Computed radiography versus mobile direct radiography for bedside chest radiographs: impact of dose on image quality and reader agreement

To asses the image quality and potential for dose reduction of mobile direct detector (DR) chest radiography as compared with computed radiography (CR) for intensive care unit (ICU) chest radiographs (CXR). Three groups of age-, weight- and disease-matched ICU patients (n=114 patients; 50 CXR per acquisition technique) underwent clinically indicated bedside CXR obtained with either CR (single read-out powder plates) or mobile DR (GOS-TFT detectors) at identical or 50% reduced dose (DR(50%)). Delineation of anatomic structures and devices used for patient monitoring, overall image quality and disease were scored by four readers. In 12 patients pairs of follow-up CR and DR images were available, and in 15 patients pairs of CR and DR(50%) images were available. In these pairs the overall image quality was also compared side-by-side. Delineation of anatomy in the mediastinum was scored better with DR or DR(50%) than with CR. Devices used for patient monitoring were seen best with DR, with DR(50%) being superior to CR. In the side-by-side comparison, the overall image quality of DR and DR(50%) was rated better than CR in 96% (46/48) and 87% (52/60), respectively. Inter-observer agreement for the assessment of pathology was fair for CR and DR(50%) (κ = 0.33 and κ = 0.39, respectively) and moderate for DR (κ = 0.48). Mobile DR units offer better image quality than CR for bedside chest radiography and allow for 50% dose reduction. Inter-observer agreement increases with image quality and is superior with DR, while DR(50%) and CR are comparable