Modeling the frequency-dependent detective quantum efficiency of photon-counting x-ray detectors.
Med Phys
; 45(1): 156-166, 2018 Jan.
Article
in En
| MEDLINE
| ID: mdl-29131361
ABSTRACT
PURPOSE:
To find a simple model for the frequency-dependent detective quantum efficiency (DQE) of photon-counting detectors in the low flux limit.METHODS:
Formula for the spatial cross-talk, the noise power spectrum and the DQE of a photon-counting detector working at a given threshold are derived. Parameters are probabilities for types of events like single counts in the central pixel, double counts in the central pixel and a neighboring pixel or single count in a neighboring pixel only. These probabilities can be derived in a simple model by extensive use of Monte Carlo techniques The Monte Carlo x-ray propagation program MOCASSIM is used to simulate the energy deposition from the x-rays in the detector material. A simple charge cloud model using Gaussian clouds of fixed width is used for the propagation of the electric charge generated by the primary interactions. Both stages are combined in a Monte Carlo simulation randomizing the location of impact which finally produces the required probabilities. The parameters of the charge cloud model are fitted to the spectral response to a polychromatic spectrum measured with our prototype detector.RESULTS:
Based on the Monte Carlo model, the DQE of photon-counting detectors as a function of spatial frequency is calculated for various pixel sizes, photon energies, and thresholds.CONCLUSION:
The frequency-dependent DQE of a photon-counting detector in the low flux limit can be described with an equation containing only a small set of probabilities as input. Estimates for the probabilities can be derived from a simple model of the detector physics.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Photons
/
Models, Theoretical
Type of study:
Clinical_trials
Language:
En
Journal:
Med Phys
Year:
2018
Document type:
Article
Affiliation country:
Germany