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Electronic portal imaging with an avalanche‐multiplication‐based video camera
Author(s) -
Pang G.,
Rowlands J. A.
Publication year - 2000
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.598929
Subject(s) - detective quantum efficiency , optics , avalanche photodiode , noise (video) , image quality , computer science , physics , computer vision , detector , image (mathematics)
The aim of this study is to investigate the degree to which the imaging quality of an existing (video‐based) electronic portal imaging device (EPID) system may be improved by using an avalanche‐multiplication‐based video camera (called the avalanche‐gain method). Due to avalanche multiplication in the target of the video camera tube, the new camera can be made up to several hundred times more sensitive than a camera using a conventional video (e.g., Saticon) tube. As a result, the camera noise which limits the performance of current video‐based EPIDs should be overwhelmed and made negligible. The detective quantum efficiency (DQE) of an EPID using the avalanche‐gain method has been measured with 6 MV and 18 MV beams obtained using a linear accelerator. It is shown that the camera noise is indeed much smaller than quantum noise and that the DQE of the system is significantly increased compared to conventional video‐based EPIDs. Variation of DQE of the avalanche‐gain video portal system with a change of demagnification was also investigated. It has been shown that the improvement of optical coupling has less effect in this system than that in a conventional video‐based EPID system.