Rapid portal imaging with a high-efficiency, large field-of-view detector.
Med Phys
; 25(12): 2333-46, 1998 Dec.
Article
en En
| MEDLINE
| ID: mdl-9874825
The design, construction, and performance evaluation of an electronic portal imaging device (EPID) are described. The EPID has the same imaging geometry as the current mirror-based systems except for the x-ray detection stage, where a two-dimensional (2D) array of 1 cm thick CsI(Tl) detector elements are utilized. The approximately 18% x-ray quantum efficiency of the scintillation detector and its 30 x 40 cm2 field-of-view at the isocenter are greater than other area-imaging EPIDs. The imaging issues addressed are theoretical and measured signal-to-noise ratio, linearity of the imaging chain, influence of frame-summing on image quality and image calibration. Portal images of test objects and a humanoid phantom are used to measure the performance of the system. An image quality similar to the current devices is achieved but with a lower dose. With approximately 1 cGy dose delivered by a 6 MV beam, a 2 mm diam structure of 1.3% contrast and an 18 mm diam object of 0.125% contrast can be resolved without using image-enhancement methods. A spatial resolution of about 2 mm at the isocenter is demonstrated. The capability of the system to perform fast sequential imaging, synchronized with the radiation pulses, makes it suitable for patient motion studies and verification of intensity-modulated beams as well as its application in cone-beam megavoltage computed tomography.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Tecnología Radiológica
Límite:
Humans
Idioma:
En
Revista:
Med Phys
Año:
1998
Tipo del documento:
Article
País de afiliación:
Reino Unido
Pais de publicación:
Estados Unidos