Characterization of two generations of digital detectors in a radiography system: Technical image quality metrics, low-contrast detectability, and visual grading analysis

Characterize and compare the performance of different generations of digital detectors in the Discovery XR656 Plus and HD systems (GE Healthcare) for a chest imaging protocol. An older digital detector (FlashPad) was replaced with a newer model (FlashPad HD), featuring higher pixel resolution and, according to vendor specifications, improved detective quantum efficiency (DQE). To evaluate its performance, three studies were conducted focusing on a chest imaging protocol: DQE measurements using a commercial meter following IEC 62220-1:2003, CDRAD phantom evaluation (Artinis Medical Systems) assessed via the image quality factor (IQFinv), and a visual grading study using the LUNGMAN anthropomorphic phantom (Kyoto Kagaku), scored across eight criteria by four radiologists. FlashPad HD outperformed the older model on all metrics, showing an approximate 15 % increase in DQE (0), a 70 % increase in IQFinv, and superior visual grading for all criteria. A weak dependence on dose level was observed in the CDRAD study, and dose dependence was statistically significant only for two of the eight visual grading criteria. DQE (0) measurements were lower for the 120 kV tube potential than for the 70 kV: 0.47 vs. 0.73 for FlashPad and 0.54 vs. 0.86 for FlashPad HD. The advantage of FlashPad HD in efficiency (DQE) was increased at higher spatial frequencies. Two generations of digital detectors were well characterized based on technical metrics and phantom studies, and the effects of smaller pixel size and improved detector efficiency were verified. The newer FlashPad HD outperforms the older FlashPad receptor on all metrics investigated.