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Table 2 Mean absolute difference and standard deviation of the CTVs DVH dosimetric parameters in the 11 cases studied

From: Impact of positioning errors in the dosimetry of VMAT left-sided post mastectomy irradiation

Perturbation

CTVth a

CTVsv a

Shift

Direction

D95b

D98b

D1c

Dmd

D95b

D98b

D1c

Dmd

3 mm

inferior

−0.4 ± 0.4

− 0.5 ± 0.6

0.0 ± 0.1

0.0 ± 0.1

− 0.4 ± 0.6

− 0.5 ± 0.4

0.0 ± 0.1

− 0.4 ± 0.4

superior

− 0.4 ± 0.5

− 0.5 ± 0.4

0.0 ± 0.1

− 0.2 ± 0.1

− 0.3 ± 0.6

− 0.7 ± 0.5

0.2 ± 0.1

− 0.5 ± 0.6

posterior

− 0.1 ± 0.3

− 0.3 ± 0.3

0.0 ± 0.0

− 0.2 ± 0.1

−0.1 ± 0.6

−0.5 ± 0.2

0.2 ± 0.1

−0.3 ± 0.3

right

−0.3 ± 0.2

−0.5 ± 0.2

0.2 ± 0.2

−0.4 ± 0.3

−0.3 ± 0.1

−0.5 ± 0.3

0.3 ± 0.6

−0.4 ± 0.3

left

− 1.1 ± 0.7

−1.5 ± 0.9

0.4 ± 0.2

0.1 ± 0.2

− 0.5 ± 0.2

−0.6 ± 0.6

0.3 ± 0.4

−0.3 ± 0.1

anterior

− 1.4 ± 0.9

−2.8 ± 1.8

0.2 ± 0.3

− 0.2 ± 0.2

−0.7 ± 0.6

− 1.4 ± 0.6

0.4 ± 0.2

− 0.5 ± 0.6

5 mm

inferior

−1.0 ± 0.3

−1.5 ± 0.7

0.1 ± 0.2

0.0 ± 0.1

−1.6 ± 0.6

− 2.3 ± 1.2

0.3 ± 0.1

− 0.7 ± 0.4

superior

−1.8 ± 0.4

− 3.2 ± 0.9

0.1 ± 0.2

−0.4 ± 0.2

− 1.1 ± 0.9

−1.8 ± 1.0

0.2 ± 0.6

− 0.7 ± 0.6

posterior

−0.9 ± 0.4

− 1.8 ± 0.6

0.1 ± 0.2

− 0.4 ± 0.3

−0.7 ± 0.3

−0.7 ± 0.5

0.4 ± 0.3

−0.6 ± 0.4

right

−1.2 ± 0.7

−1.5 ± 0.7

0.2 ± 0.5

−0.6 ± 0.3

−0.7 ± 0.4

−0.8 ± 0.7

0.5 ± 0.3

− 0.6 ± 0.5

left

−2.8 ± 1.1

−4.3 ± 0.9

0.8 ± 0.1

0.0 ± 0.3

− 1.2 ± 0.6

−2.3 ± 1.0

0.6 ± 0.3

− 0.4 ± 0.2

anterior

− 3.8 ± 1.8

−5.7 ± 2.5

0.5 ± 0.3

− 0.6 ± 0.4

−2.4 ± 1.0

−5.3 ± 1.1

0.6 ± 0.4

− 0.7 ± 0.6

10 mm

inferior

− 1.7 ± 0.5

−2.2 ± 0.9

0.3 ± 0.3

− 0.8 ± 0.2

- 5.1 ± 2.3

− 8.5 + 2.2

0.4 ± 0.2

− 1.4 ± 0.7

superior

−6.6 ± 3.4

−8-8 ± 3.1

0.2 ± 0.3

− 1.3 ± 0.7

− 4.1 ± 2.9

− 5.9 ± 3.2

0.3 ± 0.1

− 1.4 ± 0.3

posterior

−4.9 ± 2.9

−6.6 ± 2.9

0.4 ± 0.7

− 1.5 ± 0.9

−2.7 ± 1.4

−4.5 ± 1.5

0.6 ± 0.2

− 0.8 ± 0.4

right

−4.6 ± 2.0

−5.4 ± 2.6

0.2 ± 0.6

− 1.8 ± 0.5

−2.5 ± 0.9

−4.7 ± 0.8

0.7 ± 0.1

− 0.8 ± 0.4

left

− 11.9 ± 5.2

−16.1 ± 4.9

1.7 ± 0.3

−2.5 ± 1.1

− 8.3 ± 2.1

− 11.6 ± 2.1

1.3 ± 0.4

− 0.8 ± 0.3

anterior

− 13.6 ± 4.5

−17.6 ± 3.6

1.0 ± 0.3

−3.2 ± 1.8

− 11.1 ± 3.4

−15.0 ± 4.5

1.0 ± 0.6

−1.1 ± 0.4

  1. CTVtha, CTVsva: thoracic wall and supraclavicular clinical target volume, respectively; Dyb: absolute difference expressed in Gy of the dose covering y% of the volume; D1c: absolute difference expressed in Gy of the dose covering 1 cm3 of the volume; Dmd absolute difference expressed in Gy of the mean dose. The absolute difference is obtained by subtracting the dosimetric reference value from the corresponding perturbed one. Values in light grey correspond to absolute difference ≤ 1%; in bold isocenter shift directions contributing the most to worsen the target dosimetry and corresponding clinically unacceptable absolute differences