PMC3040152_01
PMC3040152_02
Contours superimposed on the default CT image (Pituitary adenoma). (a) (b) axial section (c) sagittal section (d) coronal section.
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F1
Each contour was superimposed on the original CT images (Figure 1).
Contours superimposed on the default CT image (Meningioma). (a) (b) (c) axial section (d) sagittal section (e) coronal section The red lines depict planning target volumes, and the green lines depict delineations of organs at risk from each clinician.
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F2
The median PTV was 9.22 cm3 (range, 7.17 - 14.3 cm3; Figure 2); the ratio of the largest to the smallest contoured volume was 1.99. Each contour was superimposed on the original CT images (Figure 2).
Variation in planning treatment volume (PTV) in pituitary adenoma and meningioma cases.
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F3
Next, we analyzed DVHs by superimposing the dispatched contours onto the original default plan (25 Gy in 5 fractions for D90; Figure 3). The median PTV was 6.86 cm3 (range, 6.04 - 14.6 cm3) (Figure 3), and the ratio of the largest to the smallest contoured volume was 2.41.
Influence of different contours on the DVH analysis. Each contour was layered over the original default plan (Soseikai General Hospital). The dose calculation was made by ShioRIS, and the DVH was calculated using ShioRIS-2. a) Pituitary adenoma:10 contours Left panel. PTV. Default D90 = 25 Gy/5 fractions. According to the applied contours, the D90 median dose was 24.68 Gy (23.34 - 24.78 Gy). Right panel. OAR (left optic nerve). Left optic nerve received 8.79 Gy in default plan (made by T. T.), median 12.41 Gy (8.78 - 23.64 Gy; 23.64 Gy = 268% of default plan) b) Meningioma: 11 contours Left panel. PTV. Default D90 = 30 Gy/5 fractions. According to the applied contours, the D90 median dose was 30.29 Gy (24.24 - 30.66 Gy). Right panel. OAR (right optic nerve). The right optic nerve received a median dose of 19.39 Gy (16.21 - 24.84 Gy; 18.9 Gy in the default plan). Therefore, some plans used 24.24 Gy as a D90 prescribed dose (19% lower dose than anticipated in widen PTV group) when using their contoured PTV. In addition, a higher maximum dose of 24.84 Gy (131% higher dose than default plan 18.9 Gy) was delivered to the right optic nerve in contours used in some institutes.
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F4
Next, the DVHs were reanalyzed by superimposing the contours from participants onto the default plan (Figure 4).