### Abstract

Purpose: A simplified linear model approach was proposed to accurately model the response of a flat panel detector used for breast CT (bCT). Methods: Individual detector pixel mean and variance were measured from bCT projection images acquired both in air and with a polyethylene cylinder, with the detector operating in both fixed low gain and dynamic gain mode. Once the coefficients of the linear model are determined, the fractional additive noise can be used as a quantitative metric to evaluate the system's efficiency in utilizing x-ray photons, including the performance of different gain modes of the detector. Results: Fractional additive noise increases as the object thickness increases or as the radiation dose to the detector decreases. For bCT scan techniques on the UC Davis prototype scanner (80 kVp, 500 views total, 30 frames/s), in the low gain mode, additive noise contributes 21% of the total pixel noise variance for a 10 cm object and 44% for a 17 cm object. With the dynamic gain mode, additive noise only represents approximately 2.6% of the total pixel noise variance for a 10 cm object and 7.3% for a 17 cm object. Conclusions: The existence of the signal-independent additive noise is the primary cause for a quadratic relationship between bCT noise variance and the inverse of radiation dose at the detector. With the knowledge of the additive noise contribution to experimentally acquired images, system modifications can be made to reduce the impact of additive noise and improve the quantum noise efficiency of the bCT system.

Original language | English (US) |
---|---|

Pages (from-to) | 3527-3537 |

Number of pages | 11 |

Journal | Medical Physics |

Volume | 37 |

Issue number | 7 |

DOIs | |

State | Published - Jul 2010 |

### Fingerprint

### Keywords

- additive noise
- computerized tomography (CT)
- cone-beam
- flat panel detector
- noise variance

### ASJC Scopus subject areas

- Biophysics
- Radiology Nuclear Medicine and imaging
- Medicine(all)

### Cite this

*Medical Physics*,

*37*(7), 3527-3537. https://doi.org/10.1118/1.3447720

**Noise variance analysis using a flat panel x-ray detector : A method for additive noise assessment with application to breast CT applications.** / Yang, Kai; Huang, Shih Ying; Packard, Nathan J.; Boone, John M.

Research output: Contribution to journal › Article

*Medical Physics*, vol. 37, no. 7, pp. 3527-3537. https://doi.org/10.1118/1.3447720

}

TY - JOUR

T1 - Noise variance analysis using a flat panel x-ray detector

T2 - A method for additive noise assessment with application to breast CT applications

AU - Yang, Kai

AU - Huang, Shih Ying

AU - Packard, Nathan J.

AU - Boone, John M

PY - 2010/7

Y1 - 2010/7

N2 - Purpose: A simplified linear model approach was proposed to accurately model the response of a flat panel detector used for breast CT (bCT). Methods: Individual detector pixel mean and variance were measured from bCT projection images acquired both in air and with a polyethylene cylinder, with the detector operating in both fixed low gain and dynamic gain mode. Once the coefficients of the linear model are determined, the fractional additive noise can be used as a quantitative metric to evaluate the system's efficiency in utilizing x-ray photons, including the performance of different gain modes of the detector. Results: Fractional additive noise increases as the object thickness increases or as the radiation dose to the detector decreases. For bCT scan techniques on the UC Davis prototype scanner (80 kVp, 500 views total, 30 frames/s), in the low gain mode, additive noise contributes 21% of the total pixel noise variance for a 10 cm object and 44% for a 17 cm object. With the dynamic gain mode, additive noise only represents approximately 2.6% of the total pixel noise variance for a 10 cm object and 7.3% for a 17 cm object. Conclusions: The existence of the signal-independent additive noise is the primary cause for a quadratic relationship between bCT noise variance and the inverse of radiation dose at the detector. With the knowledge of the additive noise contribution to experimentally acquired images, system modifications can be made to reduce the impact of additive noise and improve the quantum noise efficiency of the bCT system.

AB - Purpose: A simplified linear model approach was proposed to accurately model the response of a flat panel detector used for breast CT (bCT). Methods: Individual detector pixel mean and variance were measured from bCT projection images acquired both in air and with a polyethylene cylinder, with the detector operating in both fixed low gain and dynamic gain mode. Once the coefficients of the linear model are determined, the fractional additive noise can be used as a quantitative metric to evaluate the system's efficiency in utilizing x-ray photons, including the performance of different gain modes of the detector. Results: Fractional additive noise increases as the object thickness increases or as the radiation dose to the detector decreases. For bCT scan techniques on the UC Davis prototype scanner (80 kVp, 500 views total, 30 frames/s), in the low gain mode, additive noise contributes 21% of the total pixel noise variance for a 10 cm object and 44% for a 17 cm object. With the dynamic gain mode, additive noise only represents approximately 2.6% of the total pixel noise variance for a 10 cm object and 7.3% for a 17 cm object. Conclusions: The existence of the signal-independent additive noise is the primary cause for a quadratic relationship between bCT noise variance and the inverse of radiation dose at the detector. With the knowledge of the additive noise contribution to experimentally acquired images, system modifications can be made to reduce the impact of additive noise and improve the quantum noise efficiency of the bCT system.

KW - additive noise

KW - computerized tomography (CT)

KW - cone-beam

KW - flat panel detector

KW - noise variance

UR - http://www.scopus.com/inward/record.url?scp=77954751918&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77954751918&partnerID=8YFLogxK

U2 - 10.1118/1.3447720

DO - 10.1118/1.3447720

M3 - Article

VL - 37

SP - 3527

EP - 3537

JO - Medical Physics

JF - Medical Physics

SN - 0094-2405

IS - 7

ER -