Linear response theory for detectors consisting of discrete arrays

Citation
M. Albert et Ada. Maidment, Linear response theory for detectors consisting of discrete arrays, MED PHYS, 27(10), 2000, pp. 2417-2434
Citations number
55
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Radiology ,Nuclear Medicine & Imaging","Medical Research Diagnosis & Treatment
Journal title
MEDICAL PHYSICS
ISSN journal
0094-2405 → ACNP
Volume
27
Issue
10
Year of publication
2000
Pages
2417 - 2434
Database
ISI
SICI code
0094-2405(200010)27:10<2417:LRTFDC>2.0.ZU;2-O
Abstract
The optical transfer function (OTF) and the noise power or Wiener spectrum are defined for detectors consisting of a lattice of discrete elements with the assumptions of linear response, Gaussian statistics, and stationarity under the discrete group of translations which leave the lattice fixed. For the idealized classification task of determining the presence or absence o f a signal under signal known exactly/background known exactly (SKE/BKE) co nditions, the Wiener spectrum, the OTF, along with an analog of the gray-sc ale transfer characteristic, determine the signal-to-noise ratio (SNR), whi ch quantifies the ability of an ideal observer to perform this task. While this result is similar to the established result for continuous detectors, such as screen-film systems, the theory of discrete lattices of detectors m ust take into account the fact that the lattice only supports a bounded but (in the limit of a detector of arbitrarily great extent) continuous range of frequencies. Incident signals with higher spatial frequencies appear in the data at lower aliased frequencies, and there are pairs of signals which are not distinguishable by the detector (the SNR vanishes for the task of distinguishing such signals). Further, the SNR will in general change if th e signal is spatially displaced by a fraction of the lattice spacing, altho ugh this change will be small for objects larger than a single pixel. Some of the trade-offs involved in detectors of this sort, particularly in deali ng with signal frequencies above those supported by the lattice, are studie d in a simple model. (C) 2000 American Association of Physicists in Medicin e. [S0094-2405(00)00908-1].