Rationale and Objectives. To improve portal verification radiographs,
we tested the application of GLP7 film. Methods. The quality of the po
rtal verification radiograph using the XV cassette-GLP7 film combinati
on and the XL cassette-GLP7 film combination was investigated, The XV
cassette-XV2 film combination and the SA cassette-GS screen-XTL film c
ombination also were used for comparison. Results. The characteristic
curves showed that the relative speeds were 0.32 and 0.47 for the XV-G
LP7 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, resp
ectively. In the experiment using Burger's phantom, the smallest visib
le volumes were 11.8, 11.3, 28.7, and 19.6 mm(3) for the XV-GLP7, XL-G
LP7, XV-XV2, and SA-GS-XTL combinations, respectively. In the lower do
sage 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 qual
ity for clinical use.