Performance of a 41×41 cm2 amorphous silicon flat panel x-ray detector designed for angiographic and R&F imaging applications
| Autor: | Zhong S. Huang, Richard Aufrichtig, Bing Ma, Paul R. Granfors, Brian William Giambattista, George Edward Possin, Jianqiang Liu |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Physics
Silicon Models Statistical business.industry X-Rays Detector Angiography X-ray detector Image intensifier Dose-Response Relationship Radiation General Medicine Flat panel detector law.invention Radiographic Image Enhancement Detective quantum efficiency Optics law Fluoroscopy Image Processing Computer-Assisted Radiographic Image Interpretation Computer-Assisted Nyquist frequency Image sensor business Digital radiography |
| Zdroj: | Medical Physics. 30:2715-2726 |
| ISSN: | 0094-2405 |
| DOI: | 10.1118/1.1609151 |
| Popis: | We measured the physical imaging performance of a 41×41 cm 2 amorphous silicon flat panel detector designed for angiographic and R&F imaging applications using methods from the emerging IEC standard for the measurement of detective quantum efficiency (DQE) in digital radiographicdetectors.Measurements on 12 production detectors demonstrate consistent performance. The mean DQE at the detector center is about 0.77 at zero frequency and 0.27 at the Nyquist frequency (2.5 cycles/mm) when measured with a 7 mm of Al HVL spectrum at about 3.6 μGy. The mean MTF at the center of the detector for this spectrum is 0.24 at the Nyquist frequency. For radiographic operation all 2048×2048 detector elements are read out individually. For fluoroscopy, the detector operates in two 30 frame per second modes: either the center 1024×1024 detector elements are read out or the entire detector is read out with 2×2 pixel binning. A model was developed to predict differences in performance between the modes, and measurements demonstrate agreement with the model. Lag was measured using a quasi-equilibrium exposure method and was found to be 0.044 in the first frame and less than 0.007 after 1 s. We demonstrated that it is possible to use the lag data to correct for temporal correlation in images when measuring DQE with a fluoroscopic imaging technique. Measurements as a function of position on the detector demonstrate a high degree of uniformity. We also characterized dependences on spectrum, exposure level, and direction. Finally, we measured the DQE of a current state of the art image intensifier/CCD system using the same method as for the flat panel. We found the image intensifier system to have lower DQE than the flat panel at high exposure levels and approximately equivalent DQE at fluoroscopic levels. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text