Title :
Blurring and MTF determination of a radiotherapy EPID using the edge spread function
Author :
Franco, L. ; Gómez, F. ; Iglesias, A. ; Pardo, J. ; Pena, J. ; Lobato, R. ; Mosquera, J. ; Pombar, M. ; Sendón, J.R. ; Ledo, F. ; Yáñez, A.
Author_Institution :
Particle Phys. Dept., Santiago de Compostela Univ., Spain
Abstract :
We present a method based in the study of the edge spread function (ESF) obtained by using a solid metallic block image to measure the resolution of a radiotherapy EPID. With this simple method it is possible to determine the effective focal spot size of a LINAC, the intrinsic unsharpness of the portal imaging device and also its MTF response, which it is not usually tested in routine quality controls since an specific phantom is needed. Results for the spatial resolution are compared to those calculated with a bar phantom of the same material. This procedure can be implemented in the routine EPID quality control in the clinical practice. Measurements were made with the Beamview TI EPID of a Siemens Primus linac. A focal spot size of 1.057 and 1.484 mm (X, Y directions) and a f50 at isocenter of 0.272 and 0.304 lp/mm (X,Y directions) were obtained.
Keywords :
biological effects of radiation; linear accelerators; particle beam diagnostics; phantoms; radiation therapy; 1.057 mm; 1.484 mm; MTF response; Siemens Primus linac; edge spread function; effective focal spot size; electronic portal imaging device; phantom; radiotherapy; solid metallic block image; Hospitals; Image resolution; Imaging phantoms; Linear particle accelerator; Optical imaging; Pixel; Portals; Quality control; Solids; Testing;
Conference_Titel :
Nuclear Science Symposium Conference Record, 2004 IEEE
Print_ISBN :
0-7803-8700-7
DOI :
10.1109/NSSMIC.2004.1462793
