Evaluation of XD/A Plus and ST8G films for cephalometric radiography with Grenex G8 and BH-III screens

Abstract Objectives. Sensitometric properties, clinical image quality, and patient dose requirements are important considerations when selecting film for cephalometrics. Two recently released films, XD/A Plus and ST 8G green sensitive films, were studied. Methods. The films were each combined with Grenex G8 (Fuji Medical) green-fluorescing matched and BH-III (Kasei Optonix) blue-fluorescing mismatched intensifying screens. The density response and resolution for each screen-film combination were evaluated by use of the characteristic curve and modulation transfer function. The kilovoltage settings providing clinically acceptable images were assessed individually by 12 observers. Clinically acceptable images for each combination were also compared, and the skin entrance doses in the temporomandibular joint region were determined. Results. The average contrast at the most effective density range was found to be slightly higher for the BH-III group than for the G8 group. The modulation transfer function for the BH-III group was inferior to that for the G8 screens. There were no significant differences in diagnostically acceptable image quality among the four combinations; nevertheless the BH-III screen group required two to three times more exposure than the G8 screen group. Conclusions. XD/A Plus and ST8G films provide acceptable image detail for cephalometrics. To minimize the patient dose they should be used with green-emitting screens.