Investigation and Improvement of Film Radiography Speed for Non-Destructive Inspection of Industrial Specimens

Abstract

Film radiography is still used extensively in industry even the image recording efficiency of film is as low as <1% and is much lower at high energy range. The imaging plate (IP) is >10 times more sensitive than the conventional screen-film technique but its image reader and the imaging plate are relatively high costly. Fading of the image data on the IP is also a problem. This research emphasizes on improvement of the screen-film speed to reduce the exposure time by using the new PI-200 gadolinium oxysulfide (GOS) fluorescent screen. By using the PI-200 screens, the intensifying factors (IF) were found to be approximately 33.6, 39.0 and 61.3 for 100, 130 and 160 kVp x-rays while the IF’s of the conventional lead screens were approximately 2.8, 3.4 and 4.0, respectively. The IF’s for ¹⁹²Ir and ⁶⁰Co gamma rays were found to be approximately 13.7 and 7.3 while the IF’s of the conventional lead screens were approximately 5.8 and 1.4, respectively. The PI-200 screen thus could increase the speed of the conventional lead screen-film by at least 2 times depending on photon energy. Moreover, the sensitivity of the radiograph obtained from the PI-200 was comparable to those obtained from the conventional lead screen film technique. It was also found that the image quality could significantly improve by using lead filter to absorb the scattered gamma rays at low energy range particularly when the specimens contained light elements such as concrete.