Physics – Optics
Scientific paper
Jul 1997
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997spie.3115..323r&link_type=abstract
Proc. SPIE Vol. 3115, p. 323-333, Hard X-Ray and Gamma-Ray Detector Physics, Optics, and Applications, Richard B. Hoover; F. Pat
Physics
Optics
Scientific paper
This paper provides a comparison of imaging parameters of two portal imaging systems at 6 MV: a flat panel detector and a CCD-camera based portal imaging system. Measurements were made of the signal and noise and consequently of signal-to-noise per pixel as a function of the exposure. Both systems have a linear response with respect to exposure, and the noise is proportional to the square-root of the exposure, indicating photon-noise limitation. The flat-panel detector has a signal- to-noise ratio, which is higher than that observed wit the CCD-camera based portal imaging system. This is expected because most portal imaging systems using optical coupling with a lens exhibit severe quantum-sinks. The paper also presents data on the screen's photon gain (the number of light-photons per interacting x-ray photon), as well as on the magnitude of the Swank-noise, (which describes fluctuation in the screen's photon gain). Images of a Las Vegas-type aluminum contrast detail phantom, located at the ISO-Center, were generated at an exposure of 1 MU. The CCD-camera based system permits detection of aluminum-holes of 0.01194 cm diameter and 0.228 mm depth while the flat-panel detector permits detection of aluminum holes of 0.01194 cm diameter and 0.1626 mm depth, indicating a better signal-to-noise ratio. Rank order filtering was applied to the raw images from the CCD-based system in order to remove the direct hits. These are camera responses to scattered x-ray photons which interact directly with the CCD of the CCD-camera and generate 'salt and pepper type noise,' which interferes severely with attempts to determine accurate estimates of the image noise.
Cheng Chee-Wai
Dallas William J.
Roehrig Hans
Tang Chuankun
No associations
LandOfFree
Portal imaging with flat-panel detector and CCD camera does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Portal imaging with flat-panel detector and CCD camera, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Portal imaging with flat-panel detector and CCD camera will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1417652