Journal Article
- Keywords:
Relative displacement;
Electronic portal imaging device;
Gantry angle
- From:
Chinese Journal of Radiation Oncology
2013;(1):76-79
- CountryChina
- Language:Chinese
-
Abstract:
Objective To study corrective method for displacement in the procedure of electronic portal imaging device (EPID)-based intensity-modulated radiotherapy dose valuation by studying the relative mechanical displacement of different vendor EPID (aS1000,Varian; aS500,Varian; iViewGT,Elekta).Methods A 5 cm × 5 cm field was set up to acquire portal images for three kinds of EPID,then a in house software was used to analysis the portal images.The relative displacement was acquired via analyzing a series of comparation between center positions of gantry angle ranging from 0° to 360° and gantry angle at 0°.Results In the lateral direction,the maximum relative displacement of EPID with aS1000,S500 and iViewGT were (-0.23 ±0.17) mm,(2.94±0.17) mm and (0.35 ±0.09) mm,respectively.In the longitude direction,the displacements were (-4.16 ± 0.20) mm,(-4.15 ± 0.25) mm and (-1.66 ±0.11) mm,respectively.As to longitude direction,the displacements could be well fitted with the usage of quadruplicate empiric function.Conclusions There is a significant difference at the aspect of relative displacement between different vendors EPID at different gantry angles.And the displacement in the longitude direction is obviously larger than in the lateral direction.The relative displacement should be corrected when applying EPID to the intensity-modulated radiotherapy dose verification at different gantry angles.
