John F. Hamilton

A Free Response Approach To The Measurement And Characterization Of Radiographic Observer Performance

Radiographic signal detection is considered to be a point process. Realism of radio-graphic signal detection experiments is extended by allowing a random number of signals and by requiring accurate location of the signals. A substantial improvement in the simplicity of the theoretical framework of multiple signal detection experiments results from using this free response approach. The generation of false positive events is adequately described as a Poisson process, represented by a single measurable parameter. A scheme for reinterpretation of earlier conventional Receiver Operating Characteristic (ROC) curves in terms of the free response approach is presented, and a description of a much simpler and more efficient experimental procedure is provided.

Principles Governing The Transfer Of Signal Modulation And Photon Noise By Amplifying And Scattering Mechanisms

A general analysis is made of the influence of stochastic amplifying and scattering mechanisms on the transfer of signal modulation and photon noise in imaging processes. In this way we quantify the spatial-frequency dependence of signal and noise as they propagate through a multistage imaging system. Whereas by definition the signal structure (or modulation) is transferred via the MTF, the input photon noise is effectively unmodulated signal and as such bypasses the MTF. However, stochastic amplification of photon noise by one stage of an imaging process may produce noise structure that constitutes an effective signal spectrum to the next. Thus, in general, it is necessary to cascade these two components of the noise spectrum separately at each stage.