Quality of portal verification images using GLP7 film

Rationale and Objectives. To improve portal verification radiographs, we tested the application of GLP7 film. Methods. The quality of the portal verification radiograph using the XV cassette-GLP7 film combination and the XL cassette-GLP7 film combination was investigated. The XV cassette-XV2 film combination and the SA cassette-GS screen-XTL film combination also were used for comparison. Results. The characteristic curves showed that the relative speeds were 0.32 and 0.47 for the XV-GLP7 and XL-GLP7 combinations and that the average gradients were 1.93, 2.14, and 1.32 for the XV-GLP7, XL-GLP7, and XV-XV2 combinations, respectively. In the experiment using Burger's phantom, the smallest visible volumes were 11.8, 11.3, 28.7, and 19.6 mm 3 for the XV-GLP7, XL-GLP7, XV-XV2, and SA-GS-XTL combinations, respectively. In the lower dosage treatment in the clinic, there were no marked differences between the GLP7 film and XV2 film. However, in the higher dosage treatment, the GLP7 film had a better quality than did the XV2 film. Conclusion. Portal verification radiographs using GLP7 film are of sufficient quality for clinical use.