Fig 1.
Axial slices of the ArcCHECK CT phantom with the target, adjacent organ at risk (OAR), and peripheral OAR (a). Five portals were used for the planning to cover 95% of the target volume with the prescribed dose. The beam angles were 0°, 72°, 144°, 216° and 288° (b).
Table 1.
Volumes of the target, adjacent organ at risk (OAR) and peripheral OAR with respect to target size.
Table 2.
Comparison of dose deviations (%) among treatment planning system (TPS)-planned dose, ion-chamber measured isocenter dose, and the 3DVH-predicted isocenter dose.
Fig 2.
The dose deviation of the isocenter between the 3DVH-predicted dose and the treatment planning system (TPS)-planned dose is plotted as a solid line.
The dashed line represents the dose deviation between the ion-chamber measured isocenter dose and planned dose. The dose deviations decreased with increasing target size.
Table 3.
Comparison of gamma passing rates at the diode level according to target size.
Fig 3.
Variations of gamma passing rates at the diode level with various target sizes.
The gamma passing rates were calculated with both the 3%/3 mm criterion (lower graph) and the 2%/2 mm criterion (upper graph) in absolute doses with a threshold of 5%. The gamma passing rate decreased as the target size increased.
Table 4.
Comparison of 3D gamma passing rates of various regions of interest according to target size.
Fig 4.
Variation of 3D gamma passing rates for (a) target, (b) adjacent organ at risk (OAR), and (c) peripheral OAR with various target sizes.
The gamma passing rates were calculated with both the 3%/3 mm criterion (upper graph) and the 2%/2 mm criterion (lower graph) in absolute doses with a threshold of 5%. The 3D gamma passing rate decreased as the target size increased in all specific regions of interest.
Table 5.
Comparison of the various dose-volume parameters between the treatment planning system (TPS)-planned dose and the 3DVH-predicted dose.
Fig 5.
An example of a dose-volume histogram representing the dose distribution for the (a) target, (b) adjacent organ at risk (OAR), and peripheral OAR.
The treatment planning system (TPS)-planned doses are plotted as solid lines. The dashed lines represent the 3DVH software- predicted dose, which was calculated on the basis of the ArcCHECK data.
Table 6.
Dose deviation (%) with various dose parameters between the 3DVH-predicted and planned doses with respect to target size.
Table 7.
Correlations between the magnitude of dose difference and the gamma passing rate of each region of interest (ROI), calculated with both gamma 3%/3 mm and 2%/2 mm criteria.