Table 1 Characteristics and treatment details of patients with esophageal carcinoma included in this study (N = 20)

Sex, n (%)

 Male/ Female

15 (75) / 5 (25)

Age, years, median (range)

70 (54–85)

Tumor location, n (%)

 Cervical/ Upper/ Middle/ Lower thoracic

2 (10) / 8 (40) / 6 (30) / 4 (20)

SUV_max

 mean

12.1

 median, range

10.7 (3.6–31.6)

T classification, n (%)

 T2/ T3/ T4

4 (20) / 15 (75) / 1 (5)

N classification, n (%)

 N0 / N1/ N2

5 (25) / 10 (50) / 5 (25)

Stage, n (%)

 II/ III/ IV

6 (30) / 8 (40) / 6 (30)

Concurrent chemotherapy

 Yes/ No

9 (45) / 11 (55)

Dose of proton radiotherapy

 median, range

50 Gy (44–56) / 25 fractions (22–28)

Dose of carbon ion radiotherapy

 median, range

21 Gy (15–23.1) / 7 fractions (5–7)