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Therapy imaging: a signal-to-noise analysis of metal plate/film detectors

Journal Article · · Med. Phys.; (United States)
DOI:https://doi.org/10.1118/1.596114· OSTI ID:5414727
We have measured the modulation transfer functions (MTF (f)'s) and the noise power spectra (NPS (f)) of therapy x-ray detectors irradiated by /sup 60/Co, 6- and 18-MV radiotherapy beams. Using these quantities, we have calculated the noise-equivalent quanta (NEQ (f)) and the detective quantum efficiency (DQE (f)) to quantitate the limitations of therapy detectors. The detectors consisted of film or fluorescent screen-film combinations in contact with copper, lead, or tungsten metal plates. The resolution of the detectors was found to be comparable to fluorescent screen-film combinations used in diagnostic radiology, however, the signal-to-noise ratio (SNR (f)) of the detectors was limited due to film granularity. We conclude that improved images can be obtained by using alternative detector systems which have less noise or film granularity.
Research Organization:
Univ. of Toronto, Ontario
OSTI ID:
5414727
Journal Information:
Med. Phys.; (United States), Journal Name: Med. Phys.; (United States) Vol. 14:6; ISSN MPHYA
Country of Publication:
United States
Language:
English