Comparison of the new and the used imaging plates on computed radiography

Objective: To compare image quality and radiation dose of the new imaging plate (IP) with the used IP on computed radiography (CR), and to investigate the using principle in the two kinds of IP. Methods: The dark noise, uniformity and erasure thoroughness of the new and the used IP were measured respectively. Based on threshold contrast-detail detectability (TCCD) technique, the phantom TO, 16 photography was done at 75 kV, and with the two kinds of IP respectively. Three observers scored each image sequence using double blind method, calculated the threshold detection index (HT). The volunteers were randomly divided into three groups: the knee joint group, the chest group and the lumbar group. Each group had 50 cases and checked with the same condition as the phantom. Three radiologists using double blind method evaluated the imaging quality of knee joint, chest and lumbar. Results: The physical characteristic indexes of the new and the used IP were similar to each other. Under the same condition, the detection ability of the new IP was better than that of the used one. When the dose of exposure was raised about 20%, the detection ability of the used IP was close to that of the new one. Conclusions: The dose of exposure can be raised to keep the same imaging quality with the increase times of IP used. The detection ability of IP can decrease with the same dose as before, and the image quality decreases too. (authors)