Experimental determination of the modulation transfer function for high quantum efficiency electronic portal imaging detectors.
Published: 2004
Language: eng
Number of pages: 61
Description: Increasing the quantum efficiency, eta, of electronic portal imaging detectors (EPIDs) will enable the use of cone-beam megavoltage CT (MVCT) for image-guidance of radiotherapy by lowering dose requirements to obtain soft tissue contrast. As eta is increased the interaction of scattered photons within the detector causes signal blur, potentially limiting useful improvements in eta. An experimental model was developed to measure the expected modulation transfer function, MTF, for a large range of high-eta detectors without requiring a priori development of a detector prototype. For the range of eta studied, 0.02--0.86, the MTF does not drop considerably from the initial MTF. Measurements using both medium and high density build-up layers demonstrated that blur due to photon scatter is not greatly dependent on the material used to construct a high-eta EPID. Therefore, resolution in a high-eta EPID is not constrained by photon blur, and development of a high-eta EPID looks promising.
Notes: Adviser:  John Rowlands.

Thesis (M.Sc.)--University of Toronto, 2004.

Electronic version licensed for access by U. of T. users.

Source: Masters Abstracts International, Volume: 42-06, page: 2129.

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