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Table 3 The suggested asymmetrical expansion margins of ITV for target delineation of each liver segment are derived from the amplitudes of DIR from helical CT to 4DCTs

From: Quantitative analysis of respiration-induced motion of each liver segment with helical computed tomography and 4-dimensional computed tomography

Segment Average amplitude ± SD (mm) ITV margin (mm) (to cover more than 95% of each tumor)
Helical CT to phase 0 CT Helical CT to phase 50 CT
LR AP SI LR AP SI LR AP SI
S1 0.8 ± 3.1 0.4 ± 1.6 − 2.5 ± 3.9 − 1.1 ± 2.2 1.4 ± 1.8 3.0 ± 3.5 − 2.2 and 2.3 − 0.4 and 2.3 −4.4 and 4.7
S2 −1.1 ± 2.5 −0.6 ± 3.7 −2.4 ± 4.9 −0.8 ± 2.6 0.6 ± 2.1 3.9 ± 4.1 − 2.3 and 0.5 −2.4 and 1.6 − 4.7 and 5.9
S3 −0.3 ± 2.9 −1.8 ± 3.1 −2.9 ± 3.5 − 0.7 ± 3.1 0.6 ± 3.0 2.9 ± 2.5 − 2.2 and 1.1 −3.3 and 2.1 − 4.6 and 4.1
S4a 0.4 ± 2.8 −1.4 ± 2.1 −0.6 ± 3.9 −1.0 ± 1.7 0.1 ± 2.4 2.4 ± 3.4 −1.8 and 1.8 −2.4 and 1.3 − 2.4 and 4.0
S4b −0.5 ± 1.5 − 1.7 ± 2.2 −2.4 ± 3.5 − 1.8 ± 1.6 0.3 ± 2.2 2.9 ± 3.3 − 2.6 and 0.3 −2.8 and 1.4 − 4.1 and 4.5
S5 −2.2 ± 1.7 −1.4 ± 2.1 −1.9 ± 2.2 − 2.3 ± 1.3 1.7 ± 2.4 3.7 ± 2.1 −3.0 and 0.0 −2.4 and 2.9 − 3.0 and 4.7
S6 0.2 ± 4.3 − 1.2 ± 2.3 −3.2 ± 2.9 0.1 ± 4.1 1.0 ± 2.3 3.3 ± 3.7 − 1.9 and 2.3 −2.3 and 2.1 −4.6 and 5.1
S7 0.3 ± 4.2 − 1.7 ± 2.8 −3.6 ± 4.4 −1.1 ± 2.6 1.8 ± 2.1 5.0 ± 4.8 − 2.4 and 2.3 −3.1 and 2.8 −5.7 and 7.3
S8 −2.2 ± 2.5 − 1.5 ± 2.6 −1.9 ± 3.4 −1.3 ± 1.5 1.8 ± 2.5 3.2 ± 3.1 −3.4 and 0.0 −2.8 and 3.0 − 3.5 and 4.7
mean −0.5 ± 3.1 − 1.2 ± 2.6 −2.4 ± 3.7 −1.1 ± 2.5 1.0 ± 2.4 3.4 ± 3.5 − 2.5 and 1.2 −2.5 and 2.2 − 4.2 and 5.0
  1. Abbreviations: LR = left-right; AP = anterior-posterior; SI = superior-inferior; SD = standard deviation; ITV = internal target volume; CT = computed tomography
  2. Positive values denote DIR from helical CT to 4DCT, and ITV expansion in the left, posterior, or superior directions; Negative values, right, anterior, or inferior