Table 2 Treatment parameters

EBRT

Dose of pelvic irradiation

45.0 Gy in 25 fx

SIB to primary tumors (n = 4)

50.0–55.0 Gy in 25 fx

Sequential boost to the primary tumor (n = 2)

10–16 Gy in 2 Gy/fx

Total dose of primary tumor and pelvic/paraaortic lymphatic pathways

45.0 Gy (45.0–55.0 Gy)

SIB to positive lymph nodes (n = 3)

55.0–57.5 Gy

Concurrent chemotherapy with cisplatin 40 mg/m² weekly (n = 9)

5 cycles (4–5 cycles)

Concurrent chemotherapy with carboplatin AUC 2 weekly (n = 1)

3 cycles

MR-guided SBRT boost

Dose per fraction

5.2 Gy (4.0–7.0 Gy)

Total dose

21.0 Gy (8.0–28.0 Gy)

HR-CTV

35.2 ccm (12.1–111.75 ccm)

PTVopt

43.5 ccm (24.2–131.35 ccm)

Net beam on time/fraction

5.6 min (1.53–11.67 min)

Overall treatment time/fraction

77 min (44.0–89.5 min)

Rectum D2ccm (EQD2₃)

17.6 Gy₃ (1.5–24.9 Gy₃)

Bladder D2ccm (EQD2₃)

25.4 Gy₃ (5.1–35.2 Gy₃)

Sigmoid D2ccm (EQD2₃)

17.4 Gy₃ (0.3–24.9Gy₃)

Bowel D2ccm (EQD2₃)

11.6 Gy₃ (0.3–23.6 Gy₃)

Combined treatment (EBRT + MR-guided SBRT boost)

Cumulative total dose (EQD2₁₀)

73.6 Gy₁₀ (69.3–83.9 Gy₁₀)

Rectum D2ccm (EQD2₃)

63.7 Gy₃ (51.5–72.6 Gy₃)

Bladder D2ccm (EQD2₃)

72.2 Gy₃ (59.7–83.6 Gy₃)

Sigmoid D2ccm (EQD2₃)

65.8 Gy₃ (43.9–69.0 Gy₃)

Bowel D2ccm (EQD2₃)

59.9 Gy₃ (47.7–70.0 Gy₃)

Overall treatment time (OTT)

50 days (39–56 days)