FDG-PET/CT during concomitant chemo radiotherapy for esophageal cancer: Reducing target volumes to deliver higher radiotherapy doses

Figures & data

Figure 1. PTV volumes in the four scenarios. PTV40: PTV to receive 40 Gy in all scenarios; PTV50-1 and PTV50-2: PTV to receive 50 Gy derived from PET₁ (pre-RCT) and PET₂ (during-RCT); PTV66-1 and PTV66-2: PTV to receive 66 Gy derived from PET₁ and PET₂.

Table I. Planning up to 50 Gy on PET1 (scenario 1) versus on PET2 (scenario 2). Figures are medians [Minimum–Maximum]; ∆(PET2–PET1): difference between the values obtained when planning on PET2 and PET1; p: p-values for Wilcoxon signed-rank test for difference in medians (approximation with continuity correction, two-sided).

	PET1	PET2	∆(PET2–PET1)	p
Volumes (cm^3)
GTV	12.9 [3.74–44.8]	5.0 [1.74–13.5]	−7.4 [−33.7–0.7]	0.01
CTV50	75.8 [33.3–194]	63.0 [30.4–145]	−11.4 [−18.6–5.4]	0.02
PTV50	215 [102–459]	182 [94.4–343]	−16.6 [−41.8–16.2]	0.053
Doses to PTV50
D98 (Gy)	49.0 [47.1–49.5]	49.1 [47.5–49.5]	0.0 [−0.3–0.2]	0.32
D50 (Gy)	50.4 [50.0–51.1]	50.3 [50.0–50.8]	−0.05 [−1.1–0.1]	0.11
D2 (Gy)	51.7 [51.0–53.2]	51.3 [50.6–53.3]	−0.05 [−1.8–0.1]	0.21
Doses to organs at risk
Spinal cord DMax (Gy)	42.8 [34.4–44.5]	42.5 [35.0–44.2]	−0.09 [−0.8–0.6]	0.3
Lung V20 (%)	22.5 [13.6–26.0]	21.9 [12.9–25.8]	−0.15 [−1.1–0.1]	0.03
Lung V30 (%)	11.2 [3.9–19.9]	11.0 [3.8–19.6]	−0.10 [−0.4–0.2]	0.0503
Lung MLD (Gy)	13.3 [9.8–16.4]	13.3 [9.8–16.1]	−0.04 [−0.27–0.85]	0.26
Heart V40 (%)	12.8 [0.0–25.2]	13.5 [0.0–24.8]	−0.1 [−8.5–2.1]	0.68
Heart DMax (Gy)	50.4 [12.1–51.1]	50.3 [11.9–50.9]	−0.1 [−0.4–0.2]	0.13
Liver: V30 (%)	10.3 [0.0–23.0]	10.3 [0.0–22.6]	0.0 [−2.3–0.2]	0.54
Kidneys: V20 (%)	0.0 [0.0–11.6]	0.0 [0.0–12.2]	0.0 [0.0–0.6]	0.37
Esophagus: DMax (Gy)	51.8 [50.8–52.7]	51.4 [44.6–52.7]	0.0 [−6.5–0.0]	0.054

Table II. Planning up to 66 Gy on PET1 (scenario 3) versus on PET2 (scenario 4). Same abbreviations as in Table II.

	PET1	PET2	∆(PET2–PET1)	p
Volumes (cm^3)
GTV	12.9 [3.74–44.8]	5.0 [1.74–13.5]	−7.4 [−33.7–0.70]	0.01
CTV66	55.7 [19.9–106]	37.7 [17.3–60.7]	−13.6 [−50.5–0.26]	0.008
PTV66	156 [68.8–251]	108 [62.5–194]	−20.3 [−103–9.0]	0.02
Doses to PTV66
D98 (Gy)	63.6 [62.4–65.2]	63.7 [62.8–65.3]	0.2 [−0.4–0.7]	0.07
D50 (Gy)	66.1 [65.9–67.1]	66.0 [65.8–67.0]	−0.1 [−0.1–0.0]	0.02
D2 (Gy)	68.1 [67.1–70.6]	67.6 [65.9–69.5]	−0.45 [−1.4–0.0]	0.007
Doses to organs at risk
Spinal cord DMax (Gy)	44.7 [41.5–45.0]	44.1 [40.8–44.9]	−0.55 [−0.9–0.0]	0.007
Lung V20 (%)	26.8 [19.7–30.2]	23.2 [17.3–27]	−2.15 [−5.4–0.2]	0.006
Lung V30 (%)	11.8 [7.0–17.5]	11.3 [3.6–16.1]	−0.85 [−5.2–0.1]	0.009
Lung MLD (Gy)	13.4 [8.4–15.7]	13.2 [8.9–14.4]	−0.30 [−1.8–0.48]	0.04
Heart V40 (%)	26.5 [0.0–29.9]	22.7 [0.0–30]	−1.8 [−7.1–2.2]	0.047
Heart DMax (Gy)	66.3 [8.8–66.9]	65.9 [9.5–66.5]	−0.1 [−1.3–0.7]	0.31
Liver V30 (%)	9.7 [0.0–38.3]	9.7 [0.0–33.3]	−0.05 [−5.0–0.0]	0.03
Kidneys V20 (%)	0.05 [0.0–4.8]	0.0 [0.0–4.1]	0.0 [−0.7–0.0]	0.18
Esophagus DMax (Gy)	68.1 [67.3–70.3]	67.8 [66.5–71]	−0.3 [−0.8–0.7]	0.052