Can volumetric modulated arc therapy with flattening filter free beams play a role in stereotactic body radiotherapy for liver lesions? A volume-based analysis
(a) Ratio of conformity indexes calculated for dose distributions obtained for FF and FFF beams plotted with PTV volume; a CI > 100 means better conformation for FFF plans, vice versa for CI < 100. (b) and (c) FF/FFF ratio for HT and healthy liver mean doses. (d) FF/FFF homogeneity index 5%–95% for CTV and PTV plotted against PTV volume.
Ratio of FF and FFF plans for PTV conformity indexes: (a) Healthy tissue and healthy liver mean doses (b) and (c) and CTV and PTV homogeneity indexes (d) plotted against PTV volume. The ten patients considered in phase 2 were stratified in three groups according to the PTV volume.
Summary of the results obtained in phase 1 for the twelve fictitious targets drawn. For each target, the values of all the parameters analyzed are reported for both FF and FFF beams. In the last two columns, the great beam-on time differences can be observed. The two bottom lines report, for each parameter, the mean value and SD over all the volumes, the only BOT shows statistically significant differences between FF and FFF beams (normal distribution verified with Kolmogorov–Smirnov test and p-value evaluated with paired Student’s t-test).
Summary of the results obtained in phase 2 for the ten patients considered stratified in three groups according to the PTV volume. For each group, the values of all the parameters analyzed are reported for both FF and FFF beams. The results regarding OARs have great fluctuations due to the different anatomical locations of the targets. As in phase 1, BOT shows statistically significant differences.
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