Image quality evaluation of a desktop computed radiography system

The modulation transfer function (MTF), noise power spectrum (NPS), and det ective quantum efficiency (DQE) of the Lumisys ACR-2000 desktop computed ra diography (CR) reader were measured and compared to equivalent measurements acquired from a Fuji AC-3 CR system. The one-dimensional (1D) MTF was meas ured from an image of a sharp edge and the 1D NPS was derived from a 2D NPS measured from a uniform field exposure. The energy dependent ideal input s ignal to noise ratio of the incident x-ray beams was estimated using publis hed x-ray spectra and attenuation coefficients. Measurements were acquired using Agfa, Fuji, and Kodak storage phosphor plates and it was concluded th at use of the Fuji plates resulted in the highest system DQE for the ACR-20 00. The DQE was measured using exposures of 0.10, 1.0, and 10.0 mR from 70 and 120 kVp x-ray beams filtered with aluminum. The DQE of the Lumisys ACR- 2000 was lower than that of the Fuji AC-3. (C) 2000 American Association of Physicists in Medicine. [S0094-2405(00)01112-3].